Effect of coconut oil in the post-weaning starter diet on growth and carcass qualities of male lambs, weaned early and intensively fattened in winter.

The influence of medium-chain fatty acids (5% coconut oil) introduced in a starter diet (ALc) for 21 d after weaning was investigated in 230 Lacaune male lambs. They were weaned early, intensively fattened during winter and slaughtered at a constant live-weight (39 kg). Comparisons have been made regarding the individual growth rates and carcass qualities with an isocaloric and isonitrogenous reference diet (ALr) from lamb sub-samples. During the period of actual starter diet utilization, ALc induced a higher growth rate (+ 59%) independently of the weaning weight (Wto). The feed conversion ratio was lower with ALc (P < 0.01). The induced weight difference remained after the lambs were fed on the same finishing diet. The growth pattern for the entire fattening period was more regular with ALc, particularly when lamb weight was medium (12 kg) of light (Wto < 11 kg) at weaning. The volatile fatty acid pattern in the rumen fluid over time (sampling with a rumen vacuum pump) and throughout the transition between starter and fattening diets (Rusitec procedure) did not show a clear coconut oil effect. ALc induced a slight increase in the external fat layer at slaughter 2 months later, especially in heavy lambs. Firmness and colour of subcutaneous fatty tissue were not different, but ALc tended to result in firmer and whiter carcasses in the case of the heavier lambs at weaning.