Effects of feed composition and stage of lactation on the short-term feeding behavior of dairy cows.

Twenty Holstein-Friesian cows were assigned to one of four feeding groups throughout lactation in a full change-over experiment using two total mixed diets. The low concentrate total mixed diet contained 100 g of concentrate/kg of fresh matter, and the high concentrate total mixed diet contained 300 g of concentrate/kg of fresh matter. The remainder of the total mixed diet was grass silage. The two changeover groups switched total mixed diets at 153 d of lactation; the other two treatment groups remained on their assigned diets throughout lactation. For analysis of short-term feeding behavior, four periods of 3 wk each were identified. The midpoints of these periods were -102, -18, 18, and 102 d from the changeover. The concentrate content of the total mixed diet significantly affected dry matter intake and all short-term feeding behavior variables. Cows that consumed the high concentrate total mixed diet had fewer but longer visits to the feeders and ate more feed per visit than did cows consuming the low concentrate total mixed diet. With one exception, no significant effect of stage of lactation was detected for any of the short-term feeding behavior variables. Despite a highly significant decline in dry matter intake as lactation progressed for cows consuming the high concentrate total mixed diet, there were no interactions between total mixed diet and stage of lactation for any of the short-term feeding behavior variables. Large differences in feeding behavior were detected between cows consuming the same total mixed diet. These last two findings suggest that the use of short-term feeding behavior variables to predict daily intake is unlikely to be successful.