Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol81.Issue1-2.Sep1999:
Animal Feed Science and Technology
81 (1999) 105±117
Effect of diets with different digestible energy content
on the performance of rabbit does
J.J. Pascuala, C. Tolosab, C. Cerverab,*, E. Blasb,
J. FernaÂndez-Carmonab
a
Unidad de ProduccioÂn Animal, Universidad Miguel Hernandez, Escuela Politecnica Superior de Orihuela,
Carretera de Beniel, km 3.5/03312 Orihuela (Alicante), Spain
b
Departamento de Ciencia Animal, Universidad Politecnica de Valencia. P.O. Box 22012, Valencia 46071, Spain
Received 13 October 1998; received in revised form 19 February 1999; accepted 20 April 1999
Abstract
One hundred and ninety-two lactations from a total of 59 New Zealand Californian rabbit does
were used to study the influence of the dietary energy content on the reproductive performance of
rabbit does. Three experimental diets (L, M and H) were formulated to give the same fibre content
and different digestible energy (DE) content (9.9, 11.1 and 12.2 MJ DE kgÿ1 DM) using cereal
starch as the main energy source. Primiparous does given diet H showed a higher live weight during
the first gestation (p < 0.01), but no differences in the live weight were found at partum.
Primiparous does on diet H showed significantly higher DE intake and live weight gain (p < 0.01)
during lactation, but their milk yield was lower (p < 0.05) than those given diets L and M. Rabbit
does showed a higher live weight at the second mating when the dietary energy content was
increased (p < 0.001), and this was maintained subsequently. Diet H decreased the food intake of
multiparous does throughout the reproductive cycle, and especially during lactation (p < 0.001).
Milk yield during the last two weeks was lower for multiparous does given H diet (p < 0.01).
Neither the size nor the weight of litters was significantly affected by the type of diet during
lactation, but mortality at partum was higher for H diet (p < 0.05). Thus, the high starch diet
increased the live weight and the DE intake of primiparous rabbit does during lactation, but it did
not improve the performance of their litters and could induce an excessive live weight of gestating
rabbit does. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Dietary starch; Energy intake; Rabbits; Milk yield; Litter mortality
* Corresponding author. Tel.: +34-963-877432; fax: +34-963-877439
E-mail address: ccervera@dca.upv.es (C. Cervera)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 5 2 - 8
106
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
1. Introduction
Recent studies have shown a clear energy deficit during lactation of does in highly
productive situations (Partridge et al., 1986), under conditions of heat stress (FernaÂndezCarmona et al., 1996) or in the first lactation (Parigi-Bini et al., 1990, 1991). Voluntary
food intake is a main limiting factor in the energy balance of lactating does (Xiccato,
1996) and a stimulation of food ingestion would reduce the negative energy deficit of
does.
In long-term experiments, some performance traits have been improved with high
energy diets (Maertens and de Groote, 1988; Castellini and Battaglini, 1991; Barreto and
de Blas, 1993; Cervera et al., 1993). The main dietary energy sources are cereals (starch)
and fats of animal or vegetal origin. However, based on results obtained their effects on
the voluntary food intake, productivity and energy balance of reproductive does seem to
be different.
The addition of fat allows an increase in the energy content of diets without decreasing
the fibre content and seems to increase substantially the digestible energy (DE) intake and
subsequent utilization of lactating does, improving some performance traits like litter size
and weight (Fraga et al., 1989; Cervera et al., 1993; Fortun-Lamothe and Lebas, 1996;
Pascual et al., 1998a, 1999). However, it does not seem to reduce the usual negative
energy balance of lactating rabbit does (Xiccato et al., 1995; Parigi-Bini et al., 1996).
Other studies have increased the dietary energy by the inclusion of high levels of starch
(Butcher et al., 1983; Xiccato et al., 1995; Fortun-Lamothe and Lebas, 1996; Lebas and
Fortum-Lamothe, 1996), showing that energy intake is maintained in spite of a reduction
in food intake of lactating rabbits. However, the effects of these diets on the productivity
and body condition of rabbit does have not been established.
The results of all these studies have been obtained with diets in which DE and crude
fibre (CF) contents are inversely related, and FernaÂndez-Carmona et al. (1995) observed
that fibre itself could have some effect on ingestion and production of does fed ad
libitum; in these studies, the different fibre content of the experimental diets could mask
the actual effect of the high-energy diets. Therefore, the aim of the current study was to
evaluate the effect of dietary energy content on the reproductive performance of
commercial rabbit does, using diets with cereals as main dietary energy source and a
similar fibre content.
2. Material and methods
2.1. Diets
Three diets were formulated to have the same fibre content and three different levels of
DE, while keeping crude protein (CP), amino acids, vitamins and minerals at
recommended levels (Lebas, 1989). The main ingredients and chemical composition of
the diets are listed in Table 1. Acid detergent fibre (ADF) was similar in the three diets
(192, 198 and 182 g kgÿ1 DM for diets L, M and H, respectively). Apparent digestibility
coefficients of diets were determined using 15 rabbit does of three months of age (5 per
107
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 1
Main ingredients (g kgÿ1), chemical composition (g kgÿ1 DM) of experimental diets: low (L), medium (M) and
high (H) energy content
Diets
L
M
H
Ingredients
alfalfa hay
barley grain
corn grain
corn starch
oats grain
wheat bran
soyabean meal
sunflower meal
rice hull
barley straw
calcium carbonate
dicalcium phosphate
trisodium phosphate
sodium chloride
vitamin/mineral mixtureb
470
Ð
Ð
Ð
Ð
380
50
Ð
Ð
70
21
Ð
Ð
5
3
620
150
Ð
Ð
Ð
45
150
Ð
Ð
Ð
13
13
5
Ð
3
210
Ð
265
50
105
Ð
Ð
270
70
Ð
15
8
3
Ð
3
Chemical composition
dry matter (DM; g kgÿ1)
crude fibre (CF)
acid detergent fibre (ADF)
starch
digestible protein (DP)c
digestible energy (DE; MJ kgÿ1 DM)c
916
157
192
86
117
9.9
922
153
198
111
148
11.1
915
154
182
282
146
12.2
a
a
All diets contain 66 ppm robenidine.
Contains (g kgÿ1): thiamin, 0.25; riboflavin, 1.5; calcium pantothenate, 5; pyridoxine, 0.1; nicotinic acid, 12.5;
retinol, 2; cholecalciferol, 0.1; a-tocopherol, 15; phytylmenaquinone, 0.5; cyanocobalamin 0.006; choline
chloride, 100; MgSO4H2O, 7.5; ZnO, 30; FeSO47H2O, 20; CuSO45H2O, 3; KI, 0.5; CoCl26H2O, 0.2;
Na2SeO3, 0.03.
c
Values experimentally determined in 15 females of three months of age fed ad libitum.
b
treatment). Does were kept in individual metabolism cages and, after a seven-day
adaptation period, their faeces were collected individually for five days. Diets L, M and H
had 9.9, 11.1 and 12.2 MJ DE kgÿ1 DM, respectively and 117, 148 and 146 g digestible
protein (DP) kgÿ1 DM, respectively. Pelleted diets were manufactured and analysed three
times during the experimental period. Diets were offered ad libitum to both does and
litters during the experimental period.
