Nutrition and feeding of lambs for mutton production under tropical climates: A review

The present review focuses on nutrition and feeding of pre- and post-weaner lambs for improving nutrient intake, its utilization and body weight gain. A daily gain of 137 to 163 g can be achieved with feed conversion (feed/gain) ratio of 2.5 to 3.1, dry matter intake of 3.6 to 4.0% of live weight, DCP intake of 42.2 to 59.9 g and ME intake of 4.19 to 5.91 MJ /day and dietary contents of 8.0 to 8.9 MJ ME /kg and 7.5 to 8.5% DCP. To harvest optimum growth rate of pre-weaner lambs, ration should insure nitrogen intake of 12 to 16 g/day. The N intake of 109 mg (range 71 to 134 mg), ME intake of 5.14 kJ (4.19 to 5.91) and DM intake of 4.2 g (between 3.7 to 4.9 g) requires for each g of body weight gain during pre-weaning phase. An ADG of 150 g can be achieved in pre-weaner lambs with FCR of 2.66 from DM intake of 629 g/day or 3.6% of body weight on diet containing 8.22 MJ ME and 80 g DCP /kg. Crossbred lambs during post-weaning phase require dietary ME of 10.4 MJ / kg of diet and DCP of 10.44% to attain an ADG of 112 g (46 to 162 g). Lambs consume 74.68 g DCP and 886 g feed dry matter with N intake of 21.77 g/day accounting to 0.194 g N /g of gain, ME and DCP intake of 84 kJ (range 78.8 to 95.9 kJ) and 0.51 g/g of gain (range 0.35 to 0.60 g), respectively. Dry matter intake in crossbred lambs has poor relationship with average daily gain. Lambs consume 7.26 g dry matter/ g of gain, with mean daily feed intake of 885.9 g for an average daily gain of 125.3 g, which ranged between 86 to 172 g/day. The dry matter intake in lambs was 3.81% which ranged from 3.5 to 4.2% of live weight during post-weaning phase of growth, while optimum level of dry matter intake is estimated as 3.65% of live weight. With optimum dry matter intake, lambs attain ADG of 136 g (108 to 162g/day) and feed conversion ratio (feed/ gain) of 6.94 (5.7 to 8.1). Native lambs during post-weaning phase attain average daily gain of 123 g, which range from 74 to 186 g under optimum nutrition. Under various feeding regimes, lambs daily consume 21.2 g of N (12.7 to 28.0 g), 783 g of feed DM (528 to 1040 g), 7.3 MJ of ME and 65.3 g of DCP, which accounts to 0.177 g of N (0.166 to 0.307 g), 6.6 g of feed DM (4.97 to 9.78 g), 59.6 kJ of ME and 0.62 g of DCP intake/ g of gain. The mean DCP level among various diets fed to weaner lambs ranges between 7.3 to 9.9% with mean DCP of 9.04%. Dietary DCP content of 7.3% seems optimum for better growth. DMI in terms of per cent of live weight ranges from 2.9 to 5.0% with mean value of 3.68%. However, optimum DMI for better growth worked out to 2.9 to 3.5%. On DMI of 2.4 to 5.0 with mean value of 3.52%, native lambs attain ADG of 142 g (97.6 to 196 g). The feed conversion ratio of lambs can be predicted using mathematical equation. In native lambs, dietary requirement of 9.5 MJ ME and 9.04% DCP is estimated for ADG of 124 g with feed conversion ratio of 6.92. With the available research it was evident that native lambs in comparison to crossbred had better opportunity to grow beyond 180 g/ day. Growth potential of native lambs was found to be similar and on some occasions better than crossbreds if exploited under optimum nutrition and feeding management. Thus caution, indeed precaution is needed before introducing cross breeding for enhancing mutton production.