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

Abstract

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.

Influence of Immunocastration and Diet on Meat and Fat Quality of Heavy Female and Male Pigs

“…It is worth noting that the value of PUFA/SFA ratio obtained in both groups was nutritionally acceptable (the target is ≥0.4) [ 35 ]. Some authors [ 27 , 28 ] have obtained results similar to ours. However, others [ 29 , 36 ] did not detect significant influence of female immunocastration on fat quality, which could be due to the use of a different crossbreed [ 29 ] or the smaller interval between the second dose of immunocastration and the slaughter [ 36 ].…”

“…Therefore, when immunocastration is practiced in gilts, the increase of energy or decreased CP and AA in the feed could generate a reduction in cooking or thawing losses. Some authors [ 25 , 26 , 27 ] observed similar cooking losses when EG and IG were fed a standard diet, but it is known that factors relative to the freezing and cooking conditions have great influence in the water losses of meat.…”

“…Meat from IG had similar protein proportion ( p = 0.204) but lower ( p = 0.034) moisture percentage than that from EG. Bohrer et al [ 25 ] and Pérez-Ciria et al [ 27 ] detected this effect on moisture only numerically. Also, meat from IG presented greater ( p = 0.018) IMF proportion than that from EG, which could have a positive effect on texture and appearance of dry-cured hams and could reduce ham’s weight losses during the dry-curing process [ 2 , 4 ].…”

“…Also, meat from IG presented greater ( p = 0.018) IMF proportion than that from EG, which could have a positive effect on texture and appearance of dry-cured hams and could reduce ham’s weight losses during the dry-curing process [ 2 , 4 ]. There is some unanimity that gilt immunocastration seems to increase IMF percentage [ 26 , 28 ], although some authors [ 27 , 29 ] have detected this effect only numerically (not significantly), which may be due to the use of a small number of animals or to the fact that the breed used was very fatty, mitigating the effect. In fact, in these last studies [ 27 , 29 ], fat thickness at GM muscle was significantly higher in IM than in EG.…”

“…There is some unanimity that gilt immunocastration seems to increase IMF percentage [ 26 , 28 ], although some authors [ 27 , 29 ] have detected this effect only numerically (not significantly), which may be due to the use of a small number of animals or to the fact that the breed used was very fatty, mitigating the effect. In fact, in these last studies [ 27 , 29 ], fat thickness at GM muscle was significantly higher in IM than in EG.…”