|NOTTER, DAVID - Virginia Tech|
|MILLER, JAMES - Louisiana State University|
Submitted to: Journal of Animal Science
Publication Type: Abstract Only
Publication Acceptance Date: 11/15/2016
Publication Date: 2/4/2017
Citation: Burke, J.M., Notter, D., Miller, J.E. 2017. Effect of ram semen extenders and supplements on computer assisted sperm analysis parameters. Journal of Animal Science. 95 (E-Suppl. 1). 52.
Technical Abstract: Gastrointestinal nematode (GIN) infection of lambs is a major health issue that can cause anemia, reduced weight gains, poor performance, mortality and discouragement to farmers. Anthelmintic resistance limits the control of GIN by available dewormers, and most alternatives to dewormers have some drawbacks and failures. Because of the moderate heritability of parasite resistance, opportunities exist to improve flock’s resistance through programs such as the National Sheep Improvement Program (NSIP). The objective was to determine the effect of EBV of sire on FEC, packed cell volume (PCV), FAMACHA score at 90 and 120 d of age, and BW at birth, 60, 90, and 120 d of age of offspring. Between 2004 and 2015, data was collected from the ARS Katahdin research flock on 1,096 lambs from 25 sires having at least 19 offspring/sire. The average FEC of lambs born per season must have been >500 eggs/g for that group to be included in the analyses. The EBV of sires was determined by Sheep Genetics (Australia) in July 2016. Data were analyzed by Proc GLM (SAS) and included year, gender, rear type (single, twin, triplet) as discrete variables, and the post-weaning FEC (PFEC) EBV of sire as a continuous variable; age was used as a covariate. The FEC were log transformed. There was a positive effect of PFEC on FEC, PCV, and FAMACHA score of offspring at 90 (P < 0.001, P < 0.02, P < 0.001, resp.) and 120 (P < 0.001 for all variables) d of age. Or, as PFEC decreased (indicating greater GIN resistance), FEC and FAMACHA decreased and PCV increased. However, as WFEC decreased, BW at birth (P < 0.001), 60 (P < 0.001) and 90 (P < 0.001) d also decreased, but no relationship was found at 120 d of age (P = 0.14). There was a significant effect of year, gender, and rear type in all BW analyses (P < 0.001); year was a significant effect to all GIN measures, and in some models, gender, rear type and age influenced GIN measures. Genetic resistance to parasite resistance is arguably the best means of GIN control, which can be achieved through selection of sires with favorable EBVs, which led to lower FEC and higher PCV in offspring.