L.EQT.1908-Eating quality in Merino breeding programs Final Report
Genetic correlations among the sensory eating quality traits were all positive and high, both within and across cuts. Selection on any one trait improves other eating quality traits.
| Publication date: | 30 September 2022 |
| Project status: | Completed |
| Livestock species: | Sheep |
| Relevant regions: | National |
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Summary
This report presents estimates of genetic parameters for sensory eating quality traits of three lamb cuts (loin, topside and knuckle), including genetic and phenotypic correlations with objective eating quality, carcase composition, wool production and live animal carcase traits. These genetic parameter estimates for eating quality and carcase composition traits of Merinos can be used to verify the appropriateness of the current genetic parameters used in Merino genetic evaluation and in the enhancement of MERINOSELECT indexes that include an emphasis on carcase traits.
Objectives
This project, and consequently the final report, aimed to estimate genetic parameters for eating quality traits assessed on three Merino lamb cuts (loin, topside and knuckle), including genetic relationships with a range of Merino traits. The project also aimed to increase access to Australian Sheep Breeding Values (ASBVs) and comparative genotype information for eating quality traits of Merino sires by ram breeders and commercial producers. This aim had the intention to provide a selection index which could enable balanced selection for LMY, eating quality, wool production and reproduction in Merinos.
Key findings
• Heritability estimates for sensory eating quality traits assessed on loin, topside and knuckle samples were low to moderate, confirming that selection to improve these traits assessed on a range of Merino lamb cuts is possible.
• Irrespective of cut, better overall liking of the lamb meat would result from selection for increased intramuscular fat and lower shear force values.
• Selection for fleece weight is expected to lead to small reductions in overall liking of loins (post-weaning fleece weight only) versus small improvements in overall liking of topsides and knuckles.
• Following selection for improved LMY, overall liking scores in loins are expected to decline, while scores in the topside and knuckle may be expected to increase.
• While intramuscular fat and shear force values would be improved (yearling live weight only), negligible to small unfavourable responses in the overall liking scores would generally follow selection for live weight, particularly for scores of loin and topside cuts.
• Irrespective of assessed carcase fatness on live animals or on carcases, small favourable responses in intramuscular fat levels, meat tenderness and overall liking scores for loins and knuckles are expected to occur following selection for carcase fatness.
• Small, favourable responses in fleece weight (post-weaning assessment only) and mean fibre diameter are generally expected to follow selection on LMY, though coefficient of variation of diameter and staple length are expected to be altered unfavourably.
• As genetic correlations among the sensory eating quality traits were all positive and high, both within and across cuts, selection on any one trait would improve other eating quality traits.
Benefits to industry
This project, together with several other projects, has provided the data necessary to estimate genetic parameters for eating quality traits, assessed on a range of lamb cuts specifically for the Merino breed. These genetic parameter estimates will be useful in the development of a breeding value(s) for eating quality, allowing refinement of MERINOSELECT indexes to ensure that lamb produced by Merino dual purpose production systems are of acceptable quality, when eaten by consumers. For those Merino ewes mated to Terminal or Maternal sires to produce crossbred lambs, the genetic parameter estimates will provide confidence that the MERINOSELECT indexes used to generate those ewes are consistent with the eating quality objectives of the LAMBPLAN Terminal sire indexes.
MLA action
Further investment should occur to support collaboration between geneticists and meat scientists to ensure that the appropriate information (genetic and phenotypic) and automated measurement technologies are available.
Future research
1) a framework for the effective management of eating quality data in a central database
2) definition of the appropriate breeding objective trait
3) development of an economic value(s) for eating quality of Merino cuts
4) identification and evaluation of potential selection criteria traits (for the objective trait) based on automated measurements recorded on-farm and/or under the environments operating during processing of carcases in abattoirs
5) further recording of Merino eating quality and carcase composition data and genotyping to increase the accuracy of genetic parameters.
More information
| Project manager: | Peta Bradley |
| Contact email: | reports@mla.com.au |