Chemical analysis of diets and faeces followed the method of the Association of
Official Analytical Chemists (1984) for DM, CP and crude fibre, and Van Soest et al.
(1991) for ADF with a thermostable amylase pre-treatment. Gross energy was determined
by adiabatic bomb calorimetry. Dietary starch content was determined according to a
two-step enzymatic procedure, using a thermostable amylase followed by amyloglucosidase (Tecator, application note 85/86), the resulting glucose being measured by the
hexokinase/glucose-6-phosphate dehydrogenase/NADP system (Boeringher).
108
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
2.2. Animals
One hundred and ninety-two lactations (67 for each of diets L and H and 58 for diet M)
from a total of 59 New Zealand Californian rabbit does (21, 20 and 18 for diets L, M
and H, respectively) housed in a traditional building were studied during a period of two
years.
Nulliparous does were presented to the male at ca. 4.5 months of age and with a live weight
no less than 3.2 kg. Until mating, all does received the same commercial diet. Subsequently,
does were housed in individual cages and had free access to one of the experimental diets. The
experimental does were maintained for up to six reproductive cycles.
Lactating does were presented to the male 14 days after parturition, and if necessary
each week thereafter until a mating took place. Fourteen days after mating, the does were
tested for pregnancy by palpation, and non-pregnant does were remated. Does were
discarded for two reasons: pathology or fertility (three consecutive sterile matings or six
consecutive male refusals). Milk production was measured daily using the weigh (doe)±
suckle±weigh (doe) method. To prevent free nursing, does were placed in a cage next to
the nest box. Suckling took place once a day (ca. 9 : 00 a.m.) in the nest box for a short
period. Food intake and weight of does were recorded weekly during the experiment. The
size and weight of litters were noted weekly during lactation. Suckling pups were allowed
to eat the same diet as their mothers from the 21st to the 35th day of lactation, when they
were weaning. During this period, solid food intake of litters was recorded.
3. Statistical analysis
Data were analysed by variance analysis, using the general linear GLM procedure of
SAS (Statistical Analysis Systems Institute, 1990), except for the number of dead pups,
which was analyzed using a non-parametric procedure (NPAR1WAY), and for mean
separation, where a 2 test was used. Data were initially analysed according to a repeated
measures design (REPEATED procedure; Table 2). As differences throughout time were
principally due to the differences between primiparous and multiparous rabbit does, data
were analysed independently of each other. So, data of primiparous rabbit does were
analysed according to a model including the effect of the diet (L, M and H). However,
data of multiparous does were analysed according to a split-plot design including the
effect of diet, the effect of rabbit doe within diet (error to test the diet effect), the effect of
parity (2±6), the effect of lactation±gestation overlapping (0±3 weeks) and their
interactions. For the live weight, milk yield and food intake analyses the size of the litters
was added as a covariate.
4. Results
4.1. Effect of parity
The interval between parturitions was clearly affected by the parity (p < 0.001), with
higher figures for the 1st parturition (p < 0.001) due to a lower acceptance rate of the
SEa
Parity
No. of observations
Interval between parturitions (days)
Does' weight (g) at
mating
partume
weaningf
Does' weight gain (g) during
gestatione
lactationg
DEh intake of does (kJ DE kgÿ0.75 dayÿ1) during
1±35 days of lactationg
b
Pc
P Dd
***
NS
48.9
41.5
47.8
***
***
**
***
**
**
NS
***
347.5a
110.1
59.25
55.09
***
NS
NS
*
***
NS
1282
27.5
NS
***
NS
1
2
3
4
5
6
59
Ð
40
59.0a
29
50.8b
29
49.4b
18
48.3b
17
51.2b
3672a
3739a
4249a
4037b
3899b
4413b
4124b
3913b
4436b
4179b
3928b
4447b
4184b
3918b
4416b
4095b
3952b
4466b
562.1b
160.0
388.1a
132.8
294.1a
129.9
265.4a
115.8
210.2a
86.7
1265
1321
1311
1264
1243
Means within a row with different letters are significantly different (p < 0.05).
Standard error.
*p < 0.05; **p < 0.01; ***p < 0.01; NS not significant.
c
Effect of parity.
d
Effect of the interaction between parity and diet.
e
Covariate: Litter size total at partum.
f
Covariate: Litter size at 35 days.
g
Covariate: Litter size at 21 days.
h
Digestible energy.
a
Significanceb
2.42
covariate
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 2
Effect of parity on the performance of rabbit does and their litters
109
110
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
male (Table 2). Whereas 65% of multiparous rabbit does were mated before 21 days
postpartum, only 37% of primiparous does were mated in this period. Because of
primiparous does are still growing, they showed a higher live weight gain during the
gestation (p < 0.001) than that shown in the following cycles.
On the other hand, there was a significant interaction between diet and parity in the live
weight of does (p < 0.01) and in the live weight gain of does during lactation (p < 0.05),
with higher figures for H diet in the first lactation and similar figures for all diets during
the following lactations. The significant interaction between parity and diet in the DE
intake of lactating does was related to differences in this trait for the different diets
between primiparous and multiparous does. Consequently, the results for the effect of diet
were considered independently of each other.
4.2. Effect of diet
4.2.1. Primiparous does
Data in Table 3 show that there were no significant differences in the parturition
interval and live weight at mating of primiparous does (3660 g). However, some
differences in live weight (Fig. 1(a)) and in food and DE intake were noticed during the
first reproductive cycle. Pregnant does given H diet showed a higher DE intake (only
significant during the 2nd week, p < 0.05) and a greater live weight at 21st day of
gestation (p < 0.05) than does given L and M diets, although food intake was generally
higher with L diet (p < 0.01). However, does given H diet had a lower DE intake during
the last days of gestation (only significant during the last three days, p < 0.05), showing
live weight losses. So, no significant differences in the live weight of does at partum
(3721 g) and in the total weight gain during gestation were found.
Does given L diet showed a higher food intake in lactation than does given M and H
diets, but does on H diet showed a significantly higher DE intake (especially during the
first three weeks; p < 0.05). Live weight of lactating rabbit does on H diet was higher than
on L and M diets, showing a greater total weight gain during the first lactation (p < 0.01).
Type of diet had a significant effect on milk yield, although it was not consistent
throughout lactation (Fig. 2): does on H diet had higher milk yield during the 3rd week
(p < 0.01) and lower milk yield during the first and last weeks of lactation (p < 0.05) than
does on L and M diets. The total milk production was significantly lower for does given
H diet (5.74, 5.43 and 5.24 for L; M and H diets, respectively; p < 0.05).
4.2.2. Multiparous does
Similar to the first reproductive cycle, there were no significant differences in the
parturition interval for the different diets, this being shorter than for primiparous does
(50.0 vs. 59.0 days).
In contrast to the results for primiparous, when the dietary energy content was
increased, multiparous does showed a higher live weight at mating, especially for H diet
(3777, 3889 and 4291 for the L, M and H diets, respectively; p < 0.001), and this was
maintained throughout the reproductive cycle (Fig. 1(b)).
