Summary. Non-esterified fatty acid (NEFA) contents were determined (1) in cow, goat, mare and human plasmas or sera and (2) in bovine serum albumin solutions by thin-layer and gas-liquid chromatographic methods which were compared with 6 chemical methods of determination and 2 enzymatic methods (manual and automatic). The chemical methods combined two extraction techniques (isopropanol-heptane and silicic acid-diisopropyl ether) and three determination methods (titrimetry and colorimetry using either phenol red or copper soaps). Correlations between the nine various methods were high, but in some cases regression lines were different from the bissector and species-dependent. The putative occurrence of interfering compounds or the possible effect of between-species differences in NEFA composition have been discussed. The choice of a fast method depends primarily on practical considerations, but the need to standardize each method for a given species has been stressed. Automatic enzymatic assay seemed to be suitable for routine analyses.Introduction.

Summary. Effect on energy and nitrogen balances of substituting tricaprylin or coconut oil for a part of the tallow in a milk replacer for 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 appetibility 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 11. 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 < 0.05) and nitrogen (93.2 vs 89.7 % ; P < 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 < 0.01) and nitrogen (96.9 vs 93.0 % ; P < 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 < 0.101.Adjusted protein gains observed in trial 2 were 52.3 + 3. Introduction.

Summary. Ten groups of 10 growing male rats (65 g) were fed ad libitum either a control diet or rapeseed diets (15 mM glucosinolates/kg DM) supplemented either with I-alone, I--and Cu ++ (2 levels), I-+ Cu ++ and methionine or I-and Fe ++ (2 levels) ( (table 2).I-supplementation did not prevent the deleterious effects of rapeseed meal feeding. I-and Fe+ + + supplementation had detrimental effects on food intake, live weight gain and kidney weight, but beneficial effects on liver and thyroid weights and on plasma thyroid hormone levels.The low level of I-and Cu + + supplementation suppressed the depressive effects of rapeseed meal on food intake and live weight gain and reduced the deleterious effects on kidney, liver and thyrdfd weights and on plasma thyroid hormone levels, whereas the higher level almost suppressed them. The results are discussed considering the likelihood of a bivalent cation effect on glucosinolates.Introduction.

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Summary — 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 2-and 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 T 2 ) 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 3-and 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 gain/kg DM intake, respectively with C i , 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 C 2 , C0 2 or T 2 . Coconut oil diet led to a 13 or 19% (P < 0.01) higher nitrogen balance respectively in 3-or 6-week-old lambs; tricaprylin resulted in a slight increase of nitrogen balance in 3-week-old lambs (+ 11 %, P < 0.10). Growth