The relationships between faecal worm egg count and subjectively assessed wool and conformation traits in the Tygerhoek Merino flock

Matebesi-Ranthimo, P. A. M.; Cloete, S.W.P.; Wyk, J.B. van; Olivier, J.J.

doi:10.4314/sajas.v44i3.3

Cited by 3 publications

(4 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The current results are generally in line with those reported by Matebesi et al (2009a). The results reported recently on Tygerhoek Merino resource flock (Matebesi-Ranthimo et al, 2014) Estimates of the genetic (r g ), phenotypic (r p ) and environmental (r e ) correlations from the two-trait analyses of ewe reproduction with subjectively assessed wool and conformation traits are presented in Tables 5 and 6, respectively. Most of these correlations were associated with relatively high standard errors compared with the estimate, and thus are not significant.…”

Section: Resultssupporting

confidence: 79%

“…A dam permanent environmental effect of 3% affected WFS. The present heritability estimates are generally higher than those reported by Matebesi-Ranthimo et al (2014) for Tygerhoek Merino resource flock, with the exception of estimates for COL, which were higher at Tygerhoek. The present results accorded well with those reported for Cradock fine wool Merinos for the corresponding traits (Olivier, 2014).…”

Section: Resultscontrasting

confidence: 52%

“…The data editing for ewe reproduction traits was described by Matebesi-Ranthimo et al (2017), while that of subjectively assessed wool and conformation traits used in this investigation was performed as described in Matebesi-Ranthimo et al (2014). The ASReml program (Gilmour et al, 2009) was used to perform analyses similar to those applied by Matebesi-Ranthimo et al (2017).…”

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Relationship of ewe reproduction with subjectively assessed wool and conformation traits in the Elsenburg Merino flock

Matebesi-Ranthimo¹,

Cloete²,

Wyk³

et al. 2018

SA J. An. Sci.

View full text Add to dashboard Cite

Subjectively assessed wool and conformation traits are widely used to select breeding ewes and rams in the sheep industry. Data from a Merino flock that is maintained at Elsenburg Research Farm were used to investigate animal model (co)variance components for ewe reproduction traits with subjectively assessed wool and conformation traits. Ewe reproduction traits were assessed at their first lambing opportunity at two years, or over a three-year period from their lambing opportunities at two to four years old. Relationships of ewe reproduction traits with subjectively measured wool and conformation traits were also investigated. All these traits were heritable, with a range from 0.16 ± 0.03 for topline (TOPL) to 0.64 ± 0.04 for woolly face score (WFS). Genetic correlations of number of lambs born (NLB1) with colour (COL), number of lambs weaned (NLW1) with COL and belly and points (BANDP) and total weight of lamb weaned (TWW1) with COL were negative and significant. Significant genetic correlations of ewe reproduction traits over three lambing opportunities were found between number of lambs born (NLB3) and WFS (0.23 ± 0.11) and between total weight weaned (TWW3) and face cover score (FCS) (-0.33 ± 0.16). Among these traits, the noteworthy favourable genetic correlation between total fold score (TOT) and NLB1 suggested that plainer ewes were more reproductive. This is important for the South African Merino industry as plainer sheep are more desirable because of their faster growth and higher lambing percentages and reduced chances of fly strike. Selection for improved ewe reproduction in Merino sheep thus would not result in marked unfavourable correlated responses in most of these subjective wool and conformation traits.

show abstract

Section: Resultssupporting

confidence: 79%

Section: Resultscontrasting

confidence: 52%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Relationship of ewe reproduction with subjectively assessed wool and conformation traits in the Elsenburg Merino flock

Matebesi-Ranthimo¹,

Cloete²,

Wyk³

et al. 2018

SA J. An. Sci.

View full text Add to dashboard Cite

show abstract

“…Furthermore, the standard error of heritability for SC was lower in the present study. The present heritability estimates for CRIM and OIL were lower than those reported by Matebesiet al [44][45][46]. Nevertheless, the heritability estimates for CRIM and OIL based on pedigree or genomic information were lower, indicating that subjectively-assessed wool traits are greatly influenced by environmental factors.…”

Section: Genetic Parameters Of Wool Traitscontrasting

confidence: 88%

The Effect of Integrating Genomic Information into Genetic Evaluations of Chinese Merino Sheep

