Technical note
Growth performance of Malpura and crossbred lambs
under intensive feeding
S.A. Karim
*, A. Santra
Division of Animal Nutrition, Central Sheep and Wool Research Institute, Avikanagar 304501, Rajasthan, India
Received 16 December 1998; accepted 26 January 1999
Abstract
Growth performance, feed conversion ef®ciency and nutrient utilization of mutton synthetic, selected and randombred Malpura populations of lambs (60 days) were evaluated. The mutton synthetic lambs reached the 25 kg body weight in 73 days of intensive feeding while the selected and randombred Malpura populations of lambs reached the same weight in 91 and 136 days, respectively (P<0.01). The ®tted growth curve con®rmed the mutton synthetic lambs grew rapidly and were more ef®cient in feed conversion (P<0.01) followed by selected and randombred Malpura lambs. Dry matter intake and nutrient utilization was similar in mutton synthetic and selected Malpura lambs and required 75 g DM, 5.5 g DCP and 42.1 g TDN/kg W0.75for average daily gain of 148 g. The lambs were in positive N, Ca and P balance whereas their N retention was lower (25%). It is concluded from this preliminary study that growth response and feed conversion ef®ciency were higher in mutton synthetic than selected Malpura lambs and lower in randombred Malpura lambs.#2000 Elsevier Science B.V. All rights reserved.
Keywords:Feed intake; Growth; Nutrient utilization; Sheep
1. Introduction
Sheep are predominantly maintained on pasture with supplementary feed during the critical season. Hence the lambs occasionally reach 16 kg body weight at six months of age (Kaushis et al., 1990). These lambs are usually slaughtered at 20±22 kg (9± 12 months) with dressed carcass weight of 10 kg (Karim et al., 1998). The All India Co-ordinated Research Project (AICRP) was initiated to improve daily gain and productivity for mutton based on
cross-ing native sheep with the Dorset and Suffolk breeds, imported from the United Kingdom. The Mutton synthetic, Malpura and Sonadi lambs gained 170, 150 and 118 g daily (ADG) with 1:5±7 feed ef®ciency ratio under intensive feeding on 50:50 concentrate and roughage based complete feed (Karim and Rawat, 1996). Rapid daily gain in intensively fed lambs has been reported to be associated with lower feed con-version ef®ciency and higher carcass fat, sometimes exceeding 20% (Prasad et al., 1981). Hence weaning age was reduced from 90 to 60 days to improve feed conversion ef®ciency (Karim and Arora, 1997).
It was also evident in slaughter studies that irre-spective of duration of intensive feeding, the lambs that reached 25 kg body weight, had the desired
*Corresponding author. Tel.:91-1437-28143; fax:91-1437-28163.
E-mail address: sakarim@cswri.raj.nic.in (S.A. Karim)
carcass characteristics (Prasad et al., 1981). The objec-tive of the present study was to assess the relaobjec-tive growth performance, feed conversion ef®ciency and nutrient utilization pro®le of intensively fed Malpura and crossbred lambs with ®nal body weight of 25 kg.
2. Materials and methods
2.1. Animals and diets
Forty eight mutton synthetic (half-breed Malpur-aDorset/Suffolk), 20 selected Malpura (subjected to intensive selection for higher rate of gain) and 10 Malpura control (randombred) lambs weaned at 60-days of age were maintained on a diet containing 50:50 roughage and concentrate until 25 kg body weight. The diet contained 50% pala leaves (Ziziphus numularia), 33% barley grain, 14% ground nut cake, 2% mineral mixture, 1% common salt and 20 g vita-min premix (Vitablend) per 100 kg feed mixture. The chemical composition of the diet and pala leaves (Z. numularia) were 14.5 and 11.3% CP, 7.1 and 11.2% crude ®bre and 4.0 and 5.1% lignin, respectively.
2.2. Feeding and metabolism trial
The lambs were maintained (throughout the experi-ment) in individual chain link enclosures in a side open asbestos roof animal shed.Ad libitumfeed and water was offered in their respective enclosures. Each day the residual feed was quanti®ed and discarded before fresh feed was offered. Lambs were weighed at ®ve-days intervals. Towards the end of the experi-mental feeding, a metabolism trial was conducted in metabolic cages on seven each of selected Malpura and mutton synthetic lambs following protocol of four days adjustment and 7 days collection period. Feed offered and faeces and urine collected over 7 days were pooled, oven dried at 608C and preserved for chemical analysis.
2.3. Chemical analysis
Milled (2 mm screen) samples were analyzed for proximate chemical composition and urinary nitrogen was determined by the standard Micro Kjeldahl method (AOAC, 1984). Calcium (Talapatra et al.,
1940) and phosphorus (Fiske and Subbarow, 1925) in feed, faeces and urine were estimated.
2.4. Statistical analysis
Data on growth and feed conversion ef®ciency were subjected to analysis of variance (Harvey, 1975) and the treatment differences were compared using Dun-can's multiple range test (Duncan, 1955). The data on digestibility parameters and plane of nutrition were compared by Student's t-test. The growth pattern of individual lambs was charted by ®tting a polynomial curve and the constants of the three genetic groups were compared by least square analysis of variance. (Snedecor and Cochran, 1967).
