RELATIONSHIP BETWEEN GENETIC DIVERSITY IN THE NEMATODE TRICHOSTRONGYLUS-COLUBRIFORMIS AND BREEDING MANAGEMENT IN 10 DAIRY-GOAT FARMS

Ten dairy-goat farms were investigated in center-west of France for ge netic variability of Trichostrongylus colubriformis in relation to bre eding management. Farm management data were obtained from a questionna ire. Genetic variability was based on two polymorphic enzymes, malate dehydrogenase (MDH) and glucose-phosphate isomerase (GPI). After their establishment the farms were subsequently isolated from introduction of strongyle worms as shown in the questionnaire; this was also sugges ted by the absence of a relationship between genetic variability and d istance between farm locations. The genetic variability which was reco rded could then be ascribed in part to the influence of management. Th e breeding management estimates combined the fact that animal breeding was the main economic resource; that goats were or were not the only animal bred; and that there was or was not free access to exercise yar ds in winter. The farms that were similar on the basis of breeding man agement, were also similar in the frequency of allozymes, indicating t hat the chosen allozymes were not neutral in respect to environment. G enetic variability was not related to the frequency of T. colubriformi s in the strongyle community, this being possibly due to the fact that our farm samples predominantly harboured T. colubriformis. Between-fa rm genetic variability was positively correlated to the size of herd ( P < 0.01), probably due to the fact that larger herds were originally constituted from several different herds.