Milk yield and composition of dairy cows fed concentrate based on high moisture wheat or high moisture corn

Thirty-six Ayrshire cows were assigned to 18 pairs and were blocked within parity (5 pairs of primiparous heifers and 13 pairs of multiparous cows); pairs had similar calving dates. The study, which was conducted over 3 yr, was designed to determine the effects of high moisture grain on milk yield and composition and to determine in vitro DM digestibility and ruminal degradabilities of DM, N, and starch of high moisture grains. Treatment diets consisted of isonitrogenous and isoenergetic concentrates that were based on high moisture wheat or high moisture corn. Both groups were fed a mixture of grass silage, grass hay, protein supplement, and a vitamin and mineral mix for ad libitum intake. Treatment diets were fed from wk 4 to 29 and from wk 4 to 37 of lactation for cows in first and second lactations, respectively. There was no interaction between treatment diet and year of lactation. Cows fed high moisture wheat had higher 4% FCM than did cows fed high moisture corn. Milk composition was similar for the two treatment diets. Ruminal degradabilities of DM and starch were higher for high moisture wheat than for high moisture corn. In vitro DM digestibility was higher for high moisture wheat (90.5%) than for high moisture corn (71.6%). This greater digestibility contributed to the higher milk yield of dairy cows fed high moisture wheat.