High Levels of Grass Silage for Milk Production with No Grain, Medium, and High Grain Feeding. 1. Intake, Milk Production, and Body Weight Changes

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Abstract
In a three-lactation study with 18 Holstein and 6 Guernsey cows grain was fed at 3 levels, 0, 1:6, and 1:3, with maximum grass silage and 5 lb. hay daily, and pasture in summer. For each pound of grain fed, roughage dry matter decreased .23 lb. Average hay equivalent intake was 2.15 lb. per cwt over all groups. Average 245-day 4% FCM production of 12 cows with an estimated potential of 8830 lb. was 6490, 7690, and 8910 lb. on the 3 rations; for 12 cows with an estimated potential of 10,930 lb., production on the 3 rations was 8080, 10,100, and 12,960 lb., respectively. There was no evidence of carry-over effects in the reversal phase or cumulative effects in the continuous phase. There was a close relationship between potential producing ability of the cows and response, measured as the ratio of extra milk produced per pound of grain fed, comparing production on high grain with that on no grain (r = .88). Cows which had a 245-day potential of 8900 lb. FCM gave .58 lb. milk per pound grain fed, whereas those with a 245-day potential of 11,700 lb. FCM gave 1.35 lb. milk per pound grain fed. There was no evidence of diminishing returns in the high-potential cows, and relatively little for the lower-potential cows. Differences in rate of decline in production during lactation were not apparent after 6 wk. Though cows receiving no grain lost considerable weight from the 1st to 4th month, they gained rapidly in later lactation, but still did not regain precalving weight.