Directory UMM :Data Elmu:jurnal:A:Animal Feed Science and Technology:Vol87.Issue1-2.Sept2000:
Animal Feed Science and Technology
87 (2000) 95±103
Effect of feeding undegraded intake protein at a
level greater than National Research Council
recommendation on the lactational
performance of crossbred cows
J.V. Manjunathaa,1, U. Krishnamoorthyb,
M.M. Kailasb, C.K. Singha,*
a
Department of Animal Nutrition, Veterinary College, University of Agricultural Sciences,
Hebbal, Bangalore 560024, India
b
Department of Dairy Production, Dairy Science College, University of Agricultural Sciences,
Hebbal, Bangalore 560024, India
Received 29 July 1998; received in revised form 3 August 1999; accepted 22 June 2000
Abstract
Feeding two levels of undegraded intake protein (UIP) was studied in late lactation crossbred
dairy cows, as affecting dry matter intake (DMI), digestibility, nitrogen (N) balance, milk yield and
milk composition. The study included a feeding trial and a metabolism trial. The feeding trial was
carried out during two periods of 7 weeks in a switch-over design using two groups of four
multiparous cows. Group I was fed UIP according to NRC [National Research Council, 1989.
Nutrient Requirements of Dairy Cattle, 6th Revised Edition. National Academic Press, Washington,
DC, pp. 138±147] (NRC-UIP) and Group II received 260 g per day more (HNRC-UIP). The diet
consisted of mixed straw of ®nger millet and paddy (FM-P) and a compound feed mixture (CFM).
The roughage DMI for NRC-UIP and HNRC-UIP was 3.83 and 3.66 kg per day, respectively.
The 4% FCM yield was equal for the two groups and amounted to 11.1 kg per day. The fat, SNF
and protein contents (%) for NRC-UIP and HNRC-UIP were, respectively, 4.53, 8.72, 3.69 and
4.71, 8.73, 3.67. The roughage DMI, body condition score, milk yield and milk composition were
not signi®cantly different (P > 0:05). On the other hand, N retention (g per day) in HNRC-UIP
(103) was higher than in NRC-UIP (55) (P < 0:01). The results indicated that although N balance
improved with feeding higher UIP levels, it had no bene®cial effect on roughage DMI, milk yield,
milk composition and body condition score. Therefore, it is concluded that in crossbred cows in late
*
Corresponding author. Tel.: 91-80-661-2005; fax: 91-80-333-4804
E-mail address: chandrapal@yahoo.com (C.K. Singh).
1
Present address: Veterinary Dispensary, Begar, Chickmagalur District, Karnataka, India.
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 0 0 ) 0 0 1 7 7 - 2
96
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
lactation, with low levels of production, feeding UIP at levels higher than NRC (1989)
recommendations is not required. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Undegraded intake protein; NRC; Dairy cows
1. Introduction
High producing dairy cows require undegraded intake protein (UIP) because they are
unable to consume adequate dry matter (DM) in the form of rumen fermentable energy to
synthesise microbial protein in quantities suf®cient to meet the lactation requirements
(ARC (1984) and NRC (1989)). Therefore, any factor associated with the feed and/or the
animal, adversely affecting the rumen fermentable energy and/or degraded intake protein
(DIP) intake can increase the need for UIP intake. Although the UIP requirement
speci®ed by NRC (1989) is approximately 30% higher than that speci®ed by ARC
(1984), the latter was reported to be adequate for cows producing upto 30 kg of milk per
day with a silage diet (Robinson et al., 1991). However, in crossbred cows producing 10±
15 kg milk per day, fed with cereal straw and concentrate, an increase in milk yield was
reported with the feeding of UIP at levels higher than the NRC (1989) (Ramachandra and
Sampath, 1995). On the contrary, Venkatesh et al. (1998) reported that ARC (1984)
protein feeding recommendation was adequate for crossbred cows producing upto 7 kg of
milk per day, fed with cereal straw and concentrate. The differences in response to UIP
levels in these studies are perhaps attributable to differences in the quality of feedstuffs
with reference to the rumen fermentability of organic matter and/or the feeding pattern,
which both in¯uence microbial protein ¯ow to the duodenum. Since the protein
requirement of ruminants is met by the microbial protein synthesised in the rumen and the
UIP, the response to UIP is rather a re¯ection of microbial protein ¯ow to the duodenum.
In India, the common practice of feeding crossbred cows with low quality roughages ad
libitum supplemented with compound feeds, often fails to meet their energy requirements
(Nataraja, 1995). Under such circumstances supplemental UIP may improve lactational
performance since the microbial protein output is constrained by the low intake of rumen
fermentable energy. On the other hand, increasing DMI to assure adequate rumen
fermentable energy intake and optimise microbial protein ¯ow to the duodenum would be
more meaningful than to feed high levels of UIP in the diet. Therefore, this study was
undertaken to assess the response of crossbred cows to two levels of UIP when energy
requirement was met by higher allocation of compound feeds as a supplement to straw
fed ad libitum.
2. Materials and methods
2.1. Animals and diet
Eight nonpregnant multiparous crossbred cows (Holstein Friesian Bos indicus, or
Jersey Bosindicus) in late lactation were divided into two comparable groups of four
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 1
Ingredient composition (g kgÿ1 DM) of the dietsa
Ingredient
NRC-UIP
HNRC-UIP
FM-P
290
280
CFM
Corn (Deccan variety)
Cotton seed meal, s.e.
