Utilization of raw or heat-treated starch fed in liquid diet to preruminants 1. Kids

Twenty Saanen kids at average age of 7±1.5 days were fed 19 days a commercial milk replacer (MR) or a milk replacer in which 20% or 40% was substituted by heat-treated, expanded starch-soy mixture (20ES, 40ES), or 40% untreated starch-soy mixture (40US). Soy concentrate contained 65% protein and was toasted to inactivate trypsin and chymotrypsin inhibitors. Weight gain and food utilization of kids fed 20ES diet were the highest but did not differ significantly from kids fed MR. Substituting 40% of the milk replacer by expanded or untreated starch-soy mixtures reduced food consumption, body weight gain and food utilization 40%–50%. During weaning period, differences in body weight gain between the groups were smaller and non-significant, but performance of the 20ES group was still the best in comparison with the other groups. Apparent digestibility of dry matter, ash and protein was higher in the MR group than in the other groups. Heat treatment did not affect apparent digestibility of starch. Blood glucose levels were higher before and after feeding in the MR and 20ES groups than in the 40ES and 40US. Peaks of blood glucose were lower and delayed in groups fed starch compared with the MR group. The pH of rumen liquor dropped after meals more in the 40US and 40ES than in the MR and 20ES kids. The drop was accompanied by concurrent increase in concentration of total volatile fatty acids. During the suckling period, kids fed MR, 20ES and 40US were more active before than after meals. They stood more, none of them was sleeping, and only a few were sitting before meals. These differences were minor in the 40ES group. Differences in behaviour before and after meals were much smaller in all groups during the weaning period; 40ES and 40US groups spent more time in eating concentrate before and after the liquid meal than MR and 20ES kids.