Enhanced dietary energy content decreased significantly the food intake of multiparous
does throughout the reproductive cycle, especially during lactation (p < 0.001). So, DE
Table 3
Effect of diet on live weight, intake and milk yield of primiparous and multiparous rabbit does (L low, M moderate and H high energy diets)
Primiparous
Multiparous
diet
L
M
H
SEb
diet
46
52.4
38
49.0
49
48.6
1.95
NS
L
M
H
21
61.3
20
58.7
18
57.3
3.26
NS
3610
4048a
4235
3734
3703a
3785a
3604
4013a
4125
3635
3664a
3744a
3781
4324b
4282
3800
4032b
4218b
87.4
85.6
73.1
69.7
72.7
80.2
NS
*
NS
NS
**
***
NS
*
**
NS
NS
NS
3777A
4065A
4232A
3722A
3836A
3901A
3889B
4175B
4227A
3713A
3817A
3879A
4291C
4471C
4616B
4101B
4200B
4252B
25.6
8.2
41.7
24.0
121.3
124.2
***
*
**
**
*
*
*
***
NS
NS
NS
624.7
51.2a
521.4
118.1a
500.7
387.3b
62.65
71.99
NS
**
NS
NS
441.6
101.8
299.2
96.2
308.1
80.0
16.26
62.52
NS
NS
*
**
75.63b
46.99b
65.74a
43.16b
67.08a
34.44a
3.187
3.194
**
**
NS
*
78.19
60.44C
76.71
50.96B
63.02
41.22A
3.917
3.908
NS
**
NS
NS
116.6b
137.4b
104.3a
118.4a
103.8a
116.2a
4.30
4.77
**
***
*
*
131.8C
135.4B
114.3B
119.9AB
96.9A
100.7A
5.42
5.44
***
***
NS
NS
748.7
465.3
729.6
479.0
818.4
419.7
35.55
34.51
NS
NS
NS
*
774.1
598.3B
851.5
565.6AB
768.8
502.9A
36.15
32.88
NS
*
NS
NS
1154a
1360
164.0b
1158a
1315
155.2ab
1266b
1418
149.8a
46.3
53.2
7.59
*
NS
*
*
*
***
1306B
1340
174.3
1268AB
1331
154.5
1181A
1227
156.9
60.4
60.7
11.83
*
NS
NS
NS
NS
***
a,b,c Means for the effect of diet on primiparous does lacking a common letter differ (p < 0.05).
A,B,C Means for the effect of diet on multiparous does lacking a common letter differ at (p < 0.05).
a
*p < 0.05; **p < 0.01; ***p < 0.001; NS not significant.
b
Standard error.
c
Covariate: Litter size total at partum.
d
Covariate: Litter size total at 21 days.
e
Covariate: Litter size total at 35 days.
covariate
Significancea
covariate
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
No. of observations
Interval between parturitions (days)
Does' weight (g) at
mating
21st day of gestationc
pre-partumc
partumc
21st day of lactationd
weaninge
Does' weight gain (g) at
gestationc
lactationd
Food intake (g DM dayÿ1 kgÿ0.75)
Pregnant doesc
mating to 21st day
22nd day to partum
Lactating does
partum to 21st dayd
22nd day to weaninge
Energy intake (g DE dayÿ1 kgÿ0.75)
Pregnant doesc
mating to 21st day
22nd day to partum
Lactating does
partum to 21st dayd
22nd day to weaninge
Milk yield (g dayÿ1)
SEb
Significancea
111
112
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Fig. 1. Evolution of average live weight of primiparous (a) and multiparous (b) rabbit does with the different
experimental diets throughout reproductive cycle (ÐÐÐ L, - - - M and H).
intake of does was lower for H diet during the last days of gestation (p < 0.05) and during
lactation (only significant for the first three weeks; p < 0.05). Neither the live weight gain
of multiparous does during gestation nor during lactation was affected by diet. Type of
diet did not affect the milk yield of multiparous does during the first three weeks of
lactation (Fig. 2), but it was lower for does given H diet than for those given L and M
diets during the last two weeks (p < 0.001 and p < 0.01, respectively).
4.3. Litters
There was no interaction between parity and diet in the litter performance, so the effect
of diet is shown in Table 4 for all reproductive cycles. At parturition, the number of alive
pups (9.16) was similar for the different diets, but mortality at partum was higher on H
Fig. 2. Evolution of average daily milk yield of primiparous and multiparous rabbit does with the different
experimental diets (ÐÐÐ L, Ð Ð Ð M and H).
113
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 4
Effect of diet on the performance of litters (L low, M moderate and H high energy diets)
SEa
Diets
L
No. of observations
Size at
alive at partum
7th day
14th day
21st day
28th day
35th day (weaning)
Mortality (%)
at birth
from birth to weaning
Weight (g) at
alive at partumc
7th dayd
14th daye
21st dayf
28th dayg
35th day (weaning)h
Solid food intake (g DM dayÿ1 kgÿ0.75)
22±28 daysg
28±35 daysh
Solid energy intake (kJ DE dayÿ1 kgÿ0.75)
22±28 daysg
28±35 daysh
M
67
H
58
Significanceb
diet
67
9.40
8.45
8.12
7.96
7.85
7.72
9.09
8.17
7.91
7.78
7.69
7.47
8.99
8.16
7.88
7.76
7.66
7.51
0.634
0.525
0.508
0.505
0.507
0.508
NS
NS
NS
NS
NS
NS
1.662a
17.55
1.755a
17.49
4.469b
16.46
1.3525
3.8057
*
NS
483.3
1055
1758
2440
3756
5461
40.43
86.75b
400.7
859.5
499.4
1081
1808
2417
3816
5741
39.51
84.14b
438.8
933.9
covariate
488.6
1043
1777
2476
3630
5183
38.03
74.82a
463.4
912.5
14.75
36.3
64.4
88.1
156.7
167.4
3.389
3.383
38.08
35.88
NS
NS
NS
NS
NS
NS
***
***
***
***
***
***
NS
*
*
NS
NS
NS
*
NS
a,b Means within a row with different letters are significantly different (p < 0.05).
Standard error.
b
*p < 0.05; ***p < 0.01; NS not significant.
c
Covariate: Litter size alive at partum.
d
Covariate: Litter size at 7 days.
e
Covariate: Litter size at 14 days.
f
Covariate: Litter size at 21 days.
g
Covariate: Litter size at 28 days.
h
Covariate: Litter size at 35 days.
a
diet than on L and M diets (p < 0.05). Neither the size nor the weight of litters was
affected by diet, so litter size (7.57) and weight (5212 g) at weaning did not differ
between diets. A lower solid food intake of litters on H diet during the last week of
lactation (p < 0.05) was compensated for its higher DE, being DE intake similar in the
three groups at this time (504.7 kJ DE kgÿ0.75 dayÿ1).
4.4. Effect of overlapping
Data presented in Table 5 show some significant differences in the live weight and
food intake for the different overlapping periods. There was a tendency to a lower live
weight and to a higher food intake of gestating does when overlapping period increased.
