Proceedings of the New Zealand Society of Animal Production. 1995,
55: 202-204
Proceedings of the New Zealand Society of Animal Production. 1995,
55: 202-204
Selection in lambs was based on High or Low FEC or on acquired immunity (i.e. a large reduction in FEC between the responses to first and second challenge), and these flocks were managed alongside a contemporary Control Flock. There were four years of ewe data (1990-93), consisting of 2748 FEC records from 218 ewes, the daughters of 43 sires. Faecal samples were obtained for FEC beginning four weeks before the expected mean lambing rate, and finishing about four months later. Blood samples were obtained from ewes in 1993 to analyse concentrations of antibody to Haemonchus contortus and Ostertagia circumcincta, and other components. All FEC analyses used a log, (FEC+100) transformation.
The overall mean FEC for peri-parturient ewes was 65.19 (388 eggs/g on the original scale) with a phenotypic standard deviation of 0.86. Selection flock differences were significant (P<0.001). Relative to the High flock mean, the Control, Acquired and Low flock means were -0.01 ± 0.10, -0.18 ± 0.09 and -0.38 ± 0.10 log e units, i.e. a 38% lower FEC in Low than High flock ewes. The within-flock heritability of individual FEC records was 0.27 ± 0.07, and for antibody concentrations to H. contortus and O. circumcincta heritabilities were 0.18 ± 0.34 and 0.73 ± 0.31, respectively. The genetic correlation estimate between ewe lamb FEC and adult-ewe FEC was 0.63 ± 0.57. Eosinophil and total white cell counts were significantly higher in Low FEC than High FEC ewes.(P<0.05). It was concluded that lamb differences in FEC were also expressed in peri- parturient ewes, and the ewe trait itself had a significant heritability.
Keywords: NZSAPAB; faecal egg count; nematode; Perendale; sheep; peri-parturient rise
