Suplementação de novilhas no período seco e transição seca-águas

Abstract

The objective was to evaluate the effects of the concentrate supply at 1.0; 1.5; 2.0% of body weight and ad libtum, on the performance and characteristics of the carcass and meat of Nelore heifers finished in the dry period and dry-water transition. Nelore heifers were used, with initial mean body weight of 250.61 ± 26.52 kg. Four animals were slaughtered early in the study to be used as reference. The design was completely randomized, with 20 animals per treatment. The trial in the dry season lasted 112 days, divided into four periods of 28 days. All animals that did not reach the weight of 330 kg at 112 days (Phase I), continued for 45 days receiving supplementation in 1% of the BW, for a total of 157 days of termination (Phase II). In phase I, there was no effect of supplementation levels (P>0.05) for the mean daily gain, with a mean of 0.640 kg day-1. The final weight, hot carcass weight and yields, average daily carcass gain and fat trimming, were also not affected by the increase in supplementation levels (P>0.05). In phase II, when all the animals started to receive 1% of BW in supplement, the average daily gain was similar (P>0.05) between the treatments, with a mean of 0.600 kg day-1. The whole carcass weight, hot carcass weigth, cold carcass weight and yield, fat cutting, dripping loss, and subcutaneous fat thickness showed no difference between the levels of supplementation (P>0.05). The special hindquarter, forequarter, spare ribs, muscle, fat and bone in relation to 100 kg of cold carcass presented similar results (P>0.05). The same pattern of the variables was observed when the animals were supplemented in 1% of the BW in the subsequent period (P>0.05). In relation to pH, luminosity (L*), the red level (a*) and the yellow intensity and yellow (b*) chroma (C*), tone angle (H*), shear force, thawing and cooking losses, and chemical composition of the meat were also not observed influence between levels of supplementation, when offered at increasing levels, or when supplied in 1% of the BW (P>0.05). In the aging meat results, losses of exudates showed a quadratic effect for the days of aging, in which there was a greater loss for day 1 (P<0.05). There was no interaction of supplementation levels and aging times for the color coordinates L*, a* and b* (P>0.05), however, the aging days decreased the values of L* and b*, increased ΔE, and presented quadratic effect for tone angle (H*) (P<0.05). The aging also reduced the shear force and the pH of the meat (P<0.05). The strategy of finishing heifers in pastures in the dry season and in the dry-water transition season using 1% of body weight was positive, because the use of levels of supplementation above 1% of body weight the performance and characteristics of the carcass did not differ. The use of supplementation above 1% of body weight was economically unfeasible for the conditions of the present study. The aging process reduced the pH and modified the color, but most important changes occur between 1 and 14 days. Also, it improved the softness of the meat by reducing the shear force.