The study was carried out in the selected strains of Malpura and Avikalin sheep for nematode resistance versus susceptibility (Malpura resistant: MR, Malpura susceptible: MS, Avikalin resistant: AR and Avikalin susceptible: AS). Strains were selected since 2004 and inter-se breeding followed since year 2007. The objective was to decipher the genetic structure of strains and to estimate genetic parameters for fecal egg count (FEC). The population size was small (107–279); however, all the four flocks had sizable effective population size (f_e) for founders. The ratio for f_e to effective number of ancestors (f_a) was nearly 1 indicating genetic stability. Inbreeding was under control. The log transformed FEC (LFEC) was significantly (P < .05) affected by sex, year and month of recording for all 4 strains. Generation had desired genetic trend. There was low heritability for LFEC in MR(0.02), MS(0.06), AR(0.07) and AS(0.02). The estimate of the permanent environment effect (c²) was low. Repeatability (ρ) for LFEC were 0.05, 0.11, 0.07 and 0.06 for MR, MS, AR and AS, respectively. Pruning the data for repeated records in peak infection period (1: “Aug-Sep” and 2: only “Sep”) resulted in considerable increase in ρ for MR (Aug-Sep: 0.07 ± 0.03 and Sep: 0.12 ± 0.07) and AR (Aug-Sep: 0.05 ± 0.04 and Sep: 0.09 ± 0.10). Results revealed genotype x environment interaction for repeated measures across months. Low flock size and low genetic variability are hurdles for improvement in R strains. It is recommended to incorporate new candidates post selection from the other breeding flocks and admit them in the R strains for selective breeding.

该研究是在选定的Malpura和Avikalin绵羊品系中进行的，以研究线虫抗性与药敏性（Malpura抗性：MR，Malpura易感性：MS，Avikalin抗性：AR和Avikalin易感性：AS）。自2004年以来选择菌株，然后从2007年开始进行间育。目的是破译菌株的遗传结构，并估计粪便卵数（FEC）的遗传参数。人口很小（107-279）；但是，对于创始人来说，所有四个群体都具有相当大的有效种群规模（f _e）。f _e与祖先有效数量的比率（f _a）接近1，表明遗传稳定。近交受到控制。对数转化的FEC（LFEC） 受所有4个菌株的性别，记录的年份和月份的影响显着（P <.05）。产生具有期望的遗传趋势。LFEC在MR（0.02），MS（0.06），AR（0.07）和AS（0.02）中的遗传力较低。永久环境影响的估算（c ²）很低。LFEC的重复性（ρ）分别为MR，MS，AR和AS，分别为0.05、0.11、0.07和0.06。修剪数据以在感染高峰期重复记录（1：“ 8月-9月”和2：仅“ 9月”），导致MR的ρ显着增加（8月-9月：0.07±0.03和9月：0.12±0.07）和AR（八月-九月：0.05±0.04和九月：0.09±0.10）。结果揭示了基因型x环境的相互作用，需要进行数月的重复测量。低的鸡群大小和低的遗传变异性是改善R菌株的障碍。建议从其他育种鸡群中选出新的候选者，然后将它们纳入R品系进行选择性育种。