Rice bran, s.e.
Groundnut meal, s.e.
Coconut meal, s.e.
Sun¯ower meal, s.e.
Molasses
Urea
Common salt
Mineral mixture
324
52
142
42
36
7
80
6
7
14
288
110
71
±
152
±
71
7
7
14
a
Vitamin A acetate (5000 I U kgÿ1) was added to the compound feed mixture. DM: dry matter; NRC-UIP:
NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than NRC (1989) undegraded intake protein;
FM-P: mixed straw of ®nger millet and paddy; CFM: compound feed mixture; s.e.: solvent extracted.
each based on milk yield, body weight, number of lactations completed and days in
lactation (Group I 178, Group II 172). The cows, housed in individual stalls, were
provided with similar management practices. The diet included mixed straw of ®nger
millet (Eleucine coracana) and paddy (Oryza sativa) (FM-P) offered ad libitum (6 kg per
day) and a compound feed mixture (CFM) as a supplement to provide adequate energy
and other nutrients as speci®ed by the NRC (1989). The two CFM, I and II were
formulated using the published data (Krishnamoorthy et al., 1995) to be identical in
metabolizable energy (ME) and DIP but to differ in UIP by increasing the proportion of
cottonseed meal s.e. and coconut meal s.e. The ratio of DIP:UIP in CFM I and CFM II
was, respectively, 60:40 and 50:50. The protein requirements in terms of DIP and UIP
were met according to NRC (1989) in Group I (NRC-UIP) and 260 g more UIP than NRC
(1989) recommendation in Group II (HNRC-UIP). The ingredient composition of the
CFMs is presented in Table 1. The ingredients of CFM were ground with a hammer mill
to pass a 3.36 mm sieve. FM-P and CFM were offered separately. The daily allowance of
CFM was calculated based on previous weeks FM-P intake, milk yield, milk fat and body
weight. The CFM was fed in two equal portions at 6.00 and 14.00 h while milking. The
cows were milked by hand and were allowed to have free access to water at 8.00 and
15.00 h. The daily allowance of FM-P straw was offered in portions of 1.5 kg, at 9.00,
16.00, 20.00 and 24.00 h. The orts of FM-P straw from each feeding were pooled for the
day and weighed at 8.30 h. The orts of CFM, if any, were weighed 1 h after offering.
2.1.1. Lactation trial (LT)
The LT lasted for 14 weeks in two periods in a switch-over design. Each period lasted
for 7 weeks with an adjustment period of 2 weeks and an observation period of 5 weeks.
Feed intake and milk yield were recorded daily. Samples of FM-P and CFM offered were
collected once weekly for determination of DM. 2 or 3 weeks samples were pooled for
chemical analyses. Milk samples were taken 1 day per week. The cows were weighed once
98
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
in a week, after milking, before having access to water. The body weights were recorded
on a weighing platform scale (Avery). The cows were also scored for the body condition at
the beginning and at the end of each period, on a ®ve-point scale (Edmonson et al., 1989).
2.1.2. Metabolism trial (MT)
A MT lasting for 5 days was conducted in period II, during which daily intake of CFM
and FM-P, milk yield and output of faeces and urine were recorded. Faeces and urine
were collected manually as and when voided and stored separately until weighed and
sampled. Samples of feed offered, feed refusals, faeces and urine were collected every
day in the morning. One thousandth by weight of the daily faeces voided by each animal
was used for DM determination. DM in the feeds and faeces was determined by drying at
708C to a constant weight. Dried samples from 5 days were pooled, ground through a
1 mm sieve and preserved for chemical analyses and in vitro rumen studies. For Nitrogen
(N) determination, the faeces samples (1/1000 of daily voids) were preserved in 25%
sulphuric acid for 5 days. Samples of urine (1/500 of total output) from individual animals
were collected every day morning for 5 days in a 500 ml Kjeldahl ¯ask containing
15 ml concentrated sulphuric acid and stored at room temperature for N determination.
2.2. Chemical analyses
The samples of feed offered, refusals and faeces were analysed for proximate
constituents (AOAC, 1984). The neutral detergent ®bre (NDF) and acid detergent ®bre
(ADF) were determined according to Van Soest et al. (1991). The metabolizable energy
(ME) was determined by prediction equations using gas production from in vitro rumen
incubation and proximate composition (Menke and Steingass, 1988). Rate of
fermentation was calculated from gas production measurement in vitro (Krishnamoorthy
et al., 1991). Protease insoluble crude protein (PICP) was determined following
Krishnamoorthy et al. (1983), and buffer soluble crude protein (BSCP) according to
Krishnamoorthy et al. (1982). Morning and evening samples of milk were pooled in
proportion to the corresponding yield. Total solids, protein, and fat (Gerbers method)
were determined according to AOAC (1984).
2.3. Statistical analysis
The data of LT were analysed by an analysis of variance (ANOVA) in a switch over
design with two periods and two treatments (Federer, 1967). The data of MT were
analysed by the Student t-test (Snedecor and Cochran, 1968).
3. Results
3.1. Lactation trial
The chemical composition of FM-P and CFM (for the three composite samples
collected during the experimental period) is presented in Table 2.
