RAPESEED OILS LOW OR HIGH IN ERUCIC ACID IN MILK REPLACERS FOR LAMBS: THEIR EFFECTS ON GROWTH, DIGESTION, NITROGEN BALANCE AND INTERNAL ORGANS

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Abstract
Unrefined rapeseed (Brassica napus) oils which contained 0.4 (Oro), 16.0 (Bronowski) and 39.3% (Target) erucic acid were compared with butter oil as the sole source of fat in milk replacers for lambs. Lambs were fed 210 kcal gross energy/kg body weight0.73 per day for 2 wk, and then were killed to determine effects of the oils on internal organs. Lamb body weight gains were similar on the Oro and butter oil diets (37 vs. 41 g/kg0.73/day), but were less on the Bronowski and Target oil diets (32 and 19 g/kg0.73/day, respectively). Nutrients in the Oro oil diet were highly digestible, but were less than those in butter oil (94 vs. 99% apparent fat digestibility). Lambs fed the Bronowski and Target oil diets digested only 74 and 82% of the fat. Lambs fed the butter, Oro, Bronowski and Target oil diets retained 72, 62, 57 and 48%, respectively, of the nitrogen consumed. Livers from lambs fed the Target oil diet were pale and showed fatty tissue infiltration. Lambs fed the Bronowski and Target oil diets had enlarged thyroid glands. It was concluded that Oro rapeseed oil could effectively replace all or part of animal fats used in lamb milk replacers.