At the Southwest Virginia Agricultural Research & Education Center, Katahdin rams with high (HiFEC) and low (LoFEC) fecal egg count EBVs (estimated breeding values) were randomly mated to ewes. Mid-March born lambs (n=199) were managed as one group until approximately 120 days of age. Deworming occurred as necessary (FAMACHA ≥ 3).
Fecal egg count was significantly higher in hiFEC-sired lambs prior to weaning and again at 3 and 5 weeks post weaning. These differences corresponded to differences in lamb weaning and post-weaning FEC EBVs. Lambs sired by HiFEC rams required more anthelmintic treatments than those sired by LoFEC rams. The weaning and post-weaning FEC EBV of HiFEC-sired lambs was greater in lambs that died than those that survived to 120 days. The same phenomenon did not occur in LoFEC-sired lambs.
Results suggest than LoFEC-sired lambs have reduced parasite burden and are more likely to survive to weaning. Sire selection for low FEC EBV can have indirect effects on lamb survival and general immunity.
Source: Andrew Weaver et al (West Virginia University): The effect of sire FEC EBV on parasitism and survivability in grazing Katahdin lambs. Southern Section of American Society of Animal Science. January 2020.