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 2
Chemical composition (g kgÿ1 DM) of compound feed mixture (CFM) and mixed straw of ®nger millet and
paddy (FM-P) used in lactation trial (LT) and metabolic trial (MT)a
CFM
FM-P
NRC-UIP
HNRC-UIP
LT
MT
901
170
22
99
305
148
62
10.4
902
197
24
97
378
167
71
10.4
834
41
11
65
699
383
65
5.20
850
84
12
150
679
469
146
4.83
Crude protein (CP) fractions
Undegraded intake proteinb
Protease insoluble CPc
Buffer soluble CPd
Acid detergent insoluble CP
Slow degraded intake protein
69
68
53
11
48
96
92
35
8
65
21
25
14
6
6
37
55
41
20
2
Gas production (ml/200 g DM/24 h)
Rate of fermentatione
53
0.094
51
0.108
20
0.035
16
0.035
Organic matter
Crude protein
Ether extract
Total ash
Neutral detergent ®bre
Acid detergent ®bre
Acid detergent lignin
Metabolisable energy (MJ kgÿ1 DM)
a
DM: dry matter; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than NRC
(1989) undegraded intake protein.
b
Calculated from published data (Sampath, 1990).
c
Krishnamoorthy et al. (1983).
d
Krishnamoorthy et al. (1982).
e
Krishnamoorthy et al. (1991).
3.1.1. Feed intake, body condition score, milk yield and milk composition
The mean daily intakes of DM, crude protein (CP), DIP, UIP, NDF and ADF, average
body condition score, milk yield and milk composition for the two groups over 5 weeks
are presented in Table 3. The intake of DM, NDF and ADF was not signi®cantly different.
The change in condition score for NRC-UIP and HNRC-UIP was 0.15 and 0.23,
respectively, and was not signi®cantly different. The two groups had a similar 4% FCM
yield of 11.1 kg day. Milk composition (total solids, fat, solids not fat, protein) was also
not signi®cantly different.
3.2. Metabolism trial
The mean intake, digestion coef®cients and N balance for the two treatments are
presented in Table 4. The digestibility of all components, as well as TDN and DOMD
were lower for the HNRC-UIP than for the NRC-UIP diet, but none of the differences
was signi®cant (P > 0:05). The daily intake and faecal excretion of N (g per day),
although both lower for the NRC-UIP (296, 117) than for the HNRC-UIP (334, 135)
group, were not signi®cantly different (P > 0:05). The urinary N (g per day) excretion
was also lower for NRC-UIP than for HNRC-UIP, being 75 and 43, respectively, and this
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 3
Body weight, body condition score, intake, milk yield and milk composition for the two groups during the
lactation trial (Mean S:E:)a
NRC-UIP
HNRC-UIP
Body weight (kg)
390
392
NS
Body condition score
Initial
Final
Gain
2.74
2.89
0.15
2.72
2.95
0.23
NS
NS
NS
Intake (kg per day)
Dry matter
Roughage
Compound feed mixture
Total
Crude protein
Degraded intake protein
Undegraded intake protein
Slow degraded intake protein
Neutral detergent ®bre
Acid detergent ®bre
3:83 0:27
9:28 0:39
13:1 0:36
1:58 0:04
0:94 0:04
0:64 0:03
0:47 0:03
5:50 0:17
2:88 0:11
3:66 0:38
9:39 0:40
13:1 0:34
1:84 0:04
0:94 0:04
0:90 0:04
0:63 0:04
6:08 0:20
3:01 0:13
NS
NS
NS
S
NS
S
S
NS
NS
Milk yield (kg per day)
Total
4% FCM
10:2 0:63
11:1 0:66
10:1 0:63
11:1 0:65
NS
NS
Milk composition (%)
Total solids
Fat
SNF
Protein
13:3 0:25
4:53 0:12
8:72 0:15
3:69 0:14
13:5 0:21
4:71 0:13
8:73 0:11
3:67 0:12
NS
NS
NS
NS
a
S.E.: standard error; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than
NRC (1989) undegraded intake protein; NS: not signi®cant (P > 0:05); S: signi®cant (P < 0:05); FCM: fat
corrected milk; SNF: solids not fat.
difference was signi®cant (P < 0:01). N retention (g per day) in NRC-UIP and HNRCUIP amounted, respectively, to 55 and 103 and the difference was signi®cant (P < 0:01).
4. Discussion
The CFM of NRC-UIP and HNRC-UIP were formulated to be similar in ME and DIP
but to differ in UIP. The PICP of the two CFMs agreed closely with the UIP content
calculated from published dacron bag data (Sampath, 1990) (Table 2). The difference in
CP content of the two CFMs is completely attributable to the difference in UIP content.
Although both CFMs had similar DIP, the BSCP of CFM I was higher than that of CFM II
suggesting that the CFM II supplied more slowly degraded intake protein (SDIP)
(SDIP CP ÿ UIP ÿ BSCP). The HNRC-UIP group received 260 g more UIP than the
NRC-UIP group (Table 3). While the DIP supplied to both groups was similar and
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
101
Table 4
Body weight, intake, digestibility, Nitrogen (N) balance and metabolic matter (NDS) for the two groups during
the metabolism triala
NRC-UIP
HNRC-UIP
Body weight (kg)
395
390
NS
Intake (kg DM per day)
Roughage
Compound feed mixture
Total
4:79 0:19
8:68 0:38
13:5 0:19
4:63 0:41
8:80 0:43
13:4 0:34
NS
NS
NS
Digestibility (%)
Total digestible nutrients
DOMD
59.9
58.4
54.5
53.0
NS
NS
Nitrogen balance (g per day)
N intake
N output
Milk
Faeces
Urine
N retained
296 12
334 10
NS
50 4
117 13
75 6
55 8
52 2
135 6
43 3
103 6
NS
NS
S
S
Faecal NDS (kg per day)
Faecal N:NDS
2:32 0:28
0.051
2:69 0:11
0.05
NS
a
NDS: neutral detergent solubles; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g
higher than NRC (1989) undegraded intake protein; DM: dry matter; DOMD: digestible organic matter in dry
matter; NS: not signi®cant (P > 0:05); S: signi®cant (P < 0:01).
exceeded the NRC (1989) requirement (800 g per day) by 200 g, the UIP supplied to both
NRC-UIP and HNRC-UIP was in excess of the recommendation (561 g per day) by 159
and 419 g, respectively (Table 3).
