Immunocastration in Gilts: A Preliminary Study of the Effect of the Second Dose Administration Time on Growth, Reproductive Tract Development, and Carcass and Meat Quality.

Leticia Pérez-Ciria,Francisco Javier Miana-Mena,Maria Angeles Latorre,Olga Mitjana,Giuseppe Carcò,María Victoria Falceto

doi:10.3390/ani11020510

Abstract

Simple SummaryNowadays, a significant proportion of pig carcasses destined to high-quality dry-cured ham elaboration are declared unsuitable for this purpose. The main reason is the lack of backfat thickness, affecting females in particular because males are castrated. Moreover, the estrus in gilts is undesirable because it carries out productive losses. Immunocastration could resolve these problems. The protocol of immunocastration in white-breed gilts is not well established, especially in terms of the second injection. Therefore, the objective of the current trial was to evaluate the impact of immunocastration and to determine the optimum time for the second dose application in gilts intended for dry-cured ham production. In this trial, we concluded that gilt immunocastration is positive, increasing carcass fatness and decreasing reproductive tract development. Moreover, the optimum time to administer the second dose of immunocastration for this type of gilt seems to be between 9 and 12 weeks before sacrifice.Increasing fatness and avoiding puberty are desirable in gilts intended for high-quality dry-cured ham production. A total of 48 Duroc x (Landrace x Large White) females of 26.5 ± 3.70 kg body weight (BW) were used to evaluate the impact of immunocastration and to find the optimum application time of the second dose for immunocastration on growth; sex hormones; reproductive tract development; and carcass, meat, and fat quality. Gilts were allocated to four experimental treatments (n = 12): control (entire gilts, EG) and immunocastrated gilts (IG), providing the second dose at 12, 9, or 7 weeks before slaughter (with approximately 60, 75, or 90 kg BW, respectively). Mean slaughter BW was 125 kg. Immunocastrated gilts had lighter reproductive tracts and greater fat thickness than EG. Fat from IG was more saturated and less polyunsaturated than that from EG. Numerically, gilts immunocastrated 9 and 12 weeks before slaughter presented higher fatness than those immunocastrated 7 weeks before slaughter. In conclusion, immunocastration is a good strategy to improve the fatness of gilts destined to dry-cured ham elaboration, with the optimum time for the second dose application seemingly between 9 and 12 weeks before slaughter.

Highlights

In Spain, the only protected designation of origin (PDO) dry-cured ham from nonautochthonous pigs is “Teruel ham”
It is worth noting that all those authors did not find differences on average daily gain (ADG) between the first and the second dose, which was expected because the first vaccine only primes the pig immune system [27]
When the percentage of gilts with follicles in each category of size was studied, we found that immunocastrated gilts (IG) presented a greater (p = 0.0003) proportion of females with very small follicles and a lower (p < 0.05) percentage of females with small and intermediate follicles than

Summary

Introduction

In Spain, the only protected designation of origin (PDO) dry-cured ham from nonautochthonous pigs is “Teruel ham”. The relevance of fatness in Teruel ham is unquestionable; subcutaneous fat guarantees an adequate dry-curing process and IMF is related to juiciness and tenderness [3,4]. These problems have been found mainly in gilts [5,6,7] because males are castrated (barrows) and castration increases the retention of fat tissue [8]. It consists in the application of several vaccines whose active substance is a gonadotrophin-releasing factor (GnRF) analogue protein conjugate, temporarily suppressing the sexual development [12]

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Conclusion