A study of the energy requirements of weaned lambs

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Abstract
SUMMARY Two experiments were carried out to study the energy requirements of young fattening lambs for maintenance and production. Forty weaned lambs were used in each experiment, 20 being allocated to a high level of feeding (900 g air-dry feed per day) and 20 to a low level (540 g). The animals used in Experiment 1 were approximately 12 months of age and their mean live weight was 35·3±4·03 kg. Those in Experiment 2 were approximately seven months of age and their mean live weight was 36·7 ± 4·57 kg. Experiment 1 continued for 100 days and Experiment 2 for 47 days. Three digestibility trials, involving three animals from each feeding level, were carried out during the course of each experiment to obtain precise estimates of digestible organic matter intake (DOMI). The estimated mean DOMI required for maintenance for a 45-kg lamb was 400 g (0·88 lb) or 1500 kcal metabolizable energy per day. The estimated maintenance requirement was not affected by the age of the animal. The DOMI required for production ranged from 1·55 kg per kg live-weight gain for the younger animals to 1·71 kg for the older animals. Both these requirements were lower than those obtained by other workers and those suggested by the Agricultural Research Council (1965).