The additional UIP did neither in¯uence total DMI nor the roughage DMI. This is
consistent with the observations of Ramachandra and Sampath (1995). A similar milk
yield and milk composition for the two groups suggests that feeding UIP at levels higher
than the NRC recommendation is not bene®cial. Increase in milk yield on feeding more
UIP was reported in cows when ME intake was lower as a consequence of low
concentrate feeding (érskov et al., 1981). In the present study, the cows were fed to be in
positive energy balance. The mean ME intake during the LT, calculated with the ME
content of the diets obtained in the MT and corrected for level of intake (9.87 and
8.88 MJ kgÿ1 DM for NRC-UIP and HNRC-UIP, respectively) (NRC, 1989; Nataraja,
1995), amounted to 129 and 116 MJ per day for NRC-UIP and HNRC-UIP, respectively.
The ME supplied to the NRC-UIP and HNRC-UIP groups exceeded 23 and 10 MJ,
respectively, above the maintenance and milk production requirements (NRC, 1989). The
body condition score and positive N balance observed in both groups also suggest an
adequate energy intake.
Although feeding additional UIP did not in¯uence DMI, milk yield and composition,
this resulted in a signi®cant increase in N retention. In spite of ME available for gain in
NRC-UIP was higher (23 MJ) than in HNRC-UIP (10 MJ), N retained was signi®cantly
102
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
(P < 0:01) higher in HNRC-UIP (55 versus 103 g per day). This may be explained by a
higher post-ruminal delivery of amino acids. However, one would calculate that for a gain
of 48 g N, a dietary supply of 637 g digestible postruminally available protein is required.
Because the excess UIP supplied in HNRC-UIP diet was only 260 g (compared to NRCUIP), which is partly indigestible, higher N retention cannot be justi®ed by the higher
level of UIP alone. This could be explained by an increase in microbial protein ¯ow to the
duodenum, as re¯ected by the higher output (kg per day) of faecal neutral detergent
solubles (NDS) in HNRC-UIP (2:69 0:11) than in NRC-UIP group (2:32 0:28)
(Table 4). Faecal NDS largely represent undigested microbial cell walls (Van Soest,
1982). Although the ratio of faecal N to faecal NDS was about 2% lower than expected
(Van Soest, 1982), it was similar for both groups. The total OM digestibility was
marginally lower in HNRC-UIP, whereas, the rate (k) of OM fermentation in the rumen
was higher (0.108), as compared to NRC-UIP (0.094) (Table 2). Consequently, the total
fermentable organic matter in the rumen can be expected to be similar for the two groups
because of similar DMI. Therefore, the nature of DIP, may have in¯uenced the microbial
protein production in the rumen. Although the two groups received similar amounts of
DIP (1.02 and 1.01 kg per day) (Table 3), the SDIP (kg per day) was higher in HNRCUIP (0.63) than in NRC-UIP (0.47). This might have increased the ef®ciency of microbial
protein synthesis through a better synchronisation between energy and N availability in
the rumen. Slower degradation of N in the rumen is reported to increase microbial protein
¯ow to the duodenum (ARC, 1984).
Since the total protein requirement is met from microbial protein and the UIP, a
substantial reduction in UIP feeding can be achieved by increasing microbial protein ¯ow
to the duodenum. Such an approach would be more meaningful than attempting to deliver
UIP to the duodenum. With NRC-UIP, the N retention (g per day) was 55 which is an
unwanted luxury under conditions of chronic feed shortage. Similarly, Venkatesh et al.
(1998) reported a N retention of 4 and 39 g per day for crossbred cows fed on a straw
based diet according to ARC (1984) and NRC (1989) recommendations, respectively,
although there was no difference in milk yield and milk composition. The recommendations for protein feeding of ARC (1984) are about 30% lower than those of NRC (1989).
The former were also found to be adequate for medium production levels with silage
based diets (Robinson et al., 1991). So, our ®ndings and the above mentioned studies
suggest that there is scope for reducing UIP to levels lower than NRC (1989)
recommendation for cows in late lactation producing 10 kg of milk per day, fed on low
quality roughages, when adequate energy intake is assured through higher allocation of
concentrate feeding.
Acknowledgements
The authors wish to thank M/s Mysore Feeds Pvt. Ltd. Bangalore, India, for providing
the supplements. This work was a part of the project `Studies on nitrogen utilisation in
ruminants' (DR/UAS/DP/9 & 11/96) jointly sponsored by the Alexander von Humboldt
Foundation, Germany, in the form of equipment donation and the University of
Agricultural Sciences, Hebbal, Bangalore, India.
