203 Investing in parasite resistance in sheep

Abstract

Abstract Genetic parasite resistance in sheep has become an important technology in the control of gastrointestinal nematodes (GIN) due to widespread anthelmintic resistant GIN. The USDA-ARS sheep flock in Booneville, AR, has been selecting for parasite resistance since 2012 through the use of estimated breeding values (EBVs) generated through the National Sheep Improvement Program (NSIP). Objective is to show value of resistance. Recently, replacement ewes (n = 69) and rams (n = 29) from the flock were offered for sale and a sale catalog with EBVs for growth, reproduction, and parasite resistance, and recent BW was available. There were 73 purchased by 13 buyers from 7 states. Of the ram lambs that sold, post-weaning fecal egg count (FEC) EBVs ranged from -29 to -100, but of the 17 ram lambs offered, only rams with values of -97 or better sold (-100 is the highest FEC EBV and values can reach > +500; the top 10% for breed are P < 0.001). For mature ewes sold, FEC EBVs ranged from 18 to -87 with higher prices offered to ewes with better FEC EBVs (P < 0.002). For all sheep, higher prices may have been offered for animals raised as multiples rather than singles (P = 0.05). Seedstock producers wishing to improve parasite resistance can benefit by using NSIP to increase resistance and sale price. The higher parasite resistance used by commercial producers will reduce the need for deworming lambs.