Sixteen lactating Sarda ewes were fed four diets differing in the forage/concentrate ratio (two diets 75/25, two diets 60/40, on a DM basis) and in soybean oil supplementation (two diets with 100 gd-1 oil, two diets with no oil), in a 4 4 Latin square design. The inclusion of soybean oil in the diet resulted in a significant increase of both daily milk yield and fat corrected milk (.01), while diets with higher concentrate content resulted in lower levels of milk production (.05). Milk fat content did not differ among treatments, while milk fat yield was increased when ewes consumed oil added diets (P<0.01). Milk protein content was lower when oil was added to the diet (.01), which was attributed to a dilution effect, while milk protein secretion did not differ among treatments. Dietary soybean oil modified the milk fatty acid composition towards a lower level of medium chain and saturated fatty acid and a higher level of PUFA and CLA, confirming how an adequate dietary strategy can broadly modify sheep milk quality towards a more desirable composition for human health. In particular, soybean oil in the diet resulted in a significant increase of both rumenic acid (cis-9, trans-11 CLA) and vaccenic acid (trans-11 C18:1) in milk fat. Interactions among forage and oil resulted in a significant increase in rumenic acid and vaccenic acid with the HF/O diet and trans-10 C18:1 and trans-10, cis-12 CLA with the LF/O diet, probably due to a shift in rumen biohydrogenation of linoleic acid.
Effect of forage/concentrate ratio and soybean oil supplementation on milk yield, and composition from Sarda ewes
BANNI, SEBASTIANO;
2006-01-01
Abstract
Sixteen lactating Sarda ewes were fed four diets differing in the forage/concentrate ratio (two diets 75/25, two diets 60/40, on a DM basis) and in soybean oil supplementation (two diets with 100 gd-1 oil, two diets with no oil), in a 4 4 Latin square design. The inclusion of soybean oil in the diet resulted in a significant increase of both daily milk yield and fat corrected milk (.01), while diets with higher concentrate content resulted in lower levels of milk production (.05). Milk fat content did not differ among treatments, while milk fat yield was increased when ewes consumed oil added diets (P<0.01). Milk protein content was lower when oil was added to the diet (.01), which was attributed to a dilution effect, while milk protein secretion did not differ among treatments. Dietary soybean oil modified the milk fatty acid composition towards a lower level of medium chain and saturated fatty acid and a higher level of PUFA and CLA, confirming how an adequate dietary strategy can broadly modify sheep milk quality towards a more desirable composition for human health. In particular, soybean oil in the diet resulted in a significant increase of both rumenic acid (cis-9, trans-11 CLA) and vaccenic acid (trans-11 C18:1) in milk fat. Interactions among forage and oil resulted in a significant increase in rumenic acid and vaccenic acid with the HF/O diet and trans-10 C18:1 and trans-10, cis-12 CLA with the LF/O diet, probably due to a shift in rumen biohydrogenation of linoleic acid.
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