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
103
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87 (2000) 95±103
Effect of feeding undegraded intake protein at a
level greater than National Research Council
recommendation on the lactational
performance of crossbred cows
J.V. Manjunathaa,1, U. Krishnamoorthyb,
M.M. Kailasb, C.K. Singha,*
a
Department of Animal Nutrition, Veterinary College, University of Agricultural Sciences,
Hebbal, Bangalore 560024, India
b
Department of Dairy Production, Dairy Science College, University of Agricultural Sciences,
Hebbal, Bangalore 560024, India
Received 29 July 1998; received in revised form 3 August 1999; accepted 22 June 2000
Abstract
Feeding two levels of undegraded intake protein (UIP) was studied in late lactation crossbred
dairy cows, as affecting dry matter intake (DMI), digestibility, nitrogen (N) balance, milk yield and
milk composition. The study included a feeding trial and a metabolism trial. The feeding trial was
carried out during two periods of 7 weeks in a switch-over design using two groups of four
multiparous cows. Group I was fed UIP according to NRC [National Research Council, 1989.
Nutrient Requirements of Dairy Cattle, 6th Revised Edition. National Academic Press, Washington,
DC, pp. 138±147] (NRC-UIP) and Group II received 260 g per day more (HNRC-UIP). The diet
consisted of mixed straw of ®nger millet and paddy (FM-P) and a compound feed mixture (CFM).
The roughage DMI for NRC-UIP and HNRC-UIP was 3.83 and 3.66 kg per day, respectively.
The 4% FCM yield was equal for the two groups and amounted to 11.1 kg per day. The fat, SNF
and protein contents (%) for NRC-UIP and HNRC-UIP were, respectively, 4.53, 8.72, 3.69 and
4.71, 8.73, 3.67. The roughage DMI, body condition score, milk yield and milk composition were
not signi®cantly different (P > 0:05). On the other hand, N retention (g per day) in HNRC-UIP
(103) was higher than in NRC-UIP (55) (P < 0:01). The results indicated that although N balance
improved with feeding higher UIP levels, it had no bene®cial effect on roughage DMI, milk yield,
milk composition and body condition score. Therefore, it is concluded that in crossbred cows in late
*
Corresponding author. Tel.: 91-80-661-2005; fax: 91-80-333-4804
E-mail address: chandrapal@yahoo.com (C.K. Singh).
1
Present address: Veterinary Dispensary, Begar, Chickmagalur District, Karnataka, India.
0377-8401/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 3 7 7 - 8 4 0 1 ( 0 0 ) 0 0 1 7 7 - 2
96
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
lactation, with low levels of production, feeding UIP at levels higher than NRC (1989)
recommendations is not required. # 2000 Elsevier Science B.V. All rights reserved.
Keywords: Undegraded intake protein; NRC; Dairy cows
1. Introduction
High producing dairy cows require undegraded intake protein (UIP) because they are
unable to consume adequate dry matter (DM) in the form of rumen fermentable energy to
synthesise microbial protein in quantities suf®cient to meet the lactation requirements
(ARC (1984) and NRC (1989)). Therefore, any factor associated with the feed and/or the
animal, adversely affecting the rumen fermentable energy and/or degraded intake protein
(DIP) intake can increase the need for UIP intake. Although the UIP requirement
speci®ed by NRC (1989) is approximately 30% higher than that speci®ed by ARC
(1984), the latter was reported to be adequate for cows producing upto 30 kg of milk per
day with a silage diet (Robinson et al., 1991). However, in crossbred cows producing 10±
15 kg milk per day, fed with cereal straw and concentrate, an increase in milk yield was
reported with the feeding of UIP at levels higher than the NRC (1989) (Ramachandra and
Sampath, 1995). On the contrary, Venkatesh et al. (1998) reported that ARC (1984)
protein feeding recommendation was adequate for crossbred cows producing upto 7 kg of
milk per day, fed with cereal straw and concentrate. The differences in response to UIP
levels in these studies are perhaps attributable to differences in the quality of feedstuffs
with reference to the rumen fermentability of organic matter and/or the feeding pattern,
which both in¯uence microbial protein ¯ow to the duodenum. Since the protein
requirement of ruminants is met by the microbial protein synthesised in the rumen and the
UIP, the response to UIP is rather a re¯ection of microbial protein ¯ow to the duodenum.
In India, the common practice of feeding crossbred cows with low quality roughages ad
libitum supplemented with compound feeds, often fails to meet their energy requirements
(Nataraja, 1995). Under such circumstances supplemental UIP may improve lactational
performance since the microbial protein output is constrained by the low intake of rumen
fermentable energy. On the other hand, increasing DMI to assure adequate rumen
fermentable energy intake and optimise microbial protein ¯ow to the duodenum would be
more meaningful than to feed high levels of UIP in the diet. Therefore, this study was
undertaken to assess the response of crossbred cows to two levels of UIP when energy
requirement was met by higher allocation of compound feeds as a supplement to straw
fed ad libitum.
2. Materials and methods
2.1. Animals and diet
Eight nonpregnant multiparous crossbred cows (Holstein Friesian Bos indicus, or
Jersey Bosindicus) in late lactation were divided into two comparable groups of four
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 1
Ingredient composition (g kgÿ1 DM) of the dietsa
Ingredient
NRC-UIP
HNRC-UIP
FM-P
290
280
CFM
Corn (Deccan variety)
Cotton seed meal, s.e.
Rice bran, s.e.
Groundnut meal, s.e.
Coconut meal, s.e.
