Resumen

ORTIZ, Briceida et al. Effect of the potency of zeranol or trembolone + estradiol implants on performance of feedlot hair lambs under hot weather condition. Zootecnia Trop. [online]. 2013, vol.31, n.1, pp.71-77. ISSN 0798-7269.

Thirty six lambs ¾ Katahdin x ¼ Pelibuey (24,23 ± SD 2,18 kg) were used in a 28 days trial to explore the infl uence of the potency of the implant on feedlot performance of Katahdin x Pelibuey lambs under hot weather condition. The lambs were placed in elevates crates (0,6 m) following a complete randomized block design they were randomly assigned to treatments follows: 1) no implanted lambs (control), 2) lambs with an estrogenic middle potency-implant, those 12 mg of zeranol were applied (Zeranol); and 3) lambs with an mixed (androgenic + estrogenic) high potency-implant, which received 40 mg of trembolone and 8 mg of estradiol (TE). The fi nal weight was increased linearly (P<0,02) as the implant potency was increased. The animals that received implant with high potency had 27,8% higher dairy weight gain (P<0,03) compared with lambs that no received implant. The daily gain of lambs increased linearly (P<0,03) as the potency of implant that they received was increased. The dry matter intake tended to be increased (P<0,10) jointly with implantpotency increment. Feed conversion (Intake/gain) was promoted in a linear manner (P<0,02) as implant potency was increased. It is concluded that high potency Trembolone-estradiol implants, are recommendable to increase feedlot performance of intensively raised hair sheep under hot weather condition.

Palabras clave : Hair sheep; zeranol; trembolone; intensively raised; hot weather.

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