Short communication: Divergent selection for reproduction affects dag score, breech wrinkle score and crutching time in Merinos

Scholtz, A. J.; Cloete, S.W.P.; Cloete, J.J.E.; A, Kruger; Wyk, J.B. van; Linde, T. C. de K. van der

doi:10.4314/sajas.v42i3.9

Cited by 6 publications

(2 citation statements)

References 24 publications

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“…Fecal soiling, or dags, occurs when fecal matter adheres to the wool around the tail and legs ( 63 ). This is associated with higher gastrointestinal parasite burdens, such as fluke and nematodes leading to diarrhea ( 64 ), infrequent use of anthelmintic drugs, lower fecal consistency, poorer or wetter pasture, and lower live weights ( 65 ).…”

Section: Resultsmentioning

confidence: 99%

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Evaluation of Animal-Based Indicators to Be Used in a Welfare Assessment Protocol for Sheep

et al. 2017

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Sheep are managed under a variety of different environments (continually outdoors, partially outdoors with seasonal or diurnal variation, continuously indoors) and for different purposes, which makes assessing welfare challenging. This diversity means that resource-based indicators are not particularly useful and, thus, a welfare assessment scheme for sheep, focusing on animal-based indicators, was developed. We focus specifically on ewes, as the most numerous group of sheep present on farm, although many of the indicators may also have relevance to adult male sheep. Using the Welfare Quality® framework of four Principles and 12 Criteria, we considered the validity, reliability, and feasibility of 46 putative animal-based indicators derived from the literature for these criteria. Where animal-based indicators were potentially unreliably or were not considered feasible, we also considered the resource-based indicators of access to water, stocking density, and floor slipperiness. With the exception of the criteria “Absence of prolonged thirst,” we suggest at least one animal-based indicator for each welfare criterion. As a minimum, face validity was available for all indicators; however, for many, we found evidence of convergent validity and discriminant validity (e.g., lameness as measured by gait score, body condition score). The reliability of most of the physical and health measures has been tested in the field and found to be appropriate for use in welfare assessment. However, for the majority of the proposed behavioral indicators (lying synchrony, social withdrawal, postures associated with pain, vocalizations, stereotypy, vigilance, response to surprise, and human approach test), this still needs to be tested. In conclusion, the comprehensive assessment of sheep welfare through largely animal-based measures is supported by the literature through the use of indicators focusing on specific aspects of sheep biology. Further work is required for some indicators to ensure that measures are reliable when used in commercial settings.

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Section: Resultsmentioning

confidence: 99%

“…This is associated with higher gastrointestinal parasite burdens, such as fluke and nematodes leading to diarrhea ( 64 ), infrequent use of anthelmintic drugs, lower fecal consistency, poorer or wetter pasture, and lower live weights ( 65 ). The presence of fecal matter on the fleece also increases the risk of fly strike ( 63 , 65 ).…”

Section: Resultsmentioning

confidence: 99%

Evaluation of Animal-Based Indicators to Be Used in a Welfare Assessment Protocol for Sheep

et al. 2017

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Arena behaviour of Merino weaners is heritable and affected by divergent selection for number of lambs weaned per ewe mated

Cloete

Burger

Scholtz³

et al. 2020

Applied Animal Behaviour Science

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Genetic parameters for lameness, mastitis and dagginess in a multi-breed sheep population

O’Brien

McHugh

Wall³

et al. 2017

Animal

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The objective of the present study was to quantify the extent of genetic variation in three health-related traits namely dagginess, lameness and mastitis, in an Irish sheep population. Each of the health traits investigated pose substantial welfare implications as well as considerable economic costs to producers. Data were also available on four body-related traits, namely body condition score (BCS), live weight, muscle depth and fat depth. Animals were categorised as lambs (<365 days old) or ewes (⩾365 days old) and were analysed both separately and combined. After edits, 39 315 records from 264 flocks between the years 2009 and 2015 inclusive were analysed. Variance components were estimated using animal linear mixed models. Fixed effects included contemporary group, represented as a three-way interaction between flock, date of inspection and animal type (i.e. lamb, yearling ewe (i.e. females ⩾365 days but <730 days old that have not yet had a recorded lambing) or ewe), animal breed proportion, coefficients of heterosis and recombination, animal gender (lambs only), animal parity (ewes only; lambs were assigned a separate 'parity') and the difference in age of the animal from the median of the respective parity/age group. An additive genetic effect and residual effect were both fitted as random terms with maternal genetic and non-genetic components also considered for traits of the lambs. The direct heritability of dagginess was similar across age groups (0.14 to 0.15), whereas the direct heritability of lameness ranged from 0.06 (ewes) to 0.12 (lambs). The direct heritability of mastitis was 0.04. For dagginess, 13% of the phenotypic variation was explained by dam litter, whereas the maternal heritability of dagginess was 0.05. The genetic correlation between ewe and lamb dagginess was 0.38; the correlation between ewe and lamb lameness was close to zero but was associated with a large standard error. Direct genetic correlations were evident between dagginess and BCS in ewes and between lameness and BCS in lambs. The present study has demonstrated that ample genetic variation exists for all three health traits investigated indicating that genetic improvement is indeed possible.

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Short communication: Divergent selection for reproduction affects dag score, breech wrinkle score and crutching time in Merinos

Cited by 6 publications

References 24 publications

Evaluation of Animal-Based Indicators to Be Used in a Welfare Assessment Protocol for Sheep

Evaluation of Animal-Based Indicators to Be Used in a Welfare Assessment Protocol for Sheep

Arena behaviour of Merino weaners is heritable and affected by divergent selection for number of lambs weaned per ewe mated

Genetic parameters for lameness, mastitis and dagginess in a multi-breed sheep population

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