Efeito da imunização anti-GnRH e da suplementação de ractopamina no desempenho e atividade reprodutiva de fêmeas suínas em terminação

Abstract

The objective of this study was to assess the effects of immunization against GnRF and ractopamine hydrochloride (RAC) on feed intake, growth performance, and reproductive characteristics of market gilts. Seventy-two gilts were initially weighed and allotted to a pen (2 pigs/ pen) in a 2 x 2 factorial design. The treatments were: non-immunized gilts fed 0 mg RAC per kg in the diet; non-immunized gilts fed 10 mg RAC per kg in the diet; immunized gilts fed 0 mg RAC per kg in the diet; immunized gilts fed 10 mg RAC per kg in the diet. Immunization was performed at 15 (V1) and 19 wk (V2) of age, daily boar exposure (DBE) and RAC supplementation occurred from 21 to 25 wk of age, and the animals were slaughtered at 25 wk. Gilts fed RAC had improved ADG and efficiency during the additive supplementation (+112 g, P < 0.05; +12.54%, P < 0.01), from V2 to slaughter (+93 g, P < 0.01; +9.94%, P < 0.01) and during the entire period (+58 g, P < 0.05; +5.42%, P < 0.05), compared with no-RAC group, regardless of immunization. Comparing immunized and non-immunized categories, the immunized group showed a worse F:G ratio (-8%, P < 0.05) from second dose to DBE, greater ADFI (+ 430 g, P < 0.01), and ADG (+128 g, P < 0.01) from DBE to slaughter. There was alsoimproved ADG and ADFI, respectively, from second dose to slaughter (+82 g, P < 0.05; +390 g, P < 0.01), and greater ADFI (+230 g, P < 0.001) from first dose to slaughter. Ovarian and uterine weight werereduced (P < 0.01) 81.71 and 92.81%, respectively, in immunized gilts compared with non-immunized ones. Estrus was reduced by 82.06% (P < 0.01) in immunized gilts compared with control gilts. This data demonstrates that gilts immunized against GnRF had suppressed estrus, less developed reproductive organs, and improved daily gain and feed intake, primarily after the second dose. Additionally, RAC supplementation led to improved daily gain and feed efficiency in heavy weight finishing gilts.