Effect of different animal protein sources on digestive and metabolic parameters and milk production in dairy goats

Twenty-eight multiparous goats were fed a diet containing corn silage and concentrate with a ratio of 1 : 1 on a DM basis ad libitum. Two commercial concentrates were prepared using meat meal (MM) and hydrolyzed feather meal plus blood meal (FBM). Twenty-seven percent of total N in both diets was supplied by animal protein sources. No differences were observed in voluntary intakes, whereas DM, protein and fibrous fraction digestibility was slightly lower in animals fed FBM concentrate. Total VFA and NH3-N concentrations were slightly lower in the rumen fluid of goats receiving FBM diet but rumen pH was significantly higher (6.58 vs. 6.47; P<0.05) in this group as well as the acetate: propionate ratio (3.96 vs. 3.63). N excretion in milk was higher for dairy goats fed FBM concentrate than in those fed MM concentrate (29.7 vs. 27.7% of N intake, respectively; P< 0.05). Milk production was similar for both treatments but protein and casein contents were significantly higher (P<0.05) in go...