As a consequence of this, food intake in pregnant does which overlapped two or three
114
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 5
Effect of lactation and gestation overlapping on the performance of gestating multiparous rabbit does
SEa
Overlapping (weeks)
No. of observations
Live weight of does (g) at
7th day of gestation
14th day of gestation
21st day of gestation
28th day of gestation
prepartum
partum
Food intake of does
(g DM kgÿ0.75 dayÿ1)
mating to 7th day of gestation
7±14 days of gestation
14±21 days of gestion
21±28 days of gestation
28th day of gestation to prepartum
Litter size alive at birth
Litter weight (g) alive at birth
0
1
2
3
42
13
18
60
4090
4209
4329b
4376b
4497b
3965c
Ð
4185
4225b
4297b
4476b
3924c
Ð
Ð
4018a
4054a
4204a
3683a
Ð
Ð
Ð
4138a
4310a
3824b
78.22
89.48
69.30
45.91a
45.95a
9.15b
508.9
Ð
68.86
67.82
50.74ab
50.88ab
9.94b
487.9
Ð
Ð
86.24
55.82b
55.35b
7.38a
522.8
Ð
Ð
Ð
55.45b
54.32b
8.47a
486.8
Significanceb
Oc
O Dd covariatee
13.6
42.1
8.2
18.6
41.7
24.0
NS
NS
***
*
*
NS
*
NS
NS
NS
NS
NS
**
**
NS
18.027
9.111
17.291
14.964
13.790
0.861
6.28
NS
NS
***
***
*
NS
NS
NS
NS
NS
NS
NS
*
NS
NS
NS
***
a,b,c Means within a row with different letters are significantly different (p < 0.05).
Standard error.
b
*p < 0.05; **p < 0.01; ***p < 0.001; NS not significant.
c
Effect of overlapping.
d
Effect of the interaction between overlapping and diet.
e
Total litter size at partum.
a
weeks with the previous lactation was higher during the last 10 days of gestation
(p < 0.001) than those overlapping zero or one week. However, in spite of their higher
food intake, gestating does with long overlapping period showed lower live weight at 28th
day of gestation (p < 0.001), at prepartum and at partum (p < 0.05), and lower number of
pups alive at birth (p < 0.05).
5. Discussion
In recent years, most of the studies of the reproductive performance of rabbit does have
tried to improve productivity and body condition by using high energy diets. The addition
of fat to the diet seems to stimulate the DE intake and milk yield of does, inducing a
higher litter weight gain (Fraga et al., 1989; Cervera et al., 1993; Xiccato et al., 1995;
Pascual et al., 1998b, 1999), but it does not seem to affect significantly the body
condition of lactating does (Xiccato et al., 1995; Pascual et al., 1998b).
All authors have showed that the use of high starch diets implied a decrease in the food
intake and similar DE intake (Butcher et al., 1983; Xiccato et al., 1995; Lebas and
Fortum-Lamothe, 1996; Fortun-Lamothe and Lebas, 1996), but different results for the
effect on the performance of rabbit does have been found. Milk output did not increase in
the studies of Butcher et al. (1983) and Xiccato et al. (1995), and was lower in the
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
115
experiment of Lebas and Fortum-Lamothe (1996). Furthermore, growth of litters
followed a similar trend. In relation to the body condition, Butcher et al. (1983) and
Fortun-Lamothe and Lebas (1996) recorded an increase in the live weight of does given
high starch diets or the weight of their adipose tissues, but Xiccato et al. (1995) did not
find any significant change in body condition.
The results of the present study show that the high starch diet (H diet) seems to
increase the DE intake of rabbit does during their first lactation. However, in contrast to
that shown with high fat diets (Pascual et al., 1999), this high DE intake did not increase
the milk yield nor the growth of litters, but rather induced a greater live weight gain of
does in this period. These results suggest that, although live weight change is a poor
indicator of body tissue mobilization (Partridge et al., 1983; Parigi-Bini et al., 1992), this
diet with cereal starch as the main dietary energy source could reduce the current bodyreserve depletion shown in primiparous rabbit does at the end of lactation (Partridge et
al., 1983; Parigi-Bini et al., 1991; Xiccato et al., 1995). In fact, Fortun-Lamothe and
Lebas (1996) have described recently how primiparous rabbit does given a diet
supplemented with 140 g kgÿ1 of maize starch did not increase either the DE intake or
milk yield, but the weight of adipose tissues tended to be higher (28 vs. 52 g of fat for the
control and high starch diets, respectively). On the other hand, Xiccato et al. (1995) found
that primiparous does given a high energy diet presented a lower body energy content
when they were slaughtered at the second parturition. Thus, the use of high energy diets
seems to improve the negative energy balance of primiparous rabbits when the main
energy source is starch, but they were not able to improve productivity, in contrast to what
has been observed when the main energy source is fat (Xiccato et al., 1995; Pascual et al.,
1998b).
Primiparous rabbit does on H diet showed a different response from those on L and M
diets, but the responses of does on L and M diets were similar in spite of their different
dietary DE content. So, higher DE intake and live weight gain of rabbit does on H diet
during their first lactation seem to be more related to its higher starch content.
Rabbit does given H diet presented a higher live weight at the end of the first lactation
than those given L and M diets, and these differences were maintained during the
following reproductive cycles. Multiparous rabbit does fed with H diet showed a lower
DE intake throughout lactation, which could be the reason for the depletion in the milk
yield of does during the last two weeks, and for the slightly lower litter weight at
weaning. This is in agreement with the results obtained by Butcher et al. (1983) and
Lebas and Fortum-Lamothe (1996) in multiparous rabbit does. The long-term
preservation of a relatively constant body weight implies some long-term regulation of
food intake.
Type of diet during pregnancy appeared to have no effect on litter size and weight at
birth, but the incidence of pup mortality at birth increased markedly when does were fed
with H diet. Partridge et al. (1986) found that pup mortality at birth was higher for does
receiving a high energy diet during pregnancy than for animals fed with a low energy
diet: a higher individual weight at birth should increase the incidence of dystocia
(Partridge et al., 1985) or a build-up of fat in the abdominal cavity in the heaviest rabbit
does (does given H diet), which could block foetal movement along the birth canal
(Partridge et al., 1986).
116
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
On the other hand, in concurrently lactating-pregnant rabbit does energy requirements
remain high due to the rapid development of the foetuses and uterine tissues (Xiccato,
1996), and normally this is responsible for a further reduction in the fat content and body
energy levels. Consequently, pregnant does with long period of overlapping (two or three
weeks) should show a higher food intake and a lower live weight after weaning. The
results of the present study also show that multiparous rabbit does with a long
overlapping period had smaller litters at partum than the rest of the groups. These results
are in agreement with those of other workers who found a decrease in litter size alive at
birth when the remating interval was shortened (Maertens et al., 1988; Cervera et al.,
1993). For this reason, independently of the dietary energy level, the nutritional deficit
caused by a longer overlapping period could be responsible for the poor body condition of
gestating does, and consequently a reduction in the live weight of does and viability of
pups at birth was found.
In conclusion, the results obtained in the present study showed that a large increase of
dietary starch content increased the DE intake and the live weight gain of primiparous
rabbit does during lactation. This could minimise the problem of their negative energy
balance, but it could induce an excessive live weight of does. The inclusion of high levels
of starch in the diet seems to stimulate fat deposition of primiparous does, but their higher
DE intake did not improve either milk yield or performance of their litters, in contrast to
what is observed when the main energy source is fat. High energy diets reduce the food
intake of multiparous rabbit does during lactation, although this is due to their higher live
weight, and consequently no improvements in the performance of their litters were found.
Acknowledgements
The present work was supported by a grant from CICYT (AGF97-1139).
