Energy cost of protein deposition in the pre-ruminant and young ruminant lamb

P.V. Rattray and K.T. Jagusch

Ruakura Agricultural Research Centre, Hamilton

E-Mail:

Proceedings of the New Zealand Society of Animal Production. 1977, 37: 167-172

Comparative slaughter data for 105 young lambs fed milk or milk plus pasture diets and for 48 early weaned lambs fed pasture or lucerne were used to estimate the ME cost of fat and protein deposition by multiple regression analysis. The cost of fat deposition did not differ between diets and averaged 34 ± 9 kJ ME/g fat. The ME cost of protein deposition was almost three times greater on the herbage diets (142 ± 25 kJ ME/g protein) than on the milk based diets (51 ± 10 kJ ME/g protein). The majority of early weaned lambs were in negative energy balance, losing fat but still gaining protein. High estimates of maintenance and low estimates of K_m (50%) were obtained for these lambs by using regressions of energy gain or log heat production on ME intake, because in these methods the ME cost of protein deposition appears as part of the maintenance requirement. Multiple regression analysis separated these two processes. For the milk diets and herbage diets K_m was approximately 80 and 70%, while K_g was 70-80 and 30%, respectively.

Keywords: NZSAPAB;

Last Updated 24-08-2000