Genetic parameters for faecal egg count following natural nematode infections and correlation with productive traits in Polish Heath sheep

Abstract

Over a 4-year period, from May (1995) or June (1996June ( -1998 to November, in a flock of Polish Heath sheep, faecal samples from 246 ewes, 9 rams and 429 lambs were examined for gastrointestinal nematode eggs by the McMaster method. Faecal cultures were run to identify the nematode species present. The prevalence of positive egg counts was, on average, 43 to 69% in ewes and 68 to 80% in lambs. Two nematode genera predominated: Haemonchus contortus and Trichostrongylus colubriformis. In the last three samplings in 1998 increased frequency of Ostertagia (Teladorsagia) circumcincta infections was noticed.Animal model restricted maximum likelihood was used to estimate the heritability and repeatability for faecal nematode egg count (FEC) and correlations with productive traits.The obtained values of these parameters were 0.128 (±.0.011) and 0.068 (±0.005) for repeatability and heritability, respectively. A negative influence of faecal worm egg count on fleece weight of ewes and weight gain from birth to 3 rd month, from 3 rd month to 12 th month and during 12 months of lambs' life was observed. The estimated genetic correlations were: -0.014 (±0.053), -0.197 (±0.046), -0.204 (±0.073), and -0.174 (±0.074), respectively.

Microsatellite polymorphism in DRB1 gene (MHC class II) and its relation to nematode faecal egg count in Polish Heath Sheep

“…Usually the intensity in case of dams did not exceed 7 000 eggs and in case of lambs -5 000 eggs in 1 gram of faeces. Detailed results on prevalence of gastrointestinal nematode infection in the investigated flock were presented by Charon et al (2000).…”

“…In literature there are different values of heritability for FEC. The heritability for FEC estimated by Charon et al (2000) for the Polish Heath Sheep was 0.128.…”

Genetic markers to gastrointestinal nematode resistance in sheep: a review

“…Within Ovar-MHC class I locus have been found a few RFLP and polymorphic microsatellite sequences which differ among sheep breeds Charon et al, 2001;Gruszczyńska et al, 2002). Sheep with gastrointestinal nematodes-resistant alleles at this locus have displayed significant reduction in FEC of T. circumcincta in Scottish Blackface sheep and in FEC of other gastrointestinal nematode species in Polish Heath sheep (Charon et al, 2000). Within Class III genes an allele of C4 gene is supposed to be involved in determining the resistance/susceptibility to gastro intestinal parasites (Wetherall et al, 1991).…”

“…In order to get a desirable resistant flock a vast selection work must be made using such parameters as number of parasite eggs in sheep faeces (FEC), packed cell volume (PCV) which measures hemophilia caused mainly by infections with blood suckling internal parasites, such as H. contortus, and less commonly eosinophilia. All three parameters have shown heritability which ranged between 0.12 and 0.44 for FEC (Watson et al, 1986;Baker et al, 1991;Morris et al, 1997;Charon et al, 2000) 0.15 and 0.36 for PCV (Alberts et al, 1987;Vanisetti et al, 2004) and for eosinophilia at the level of 0.31 (Stear et al, 2002). Furthermore, these three parameters indicate repeatability within the seasons and years (Doligalska et al, 1997;Moskwa et al, 1998;Moskwa et al, 2000;Vanimisetti et al, 2004) on the average 0.48 for FEC (Barger & Dash, 1987;Doligalska et al, 1997) 0.44 for PCV (Bekele et al, 1991) and 0.38 for eosinophil counts (Moskwa et al, 1998;Doligalska et al, 1999).…”

“…All three parameters have shown heritability which ranged between 0.12 and 0.44 for FEC (Watson et al, 1986;Baker et al, 1991;Morris et al, 1997;Charon et al, 2000) 0.15 and 0.36 for PCV (Alberts et al, 1987;Vanisetti et al, 2004) and for eosinophilia at the level of 0.31 (Stear et al, 2002). Furthermore, these three parameters indicate repeatability within the seasons and years (Doligalska et al, 1997;Moskwa et al, 1998;Moskwa et al, 2000;Vanimisetti et al, 2004) on the average 0.48 for FEC (Barger & Dash, 1987;Doligalska et al, 1997) 0.44 for PCV (Bekele et al, 1991) and 0.38 for eosinophil counts (Moskwa et al, 1998;Doligalska et al, 1999). In addition, FEC values have been negative correlated with either PCV or eosinophils count (Moskwa et al, 1998;Amarante et al, 1999;Stear et al, 2002;Amarante et al, 2003;Vanimisetti et al, 2004).…”