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81 (1999) 105±117
Effect of diets with different digestible energy content
on the performance of rabbit does
J.J. Pascuala, C. Tolosab, C. Cerverab,*, E. Blasb,
J. FernaÂndez-Carmonab
a
Unidad de ProduccioÂn Animal, Universidad Miguel Hernandez, Escuela Politecnica Superior de Orihuela,
Carretera de Beniel, km 3.5/03312 Orihuela (Alicante), Spain
b
Departamento de Ciencia Animal, Universidad Politecnica de Valencia. P.O. Box 22012, Valencia 46071, Spain
Received 13 October 1998; received in revised form 19 February 1999; accepted 20 April 1999
Abstract
One hundred and ninety-two lactations from a total of 59 New Zealand Californian rabbit does
were used to study the influence of the dietary energy content on the reproductive performance of
rabbit does. Three experimental diets (L, M and H) were formulated to give the same fibre content
and different digestible energy (DE) content (9.9, 11.1 and 12.2 MJ DE kgÿ1 DM) using cereal
starch as the main energy source. Primiparous does given diet H showed a higher live weight during
the first gestation (p < 0.01), but no differences in the live weight were found at partum.
Primiparous does on diet H showed significantly higher DE intake and live weight gain (p < 0.01)
during lactation, but their milk yield was lower (p < 0.05) than those given diets L and M. Rabbit
does showed a higher live weight at the second mating when the dietary energy content was
increased (p < 0.001), and this was maintained subsequently. Diet H decreased the food intake of
multiparous does throughout the reproductive cycle, and especially during lactation (p < 0.001).
Milk yield during the last two weeks was lower for multiparous does given H diet (p < 0.01).
Neither the size nor the weight of litters was significantly affected by the type of diet during
lactation, but mortality at partum was higher for H diet (p < 0.05). Thus, the high starch diet
increased the live weight and the DE intake of primiparous rabbit does during lactation, but it did
not improve the performance of their litters and could induce an excessive live weight of gestating
rabbit does. # 1999 Elsevier Science B.V. All rights reserved.
Keywords: Dietary starch; Energy intake; Rabbits; Milk yield; Litter mortality
* Corresponding author. Tel.: +34-963-877432; fax: +34-963-877439
E-mail address: ccervera@dca.upv.es (C. Cervera)
0377-8401/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 9 9 ) 0 0 0 5 2 - 8
106
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
1. Introduction
Recent studies have shown a clear energy deficit during lactation of does in highly
productive situations (Partridge et al., 1986), under conditions of heat stress (FernaÂndezCarmona et al., 1996) or in the first lactation (Parigi-Bini et al., 1990, 1991). Voluntary
food intake is a main limiting factor in the energy balance of lactating does (Xiccato,
1996) and a stimulation of food ingestion would reduce the negative energy deficit of
does.
In long-term experiments, some performance traits have been improved with high
energy diets (Maertens and de Groote, 1988; Castellini and Battaglini, 1991; Barreto and
de Blas, 1993; Cervera et al., 1993). The main dietary energy sources are cereals (starch)
and fats of animal or vegetal origin. However, based on results obtained their effects on
the voluntary food intake, productivity and energy balance of reproductive does seem to
be different.
The addition of fat allows an increase in the energy content of diets without decreasing
the fibre content and seems to increase substantially the digestible energy (DE) intake and
subsequent utilization of lactating does, improving some performance traits like litter size
and weight (Fraga et al., 1989; Cervera et al., 1993; Fortun-Lamothe and Lebas, 1996;
Pascual et al., 1998a, 1999). However, it does not seem to reduce the usual negative
energy balance of lactating rabbit does (Xiccato et al., 1995; Parigi-Bini et al., 1996).
Other studies have increased the dietary energy by the inclusion of high levels of starch
(Butcher et al., 1983; Xiccato et al., 1995; Fortun-Lamothe and Lebas, 1996; Lebas and
Fortum-Lamothe, 1996), showing that energy intake is maintained in spite of a reduction
in food intake of lactating rabbits. However, the effects of these diets on the productivity
and body condition of rabbit does have not been established.
The results of all these studies have been obtained with diets in which DE and crude
fibre (CF) contents are inversely related, and FernaÂndez-Carmona et al. (1995) observed
that fibre itself could have some effect on ingestion and production of does fed ad
libitum; in these studies, the different fibre content of the experimental diets could mask
the actual effect of the high-energy diets. Therefore, the aim of the current study was to
evaluate the effect of dietary energy content on the reproductive performance of
commercial rabbit does, using diets with cereals as main dietary energy source and a
similar fibre content.
2. Material and methods
2.1. Diets
Three diets were formulated to have the same fibre content and three different levels of
DE, while keeping crude protein (CP), amino acids, vitamins and minerals at
recommended levels (Lebas, 1989). The main ingredients and chemical composition of
the diets are listed in Table 1. Acid detergent fibre (ADF) was similar in the three diets
(192, 198 and 182 g kgÿ1 DM for diets L, M and H, respectively). Apparent digestibility
coefficients of diets were determined using 15 rabbit does of three months of age (5 per
107
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 1
Main ingredients (g kgÿ1), chemical composition (g kgÿ1 DM) of experimental diets: low (L), medium (M) and
high (H) energy content
Diets
L
M
H
Ingredients
alfalfa hay
barley grain
corn grain
corn starch
oats grain
wheat bran
soyabean meal
sunflower meal
rice hull
barley straw
calcium carbonate
dicalcium phosphate
trisodium phosphate
sodium chloride
vitamin/mineral mixtureb
470
Ð
Ð
Ð
Ð
380
50
Ð
Ð
70
21
Ð
Ð
5
3
620
150
Ð
Ð
Ð
45
150
Ð
Ð
Ð
13
13
5
Ð
3
210
Ð
265
50
105
Ð
Ð
270
70
Ð
15
8
3
Ð
3
Chemical composition
dry matter (DM; g kgÿ1)
crude fibre (CF)
acid detergent fibre (ADF)
starch
digestible protein (DP)c
digestible energy (DE; MJ kgÿ1 DM)c
916
157
192
86
117
9.9
922
153
198
111
148
11.1
915
154
182
282
146
12.2
a
a
All diets contain 66 ppm robenidine.
Contains (g kgÿ1): thiamin, 0.25; riboflavin, 1.5; calcium pantothenate, 5; pyridoxine, 0.1; nicotinic acid, 12.5;
retinol, 2; cholecalciferol, 0.1; a-tocopherol, 15; phytylmenaquinone, 0.5; cyanocobalamin 0.006; choline
chloride, 100; MgSO4H2O, 7.5; ZnO, 30; FeSO47H2O, 20; CuSO45H2O, 3; KI, 0.5; CoCl26H2O, 0.2;
Na2SeO3, 0.03.
c
Values experimentally determined in 15 females of three months of age fed ad libitum.
b
treatment). Does were kept in individual metabolism cages and, after a seven-day
adaptation period, their faeces were collected individually for five days. Diets L, M and H
had 9.9, 11.1 and 12.2 MJ DE kgÿ1 DM, respectively and 117, 148 and 146 g digestible
protein (DP) kgÿ1 DM, respectively. Pelleted diets were manufactured and analysed three
times during the experimental period. Diets were offered ad libitum to both does and
litters during the experimental period.
