Evaluation of Rye Grain in the Diets of Young Holstein Calves and Lactating Dairy Cows

Sixty young Holstein calves were fed five diets containing various amounts of rye grain up to 18 wk of age. Average daily gain and feed consumption were similar during the first 6 wk; however, calves receiving 60% rye consumed less feed and gained slower than the barley control and 80% roasted rye fed groups in the next 12 wk. Ratios of feed to gain were not different among the five treatments. Apparent digestibilities of the calf diets measured at 10 wk of age were not different; however, calves fed 60 and 80% rye diets tended to show lower digestibilities than the barley control group. Roasting of rye improved digestibilities of acid-detergent fiber and ether extract but slightly reduced protein digestion. Twelve lactating Holstein cows were fed four diets containing 0, 25, 50, and 75% rolled rye in the grain mixtures and grass silage in a switch back design. Grass silage and grain mixtures were offered separately in a 40:60 ratio (dry matter) twice daily but free choice. Replacement of barley with rye in the grain mixtures reduced the total dry matter intake by lactating cows with little effect on average daily milk production, milk composition, and milk prolactin.