<![CDATA[Ewes’ genotype and physiological stage are important factors associated with gastrointestinal nematode infection. The aims were to evaluate the parasitic (fecal eggs count, FEC), health (anemia level, FAMACHA; packed cell volume, PCV; hemoglobin, HGB), and productive response (live weight, LW; body condition score, BCS) of hair ewes managed under a selective deworming program with levamisole (7.5 mg/kg of live weight) at reproductive stages (not pregnant, NPW, n=17; ewes between the first and second third of gestation, 1-3PW, n=22; ewes in the last third of gestation and peripartum, 4-5PWN, n=16) and genotype groups (Pelibuey, PB, n=12; Katahdin, KT, n=12; Pelibuey × Katahdin, F1 PB×KT, n=16; and Pelibuey × Dorper F1 PB×DP, n=15). The effects of treatments were studied using analysis of variance, considering the reproductive stages and genotypes as treatments through 4 evaluation periods (days 20, 48, 76, and 104). FEC values were higher (p<0.01) for ewes at 4-5PW than 1-3PW and NPW. FAMACHA, PCV, LW, and BCS were similar in ewes regardless of the reproductive stage. On day 48 post-deworming (levamisole at 7.5 mg/kg of LW), the proportion of ewes with >800 e/g was higher (13.74%) at 4-5PW than at the peripartum stage. On day 76, the accumulated proportion of ewes that were dewormed was higher (p<0.05) at 4-5PW than at the peripartum stage. The accumulated total proportion revealed that the genotype F1 PB×DP ewes had the highest deworming requirement (p<0.05), being dewormed at least once (32.8%). According to the indicators of LW, BCS, FAMACHA, FEC, PCV, HGB, and proportion of dewormed animals, ewes with the F1 PB×KT genotype showed the best performance. Therefore, reproductive stage-orientated management and the use of the best genotype for grazing conditions combined with a selective deworming program can contribute significantly to the control of gastrointestinal nematodes.]]>