Chemical analysis of diets and faeces followed the method of the Association of
Official Analytical Chemists (1984) for DM, CP and crude fibre, and Van Soest et al.
(1991) for ADF with a thermostable amylase pre-treatment. Gross energy was determined
by adiabatic bomb calorimetry. Dietary starch content was determined according to a
two-step enzymatic procedure, using a thermostable amylase followed by amyloglucosidase (Tecator, application note 85/86), the resulting glucose being measured by the
hexokinase/glucose-6-phosphate dehydrogenase/NADP system (Boeringher).
108
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
2.2. Animals
One hundred and ninety-two lactations (67 for each of diets L and H and 58 for diet M)
from a total of 59 New Zealand Californian rabbit does (21, 20 and 18 for diets L, M
and H, respectively) housed in a traditional building were studied during a period of two
years.
Nulliparous does were presented to the male at ca. 4.5 months of age and with a live weight
no less than 3.2 kg. Until mating, all does received the same commercial diet. Subsequently,
does were housed in individual cages and had free access to one of the experimental diets. The
experimental does were maintained for up to six reproductive cycles.
Lactating does were presented to the male 14 days after parturition, and if necessary
each week thereafter until a mating took place. Fourteen days after mating, the does were
tested for pregnancy by palpation, and non-pregnant does were remated. Does were
discarded for two reasons: pathology or fertility (three consecutive sterile matings or six
consecutive male refusals). Milk production was measured daily using the weigh (doe)±
suckle±weigh (doe) method. To prevent free nursing, does were placed in a cage next to
the nest box. Suckling took place once a day (ca. 9 : 00 a.m.) in the nest box for a short
period. Food intake and weight of does were recorded weekly during the experiment. The
size and weight of litters were noted weekly during lactation. Suckling pups were allowed
to eat the same diet as their mothers from the 21st to the 35th day of lactation, when they
were weaning. During this period, solid food intake of litters was recorded.
3. Statistical analysis
Data were analysed by variance analysis, using the general linear GLM procedure of
SAS (Statistical Analysis Systems Institute, 1990), except for the number of dead pups,
which was analyzed using a non-parametric procedure (NPAR1WAY), and for mean
separation, where a 2 test was used. Data were initially analysed according to a repeated
measures design (REPEATED procedure; Table 2). As differences throughout time were
principally due to the differences between primiparous and multiparous rabbit does, data
were analysed independently of each other. So, data of primiparous rabbit does were
analysed according to a model including the effect of the diet (L, M and H). However,
data of multiparous does were analysed according to a split-plot design including the
effect of diet, the effect of rabbit doe within diet (error to test the diet effect), the effect of
parity (2±6), the effect of lactation±gestation overlapping (0±3 weeks) and their
interactions. For the live weight, milk yield and food intake analyses the size of the litters
was added as a covariate.
4. Results
4.1. Effect of parity
The interval between parturitions was clearly affected by the parity (p < 0.001), with
higher figures for the 1st parturition (p < 0.001) due to a lower acceptance rate of the
SEa
Parity
No. of observations
Interval between parturitions (days)
Does' weight (g) at
mating
partume
weaningf
Does' weight gain (g) during
gestatione
lactationg
DEh intake of does (kJ DE kgÿ0.75 dayÿ1) during
1±35 days of lactationg
b
Pc
P Dd
***
NS
48.9
41.5
47.8
***
***
**
***
**
**
NS
***
347.5a
110.1
59.25
55.09
***
NS
NS
*
***
NS
1282
27.5
NS
***
NS
1
2
3
4
5
6
59
Ð
40
59.0a
29
50.8b
29
49.4b
18
48.3b
17
51.2b
3672a
3739a
4249a
4037b
3899b
4413b
4124b
3913b
4436b
4179b
3928b
4447b
4184b
3918b
4416b
4095b
3952b
4466b
562.1b
160.0
388.1a
132.8
294.1a
129.9
265.4a
115.8
210.2a
86.7
1265
1321
1311
1264
1243
Means within a row with different letters are significantly different (p < 0.05).
Standard error.
*p < 0.05; **p < 0.01; ***p < 0.01; NS not significant.
c
Effect of parity.
d
Effect of the interaction between parity and diet.
e
Covariate: Litter size total at partum.
f
Covariate: Litter size at 35 days.
g
Covariate: Litter size at 21 days.
h
Digestible energy.
a
Significanceb
2.42
covariate
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 2
Effect of parity on the performance of rabbit does and their litters
109
110
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
male (Table 2). Whereas 65% of multiparous rabbit does were mated before 21 days
postpartum, only 37% of primiparous does were mated in this period. Because of
primiparous does are still growing, they showed a higher live weight gain during the
gestation (p < 0.001) than that shown in the following cycles.
On the other hand, there was a significant interaction between diet and parity in the live
weight of does (p < 0.01) and in the live weight gain of does during lactation (p < 0.05),
with higher figures for H diet in the first lactation and similar figures for all diets during
the following lactations. The significant interaction between parity and diet in the DE
intake of lactating does was related to differences in this trait for the different diets
between primiparous and multiparous does. Consequently, the results for the effect of diet
were considered independently of each other.
4.2. Effect of diet
4.2.1. Primiparous does
Data in Table 3 show that there were no significant differences in the parturition
interval and live weight at mating of primiparous does (3660 g). However, some
differences in live weight (Fig. 1(a)) and in food and DE intake were noticed during the
first reproductive cycle. Pregnant does given H diet showed a higher DE intake (only
significant during the 2nd week, p < 0.05) and a greater live weight at 21st day of
gestation (p < 0.05) than does given L and M diets, although food intake was generally
higher with L diet (p < 0.01). However, does given H diet had a lower DE intake during
the last days of gestation (only significant during the last three days, p < 0.05), showing
live weight losses. So, no significant differences in the live weight of does at partum
(3721 g) and in the total weight gain during gestation were found.
Does given L diet showed a higher food intake in lactation than does given M and H
diets, but does on H diet showed a significantly higher DE intake (especially during the
first three weeks; p < 0.05). Live weight of lactating rabbit does on H diet was higher than
on L and M diets, showing a greater total weight gain during the first lactation (p < 0.01).
Type of diet had a significant effect on milk yield, although it was not consistent
throughout lactation (Fig. 2): does on H diet had higher milk yield during the 3rd week
(p < 0.01) and lower milk yield during the first and last weeks of lactation (p < 0.05) than
does on L and M diets. The total milk production was significantly lower for does given
H diet (5.74, 5.43 and 5.24 for L; M and H diets, respectively; p < 0.05).
4.2.2. Multiparous does
Similar to the first reproductive cycle, there were no significant differences in the
parturition interval for the different diets, this being shorter than for primiparous does
(50.0 vs. 59.0 days).
In contrast to the results for primiparous, when the dietary energy content was
increased, multiparous does showed a higher live weight at mating, especially for H diet
(3777, 3889 and 4291 for the L, M and H diets, respectively; p < 0.001), and this was
maintained throughout the reproductive cycle (Fig. 1(b)).
