Effect of Immunocastration and Diet on Growth Performance, Serum Metabolites and Sex Hormones, Reproductive Organ Development and Carcass Quality of Heavy Gilts

SIMPLE SUMMARY: Currently, a considerable proportion of the carcasses intended for the production of Teruel dry-cured ham are declared unsuitable for this purpose, mainly due to their lack of fat. This problem is detected especially in females, because males are castrated to avoid boar taint, and castration increases fat deposition. Immunocastration (immunization against gonadotrophin releasing factor) could resolve this issue, as that collateral effect has been reported in the literature. Increasing energy or reducing protein and amino acids in the diet could also result in greater fatness. Additionally, immunocastrated gilts could have different feeding pattern to entire females, and thus it is interesting to study feeding plans. Therefore, a study was conducted to evaluate the influence of immunocastration and provided diet on growth performance, serum metabolites and sex hormones, reproductive organ development, and carcass quality. In this trial, it was concluded that immunocastration is a positive strategy to apply in gilts intended for Teruel dry-cured ham production, because it increases growth rate and fatness. On the other hand, irrespective of immunocastration, a rise in dietary energy or a drop in dietary crude protein and amino acids in gilts from 76 to 134 kg could also be beneficial strategies for pig farmers. ABSTRACT: It is desirable to increase fatness in gilts destined for Teruel dry-cured ham production. A total of 192 Duroc × (Landrace × Large White) gilts of 40.3 ± 4.80 kg body weight (BW) were used to assess the impact of immunocastration and feeding on growth performance, serum metabolites and sex hormones, reproductive organ development, and carcass quality. Six treatments were arranged factorially (2 × 3) with two types of gilt (entire gilts (EG) vs. immunocastrated gilts (IG)) and three experimental diets (control vs. high energy vs. low crude protein and amino acids) provided from 76 to 134 kg BW (n = 4 per treatment, being the replicate the pen with eight pigs). Immunocastration was carried out at 58 and 77 kg BW. The IG grew faster and showed lighter reproductive tracts and greater fatness than EG. The experimental feeds had limited effect on carcass quality, but the high-energy diet improved gain-to-feed ratio and the low-protein and -amino-acids diet did not impair growth performance. In conclusion, immunocastration was a better strategy than the tested diets to increase the fatness of gilts intended for Teruel dry-cured ham, although increasing energy or decreasing crude protein and amino acid levels in the diet could be beneficial strategies for pig farmers.