[Effect of the replacement of a part of the tallow in a milk supply with tricaprylin or coconut oil on the use of energy and nitrogen by the preruminant calf].

The advantages of using caprylic acid in the feed of preruminant calf have been investigated and compared to those of coconut oil. Two trials were carried out. Trial 1 studied the effect on the appetence and digestibility of a conventional milk replacer when tricaprylin ( TC8 ) was substituted for one-half of the tallow in the replacer. Trial 2 investigated diet digestibility and energy and nitrogen balances in 3 groups of 6 Friesian male preruminant calves each, using two open-circuit respiratory chambers. Group 1 was fed a control diet based on skim-milk powder and tallow (diet 1). In group 2, 2/3 of the tallow was replaced by coconut oil (diet 2). In group 3, 1/3 of the tallow was replaced by coconut oil and the other 1/3 by TC8 (diet 3). Apparent digestibility of energy (94.4 vs 90.7%; P less than 0.05) and nitrogen (93.2 vs 89.7%; P less than 0.10) and energy metabolizability , q (91.6 vs 88.1%, NS) were higher with diet 2 than with diet 1. TC8 intake also favoured a higher apparent digestibility of energy (98.0 vs 92.9%; P less than 0.01) and nitrogen (96.9 vs 93.0%; P less than 0.001) in trial 1 but not in trial 2 where diet 3 had only a slightly higher apparent digestibility than diet 1 (92.9% for energy and 90.7% for nitrogen; P less than 0.10). Adjusted protein gains observed in trial 2 were 52.3 +/- 3.4, 58. 9b +/- 5.3 and 56. 5ab +/- 5.4 kcal/d/kg W0 .75, respectively, for each of the 3 diets; adjusted lipid gains were 66. 8a +/- 4.0, 59.6b +/- 4.2 and 61. 2ab +/- 6.7 kcal/d/kg W0 .75; and adjusted energy gains were 119.2 +/- 6.2, 118.4 +/- 6.1 and 117.5 +/- 6.6 kcal/d/kg W0 .75 (a, b = data with different superscripts are significantly different; P less than 0.05). Metabolizable energy (EM) efficiency for tissue deposition was of the order of 0.67 +/- 0.14, and maintenance requirements amounted to an average of 95 kcal EM/d/kg W0 .75.