GnRH-A主动免疫家兔的去势效果

为了探讨促性腺激素释放激素类似物(gonadotropin releasing hormone analogue,GnRH-A)对动物免疫去势的效果及作用机理.在30只日本大耳白兔(Oryctolagus cuniculus)(EG-Ⅰ与EG-Ⅱ组)的颈背部皮下分2.3点注射1.0ml(100/gml)自制的GnRH-A抗原乳剂,EG-Ⅱ组3周后加强免疫一次;测定睾丸长度与重量、体重、血清GnRH抗体效价及睾酮浓度.结果表明,EG-Ⅱ组睾丸长度与EG-I组差异极显著(P<0.01);EG-Ⅱ组的GnRH抗体水平明显高于EG-Ⅰ组;EG-Ⅱ组、EG-Ⅰ组与对照组的血清睾酮浓度差异逐渐增加,102 d时EG-Ⅱ组睾酮浓度极显著低于对照组(P<0.01),且第28 d后EG-Ⅱ组睾酮浓度显著低于EG-Ⅰ组(P<0.05);EG-Ⅱ组体重和日增重最大,显著高于EG-Ⅰ组及对照组(P<0.05).GnRH-A主动免疫家兔对睾丸发育、血清GnRH抗体效价和睾酮浓度具有显著的影响,加强免疫效果更理想.     

GnRH-A免疫去势对雄兔血清睾酮和血液细胞的作用

目的研究促性腺激素释放激素-A（GnRH-A）免疫去势时血清睾酮含量和血液细胞成分的变化特点及其相互关系,从而探讨GnRH-A免疫去势的效果和作用机理。方法将GnRH-A与BSA连接为复合物,加入弗氏不完全佐剂制成抗原乳剂;30只兔均分为实验1组（EG-1）、实验2组（EG-2）和对照组（CG）,EG-1和EG-2注射1.0mL（100μg/mL）GnRH-A抗原,EG-2组3周后再加强注射一次;用间接ELISA法测定睾酮含量,用CD-1200全自动血液分析仪测定15项参数值;统计分析血清睾酮含量和血液细胞之间的相关关系和回归方程。结果EG-2的血清睾酮含量显著低于EG-1和对照组（P〈0.05）,EG-1在前4周明显下降,低于对照组（P〈0.05）,此后持续上升并明显高于实验前值,至第16周时与对照组相近;而对照组血清睾酮含量呈不断增高,到第13周明显高于第1周（P〈0.05）。EG-2的WBC、LYM、MID和GRN在第4～7周明显高于正常值（P〈0.05）,而RBC、HGB和HCT则低于正常值（P〈0.05）;到13周后,EG-2和EG-1的15项血液细胞逐渐恢复正常水平,与对照组差异无显著性（P〉0.05）。血清睾酮含量和血液细胞的相关系数和回归方程无明显的规律性和特征性。结论GnRH-A主动免疫对家兔的血清睾酮和血液细胞WBC、LYM、MID、GRN、WBC、LYM、MID和GRN等具有明显的影响,但作用持续时间仅4～7周。     

Effect of dietary energy level in finishing phase on performance,carcass and meat quality in immunocastrates and barrows in comparison with gilts and entire male pigs

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.