Notter D R, Burke J M, Miller J E, Morgan J L M
J Anim Sci. 2017 Jan;95(1):103-112. doi: 10.2527/jas.2016.0955.
Selection for low fecal egg counts (FEC) can be used to genetically enhance resistance to gastrointestinal nematode parasites in growing lambs, thereby reducing the frequency of use of anthelmintics, facilitating marketing of organic lamb, and reducing the risk of development of anthelmintic resistance by the parasite. Recording of FEC in lambs has, therefore, been incorporated into several national sheep genetic evaluation programs. Ewes in late gestation and early lactation are also vulnerable to parasite infection and commonly experience a periparturient rise in FEC. This study was designed to assess factors associated with the periparturient rise in FEC in Katahdin ewes and associated changes in FEC in their lambs. Data came from 1,487 lambings by 931 Katahdin ewes from 11 farms in the Eastern United States. Fecal egg counts were measured in ewes at approximately 0, 30, and 60 d postpartum and in their lambs at approximately 60, 90, and 120 d of age. Approximately 1,400 lambs were evaluated at each measurement age. Data were analyzed separately for ewes and lambs and also initially analyzed separately for each measurement time. Repeated-measures analyses were then used to evaluate responses across measurement times. In ewes, FEC peaked at approximately 28 d postpartum, and we concluded that informative periparturient FEC could be obtained from 1 wk before until approximately 5 wk after lambing. Yearling ewes had higher FEC than adult ewes ( < 0.01), and ewes that nursed twin or triplet lambs had higher FEC than ewes that nursed single lambs ( < 0.01). In lambs, FEC increased through approximately 120 d of age. Lambs from yearling ewes and lambs nursed in larger litters were, like their dams, at greater risk of parasitism ( < 0.05). Ewes and lambs in these groups would benefit from enhanced monitoring of parasite loads at lambing and in early lactation. Correlations () between FEC in lambs at 90 d of age and FEC in ewes at 0, 30, and 60 d postpartum of 0.05 to 0.09 ( ≤ 0.05) support the presence of a genetic relationship between these 2 indicators of parasite resistance.
选择低粪蛋计数（FEC）可用于遗传增强生长羔羊对胃肠道线虫寄生虫的抗性，从而减少驱虫药的使用频率，促进有机羔羊的销售，并降低寄生虫产生抗驱虫药能力的风险。因此，羔羊FEC的记录已被纳入多个国家绵羊遗传评估计划。妊娠后期和泌乳早期的母羊也易受寄生虫感染，并且通常在围产期经历FEC升高。本研究旨在评估与卡他丁母羊围产期FEC升高相关的因素以及其羔羊FEC的相关变化。数据来自美国东部11个农场的931只卡他丁母羊的1487次产羔。在产后约0、30和60天测量母羊的粪蛋计数，并在羔羊约60、90和120日龄时测量其粪蛋计数。在每个测量年龄约评估1400只羔羊。对母羊和羔羊的数据分别进行分析，并且最初也对每个测量时间分别进行分析。然后使用重复测量分析来评估不同测量时间的反应。在母羊中，FEC在产后约28天达到峰值，并且我们得出结论，围产期有意义的FEC可以在产羔前1周直至产后约5周获得。周岁母羊的FEC高于成年母羊（<0.01），哺乳双羔或三羔的母羊的FEC高于哺乳单羔的母羊（<0.01）。在羔羊中，FEC在约120日龄前增加。周岁母羊所生的羔羊以及在较大窝中哺乳的羔羊，与其母羊一样，寄生虫感染风险更大（<0.05）。这些组中的母羊和羔羊将受益于在产羔时和泌乳早期加强对寄生虫负荷的监测。90日龄羔羊的FEC与产后0、30和60天母羊的FEC之间的相关性（）为0.05至0.09（≤0.05），支持这两个寄生虫抗性指标之间存在遗传关系。
