Castration alternative offers faster growth, more quality meat in study
A novel castration alternative allows male pigs to grow faster and produce more high-quality meat than physically castrated or entire hogs, a new analysis shows.1
The technology involves administering a protein compound that works like a vaccine2 to inhibit gonadotropin releasing hormone (GnRH) in male pigs, thereby temporarily delaying puberty. This blocks the production of the two naturally occurring compounds (androstenone and skatole) that cause boar taint, an unpleasant odor that can occur when cooking meat from sexually mature male pigs.
Carried out by experts from Germany, Belgium and the US in collaboration with Zoetis, the meta-analysis — published in journal Research in Veterinary Science — examined 78 studies that made direct comparisons between physical castrates, entire males and pigs that had been given the boar-taint-blocking vaccine.
The analysis looked at performance and carcass data from producers and slaughterhouses of varying scales, including conventionally raised pigs as well as heavy-weight pigs used in the production of high-quality cured products.
“While previous work has confirmed vaccinated pigs grow faster and have better feed conversion ratios than physically castrated males, we wanted to update the results to focus on aspects that are most relevant to pig producers and slaughterhouses,” said Alvaro Aldaz, DVM, one of the publication’s authors and a swine veterinarian at Zoetis.
“Therefore, in addition to evaluating growth rates and feed conversion, we also assessed boar taint across the different systems by analyzing the number of pigs that exceeded the consumer threshold for detecting androstenone and skatole.”
The analysis revealed that compared to physically castrated males, vaccinated pigs gained an additional 32.5g/day and yielded 0.63kg more high-quality meat.
Meanwhile, feed conversion over the entire feeding period was significantly better in the vaccinated pigs, resulting in an average of 0.23kg less feed consumed per kg of weight gained.
Compared to entire males, vaccinated pigs gained an additional 65g/day. While feed conversion ratios were slightly higher (+0.075kg/kg), immunized pigs yielded 1.39kg more valuable meat than physical castrates.
Among heavy-weight (97kg+) pigs, the analysis found that vaccinated pigs were leaner than their physically castrated counterparts, but gained 0.3kg more ham and met back and intramuscular fat requirements for the production of high-quality cured pork products.
There was no difference in boar taint detection between carcasses from vaccinated pigs and physical castrates. As expected, significantly higher boar taint levels were associated with meat from entire males.
More than a castration alternative
“Results from our meta-analysis confirm growth performance advantages of vaccinated pigs compared with physically castrated and with entire male pigs, and reveal a higher gain of valuable meat and a similar very low risk of boar taint as estimated for physically castrated pigs,” the researchers concluded.
Aldaz added, “These findings confirm the benefits of vaccinating pigs to control boar taint, not only as a castration alternative, but also as a tool to enhance meat yield and quality in entire male production. With interest in castration alternatives growing in Europe and elsewhere, our analysis confirms that immunizing against GnRH offers producers a safe and effective option for maximizing the growth and efficiency benefits of entire male production, while minimizing the risks.”
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1 Poulsen et al. “The effect of immunization against gonadotropin-releasing factor on growth performance, carcass characteristics and boar taint relevant to pig producers and the pork packing industry: A meta-analysis.” Research in Veterinary Science, vol. 119: 182-195.
2 The compound is classified as a vaccine in all major swine markets except the US, where it is registered as a pharmaceutical.
Posted on April 3, 2019