Sun¯ower meal, s.e.
Molasses
Urea
Common salt
Mineral mixture
324
52
142
42
36
7
80
6
7
14
288
110
71
±
152
±
71
7
7
14
a
Vitamin A acetate (5000 I U kgÿ1) was added to the compound feed mixture. DM: dry matter; NRC-UIP:
NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than NRC (1989) undegraded intake protein;
FM-P: mixed straw of ®nger millet and paddy; CFM: compound feed mixture; s.e.: solvent extracted.
each based on milk yield, body weight, number of lactations completed and days in
lactation (Group I 178, Group II 172). The cows, housed in individual stalls, were
provided with similar management practices. The diet included mixed straw of ®nger
millet (Eleucine coracana) and paddy (Oryza sativa) (FM-P) offered ad libitum (6 kg per
day) and a compound feed mixture (CFM) as a supplement to provide adequate energy
and other nutrients as speci®ed by the NRC (1989). The two CFM, I and II were
formulated using the published data (Krishnamoorthy et al., 1995) to be identical in
metabolizable energy (ME) and DIP but to differ in UIP by increasing the proportion of
cottonseed meal s.e. and coconut meal s.e. The ratio of DIP:UIP in CFM I and CFM II
was, respectively, 60:40 and 50:50. The protein requirements in terms of DIP and UIP
were met according to NRC (1989) in Group I (NRC-UIP) and 260 g more UIP than NRC
(1989) recommendation in Group II (HNRC-UIP). The ingredient composition of the
CFMs is presented in Table 1. The ingredients of CFM were ground with a hammer mill
to pass a 3.36 mm sieve. FM-P and CFM were offered separately. The daily allowance of
CFM was calculated based on previous weeks FM-P intake, milk yield, milk fat and body
weight. The CFM was fed in two equal portions at 6.00 and 14.00 h while milking. The
cows were milked by hand and were allowed to have free access to water at 8.00 and
15.00 h. The daily allowance of FM-P straw was offered in portions of 1.5 kg, at 9.00,
16.00, 20.00 and 24.00 h. The orts of FM-P straw from each feeding were pooled for the
day and weighed at 8.30 h. The orts of CFM, if any, were weighed 1 h after offering.
2.1.1. Lactation trial (LT)
The LT lasted for 14 weeks in two periods in a switch-over design. Each period lasted
for 7 weeks with an adjustment period of 2 weeks and an observation period of 5 weeks.
Feed intake and milk yield were recorded daily. Samples of FM-P and CFM offered were
collected once weekly for determination of DM. 2 or 3 weeks samples were pooled for
chemical analyses. Milk samples were taken 1 day per week. The cows were weighed once
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
in a week, after milking, before having access to water. The body weights were recorded
on a weighing platform scale (Avery). The cows were also scored for the body condition at
the beginning and at the end of each period, on a ®ve-point scale (Edmonson et al., 1989).
2.1.2. Metabolism trial (MT)
A MT lasting for 5 days was conducted in period II, during which daily intake of CFM
and FM-P, milk yield and output of faeces and urine were recorded. Faeces and urine
were collected manually as and when voided and stored separately until weighed and
sampled. Samples of feed offered, feed refusals, faeces and urine were collected every
day in the morning. One thousandth by weight of the daily faeces voided by each animal
was used for DM determination. DM in the feeds and faeces was determined by drying at
708C to a constant weight. Dried samples from 5 days were pooled, ground through a
1 mm sieve and preserved for chemical analyses and in vitro rumen studies. For Nitrogen
(N) determination, the faeces samples (1/1000 of daily voids) were preserved in 25%
sulphuric acid for 5 days. Samples of urine (1/500 of total output) from individual animals
were collected every day morning for 5 days in a 500 ml Kjeldahl ¯ask containing
15 ml concentrated sulphuric acid and stored at room temperature for N determination.
2.2. Chemical analyses
The samples of feed offered, refusals and faeces were analysed for proximate
constituents (AOAC, 1984). The neutral detergent ®bre (NDF) and acid detergent ®bre
(ADF) were determined according to Van Soest et al. (1991). The metabolizable energy
(ME) was determined by prediction equations using gas production from in vitro rumen
incubation and proximate composition (Menke and Steingass, 1988). Rate of
fermentation was calculated from gas production measurement in vitro (Krishnamoorthy
et al., 1991). Protease insoluble crude protein (PICP) was determined following
Krishnamoorthy et al. (1983), and buffer soluble crude protein (BSCP) according to
Krishnamoorthy et al. (1982). Morning and evening samples of milk were pooled in
proportion to the corresponding yield. Total solids, protein, and fat (Gerbers method)
were determined according to AOAC (1984).
2.3. Statistical analysis
The data of LT were analysed by an analysis of variance (ANOVA) in a switch over
design with two periods and two treatments (Federer, 1967). The data of MT were
analysed by the Student t-test (Snedecor and Cochran, 1968).
3. Results
3.1. Lactation trial
The chemical composition of FM-P and CFM (for the three composite samples
collected during the experimental period) is presented in Table 2.
