Studying the Potential Effects of an Indicator of Haemonchus Contortus Resistance on Production Traits in Rideau Arcott Sheep

Hematophagous parasite Haemonchus contortus has caused flock illness, production loss, and death in the Canadian sheep population. Numerous factors affect the ability of the animals to resist the parasite, including age, sex, nutrition, breed and the individual itself, which has led to selection programs to diminish infection but with unknown consequences in sheep production traits. The objective of this study was to assess the relationship between fecal egg counts (FEC) (indicative of resistance to parasite infestation) and 23 production traits in 455 Rideau Arcott sheep located at a local farm in Guelph, Ontario, Canada between 2012 to 2016. The parameters analyzed consisted of weight gain, lamb survival direct and maternal, birth weight direct and maternal, 50-d weight direct and maternal, 100-d weight direct, loin depth direct, fat depth direct, body condition scores, age at first lambing, number born at first lambing, total weight weaned at first lambing, lambing interval, number born at later lambing, total weight weaned at later lambing, number birthed, weight at 50 and 100 d, and FAffa MAlan CHArt (FAMACHA) scores. Correlations were analyzed in SAS (SAS Institute Inc., Cary, North Carolina) using the PROC CORR procedure. Pearson’s correlation coefficients (R) were considered significant at P ≤ 0.05. Only lambs born at first lambing (R = 0.101; P = 0.032), lambing interval (R = 0.093; P = 0.049), and number of lambs born at later lambing (R = 0.099; P = 0.035) were positively correlated with FEC. Results suggest that Rideau Arcott sheep with higher genetic merit for reproductive traits could have marginally lower resilience to Haemonchus contortus infection. When sufficient data is available, future research will aim to estimate the genetic correlations between FEC and production traits to improve the accuracy of selection.