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 +- 109 kg body weight, 34.5 +- 2.5 kg/d milk yield, were randomly assigned to four dietary treatments in a 4 x 4 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 soybean meal and totally replaced barley meal of the base diet. The unprocessed or differently processed pea did not affect dry matter intake. The extruded pea group had a 3.2% increase (P0.05) of milk yield compared to the control group. When estimated as contrast analysis, the technological treatment (extruded or expanded) on peas did not modify milk yield and composition. Among pea diets, animal fed extruded pea had the higher (P0.05) milk protein content, although not different from the one of the control group. Rumen acetate was reduced (P0.05) and butyrate and valerate were increased (P0.05) in animals fed extruded pea compared to control. No differences were observed among feeding groups on blood parameters except for cholesterol level, higher (P0.05) in animals fed the expanded pea diet. There were no effects of diets on milk rennet coagulation characteristics. 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