Raw, extruded and expanded pea (Pisum sativum) in dairy cows diets

The objective of the study was to evaluate the nutritive value of raw, extruded or expanded peas relative to soybean meal in lactating dairy cows feeding. Twenty four Italian Holstein cows (8 primiparous and 16 pluriparous), 604 &plusmn; 109 kg body weight, 34.5 &plusmn; 2.5 kg/d milk yield, were randomly assigned to four dietary treatments in a 4x4 Latin square arrangement with periods of four weeks and washout period of seven days. Diets were fed ad libitum(5% orts). The bulk of the base diet on a dry matter basis was corn silage (31.2%), alfalfa hay (16.7%), grass hay (4.1%), protein supplement (10.3%), whole cotton seed (8.5%), corn and barley mix (24.9%), soybean meal (3.4%) and calcium soap (0.9%). The pea (2.5 kg/cow/day) partially replaced the soybean meal and totally replaced the barley meal of the base diet. The unprocessed or differently processed pea did not affect the dry matter intake. The extruded pea group had a 3.2% increase (P< 0.05) of the milk yield compared to the control group. When estimated as contrast analysis, the technological treatment (extruded or expanded) on peas did not modify the milk yield and composition. Among pea diets, animal fed the extruded pea had the higher (P< 0.05) milk protein content, although not different than that of the control group. The rumen acetate was reduced (P< 0.05) and the butyrate and valerate were increased (P< 0.05) in animals fed extruded pea compared to the control. No differences were observed among feeding groups on blood parameters except for the cholesterol level higher (P< 0.05) in animals fed the expanded pea diet. There were no effects of diets on milk rennet coagulation characteris- tics. Results support the partial substitution of soybean meal and the total substitution of barley meal with peas in diets for lactating cows with no negative effects on milk yield and composition.