TAILIEUCHUNG - Báo cáo sinh học: " A short-term divergent selection for resistance to Teladorsagia circumcincta in Romanov sheep using natural or artificial challenge"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: A short-term divergent selection for resistance to Teladorsagia circumcincta in Romanov sheep using natural or artificial challenge | Genet. Sel. Evol. 36 2004 217-242 217 INRA EDP Sciences 2004 DOI gse 2003060 Original article A short-term divergent selection for resistance to Teladorsagia circumcincta in Romanov sheep using natural or artificial challenge Lucas GRUNERa Jacques Bouixb Jacqueline Vu Tien KHANGb Nathalie MANDONNETa Francis Eychennec Jacques CoRTETa Christine SAUVEa Claude LiMOuziNd a Bioagresseurs sante et environnement Institut national de la recherche agronomique 37380 Nouzilly France b Station d amelioration genetique des animaux Inra BP 27 31326 Castanet-Tolosan France cDomaine de Langlade Inra Pompertuzat 31450 Montgiscard France d UE Pathologie aviaire et parasitologie Inra 37380 Nouzilly France Received 2 April 2003 accepted 29 October 2003 Abstract - This experiment was conducted to assess the efficiency of selection on the basis of response to artificial challenges in order to breed sheep resistant to natural infection. A shortterm divergent selection process was designed to estimate the genetic parameters of these two traits. Two flocks including 100 Romanov ram lambs each were challenged in 1990 when they were 6 months old. One flock received three artificial infections with 20 000 third-stage Telador-sagia circumcincta larvae at intervals of 7 weeks. Faecal egg counts FEC were performed on Days 22 25 and 28 post infection . and the animals were drenched on Day 28 . The other flock was grazed for 5 months on a pasture contaminated with the same species. Faecal samples were taken from the lambs at similar ages. About 5 rams with the lowest FEC and 5 with the highest FEC were selected in each flock and mated with unselected ewes. Their offspring 200 animals were challenged in 1992 half in the same way as their sires and the other half by the other method. Because of a drought in the summer of 1990 it was necessary to repeat part of the experiment and in 1992 the 5 and 8 rams with the lowest and highest FEC respectively were selected from the offspring .

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