Chen

Luo

Zhao

et al. 2020

Animals

View full text Add to dashboard Cite

Genomic evaluations are a method for improving the accuracy of breeding value estimation. This study aimed to compare estimates of genetic parameters and the accuracy of breeding values for wool traits in Merino sheep between pedigree-based best linear unbiased prediction (PBLUP) and single-step genomic best linear unbiased prediction (ssGBLUP) using Bayesian inference. Data were collected from 28,391 yearlings of Chinese Merino sheep (classified in 1992–2018) at the Xinjiang Gonaisi Fine Wool Sheep-Breeding Farm, China. Subjectively-assessed wool traits, namely, spinning count (SC), crimp definition (CRIM), oil (OIL), and body size (BS), and objectively-measured traits, namely, fleece length (FL), greasy fleece weight (GFW), mean fiber diameter (MFD), crimp number (CN), and body weight pre-shearing (BWPS), were analyzed. The estimates of heritability for wool traits were low to moderate. The largest h2 values were observed for FL (0.277) and MFD (0.290) with ssGBLUP. The heritabilities estimated for wool traits with ssGBLUP were slightly higher than those obtained with PBLUP. The accuracies of breeding values were low to moderate, ranging from 0.362 to 0.573 for the whole population and from 0.318 to 0.676 for the genotyped subpopulation. The correlation between the estimated breeding values (EBVs) and genomic EBVs (GEBVs) ranged from 0.717 to 0.862 for the whole population, and the relative increase in accuracy when comparing EBVs with GEBVs ranged from 0.372% to 7.486% for these traits. However, in the genotyped population, the rank correlation between the estimates obtained with PBLUP and ssGBLUP was reduced to 0.525 to 0.769, with increases in average accuracy of 3.016% to 11.736% for the GEBVs in relation to the EBVs. Thus, genomic information could allow us to more accurately estimate the relationships between animals and improve estimates of heritability and the accuracy of breeding values by ssGBLUP.

show abstract

Genetic relationships between internal parasite resistance and production traits in Merino sheep

Brown

Fogarty

2017

Anim. Prod. Sci.

View full text Add to dashboard Cite

Breeding Merino sheep that are resistant to internal parasites alleviates the high costs associated with treatment of worm infestation and loss of production, as well as mitigating the development of anthelmintic resistance among the major worm species. Faecal worm egg count ((cube root transformation), wec) can be used in sheep as a measure of internal parasite resistance. Accurate estimates of genetic parameters for wec are required for calculation of Australian Sheep Breeding Values and inclusion of worm resistance in sheep breeding programs. This study provides updated estimates of heritability for wec and its genetic correlations with production traits. Data were analysed from a wide range of Australian and New Zealand Merino sheep in the MERINOSELECT database, which included 141 flocks with 801 flock years and up to 217 137 animals with wec recorded in at least one of four ages (W = weaning, P = post weaning, Y = yearling, H = hogget). The heritability estimates ranged from 0.16 ± 0.01 for Ywec to 0.29 ± 0.01 for Wwec, with generally high genetic correlations between the ages. Bivariate analyses estimated genetic correlations between wec at the various ages and growth, carcass quality, reproduction and wool production traits at various ages. These genetic correlations were generally small or close to zero, albeit with some significantly different from zero. The moderate heritability for wec (0.2–0.3) and its high phenotypic variation (coefficient of variation >30%) shows that relatively rapid selection response for worm resistance could be achieved. Inclusion of wec in sheep breeding programs to increase worm resistance would be expected to have little if any impact on other important production traits. These genetic parameters have been incorporated into MERINOSELECT by Sheep Genetics to provide Australian Sheep Breeding Values for wec and appropriate indices for wool and meat production. There is evidence that genotype × environment interactions may be important in some environments by reducing the accuracy of Australian Sheep Breeding Values for wec. Hence it may be prudent for breeders to implement strategies that manage the risk of any impact of genotype × environment on their breeding program.

show abstract

The relationships between faecal worm egg count and subjectively assessed wool and conformation traits in the Tygerhoek Merino flock

Cited by 3 publications

References 14 publications

Relationship of ewe reproduction with subjectively assessed wool and conformation traits in the Elsenburg Merino flock

Relationship of ewe reproduction with subjectively assessed wool and conformation traits in the Elsenburg Merino flock

The Effect of Integrating Genomic Information into Genetic Evaluations of Chinese Merino Sheep

Genetic relationships between internal parasite resistance and production traits in Merino sheep

Contact Info

Product

Resources

About