Yazwinski T A, Goode L, Moncol D J, Morgan G W, Linnerud A C
J Anim Sci. 1980 Aug;51(2):279-84. doi: 10.2527/jas1980.512279x.
Resistance to Haemonchus contortus infection was studied in two experiments conducted with 52 lambs of widely different genetic background. Breed groups compared were: Dorset (D), Barbados Blackbelly (B), Dorset x Blackbelly (D x B), Suffolk x Blackbelly (S x B), Suffolk x Dorset x Blackbelly (S x D x B,[1/4 B]) and nonBlackbelly (NB, D and S). In each experiment, lambs were raised on concrete from birth and were essentially parasite free until infective larvae were administered. In Exp. 1, D x B, S x D x B and D wether lambs approximately 3 months old were infected with a standard dose of invective larvae estimated to be 98% H. contortus. D x B lambs had a longer (P < .05) prepatency period and, at necropsy 17-day postinfection, had a higher (P < .05) percentage of female parasites classified as immature than did the other breed groups. These data showed that the development of H. contortus larvae was inhibited in D x B host animals. In Exp. 2, B, D x B, S x B and NB ewe and wether lambs approximately 4 months old were treated with three sensitizing doses of H. contortus larvae. These were followed by a challenge infection. On the basis of fecal egg counts (eggs per gram feces, EPG), there was no evidence that the challenge infection induced a self-cure reaction in any breed group. All lambs with B breeding had significantly higher Hb levels at the end of the experiment than did NB lambs. b and S x B lambs had higher (P < .05) Hb levels than the D x B lambs, and B lambs had the highest (P < .05) mean corpuscular hemoglobin concentrations. Five days after the challenge infection, B, D x B and S x B lambs also had significantly higher white blood cell levels than did NB lambs. Significant sex differences were also observed in Exp. 2. Ewe lambs had lower final EPG levels, higher preinfection and postinfection Hb levels and higher maximum postinfection cosinophil levels. Breed x sex interactions for these parameters were not significant.
在两项实验中，对52只遗传背景差异很大的羔羊进行了抗捻转血矛线虫感染的研究。比较的品种组有：陶赛特羊（D）、巴巴多斯黑腹羊（B）、陶赛特羊×黑腹羊（D×B）、萨福克羊×黑腹羊（S×B）、萨福克羊×陶赛特羊×黑腹羊（S×D×B，[1/4 B]）和非黑腹羊（NB，即D和S）。在每项实验中，羔羊从出生起就在水泥地面上饲养，在给予感染性幼虫之前基本上没有寄生虫。在实验1中，约3月龄的D×B、S×D×B和D阉羊用估计98%为捻转血矛线虫的标准剂量感染性幼虫进行感染。D×B羔羊的潜隐期更长（P<0.05），在感染后17天剖检时，与其他品种组相比，被归类为未成熟的雌性寄生虫百分比更高（P<0.05）。这些数据表明，捻转血矛线虫幼虫在D×B宿主动物中的发育受到抑制。在实验2中，约4月龄的B、D×B、S×B和NB母羊及阉羊用三剂致敏剂量的捻转血矛线虫幼虫进行处理。随后进行攻击感染。根据粪便虫卵计数（每克粪便中的虫卵数，EPG），没有证据表明攻击感染在任何品种组中诱发了自愈反应。所有具有B品种血统的羔羊在实验结束时的血红蛋白水平均显著高于NB羔羊。b和S×B羔羊的血红蛋白水平高于D×B羔羊（P<0.05），而B羔羊的平均红细胞血红蛋白浓度最高（P<0.05）。攻击感染后5天，B、D×B和S×B羔羊的白细胞水平也显著高于NB羔羊。在实验2中还观察到显著的性别差异。母羔羊的最终EPG水平较低，感染前和感染后的血红蛋白水平较高，感染后嗜酸性粒细胞的最高水平也较高。这些参数的品种×性别交互作用不显著。
