Efeitos da injeção da vitamina A durante a gestaçao ou recem nascidos no desempenho, qualidade da carne, e lipogenesis muscular

Abstract

This study evaluated the effects of VA injection in pregnant cows or neonatal calves on offspring performance, beef quality and expression of genes in the muscle tissue of Angus × Nellore animals finished in the feedlot. Thirty-six calves were randomly assigned in a 3 × 2 factorial design (3 vitamin A protocols and sex). Vitamin A protocols were done as follows: no VA injection (Control); VA injection in cows at 250 d of gestation (VAcow; 2.000.000 IU single dose); VA injection in calves just after birth and 60 d of age (VAcalf; 200.000 IU each dose). Animals were taken to the feedlot with an average body weight of 213±25.7 kg, distributed into 12 pens, with three animals per pen. The feedlot lasted 207 d of feeding. Steers had greater (P = 0.03) average daily gain (ADG). Back fat thickness was greater in heifers (P <0.001) with a tendency for higher values in VAcow animals (P = 0.08). The ribeye area and intramuscular fat content was greater (P = 0.04) in VAcow steers. Being intramuscular fat content similar to the heifers, regardless vitamin A protocol. Besides, the expression of CPT2, DKL1 and ZNF423 genes were downregulated (P < 0.05) in VAcow animals. Meanwhile, the RXRA gene was less expressed (P = 0.05) in VAcow and VAcalf animals. Regarding progeny sex, the expression of the PPARG, SREBF1, CPT2, ACOX, GHR, MYH1, MYH2 genes were higher (P < 0.05) in females. However, PAX7 expression was higher (P = 0.05) in males. In conclusion, VA injection during gestation can improve intramuscular fat in steers and alter the expression of several genes, demonstrating that this vitamin has a long-term effect on the progeny. In addition, vitamin A injection did not increase intramuscular fat in heifers.