Enhanced dietary energy content decreased significantly the food intake of multiparous
does throughout the reproductive cycle, especially during lactation (p < 0.001). So, DE
Table 3
Effect of diet on live weight, intake and milk yield of primiparous and multiparous rabbit does (L low, M moderate and H high energy diets)
Primiparous
Multiparous
diet
L
M
H
SEb
diet
46
52.4
38
49.0
49
48.6
1.95
NS
L
M
H
21
61.3
20
58.7
18
57.3
3.26
NS
3610
4048a
4235
3734
3703a
3785a
3604
4013a
4125
3635
3664a
3744a
3781
4324b
4282
3800
4032b
4218b
87.4
85.6
73.1
69.7
72.7
80.2
NS
*
NS
NS
**
***
NS
*
**
NS
NS
NS
3777A
4065A
4232A
3722A
3836A
3901A
3889B
4175B
4227A
3713A
3817A
3879A
4291C
4471C
4616B
4101B
4200B
4252B
25.6
8.2
41.7
24.0
121.3
124.2
***
*
**
**
*
*
*
***
NS
NS
NS
624.7
51.2a
521.4
118.1a
500.7
387.3b
62.65
71.99
NS
**
NS
NS
441.6
101.8
299.2
96.2
308.1
80.0
16.26
62.52
NS
NS
*
**
75.63b
46.99b
65.74a
43.16b
67.08a
34.44a
3.187
3.194
**
**
NS
*
78.19
60.44C
76.71
50.96B
63.02
41.22A
3.917
3.908
NS
**
NS
NS
116.6b
137.4b
104.3a
118.4a
103.8a
116.2a
4.30
4.77
**
***
*
*
131.8C
135.4B
114.3B
119.9AB
96.9A
100.7A
5.42
5.44
***
***
NS
NS
748.7
465.3
729.6
479.0
818.4
419.7
35.55
34.51
NS
NS
NS
*
774.1
598.3B
851.5
565.6AB
768.8
502.9A
36.15
32.88
NS
*
NS
NS
1154a
1360
164.0b
1158a
1315
155.2ab
1266b
1418
149.8a
46.3
53.2
7.59
*
NS
*
*
*
***
1306B
1340
174.3
1268AB
1331
154.5
1181A
1227
156.9
60.4
60.7
11.83
*
NS
NS
NS
NS
***
a,b,c Means for the effect of diet on primiparous does lacking a common letter differ (p < 0.05).
A,B,C Means for the effect of diet on multiparous does lacking a common letter differ at (p < 0.05).
a
*p < 0.05; **p < 0.01; ***p < 0.001; NS not significant.
b
Standard error.
c
Covariate: Litter size total at partum.
d
Covariate: Litter size total at 21 days.
e
Covariate: Litter size total at 35 days.
covariate
Significancea
covariate
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
No. of observations
Interval between parturitions (days)
Does' weight (g) at
mating
21st day of gestationc
pre-partumc
partumc
21st day of lactationd
weaninge
Does' weight gain (g) at
gestationc
lactationd
Food intake (g DM dayÿ1 kgÿ0.75)
Pregnant doesc
mating to 21st day
22nd day to partum
Lactating does
partum to 21st dayd
22nd day to weaninge
Energy intake (g DE dayÿ1 kgÿ0.75)
Pregnant doesc
mating to 21st day
22nd day to partum
Lactating does
partum to 21st dayd
22nd day to weaninge
Milk yield (g dayÿ1)
SEb
Significancea
111
112
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Fig. 1. Evolution of average live weight of primiparous (a) and multiparous (b) rabbit does with the different
experimental diets throughout reproductive cycle (ÐÐÐ L, - - - M and H).
intake of does was lower for H diet during the last days of gestation (p < 0.05) and during
lactation (only significant for the first three weeks; p < 0.05). Neither the live weight gain
of multiparous does during gestation nor during lactation was affected by diet. Type of
diet did not affect the milk yield of multiparous does during the first three weeks of
lactation (Fig. 2), but it was lower for does given H diet than for those given L and M
diets during the last two weeks (p < 0.001 and p < 0.01, respectively).
4.3. Litters
There was no interaction between parity and diet in the litter performance, so the effect
of diet is shown in Table 4 for all reproductive cycles. At parturition, the number of alive
pups (9.16) was similar for the different diets, but mortality at partum was higher on H
Fig. 2. Evolution of average daily milk yield of primiparous and multiparous rabbit does with the different
experimental diets (ÐÐÐ L, Ð Ð Ð M and H).
113
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 4
Effect of diet on the performance of litters (L low, M moderate and H high energy diets)
SEa
Diets
L
No. of observations
Size at
alive at partum
7th day
14th day
21st day
28th day
35th day (weaning)
Mortality (%)
at birth
from birth to weaning
Weight (g) at
alive at partumc
7th dayd
14th daye
21st dayf
28th dayg
35th day (weaning)h
Solid food intake (g DM dayÿ1 kgÿ0.75)
22±28 daysg
28±35 daysh
Solid energy intake (kJ DE dayÿ1 kgÿ0.75)
22±28 daysg
28±35 daysh
M
67
H
58
Significanceb
diet
67
9.40
8.45
8.12
7.96
7.85
7.72
9.09
8.17
7.91
7.78
7.69
7.47
8.99
8.16
7.88
7.76
7.66
7.51
0.634
0.525
0.508
0.505
0.507
0.508
NS
NS
NS
NS
NS
NS
1.662a
17.55
1.755a
17.49
4.469b
16.46
1.3525
3.8057
*
NS
483.3
1055
1758
2440
3756
5461
40.43
86.75b
400.7
859.5
499.4
1081
1808
2417
3816
5741
39.51
84.14b
438.8
933.9
covariate
488.6
1043
1777
2476
3630
5183
38.03
74.82a
463.4
912.5
14.75
36.3
64.4
88.1
156.7
167.4
3.389
3.383
38.08
35.88
NS
NS
NS
NS
NS
NS
***
***
***
***
***
***
NS
*
*
NS
NS
NS
*
NS
a,b Means within a row with different letters are significantly different (p < 0.05).
Standard error.
b
*p < 0.05; ***p < 0.01; NS not significant.
c
Covariate: Litter size alive at partum.
d
Covariate: Litter size at 7 days.
e
Covariate: Litter size at 14 days.
f
Covariate: Litter size at 21 days.
g
Covariate: Litter size at 28 days.
h
Covariate: Litter size at 35 days.
a
diet than on L and M diets (p < 0.05). Neither the size nor the weight of litters was
affected by diet, so litter size (7.57) and weight (5212 g) at weaning did not differ
between diets. A lower solid food intake of litters on H diet during the last week of
lactation (p < 0.05) was compensated for its higher DE, being DE intake similar in the
three groups at this time (504.7 kJ DE kgÿ0.75 dayÿ1).
4.4. Effect of overlapping
Data presented in Table 5 show some significant differences in the live weight and
food intake for the different overlapping periods. There was a tendency to a lower live
weight and to a higher food intake of gestating does when overlapping period increased.
