224 D
. Rinaldo et al. Livestock Production Science 66 2000 223 –234
conditions on growth performance in pigs, except for using the comparative slaughter method. Data on
investigations concerning very high constant ambient body composition of pigs slaughtered at 35 kg live
temperatures in the range of 32–358C Holmes, weight and on energy balance are to be presented in
1973; Straub et al., 1976; Campbell and Taverner, another paper. The present one shows data on
1988. Studies on the influence of relative humidity carcass composition of animals killed at 90 kg live
on productive traits in pigs are scarce Granier et al., weight.
1998. Therefore, this trial was designed to evaluate For each of the two climatic treatments, i.e.
the effects of tropical humid climate and season of tropical climate and controlled environment at 208C
the year on voluntary feed intake and growth per- and 75 RH, there were two replicates within each
formance of Large White pigs reared in intensive of the two seasons. For each replicate, six litters
conditions. were weaned simultaneously at 2862 days of age.
Within each litter, four animals, one pair of castrates and one pair of females, were chosen and entered the
2. Materials and methods experimental building. One pig of each pair was
placed in tropical climate in a semi-open room and The experiment was carried out to determine the
the other one in a climatic room where both air effects of tropical climate and season on voluntary
temperature and humidity were controlled. Litter feed intake FI, growth performance, organ weights
mates were thus assigned to one of the two climatic and carcass characteristics of Large White growing
treatments to get a balanced block design at the pigs, as compared to a control environment. There-
beginning of the trial, according to litter origin, sex fore, two climatic treatments were used: tropical
and live weight. Air humidity was set at 75 when climate vs. constant air temperature of 208C and air
the animals got into the climatic room and then humidity of 75. The temperature of 208C is within
remained unchanged until the end of the trial. On the the thermoneutral zone of both 20 and 60 kg pigs
day the piglets entered the climatic room, the am- Verstegen and Close, 1994. The influence of the
bient temperature was fixed at 288C. It was pro- season was assessed by comparing the cool part of
gressively lowered to 208C over 8 days and then the year, from November to February, to the warm
remained constant over the experiment. The first 2 period, from April to October, as described in Table
weeks were a pre-experimental period during which 1. This experiment was conducted in Guadeloupe
the pigs adapted to both diet and climatic conditions. F.W.I., 168 Lat. N., 618 Long. W. in a tropical
The trial began after the 2 weeks adaptation period humid area.
when pigs averaged 6 weeks of age and a body weight of 14.962.5 kg. Individual weights and
2.1. Experimental procedure voluntary FI of the animals were determined weekly
during the whole experimental period. A total of 96 pigs fed ad libitum were involved in
Thirty-six pigs, half of which from each climatic this trial from 15 to 35 kg live weight. Thirty-six
treatment, were slaughtered when they attained 35 kg pigs were slaughtered at around 35 kg live weight
live weight. In replicates 1 and 2, 12 animals were and the remaining 60 animals were killed at 90 kg, to
slaughtered. They corresponded to a pair of pigs evaluate the energy balance between 35 and 90 kg
chosen at random within each of the six litters. In
Table 1 Description of the experimental design
Replicate Season
Dates Litters
Number of pigs slaughtered at 35 kg
1 Cool
November 1994 to February 1995 6
12 2
Warm April 1995 to October 1995
6 12
3 Cool
November 1996 to February 1997 6
6 4
Warm April 1997 to October 1997
6 6
D . Rinaldo et al. Livestock Production Science 66 2000 223 –234
225
replicates 3 and 4, six animals consisting to a pair of was assessed from the weights of fat cuts and muscle
pigs from each of the three litters chosen at random, percentage from the weights of lean cuts and half-
were killed. The sacrificed animals were selected in carcass, using predicting equations Desmoulin et al.,
order that the average body weight of the remaining 1988.
pigs was similar in the two climatic treatments. The remaining pigs were slaughtered at an average body
2.2. Feeding and housing weight of 91.962.9 kg. At slaughter, the animals
were weighed after a 12 h fast, stunned, exsangui- The animals were fed ad libitum and had free
nated and eviscerated. The weights of liver, heart, access to water using a nipple water drinker. Two
spleen, kidneys and lungs were recorded. The full commercial diets, based on cereals and soybean
and empty digestive tract was weighed. The weight meal, were provided to the experimental pigs. From
of the hot carcass was determined. After a 24 h 14.962.5 to 34.763.6 kg live weight, the diet
chilling at 48C, the carcass of the animals was contained 9.74 MJ Net Energy NE kg and 18.3
weighed and split. The left half-carcass was divided crude protein Table 2. From 34.763.6 to 91.962.9
into fat cuts, such as backfat, leaf fat and belly, and kg live weight, the diet supplied 9.47 MJ NE kg and
lean cuts, such as loin and ham, according to the 17.0 crude protein Table 2.
