77 Ruminal fermentation pattern of Nellore cattle previously submitted to either nutritional restriction or intake concentrate feedstuffs prior to adaptation to high-concentrate diets.

Abstract

The objective of this study was to evaluate the effect of nutritional restriction or consumption of concentrate ingredients prior to the adaptation period to high-concentrate diet on ruminal fermentation pattern of cannulated Nellore cattle.The experiment was designed as a replicated 3 x 3 Latin squares, in which six 15-mo-old Nellore steers (323 ± 23 kg) cannulated in the rumen were fed according to the treatments: Restriction (Tifton hay fed at 1.4% BW + supplement); Control (Tifton hay fed ad libitum + supplement) and Concentrate (Tifton hay fed ad libitum + 0.5% BW of concentrate and supplement).Each period of this study lasted 33-d with two 10-d washout interval, divided as follows: 14 days of pre-adaptation (when treatments were applied), 12 days of adaptation diet (72% concentrate for 6-d and 79% concentrate for 6-d) and 7 days of finishing diet (86% concentrate). Rumen fermentation pattern was assessed by continuously measuring ruminal pH via data loggers and by collecting samples for determination of SCFA concentrations. Measurements were taken on days 16 and 28 of each period. No treatment effect was observed (P>0.05) for butyrate concentration and mean ruminal pH on both adaptation and finishing periods. Cattle receiving concentrate on pre-adaptation presented (P<0.05) greater concentrations of acetate (Control: 66.09b, Concentrate: 69.80a, Restriction: 68.63b) and propionate (Control: 22.45b, Concentrate: 25.47a, Restriction: 24.44ab) than cattle on control group in the adaptation period. In the finishing period, cattle previously restricted had lower (P=0.05) propionate concentration than those on control group (Control: 28.34a, Concentrate: 25.89ab, Restriction: 25.09b). Acetate concentration was not affected (P=0.83) in the finishing period. Cattle previously restricted had (P=0.01) the largest pH area below 5.2 expressed as pH x h/d (Control: 0.01b, Concentration: 0.05b, Restricted: 11.66a) in the adaptation period. Consumption of concentrate prior to adaptation did not negatively impacted ruminal fermentation pattern.