LOPEZ, O et al. Effect of the supplementation with concentrate feed on the in vitro fermentation of diets for cows under silvopastoral system conditions. []. , 37, 4, pp. 426-434. ISSN 0864-0394.

The effect of the supplementation with concentrate feed (C0: control; C5: 5 % of the ME requirements; C10: 10 % of the ME requirements) on the ruminal degradability of diets for dairy cows based on Panicum maximum and Leucaena leucocephala, was evaluated through the in vitro gas production (GP) technique. To formulate the diets it was assumed that the animals weighed 480 kg, that they were in their third lactation and produced 10 kg of milk per day, which is representative of the dairy farm where the feed samples were taken. The in vitro GP, the gas production parameters (b, c, L), the in vitro dry matter digestibility (IVDMD), the metabolizable energy (ME) and the short-chain fatty acids (SCFA) were estimated, which were compared through a variance analysis, in a completely randomized design with three treatments and three repetitions. The diets were incubated in vitro, and for such purpose ruminal inoculum from clinically healthy Limousine cows was used. The supplementation with concentrate feed linearly increased (p < 0,01) the gas production at 24 h and 48 h; while at 96 h the effect was quadratic (p < 0,05), with the lowest value for C5. The IVDMD and ME (p < 0,001), as well as the SCFA (p < 0,05), increased linearly with the increase of the concentrate feed, although in C10 the IVDMD was lower; nevertheless, the ME and SCFA increased. It is concluded that in diets based on P. maximum and L. leucocephala the addition of concentrate feed in 5 % did not have effect on the ME or on the production of SCFA, for which it is necessary to add at least 10 % of this supplement to the diet, based on the ME requirements of the animals.

: Panicum maximum; Leucaena leucocephala; gasses; milk production.

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