Gauly M, Schackert M, Hoffmann B, Erhardt G
Institute of Animal Breeding and Genetics, University of Göttingen, Germany.
Dtsch Tierarztl Wochenschr. 2006 May;113(5):178-81.
36 intact male and 69 female lambs of two breeds (n = 63 Merinoland; n = 42 Rhön) aged 12 weeks were orally infected with 5000 infective-stage larvae, L3, of the nematode Haemonchus contortus. After 4 and 8 weeks faecal egg counts (FEC), haematocrit values and plasma testosterone levels were determined. All lambs were slaughtered at 20 weeks of age. The gastrointestinal tracts were examined for the presence of adult stages of H. contortus. Male lambs showed significantly higher log FEC (p < 0.001), higher mean establishment rates (p < 0.05), higher worm burdens (p < 0.01) and lower haematocrit values (p < 0.001) when compared with female lambs. Correlations between economically important traits (body weight, daily weight gain) and parasitological parameters were significantly higher in male animals. Testosterone level was 4 weeks after infection significantly positive correlated with worm burden. The results suggest that female lambs are more resistant against an experimental H. contortus infection when compared with male lambs. Testosterone seems to play an important role in resistance. This approach can be of importance if parasite resistance is incorporated into breeding programs and the estimated breeding values for rams are only based on male offspring information. Therefore male breeding values are probably not representative for the whole population.
将两个品种（n = 63只美利奴兰德羊；n = 42只罗恩羊）的36只完整雄性和69只雌性12周龄羔羊经口感染5000条捻转血矛线虫感染期幼虫（L3）。在感染4周和8周后，测定粪便虫卵计数（FEC）、血细胞比容值和血浆睾酮水平。所有羔羊在20周龄时屠宰。检查胃肠道是否存在捻转血矛线虫成虫阶段。与雌性羔羊相比，雄性羔羊的对数FEC显著更高（p < 0.001），平均定殖率更高（p < 0.05），虫负荷更高（p < 0.01），血细胞比容值更低（p < 0.001）。在雄性动物中，经济重要性状（体重、日增重）与寄生虫学参数之间的相关性显著更高。感染后4周睾酮水平与虫负荷显著正相关。结果表明，与雄性羔羊相比，雌性羔羊对实验性捻转血矛线虫感染更具抵抗力。睾酮似乎在抵抗力中起重要作用。如果将寄生虫抗性纳入育种计划，且公羊的估计育种值仅基于雄性后代信息，那么这种方法可能很重要。因此，雄性育种值可能不能代表整个群体。
