Animal Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Scheldeweg 68, 9090 Melle, Belgium.
Animal Sciences Unit, Flanders Research Institute for Agriculture, Fisheries and Food (ILVO), Scheldeweg 68, 9090 Melle, Belgium.
Animal. 2022 Jan;16(1):100437. doi: 10.1016/j.animal.2021.100437. Epub 2022 Jan 7.
Immunocastration, a technique consisting of two vaccinations against gonadotropin-releasing hormone (GnRH), can be used as alternative to surgical castration of piglets. It reduces boar taint and allows higher economic and ecological efficiency compared to barrows. The feeding strategy of immunocastrates, however, can still be improved. After second vaccination, when immunisation becomes fully effective, feed intake of immunocastrates increases sharply. This study aimed to investigate whether energy intake of immunocastrates after second vaccination could be reduced by lowering the dietary energy level of the finishing phase, without negatively affecting animal performance and quality of pork production. We hypothesised that immunocastrates already reach their limits in voluntary feed intake after second vaccination, and therefore would not be able to compensate the lower dietary energy level, in contrast to barrows. Therefore, this study aimed to assess the effect of high-energy diet (HE, net energy (NE) = 10.2 MJ/kg) compared to low-energy diet (LE, NE = 8.8 MJ/kg) in barrows and immunocastrates and as a reference, gilts and entire male pigs on a standard high-energy diet were included. CP and standardised ileal digestible amino acid levels were similar in both diets. For each treatment, eight pen replicates of six pigs per pen were evaluated on performance, carcass quality, meat and fat quality, digestibility, economic and ecological sustainability, behaviour and effectiveness of immune response. No difference in feed intake of immunocastrates between LE and HE could be demonstrated. As a result, daily energy intake of immunocastrates was higher on HE compared to LE, which resulted in a higher daily gain on HE. Feed conversion ratio (FCR) of immunocastrates on HE did not differ significantly with FCR of entire males. Barrows did not show higher average daily gain on HE compared to LE. Nitrogen efficiency was better in HE compared to LE, without negative effects on digestibility, carcass quality, economic parameters, behaviour or immune response. Small positive effects on the palatability of the meat of immunocastrates on HE were observed, although consumers did not prefer one of both feeds. Immunocastration was successful in reducing sexual and aggressive behaviour as well as in lowering the prevalence of boar taint from 15% in EM to 0% in immunocastrates. However, in two out of 96 immunocastrates (one on HE and one on LE), the immunocastration was not fully effective. In conclusion, this study did not show advantages of feeding immunocastrates or barrows a low-energy diet.
免疫去势是一种通过两次接种促性腺激素释放激素（GnRH）疫苗来实现的技术，可以作为仔猪去势的替代方法。与公猪相比，它可以减少公猪异味，并提高经济效益和生态效率。然而，免疫去势猪的饲养策略仍有待改进。在第二次接种后，当免疫完全有效时，免疫去势猪的采食量会急剧增加。本研究旨在探讨在不影响猪肉生产质量和动物性能的情况下，通过降低育肥后期的日粮能量水平，是否可以减少免疫去势猪第二次接种后的能量摄入。我们假设，免疫去势猪在第二次接种后，其自愿采食量已经达到极限，因此无法补偿较低的日粮能量水平，而公猪则可以。因此，本研究旨在评估高能量日粮（HE，净能（NE）= 10.2 MJ/kg）与低能量日粮（LE，NE = 8.8 MJ/kg）对免疫去势猪和公猪的影响，并作为参考，还包括了母猪和公猪的标准高能量日粮。两种日粮的 CP 和标准化回肠可消化氨基酸水平相似。对于每种处理，每个处理有 8 个重复栏，每个重复栏有 6 头猪，评估其生产性能、胴体质量、肉和脂肪质量、消化率、经济和生态可持续性、行为和免疫反应效果。结果表明，免疫去势猪在 LE 和 HE 组之间的采食量没有差异。因此，免疫去势猪在 HE 组的日能量摄入高于 LE 组，这导致 HE 组的日增重更高。HE 组的免疫去势猪的饲料转化率（FCR）与公猪的 FCR 没有显著差异。公猪在 HE 组的平均日增重没有明显高于 LE 组。氮效率在 HE 组优于 LE 组，对消化率、胴体质量、经济参数、行为或免疫反应没有负面影响。HE 组免疫去势猪的肉的适口性略有提高，尽管消费者并不喜欢这两种饲料中的任何一种。免疫去势成功降低了公猪的性行为和攻击性，并将公猪异味的发生率从 EM 的 15%降低到免疫去势猪的 0%。然而，在 96 头免疫去势猪中有 2 头（1 头在 HE 组，1 头在 LE 组）的免疫去势效果不完全有效。总之，本研究没有显示出给免疫去势猪或公猪饲喂低能量日粮的优势。