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 2
Chemical composition (g kgÿ1 DM) of compound feed mixture (CFM) and mixed straw of ®nger millet and
paddy (FM-P) used in lactation trial (LT) and metabolic trial (MT)a
CFM
FM-P
NRC-UIP
HNRC-UIP
LT
MT
901
170
22
99
305
148
62
10.4
902
197
24
97
378
167
71
10.4
834
41
11
65
699
383
65
5.20
850
84
12
150
679
469
146
4.83
Crude protein (CP) fractions
Undegraded intake proteinb
Protease insoluble CPc
Buffer soluble CPd
Acid detergent insoluble CP
Slow degraded intake protein
69
68
53
11
48
96
92
35
8
65
21
25
14
6
6
37
55
41
20
2
Gas production (ml/200 g DM/24 h)
Rate of fermentatione
53
0.094
51
0.108
20
0.035
16
0.035
Organic matter
Crude protein
Ether extract
Total ash
Neutral detergent ®bre
Acid detergent ®bre
Acid detergent lignin
Metabolisable energy (MJ kgÿ1 DM)
a
DM: dry matter; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than NRC
(1989) undegraded intake protein.
b
Calculated from published data (Sampath, 1990).
c
Krishnamoorthy et al. (1983).
d
Krishnamoorthy et al. (1982).
e
Krishnamoorthy et al. (1991).
3.1.1. Feed intake, body condition score, milk yield and milk composition
The mean daily intakes of DM, crude protein (CP), DIP, UIP, NDF and ADF, average
body condition score, milk yield and milk composition for the two groups over 5 weeks
are presented in Table 3. The intake of DM, NDF and ADF was not signi®cantly different.
The change in condition score for NRC-UIP and HNRC-UIP was 0.15 and 0.23,
respectively, and was not signi®cantly different. The two groups had a similar 4% FCM
yield of 11.1 kg day. Milk composition (total solids, fat, solids not fat, protein) was also
not signi®cantly different.
3.2. Metabolism trial
The mean intake, digestion coef®cients and N balance for the two treatments are
presented in Table 4. The digestibility of all components, as well as TDN and DOMD
were lower for the HNRC-UIP than for the NRC-UIP diet, but none of the differences
was signi®cant (P > 0:05). The daily intake and faecal excretion of N (g per day),
although both lower for the NRC-UIP (296, 117) than for the HNRC-UIP (334, 135)
group, were not signi®cantly different (P > 0:05). The urinary N (g per day) excretion
was also lower for NRC-UIP than for HNRC-UIP, being 75 and 43, respectively, and this
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J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
Table 3
Body weight, body condition score, intake, milk yield and milk composition for the two groups during the
lactation trial (Mean S:E:)a
NRC-UIP
HNRC-UIP
Body weight (kg)
390
392
NS
Body condition score
Initial
Final
Gain
2.74
2.89
0.15
2.72
2.95
0.23
NS
NS
NS
Intake (kg per day)
Dry matter
Roughage
Compound feed mixture
Total
Crude protein
Degraded intake protein
Undegraded intake protein
Slow degraded intake protein
Neutral detergent ®bre
Acid detergent ®bre
3:83 0:27
9:28 0:39
13:1 0:36
1:58 0:04
0:94 0:04
0:64 0:03
0:47 0:03
5:50 0:17
2:88 0:11
3:66 0:38
9:39 0:40
13:1 0:34
1:84 0:04
0:94 0:04
0:90 0:04
0:63 0:04
6:08 0:20
3:01 0:13
NS
NS
NS
S
NS
S
S
NS
NS
Milk yield (kg per day)
Total
4% FCM
10:2 0:63
11:1 0:66
10:1 0:63
11:1 0:65
NS
NS
Milk composition (%)
Total solids
Fat
SNF
Protein
13:3 0:25
4:53 0:12
8:72 0:15
3:69 0:14
13:5 0:21
4:71 0:13
8:73 0:11
3:67 0:12
NS
NS
NS
NS
a
S.E.: standard error; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g higher than
NRC (1989) undegraded intake protein; NS: not signi®cant (P > 0:05); S: signi®cant (P < 0:05); FCM: fat
corrected milk; SNF: solids not fat.
difference was signi®cant (P < 0:01). N retention (g per day) in NRC-UIP and HNRCUIP amounted, respectively, to 55 and 103 and the difference was signi®cant (P < 0:01).
4. Discussion
The CFM of NRC-UIP and HNRC-UIP were formulated to be similar in ME and DIP
but to differ in UIP. The PICP of the two CFMs agreed closely with the UIP content
calculated from published dacron bag data (Sampath, 1990) (Table 2). The difference in
CP content of the two CFMs is completely attributable to the difference in UIP content.
Although both CFMs had similar DIP, the BSCP of CFM I was higher than that of CFM II
suggesting that the CFM II supplied more slowly degraded intake protein (SDIP)
(SDIP CP ÿ UIP ÿ BSCP). The HNRC-UIP group received 260 g more UIP than the
NRC-UIP group (Table 3). While the DIP supplied to both groups was similar and
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
101
Table 4
Body weight, intake, digestibility, Nitrogen (N) balance and metabolic matter (NDS) for the two groups during
the metabolism triala
NRC-UIP
HNRC-UIP
Body weight (kg)
395
390
NS
Intake (kg DM per day)
Roughage
Compound feed mixture
Total
4:79 0:19
8:68 0:38
13:5 0:19
4:63 0:41
8:80 0:43
13:4 0:34
NS
NS
NS
Digestibility (%)
Total digestible nutrients
DOMD
59.9
58.4
54.5
53.0
NS
NS
Nitrogen balance (g per day)
N intake
N output
Milk
Faeces
Urine
N retained
296 12
334 10
NS
50 4
117 13
75 6
55 8
52 2
135 6
43 3
103 6
NS
NS
S
S
Faecal NDS (kg per day)
Faecal N:NDS
2:32 0:28
0.051
2:69 0:11
0.05
NS
a
NDS: neutral detergent solubles; NRC-UIP: NRC (1989) undegraded intake protein; HNRC-UIP: 260 g
higher than NRC (1989) undegraded intake protein; DM: dry matter; DOMD: digestible organic matter in dry
matter; NS: not signi®cant (P > 0:05); S: signi®cant (P < 0:01).
exceeded the NRC (1989) requirement (800 g per day) by 200 g, the UIP supplied to both
NRC-UIP and HNRC-UIP was in excess of the recommendation (561 g per day) by 159
and 419 g, respectively (Table 3).
