Changes in the body condition scores of Nigerian West African Dwarf sheep experimentally infected with mixed infections of Haemonchus contortus and Trichostrongylus colubriformis

Weekly changes in body condition scores and body weights were determined in West African Dwarf sheep following trickle exposure to weekly escalating mixed infections with Haemonchus contortus and Trichostrongylus colubriformis starting with single doses of 500 infective larvae (L(3)) at wk1, 1000 L(3) at wk2, 2000 L(3) at wk3 and 4000 L(3) at wk4. Thirty-three animals were randomly assigned to two groups namely, Group 1 (n=27) and Group 2 (n=6). Group 1 animals were used for experimental infections and Group 2 animals served as uninfected controls. Body condition scores (BCS), body weights (BW), faecal egg counts (FEC) per gram of faeces and worm burden (Wb) were determined using standard procedures. Lambs in group 1 with epg ≤ 1000 were classified as strong responders (n=16), those with epg between 1000 and 10,000 as intermediate (n=5) and lambs with epg>10,000 on any sampling day were classified as weak responders (n=6). Based on this classification, the mean epg of lambs classified as strong responders was significantly lower (P<0.001) than the epg of lambs classified as weak responders. The body condition scores and body weights of the strong responder lambs were comparable with those of the uninfected control and they were significantly higher than those of the weak and intermediate responders from wk5 till the end of the experiment. There was an inverse and significant relationship between the average BCS of days 56 and 59 and the average FEC of days 56 and 59 (r(s)=-572; P=0.017; n=27) as well as with Wb (r(s)=-531; P=0.028; n=27). We concluded that changes in the body scores are good indicators of the intensity of gastrointestinal nematode infection in the Nigerian WAD sheep.