Clustering and genetic analysis of body weight and body condition score variations in meat sheep

Overview & Synopsis

The overall sustainability and innovative capacity of small ruminant sector in Europe have to be improved to cope with current and future economic, environmental and societal challenges. This involves improving robustness in sheep to cope with fluctuating environmental conditions, for instance to increase grazing. The ability of ewes to mobilize or to restore body reserves is a key mechanism to cope with fluctuations in feed resources. The purposes of this work were to characterize the different patterns of BW and BCS variations throughout productive cycles and to analyze the genetic variability of BW and BCS variations in meat sheep. Temporal changes in body reserves dynamics were investigated using Body Weight (BW) and Body Condition Score (BCS) measured frequently throughout repeated entire productive cycles in ewes reared exclusively outdoors in harsh conditions. Cluster analysis showed three different clusters for BCS variations whatever productive cycle and one to four clusters for BW variations depending on productive cycle. Major clusters were mainly characterized by body reserves accretion during dry-off period and early pregnancy and body reserves mobilization during mid-pregnancy and suckling. The heritability values were low to medium for BW variations (h2=0.11 to 0.19) and BCS variations (h2=0.06 to 0.15). Moderate to high genetic correlations between BW and BCS variations indicated both traits were genetically related. High negative genetic correlations for BCS and BW variations between dry-off period and pregnancy and/or suckling indicated body reserves mobilization and accretion were two genetically correlated processes. The present data demonstrated body reserves variations were heritable indicating such traits could be used in selection to increase robustness.