A comparison of Criollo and Suffolk ewes for resistance to Haemonchus contortus during the periparturient period

Abstract

Criollo and Suffolk ewes were compared for resistance to an experimental infection with Haemonchus contortus in the periparturient period. Measures on days −28, −14, 0 (lambing date), 14, 28, and 42 were taken on number of eggs per gram of faeces (EPG), packed cell volume (PCV), blood eosinophil numbers (BEN), and body weight (BW) in 28 Criollo and 25 Suffolk ewes. One half of the ewes of each genotype was inoculated orally with 3000 L3 of H. contortus in a single dose. Phenotypic correlations between response variables were estimated. Criollo ewes had lower means than Suffolk ewes for EPG (570.7 ± 208.1 vs. 1363.9 ± 245.5) and BW (50.4 ± 1.2 vs. 81.0 ± 1.4 kg), and a higher mean for PCV (35.0 ± 0.6 vs. 32.7 ± 0.6%). BW of inoculated Criollo ewes increased from day −28 to day 42, while that of inoculated Suffolk ewes decreased. Non-inoculated Criollo and Suffolk ewes had slightly increased BW from day −28 to lambing date; after lambing, BW of inoculated Suffolk ewes decreased, while that of inoculated Criollo ewes increased. Birth type and lambing number affected (p < .05) EPG, PCV, and BW. Negative correlations were found (p < .01) between EPG and PCV with BW. Criollo ewes were more resistant than Suffolk ewes to H. contortus.

Keywords

• Gastrointestinal nematodes
• infection
• parasitological traits
• hematological traits
• physical traits