The effect of bypass fat in the diet on milk composition of dairy ewes.

The objective of this work was to investigate the effect of dietary bypass fat on milk composition of Bergamasca dairy ewes. The experiment was carried out at the Ewe Milk Production Research Unit of the College of Veterinary Medicine and Animal Science of São Paulo State University. Eighty Bergamasca ewes were divided into two groups and fed one of two diets: A - balanced diet (concentrate + corn silage); or B - same diet as A, with bypass fat (35 g/ewe/day) added to the concentrate. Lambs were kept with their mothers on pasture during daytime and were separated at night. After the morning milking, the lambs were returned to their mothers and weaned at 45 days of age. The ewes were machine-milked for 60 days. Milk samples were collected once weekly for analysis of lactose, protein, fat and total solids. The data were analyzed by one-way analysis of variance. For the first 45 days of lactation, significant differences (P<.05) were observed for protein and lactose, with ewes fed diet B having higher means, whereas differences were not observed (P>.05) for fat and total solids. After 45 days of lactation, significant differences (P<.05) were found only for fat and lactose, which may be explained by the higher milk production of ewes fed diet B because some researchers have reported a negative correlation between production and concentration of milk constituents. [ABSTRACT FROM AUTHOR]