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Reducing labour at lambing: improving ewe mothering ability through breeding


Genetics, the study of genes and genetic variation, is a powerful tool at the disposal of farmers to identify the genetically elite animals to be the parents of the next generation. All improvements achieved through breeding are permanent and cumulative, Áine O'Brien, Researcher at Moorpark explains

Genetics, the study of genes and genetic variation

Genetics, the study of genes and genetic variation, is a powerful tool at the disposal of farmers to identify the genetically elite animals to be the parents of the next generation. All improvements achieved through breeding are permanent and cumulative, meaning their consequences will be seen in the flock for many years to come. 

Lambing on sheep farms accounts for over 25% of the annual labour requirement representing more than double the labour requirement at other key time points such as weaning, mating, or housing. Therefore, measures that could potentially reduce the labour requirement or time spent per ewe must be investigated. One such trait that is currently under investigation by Teagasc is ewe mothering ability. Ideally a ewe will lamb unassisted, produce sufficient colostrum and milk, as well as being attentive and encouraging towards her lambs. Ewes that do not achieve these milestones on their own require intervention from the farmer which incurs a cost (i.e., labour requirement) including the stress on farmers at the busiest time of the year.

Measuring ewe mothering ability

Ewe mothering ability is measured on a five-point scale based on the attentive behaviour demonstrated by the ewe towards her lambs where 1=the ewe showed no interest in her lambs and 5=the ewe licked her lambs immediately, was very protective, followed the lambs closely to a bonding pen and bleated for her lambs. Analysis was undertaken on over 25,000 flock-book recorded and commercial crossbred ewes that were scored for ewe mothering ability. The overall frequency of poor ewe mothering ability was 16.1%, while 83.9% of ewes were scored as displaying good ewe mothering ability. The heritability of a trait reflects the extent to which the trait of interest is under genetic control and can be referred to as the resemblance between relatives. The heritability estimate for ewe mothering ability is 6%, meaning that 6% of the differences in ewe mothering ability are solely due to her genetics.

Findings

Ewe mothering ability improved with parity meaning that ewes that had more litters had better ewe mothering ability which may be explained by the ewe’s previous experience. There was no difference in ewe mothering ability among ewes that lambed for the first time at one year of age versus those that lambed for the first time at two years of age.

Breeding goals

For any trait to be included in a breeding goal it must

  1. exhibit genetic variation;
  2. be economically or socially important; and
  3. be easily measureable on a large scale.

Ewe mothering ability fulfils each of these criterion and can therefore be included in the national sheep breeding index. In the future, the selection of sires with a superior breeding value for ewe mothering ability would improve the trait. Such a strategy could, overtime, reduce the labour requirement at lambing.

For more on this fascinating topic check out the Teagasc Sheep Breeding & Genetics webpage