Resumen

BARAJAS CRUZ, Rubén et al. Effect of shade in ffeddlot pen on growth performance of finishing bulls during the hot season. Zootecnia Trop. [online]. 2010, vol.28, n.4, pp.513-520. ISSN 0798-7269.

With the objective of determine the effect of shade in feedlot pen on growth performance of finishing bulls during the hot season, a 50 days long feedlot trial was performed. Sixty (403,35 ± 2,47 kg) Cebu crossed bull (75% Bos indicus) coming from the same lot with 112 previous fattening-days were used. In a complete randomized block design, in groups of five animals were assigned to two treatments: a) Pens without shade (Control); or b) Pens fitted with roof that provides 3 m2 of shade by animal (Shade treatment). Shade diminished (P = 0,04) air temperature (36,88 vs 35,95 ºC) not modifies relative humidity (P = 0,23). Ending weight and average daily gain were not affected by treatments (P > 0,80). Animals deprived of shade consumed 6% more food (P = 0,07) that shade-protected (8,932 vs 8367 kg/day). Feed conversion was enhanced (P = 0,10) 7,9% by shade (8,247 vs 7,594 kg/kg). Shade increased (P = 0,04) the NEm and NEg retained from the diet in 6,4 and 8,5%, respectively. Usage efficiency of NEm (observed/expected) was 0,92 and 0,98 for treatments without and with shade, respectively. Carcass weight and carcass dressing were not modified (P > 0,80). It is concluded, that the use of shade in feedlot pen during hot season is necessary to help the bovines to cope heat stress and mitigate its effects on growth performance during the finishing.

Palabras clave : shade; finishing bulls; growth performance.

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