tailieunhanh - báo cáo khoa học: "Environmental and genetic factors affecting udder characters and milk production in Chios sheep"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Environmental and genetic factors affecting udder characters and milk production in Chios sheep | Génét. Sél. Evol. 1988 20 4 477-488 Environmental and genetic factors affecting udder characters and milk production in Chios sheep . MAVROGENIS c. PAPACHRISTOFOROU p. LYSANDRIDES and A. ROUSHIAS Agricultural Research Institute Nicosia Cyprus Department of Agriculture Nicosia Cyprus Summary A total of 1156 records collected at three experimental farms Agricultural Research Institute Athalassa Orites from 1978 to 1981 were used to study environmental and genetic factors influencing udder characteristics and milk production in Chios sheep. All udder traits were recorded following weaning 42 3 days concurrently with the first milk recording 7 3 days after weaning . Most traits studied were significantly affected by flock and year of lambing. Seasonal effects were significant for udder circumference test-day milk and total milk production. Lactation number had a linear effect on udder circumference udder depth udder floor and udder quality but a quadratic influence on milk production. Milk production was significantly affected by udder floor but not by udder quality and milking ease. Most heritability estimates except for udder floor and milking ease were moderate to high ranging from to . Udder depth and udder circumference traits that probably best describe the type and volume of the udder had moderate to high estimates of heritability and were positively correlated genetically and phenoty-pically with milk production. All three production traits test-day 90-day and total milk yield had moderate to high heritability estimates and were highly correlated with each other both genetically and phenotypically. Key words udder characteristics milk production Chios sheep genetic parameters. Résumé Facteurs environnementaux et génétiques affectant les caractéristiques de la mamelle et la production laitière en race ovine Chios Un total d 1156 enregistrements recueillis dans trois fermes experimentales Agricultural Research Insti Ute .