TAILIEUCHUNG - Báo cáo sinh học: " Mapping quantitative trait loci (QTL) in sheep. IV. Analysis of lactation persistency and extended lactation traits in sheep"

Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học quốc tế đề tài: Mapping quantitative trait loci (QTL) in sheep. IV. Analysis of lactation persistency and extended lactation traits in sheep | Jonas et al. Genetics Selection Evolution 2011 43 22 http content 43 1 22 GSE Ge n et i cs Selection Evolution RESEARCH Open Access Mapping quantitative trait loci QTL in sheep. IV. Analysis of lactation persistency and extended lactation traits in sheep Elisabeth Jonas Peter C Thomson Evelyn JS Hall David McGill Mary K Lam and Herman W Raadsma Abstract Background In sheep dairy production total lactation performance and length of lactation of lactation are of economic significance. A more persistent lactation has been associated with improved udder health. An extended lactation is defined by a longer period of milkability. This study is the first investigation to examine the presence of quantitative trait loci QTL for extended lactation and lactation persistency in sheep. Methods An Awassi X Merino X Merino single-sire backcross family with 172 ewes was used to map QTL for lactation persistency and extended lactation traits on a framework map of 189 loci across all autosomes. The Wood model was fitted to data from multiple lactations to estimate parameters of ovine lactation curves and these estimates were used to derive measures of lactation persistency and extended lactation traits of milk protein fat lactose useful yield and somatic cell score. These derived traits were subjected to QTL analyses using maximum likelihood estimation and regression analysis. Results Overall one highly significant LOD four significant LOD and five suggestive LOD QTL were detected across all traits in common by both mapping methods. One additional suggestive QTL was identified using maximum likelihood estimation and four suggestive P and two significant P QTL using the regression approach only. All detected QTL had effect sizes in the range of to SD corresponding to QTL heritabilities of to . The comparison of the detected QTL with results in cattle showed conserved linkage regions. Most of the QTL identified .

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