procedure defined by Ollivier 1970. Fat percentage The pigs were individually housed in wire cages
Table 2 Composition of the diets
Ingredients 15–35 kg live weight
35–90 kg live weight Corn
32.0 48.7
Wheat 20.0
10.0 Soybean meal
19.6 16.2
Wheat red shorts 15.0
10.0 Dried whey
5.00 –
Fish meal 2.50
– Wheat bran
1.80 11.8
Soybean Oil 1.30
– Lysine HCl
0.17 0.10
Choline 50 0.09
0.07 DL Methionine
0.04 –
Calcium carbonate 0.80
1.40 Dicalcium phosphate
0.80 1.00
Salt –
0.33 Vitamin–mineral mixture
0.90 0.33
a b
Chemical composition Mean s.d.
Mean s.d. Measured by chemical analysis:
Dry matter 88.4
0.5 88.4
0.4 Crude protein
18.3 2.0
17.0 0.5
NDF 9.5
0.5 11.2
1.1 ADF
2.8 0.2
3.5 0.3
Crude fat 3.4
0.2 2.2
0.1 Assessed by calculation:
Lysine 1.14
0.85 Methionine1cystine
0.70 0.57
Threonine 0.73
0.60 Tryptophan
0.24 0.19
c
Net Energy MJ kg 9.74
9.47
a
Mean of 3 determinations.
b
Mean of 10 determinations.
c
According to Noblet et al. 1994 s.d.: standard deviation.
226 D
. Rinaldo et al. Livestock Production Science 66 2000 223 –234
0.85 3 1.50 m with metal slatted floors and housing method. The protein content was calculated as N 3
equipment was the same whatever the climatic 6.25. Neutral Detergent Fiber NDF and Acid
treatment. Each cage was equipped with a feed Detergent Fiber ADF content of feed were mea-
dispenser and a nipple water drinker. In the semi- sured by the Van Soest et al. 1991 method.
open room placed in tropical climate, air temperature Empty body weight EBW was calculated as
and relative humidity were measured every 60 s at follows:
two different locations using probes set at the EBW 5 Live weight
animals’ level. In the climatic room, both air tem- 2 weight of full digestive tract
perature and relative humidity were regulated within 60.58C and 3, respectively. Light and dark cycle
2 weight of empty digestive tract in the climatic room mimicked that of the tropical
place by using an automate. Air speed was not Treatment effects were assessed by analysis of
21
controlled but was lower than 0.15 m s and
covariance using the following model and the gener-
3 21
ventilation rate was set at 50 m h . The volume of
al linear model G.L.M. procedure of S.A.S. 1994:
3
the climatic room was 200 m . Y
5 m 1 C 1 S 1 R S 1 Se 1 L R 3 S
ijklmn i
j k
j l
m k
j
2.3. Analyses, calculations and statistics 1 CS 1
b X 2 x 1 e
ij ijklmn
ijklmn
Feed samples were taken weekly. These samples where
m is the adjusted mean; C, S, R, Se and L were analysed for fat content using the Soxhlet
correspond to climatic treatment, season, replicate, method and for nitrogen content using the Kjeldhal
sex and litter effects. In this model, CS represents the
Fig. 1. Maximal and minimal ambient temperature 8C recorded at the level of the animals under tropical climate. Each point represents the average of the data recorded over 3 successive days and is an average of the two replicates in each season.
D . Rinaldo et al. Livestock Production Science 66 2000 223 –234
227
interaction between climatic treatment and season, x pared using the Newman and Keuls test. Feed intake
is the covariable and e is the residual error.
was related to body weight by regression analysis,
ijklmn
Covariance analysis was used to adjust performance using all the data collected n 5720.
data to constant live weight at the beginning of the period and weights of organs and carcass characteris-
tics were adjusted to constant empty body weight.
3. Results
