Unfavorable Genetic Correlation
Swiss researchers analyzed data from 20 herds to determine heritabilities of and genetic correlations between phenotypic traits linked to gastrointestinal nematodes (GIN) and milk yield in two major dairy goat breeds (Alpine and Saanen). For all goats (n=1303), individual recordings of fecal egg counts (FEC), FAMACHA© eye score, packed cell volume (PCV), and milk yield were performed twice a year with an anthelmintic treatment in between.
The heritabilities of FEC, FAMACHA© and PCV were determined to be 0.07, 0.22 and 0.22, respectively. The genetic correlation between FEC and FAMACHA© was close to zero and −0.41 between FEC and PCV. The phenotypic correlation between FEC and milk yield was close to zero, whereas the genetic correlation was an unfavorable 0.49.
The data suggested a low heritability of FEC in Saanen and Alpine goats and an unfavorable genetic correlation of FEC with milk yield. In addition, FAMACHA© and PCV did not prove to be suitable as auxiliary traits to select for GIN resistance. As compared to other studies, a lower percentage of Haemonchus contortus (~50%) may explain why the correlations between FEC and FAMACHA©/PCV were not strong. Source: Parasite, August 2017. Read full article.