The aim of thiswork was to evaluate the effect of bypass fat on milk production and compositionin Bergamasca ewes. It was used 77 ewes which were distributed by parity andage orders in two groups: control diet (C): corn silage and concentrate; andbypass fat diet (GP): corn silage + concentrated + bypass fat (35 g/ewe/day)added in the concentrate. Diets were isoenergetic and isonitrogenous with 70%of total digestible nutrients and 16% of crude protein on dry matter basis.Lambs were kept to their mothers until 45 days of age, when they were weaned.Forty-eight hours after lambing, ewes were milked once a day at 7:00 a.m. fordaily measurement of milk production during 60 days. Milk samples were weeklycollected for analysis of centesimal composition and casein content. The bypassfat diet presented higher daily average milk production after weaning (0.531vs 0.489 kg/day), however, average milk production of the whole experimentalperiod was not different between control and bypass diet (0.453 vs 0.468 kg/day,respectively). No differences were observed among control and bypass diets formilk fat content until the 6th week of lactation; they were observed only afterweaning. Alpha (α)and beta (β)casein content presented differences between control and bypass diet groups(31.73 vs 18.56 Kda for alpha casein and 32.67 vs 26.44 Kda for beta casein,respectively). Bypass fat added to diet do not change milk production and centesimalcomposition until weaning.
