R. Souchet

Effects of substitution of tricaprylin or coconut oil for tallow in milk replacers offered to preruminant lambs

mdash; The effects of tricaprylin or coconut oil on the digestibility of milk-substitute constituents, nitrogen balance, growth-rate and feed efficiency before weaning have been studied in 2 successive trials using 12 male Charmois (trial 1) and 20 male Limousin and Romanov x Limousin preruminant lambs (trial 2). In trial 1, 3 different diets (C i, T,a, T,b) containing 230, 161 or 92 g tallow and 0, 69 or 138 g tricaprylin per kg dry matter (DM) were prepared. Digestibility of the milk-substitutes was studied in 2and 3-week-old lambs, and growth-rate and feed efficiency were studied up to weaning. In trial 2, 3 other diets (C 2, C0 2 and T2) containing 249, 166 or 166 g tallow, 0, 83 or 0 g coconut oil, and 0, 0 or 93 g tricaprylin per kg DM, were prepared. They were used for digestibility and nitrogen balance determination in 3and 6-week-old lambs. Growth rates and feed efficiency were obtained between 10 days and weaning. In trial 1, the level of intake was 14 and 29% higher in lambs fed T1 a and Ti b than in lambs fed Ci . Apparent digestibility of the diets was significantly higher (P < 0.05) after tricaprylin substitution for part of the tallow. The extent of the effect increased with the level of tricaprylin (P < 0.025). Mean apparent respective digestibilities of energy and nitrogen were 0.907, 0.947 or 0.971 and 0.924, 0.961 or 0.972, growth rates 195, 265 or 282 g/day (P < 0.05) and feed efficiency 670, 797 or 725 g gain/kg DM intake, respectively with Ci, T,a or T!b milk substitutes. In trial 2, tricaprylin intake did not have any effect; coconut oil led to a slight increase in nitrogen digestibility, but only in 6-week-old lambs (from 0.970 to 0.979; P < 0.05). Mean apparent respective digestibilities of energy and nitrogen were 0.967, 0.969 or 0.972 and 0.965, 0.971 or 0.967 respectively for C2, C0 2 or T2. Coconut oil diet led to a 13 or 19% (P < 0.01) higher nitrogen balance respectively in 3or 6-week-old lambs; tricaprylin resulted in a slight increase of nitrogen balance in 3-week-old lambs (+ 11 %, P < 0.10). Growth-rates and feed efficiency were respectively 179, 211 or 199 g/day and 25.8, 26.7 or 27.0 g gain/MJ GE for C2, C0 2 or T2.