As a consequence of this, food intake in pregnant does which overlapped two or three
114
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
Table 5
Effect of lactation and gestation overlapping on the performance of gestating multiparous rabbit does
SEa
Overlapping (weeks)
No. of observations
Live weight of does (g) at
7th day of gestation
14th day of gestation
21st day of gestation
28th day of gestation
prepartum
partum
Food intake of does
(g DM kgÿ0.75 dayÿ1)
mating to 7th day of gestation
7±14 days of gestation
14±21 days of gestion
21±28 days of gestation
28th day of gestation to prepartum
Litter size alive at birth
Litter weight (g) alive at birth
0
1
2
3
42
13
18
60
4090
4209
4329b
4376b
4497b
3965c
Ð
4185
4225b
4297b
4476b
3924c
Ð
Ð
4018a
4054a
4204a
3683a
Ð
Ð
Ð
4138a
4310a
3824b
78.22
89.48
69.30
45.91a
45.95a
9.15b
508.9
Ð
68.86
67.82
50.74ab
50.88ab
9.94b
487.9
Ð
Ð
86.24
55.82b
55.35b
7.38a
522.8
Ð
Ð
Ð
55.45b
54.32b
8.47a
486.8
Significanceb
Oc
O Dd covariatee
13.6
42.1
8.2
18.6
41.7
24.0
NS
NS
***
*
*
NS
*
NS
NS
NS
NS
NS
**
**
NS
18.027
9.111
17.291
14.964
13.790
0.861
6.28
NS
NS
***
***
*
NS
NS
NS
NS
NS
NS
NS
*
NS
NS
NS
***
a,b,c Means within a row with different letters are significantly different (p < 0.05).
Standard error.
b
*p < 0.05; **p < 0.01; ***p < 0.001; NS not significant.
c
Effect of overlapping.
d
Effect of the interaction between overlapping and diet.
e
Total litter size at partum.
a
weeks with the previous lactation was higher during the last 10 days of gestation
(p < 0.001) than those overlapping zero or one week. However, in spite of their higher
food intake, gestating does with long overlapping period showed lower live weight at 28th
day of gestation (p < 0.001), at prepartum and at partum (p < 0.05), and lower number of
pups alive at birth (p < 0.05).
5. Discussion
In recent years, most of the studies of the reproductive performance of rabbit does have
tried to improve productivity and body condition by using high energy diets. The addition
of fat to the diet seems to stimulate the DE intake and milk yield of does, inducing a
higher litter weight gain (Fraga et al., 1989; Cervera et al., 1993; Xiccato et al., 1995;
Pascual et al., 1998b, 1999), but it does not seem to affect significantly the body
condition of lactating does (Xiccato et al., 1995; Pascual et al., 1998b).
All authors have showed that the use of high starch diets implied a decrease in the food
intake and similar DE intake (Butcher et al., 1983; Xiccato et al., 1995; Lebas and
Fortum-Lamothe, 1996; Fortun-Lamothe and Lebas, 1996), but different results for the
effect on the performance of rabbit does have been found. Milk output did not increase in
the studies of Butcher et al. (1983) and Xiccato et al. (1995), and was lower in the
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
115
experiment of Lebas and Fortum-Lamothe (1996). Furthermore, growth of litters
followed a similar trend. In relation to the body condition, Butcher et al. (1983) and
Fortun-Lamothe and Lebas (1996) recorded an increase in the live weight of does given
high starch diets or the weight of their adipose tissues, but Xiccato et al. (1995) did not
find any significant change in body condition.
The results of the present study show that the high starch diet (H diet) seems to
increase the DE intake of rabbit does during their first lactation. However, in contrast to
that shown with high fat diets (Pascual et al., 1999), this high DE intake did not increase
the milk yield nor the growth of litters, but rather induced a greater live weight gain of
does in this period. These results suggest that, although live weight change is a poor
indicator of body tissue mobilization (Partridge et al., 1983; Parigi-Bini et al., 1992), this
diet with cereal starch as the main dietary energy source could reduce the current bodyreserve depletion shown in primiparous rabbit does at the end of lactation (Partridge et
al., 1983; Parigi-Bini et al., 1991; Xiccato et al., 1995). In fact, Fortun-Lamothe and
Lebas (1996) have described recently how primiparous rabbit does given a diet
supplemented with 140 g kgÿ1 of maize starch did not increase either the DE intake or
milk yield, but the weight of adipose tissues tended to be higher (28 vs. 52 g of fat for the
control and high starch diets, respectively). On the other hand, Xiccato et al. (1995) found
that primiparous does given a high energy diet presented a lower body energy content
when they were slaughtered at the second parturition. Thus, the use of high energy diets
seems to improve the negative energy balance of primiparous rabbits when the main
energy source is starch, but they were not able to improve productivity, in contrast to what
has been observed when the main energy source is fat (Xiccato et al., 1995; Pascual et al.,
1998b).
Primiparous rabbit does on H diet showed a different response from those on L and M
diets, but the responses of does on L and M diets were similar in spite of their different
dietary DE content. So, higher DE intake and live weight gain of rabbit does on H diet
during their first lactation seem to be more related to its higher starch content.
Rabbit does given H diet presented a higher live weight at the end of the first lactation
than those given L and M diets, and these differences were maintained during the
following reproductive cycles. Multiparous rabbit does fed with H diet showed a lower
DE intake throughout lactation, which could be the reason for the depletion in the milk
yield of does during the last two weeks, and for the slightly lower litter weight at
weaning. This is in agreement with the results obtained by Butcher et al. (1983) and
Lebas and Fortum-Lamothe (1996) in multiparous rabbit does. The long-term
preservation of a relatively constant body weight implies some long-term regulation of
food intake.
Type of diet during pregnancy appeared to have no effect on litter size and weight at
birth, but the incidence of pup mortality at birth increased markedly when does were fed
with H diet. Partridge et al. (1986) found that pup mortality at birth was higher for does
receiving a high energy diet during pregnancy than for animals fed with a low energy
diet: a higher individual weight at birth should increase the incidence of dystocia
(Partridge et al., 1985) or a build-up of fat in the abdominal cavity in the heaviest rabbit
does (does given H diet), which could block foetal movement along the birth canal
(Partridge et al., 1986).
116
J.J. Pascual et al. / Animal Feed Science and Technology 81 (1999) 105±117
On the other hand, in concurrently lactating-pregnant rabbit does energy requirements
remain high due to the rapid development of the foetuses and uterine tissues (Xiccato,
1996), and normally this is responsible for a further reduction in the fat content and body
energy levels. Consequently, pregnant does with long period of overlapping (two or three
weeks) should show a higher food intake and a lower live weight after weaning. The
results of the present study also show that multiparous rabbit does with a long
overlapping period had smaller litters at partum than the rest of the groups. These results
are in agreement with those of other workers who found a decrease in litter size alive at
birth when the remating interval was shortened (Maertens et al., 1988; Cervera et al.,
1993). For this reason, independently of the dietary energy level, the nutritional deficit
caused by a longer overlapping period could be responsible for the poor body condition of
gestating does, and consequently a reduction in the live weight of does and viability of
pups at birth was found.
In conclusion, the results obtained in the present study showed that a large increase of
dietary starch content increased the DE intake and the live weight gain of primiparous
rabbit does during lactation. This could minimise the problem of their negative energy
balance, but it could induce an excessive live weight of does. The inclusion of high levels
of starch in the diet seems to stimulate fat deposition of primiparous does, but their higher
DE intake did not improve either milk yield or performance of their litters, in contrast to
what is observed when the main energy source is fat. High energy diets reduce the food
intake of multiparous rabbit does during lactation, although this is due to their higher live
weight, and consequently no improvements in the performance of their litters were found.
Acknowledgements
The present work was supported by a grant from CICYT (AGF97-1139).
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