Regulation of feed intake in dairy cows II Association between digestible dry matter intake and cellulose digestibility in cows fed increasing levels of grain concentrate

Conrad, H.R.; Hibbs, J.W.; Pratt, A.D.

Journal of Dairy Science 49(9): 1038-1041

1966


ISSN/ISBN: 0022-0302
DOI: 10.3168/jds.s0022-0302(66)88012-8
Accession: 025363361

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Abstract
For part 1 see Abst. 6601, Vol. 34. 2. In one trial 6 cows were given concentrates to appetite and 4 to 7 kg hay and in 2 subsequent trials with a similar number of cows ratios of roughage to concentrate were 2: 1, 1: 1 and 1: 2. The roughage was silage with high dry matter (DM) content. Digestibility of cellulose decreased as proportion of concentrate increased. From results of all 3 trials a multiple regression analysis was done in which the logarithms of productive energy were regressed on the logarithms of intake of digestible DM and percentage digestibility of cellulose. There was a negative partial regression of - 0.96 for digestibility of cellulose and a positive one of + 1.53 for intake of DM. The independent variables accounted for 90% of the total variation. Results indicated that the net energy of dairy rations of hay or silage and concentrates may increase in a non-linear way as the proportion of concentrate in the diet increases. The apparent saving in energy of feed is proportional to the reciprocal of cellulose digested.