3. Results and discussion
9±12-months of age with gained 50 g daily (Kaushis et al., 1990). Correspondingly under intensive feeding in this study the same genetic group gained 111 g indicating that even the indigenous lambs have higher growth potential which could to be exploited by adequate feeding. Mutton synthetic lambs were signi®cantly more ef®cient in feed conversion compared to selected and randombred Malpura lambs (Table 1). The feed conversion ef®ciency observed in the present study was comparable to earlier studies on these genetic
groups under similar weaning and feeding manage-ment (Karim and Arora, 1997).
Metabolism trials were conducted on selected Mal-pura and mutton synthetic lambs at body weights of 21 and 22 kg, respectively. The average daily dry matter intake of the two genetic groups was 754 and 755 g amounting to 3.5% of their body weight or 75 g/kg W0.75. The daily dry matter intake of the lambs was similar and comparable to earlier studies (Shinde and Singh, 1995). Nutrients digestibilities were
compar-Fig. 1. Body weight changes of sheep.
Table 1
Growth performance and feed conversion ef®ciency of experimental lambsa,b,c
Source Mutton
synthetic
Selected Malpura
Malpura control
S.E.M. Level of significance
No. of lambs 48 20 10 ± ±
Initial body weight (kg) 14.0b 13.1b 10.6a 0.83 **
Final body weight (kg) 25.4 25.2 25.1 0.09 NSd
Duration of feeding (days) 73a 91b 136c 9.19 **
Average daily gain (g) 161.7a 134.7b 111.5a 10.43 **
Feed intake during the experiment (kg) 66.1a 75.3b 108.2c 4.81 **
Feed efficiency ratio 5.65a 6.15b 7.50c 0.34 **
Percent feed efficiency 17.7c 16.5b 14.3a 0.91 **
able in the two genetic groups (Table 2). Selected Malpura and mutton synthetic lambs were in positive nitrogen balance and their N retention was about 25%. Comparatively lower N retention of experimental lambs was due to incorporation of 50% pala (Z. nummularia) leaves in the diet which could be asso-ciated with higher tannin content (Kumar and
D'Mello, 1995). Similarly both the groups were in positive Ca and P balance whereas the ratio of their balance was wider (Ca:P5:1) due to pala leaves with higher Ca content in the diet.
The mutton synthetic lambs on an average con-sumed 75 g DM, 5.6 g DCP and 41.9 g TDN/kg W0.75 and had 162 g average daily gain while the selected
Table 2
Feed intake, its digestibility and plane of nutrition in Malpura and mutton synthetic lambs
Sources Malpura selected Mutton synthetic S.E.M.
Number of lambs 8 8 ±
Body weight (kg) during trial 20.9 21.8 10.4
Dry matter intake
g/day 754.0 755.1 41.8
g/kg body weight/day 35.4 34.6 1.91
g/kg W0.75/day 75.4 74.8 4.14
Nutrient digestibility(%)
Dry matter 60.3 61.4 1.51
Crude protein 54.8 56.3 3.08
Ether extract 56.4 56.5 2.17
Crude fibre 37.5 35.9 2.45
Nitrogen free extract 71.0 71.2 1.58
Nutritive value of ration(%)
DCP 7.3 7.5 0.41
TDN 56.2 56.1 1.29
Nutrient intake DCP
g/day 53.7 56.2 4.98
g/kg body weight/day 2.6 2.6 0.21
g/kg W0.75/day 5.5 5.6 0.47
TDN
g/day 413.0 422.6 26.40
g/kg body weight/day 19.9 19.4 1.06
g/kg W0.75/day 42.4 41.9 2.29
Nitrogen balance
N-intake (g/day) 15.6 16.0 1.01
N-excretion (g/day)
Faecal 7.0 7.0 0.63
Urinary 4.6 5.0 0.47
N-retained 4.0 4.0 0.72
N-retention as % of intake 25.6 25.0 1.33
Mineral balance(g/day)
Calcium intake 18.7 19.3 1.3
Faecal excretion 8.4 8.0 0.64
Urinary excretion 0.09 0.01 0.04
Retention 10.2 11.3 0.81
Phosphorus intake 3.2 3.3 0.32
Faecal excretion 1.3 1.2 0.15
Urinary excretion 0.03 0.02 0.01
Malpura lambs with similar dry matter and nutrient intake (75 g DM, 5.5 g DCP and 42.4 g TDN/kg W0.75) had 135 g ADG. Growth response in mutton synthetic lambs indicated their ef®cient utilization of feed nutrients for body tissue accretion.
4. Conclusion
Growth performance and feed conversion ef®ciency was higher in mutton synthetic lambs followed by selected Malpura lambs and lower in random bred Malpura lambs. Dry matter intake, nutrient utilization and plane of nutrition in mutton synthetic and selected Malpura lambs were similar.
Acknowledgements
We are grateful to the director of the institute for providing facilities.
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