Dag score is negatively correlated with breech bareness score of sheep

Abstract

At weaning in two consecutive years, traditional Romney and composite lambs (crosses with East Friesian and Texel; n = 3254) were observed on a conventional farm and Perendale and composite lambs (crosses with Texel, Wiltshire and small numbers of Finnish Landrace; n = 2095) were observed on an organic farm. Both were ram breeding farms recording pedigree and performance, and the composite breeds were developed from, and run with, the original flock on each farm. Breech bareness was scored on the lambs between 80 and 120 days of age on a scale from 1, with wool right to the edge of the anus, to 5, where a large bare area surrounded the perineum. Dag score was recorded on a 0--5 scale where an increasing score indicated more dags. Within farms, mean dag score was more pronounced in traditional Romney (1.2) than in composite lambs (0.4), and Perendales were more daggy (1.3) than composite lambs (0.7) across both years (P < 0.001). Dag score was phenotypically correlated with breech bareness score on the Romney farm (À0.18 AE 0.02) and Perendale farm (À0.27 AE 0.03). Combining data from both flocks, heritabilities of breech bareness score (0.55 AE 0.04) and dag score (0.41 AE 0.05) were high, and a strong genetic correlation was observed between the two traits (À0.59 AE 0.07). Mean dag score of ram lambs was greater than ewe lambs (0.8 v. 0.7, P < 0.001) and lambs reared as twins were more daggy than singles (0.8 v. 0.7, P = 0.008). Composite sheep have been adopted throughout New Zealand for the advantages they deliver in lamb production, but through breech bareness they also provide an opportunity to limit dag production and thereby improve both welfare and profitability. Genetically increased breech bareness and decreased dagginess could be used in Australia as alternatives to mulesing.

Genetic parameters for breech cover, wrinkle and wool coverage scores and their implications for Merino sheep breeding programs and flock management

“…The low heritability estimates for MBCOV, YBCOV and ABCOV (0.01-0.16) in the current study, while lower than published estimates which range from 0.23 to 0.55 (Scobie et al, 2007(Scobie et al, , 2008Edwards et al, 2009;Greeff and Karlsson, 2009;Smith et al, 2009;Brown et al, 2010;Bird-Gardiner et al, 2014;Greeff et al, 2014), indicate that achieving a permanent decrease in breech cover is possible through selection. The phenotypic variance for BCOV in this study ranged from 0.43 to 0.55 across the three stages of assessment from marking to adult, which was similar to that reported by both Brown et al (2010) and Smith et al (2009) but greater than that of Greeff et al (2014) and Bird-Gardiner et al (2014).…”

Identifying indicator traits for breech strike in Merino sheep in a Mediterranean environment

“…Thus, although greasy wool colour is a heritable trait, it was not genetically or phenotypically associated with breech strike and, therefore, does not seem to offer potential as an indicator trait for breech strike for the Mediterranean regions. Scobie et al (2008) showed that larger bare breech skin area was significantly correlated with a lower dag score in non-Merino crosses. The present study found that breech cover is a heritable trait at different ages, which supports the results of Edwards et al (2009).…”

“…This was probably due to the effectiveness of the mulesing operation that was introduced in the early thirties, regular crutching and jetting sheep with chemicals. Several studies have indicated that faecal soiling (dags) in the breech, wrinkles and bare area in the breech (Scobie et al 2008(Scobie et al , 2002(Scobie et al , 2007Edwards et al 2009;Greeff and Karlsson 2009;Smith et al 2009;Scholtz et al 2010) are the main candidates as potential indicator traits for breech strike resistance. The size of the bare area in the breech received strong focus of attention as a solution for surgical mulesing, as removal of wool around the anus through breeding reduces the potential to develop dags, as was shown by Scobie et al (2008) in Romney sheep.…”

“…Several studies have indicated that faecal soiling (dags) in the breech, wrinkles and bare area in the breech (Scobie et al 2008(Scobie et al , 2002(Scobie et al , 2007Edwards et al 2009;Greeff and Karlsson 2009;Smith et al 2009;Scholtz et al 2010) are the main candidates as potential indicator traits for breech strike resistance. The size of the bare area in the breech received strong focus of attention as a solution for surgical mulesing, as removal of wool around the anus through breeding reduces the potential to develop dags, as was shown by Scobie et al (2008) in Romney sheep. However, apart from the preliminary studies by Greeff and Karlsson (2009), no study to elucidate the role of dags, skin wrinkle, body conformation and wool traits that may contribute to breech strike has been carried out on Merino sheep in a Mediterranean environment.…”

Prevalence of breech‐strike in mulesed, clipped and unmulesed Merino hoggets in south‐eastern Australia

“…Dag and breech wrinkle appear to be the two most important risk factors for breech‐strike of fine‐wool Merino sheep in south‐eastern Australia 14,17 . There is little natural variation in the amount of bare breech area or association of bare area with reduced risk of breech‐strike in fine‐wool Merinos, 17 although this trait does reduce the risk of breech‐strike in meat breeds and Merino cross‐bred sheep when bare area scores are ≥4 31,32 …”