Genetic analysis of milking ability in Lacaune dairy ewes

Abstract

-The milking ability of Lacaune ewes was characterised by derived traits of milk flow patterns, in an INRA experimental farm, from a divergent selection experiment in order to estimate the correlated effects of selection for protein and fat yields. The analysis of selected divergent line effects (involving 34 616 data and 1204 ewes) indicated an indirect improvement of milking traits (+17% for maximum milk flow and -10% for latency time) with a 25% increase in milk yield. Genetic parameters were estimated by multi-trait analysis with an animal model, on 751 primiparous ewes. The heritabilities of the traits expressed on an annual basis were high, especially for maximum flow (0.54) and for latency time (0.55). The heritabilities were intermediate for average flow (0.30), time at maximum flow (0.42) and phase of increasing flow (0.43), and low for the phase of decreasing flow (0.16) and the plateau of high flow (0.07). When considering test-day data, the heritabilities of maximum flow and latency time remained intermediate and stable throughout the lactation. Genetic correlations between milk yield and milking traits were all favourable, but latency time was less milk yield dependent (-0.22) than maximum flow (+0.46). It is concluded that the current dairy ewe selection based on milk solid yield is not antagonistic to milking ability. dairy sheep / milk flow / milking ability / milking trait / divergent selection

Impact of simplified methods of monthly and twice monthly milk recording on genetic parameter estimates and genetic evaluation in dairy ewes under a low input production system

“…Heritability estimates ranged from 18 to 21.8 for monthly designs (table 7) and were similar to those obtained with the bimonthly designs (17.8 to 21.5). These values were clearly higher to those reported in previous studies (7 and 11) on the same breed (Othmane, 2004;Ilahi and Othmane, 2011a) and fell within the range of results (15 -23) already published on other dairy sheep breeds (Othmane et al, 2002b;Ilahi and Othmane, 2011b;Marie-Etancelin et al, 2006). (Othmane and Trabelsi, 2007).…”

Genetic Correlation Between Female Fertility and Milk Yield in Lacaune Sheep

“…In French dairy sheep, the primary selection objective has been milk production, and for the last decade increasing attention has been given to functional traits like disease resistance (e.g., mastitis, scrapie) and udder morphology but not to reproduction traits (Barillet et al, 2006;Marie-Etancelin et al, 2006;Barillet, 2007). Genetic parameters for dairy traits are similar for sheep and cattle (Barillet, 1997).…”

Effects of Parity and Somatic Cell Count Threshold on Udder Morphology, Milkability Traits, and Milk Quality in Canarian Goats

“…On the contrary, Refs. [11,34] reported that AvMF and HMG had a decreasing trend with parity number in dairy ewes. These authors explained that milkability worsens because of the progressive deterioration of the degree of udder suspension with the age of the ewes.…”