The additional UIP did neither in¯uence total DMI nor the roughage DMI. This is
consistent with the observations of Ramachandra and Sampath (1995). A similar milk
yield and milk composition for the two groups suggests that feeding UIP at levels higher
than the NRC recommendation is not bene®cial. Increase in milk yield on feeding more
UIP was reported in cows when ME intake was lower as a consequence of low
concentrate feeding (érskov et al., 1981). In the present study, the cows were fed to be in
positive energy balance. The mean ME intake during the LT, calculated with the ME
content of the diets obtained in the MT and corrected for level of intake (9.87 and
8.88 MJ kgÿ1 DM for NRC-UIP and HNRC-UIP, respectively) (NRC, 1989; Nataraja,
1995), amounted to 129 and 116 MJ per day for NRC-UIP and HNRC-UIP, respectively.
The ME supplied to the NRC-UIP and HNRC-UIP groups exceeded 23 and 10 MJ,
respectively, above the maintenance and milk production requirements (NRC, 1989). The
body condition score and positive N balance observed in both groups also suggest an
adequate energy intake.
Although feeding additional UIP did not in¯uence DMI, milk yield and composition,
this resulted in a signi®cant increase in N retention. In spite of ME available for gain in
NRC-UIP was higher (23 MJ) than in HNRC-UIP (10 MJ), N retained was signi®cantly
102
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
(P < 0:01) higher in HNRC-UIP (55 versus 103 g per day). This may be explained by a
higher post-ruminal delivery of amino acids. However, one would calculate that for a gain
of 48 g N, a dietary supply of 637 g digestible postruminally available protein is required.
Because the excess UIP supplied in HNRC-UIP diet was only 260 g (compared to NRCUIP), which is partly indigestible, higher N retention cannot be justi®ed by the higher
level of UIP alone. This could be explained by an increase in microbial protein ¯ow to the
duodenum, as re¯ected by the higher output (kg per day) of faecal neutral detergent
solubles (NDS) in HNRC-UIP (2:69 0:11) than in NRC-UIP group (2:32 0:28)
(Table 4). Faecal NDS largely represent undigested microbial cell walls (Van Soest,
1982). Although the ratio of faecal N to faecal NDS was about 2% lower than expected
(Van Soest, 1982), it was similar for both groups. The total OM digestibility was
marginally lower in HNRC-UIP, whereas, the rate (k) of OM fermentation in the rumen
was higher (0.108), as compared to NRC-UIP (0.094) (Table 2). Consequently, the total
fermentable organic matter in the rumen can be expected to be similar for the two groups
because of similar DMI. Therefore, the nature of DIP, may have in¯uenced the microbial
protein production in the rumen. Although the two groups received similar amounts of
DIP (1.02 and 1.01 kg per day) (Table 3), the SDIP (kg per day) was higher in HNRCUIP (0.63) than in NRC-UIP (0.47). This might have increased the ef®ciency of microbial
protein synthesis through a better synchronisation between energy and N availability in
the rumen. Slower degradation of N in the rumen is reported to increase microbial protein
¯ow to the duodenum (ARC, 1984).
Since the total protein requirement is met from microbial protein and the UIP, a
substantial reduction in UIP feeding can be achieved by increasing microbial protein ¯ow
to the duodenum. Such an approach would be more meaningful than attempting to deliver
UIP to the duodenum. With NRC-UIP, the N retention (g per day) was 55 which is an
unwanted luxury under conditions of chronic feed shortage. Similarly, Venkatesh et al.
(1998) reported a N retention of 4 and 39 g per day for crossbred cows fed on a straw
based diet according to ARC (1984) and NRC (1989) recommendations, respectively,
although there was no difference in milk yield and milk composition. The recommendations for protein feeding of ARC (1984) are about 30% lower than those of NRC (1989).
The former were also found to be adequate for medium production levels with silage
based diets (Robinson et al., 1991). So, our ®ndings and the above mentioned studies
suggest that there is scope for reducing UIP to levels lower than NRC (1989)
recommendation for cows in late lactation producing 10 kg of milk per day, fed on low
quality roughages, when adequate energy intake is assured through higher allocation of
concentrate feeding.
Acknowledgements
The authors wish to thank M/s Mysore Feeds Pvt. Ltd. Bangalore, India, for providing
the supplements. This work was a part of the project `Studies on nitrogen utilisation in
ruminants' (DR/UAS/DP/9 & 11/96) jointly sponsored by the Alexander von Humboldt
Foundation, Germany, in the form of equipment donation and the University of
Agricultural Sciences, Hebbal, Bangalore, India.
J.V. Manjunatha et al. / Animal Feed Science and Technology 87 (2000) 95±103
103
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