Quantifying disease and defect carcass losses at processing to improve feedback in the lamb supply chain: an arthritis case study

Context Lamb producers are currently limited in their ability to make informed on-farm management changes with respect to disease and defects identified at processing. This is due to the limited accuracy and detail of information included in disease and defect feedback supplied by processors. Increasing transparency of the feedback can allow producers to make more informed on-farm decisions, and, subsequently, improve productivity and animal welfare. Aims Using arthritis as a case study, the aim was to develop a scoring system that estimates hot standard carcass weight (HSCW) losses due to trimming at processing, so as to improve feedback to lamb producers. Methods An observational cross-sectional study was conducted at a southern New South Wales commercial processing facility, over 6 months and in five week-long blocks, from 21 February 2019 to 5 July 2019. Carcass trim components removed due to the presence of arthritis (shank or leg) were recorded for 217 of the 42164 lamb carcasses processed. Utilising average lot HSCWs, the total proportion of HSCW lost due to arthritis trimming (TPL) was calculated for each arthritic carcass. Linear regression analysis, with a logit-transform of TPL, was fitted to the data. Key results Processing lot and trim-component category were found to be significant (P << 0.001) explanatory variables for variation in TPL. Trim-component categories that were not significantly (P > 0.05) different were combined, with final categories being assigned arthritis trim scores as follows: 1, any forequarter shank; 2, any hindquarter shank; 3, any forequarter leg; and 4, any hindquarter leg. At an over-the-hooks carcass price of AU$7.83/kg and an average HSCW of 23.13 kg, these scores were used to estimate producer revenue losses per carcass (range AU$2.95–AU$18.08). Conclusions The accuracy and detail of information provided as feedback to lamb producers can be improved. For arthritis, this can be achieved using a trim-scoring system. Implications Altering feedback to include HSCW losses for processed lots in both kilograms and dollars against the associated disease or defect will better equip producers to make cost-effective on-farm management changes and reduce the impact on the lamb supply chain.

Impacts of major health conditions affecting the Australian sheepmeat value chain: a review

Major health conditions in sheep contribute to substantial economic losses throughout the sheepmeat supply chain in Australia. A systematic review was undertaken to explore the measurable impact of six conditions: arthritis, sheep measles, pleurisy, pneumonia, grass seeds and rib fractures, on the production of lamb and mutton across the meat value chain. Peer-reviewed scientific literature from three databases and non-peer-reviewed articles and reports from Australian government and non-government websites were searched between 11 and 17 November 2019. Original articles, including studies conducted in Australia and New Zealand, that had measurable impacts on conditions of interest were included. The search yielded 16 articles and reports and were classified as producer impact and/or processor impact studies. Mortalities were quantified for pneumonia and arthritis, with pneumonia having the highest impact for producers. Grass seed infestation resulted in the highest impact on carcase and liveweight losses compared to arthritis and pneumonia. Arthritis had the highest trim weight losses for both lamb and mutton and the highest rate of carcase condemnation. Grass seed was the only condition where other impacts on the processor (chain speed and staff relocation to the boning room) were quantified. Although quantifiable production and processing losses were available for some conditions, this review has highlighted that limited quantifiable data based on scientifically sound research were not available for other conditions. The evidence for some conditions found in this review can be used to target future research activities and to further assist producers in making informed management decisions on prevention and control.

Sustainable lamb production: Evaluation of factors affecting lamb growth using hierarchical, cross classified and multiple memberships models

In light of current concerns about the sustainability of red meat production in a world with increasing global demand for food from animal origin there is a need for a better understanding of factors that influence the growth rate and feed conversion efficiency of animals on commercial farms. The primary objective of this observational study was to use longitudinal data to quantify the simultaneous effects of multiple ewe and lamb factors on lamb growth rate. A secondary aim was to evaluate model structures that specifically account for lamb grouping effects during the growth period and compare these to classical hierarchical growth rate models. A total of 4172 weight recordings from 805 lambs and data on disease events were collected over a 6-month period from a commercial pedigree sheep flock. Three mixed model structures were compared, hierarchical, cross classified and multiple membership, and final estimates determined within a Bayesian framework. The multiple membership structure provided the best model fit and was used for final inference; taking account of the effect of lamb grouping over time provided the best estimates of lamb growth rate. Ewe lameness and mastitis cases had a deleterious impact on lamb growth. Lambs from ewes identified with mastitis during lactation were on average 3.0 (standard error (SE) 1.6) kg lighter during the four month growth period than lambs from unaffected ewes. Lambs from ewes that were not lame during pregnancy were 3.0 (SE 1.2) kg heavier at eight weeks of age than lambs from ewes with a least one lameness case during the same period. Lambs from ewes lame either during the first 4 weeks or between 4-8 weeks of a lamb's life (but not lame during pregnancy) were also significantly heavier at 56 days of age, than lambs reared by ewes that were lame during pregnancy (2.8 (SE 1.2) and 3.4 (SE 1.2) kg respectively). Cases of pneumonia and bacterial arthritis in lambs had a significant negative impact on lamb growth with affected lambs being on average 5.5 (SE 1.1) kg and 2.2 (SE 1.2) kg less than non-affected lambs respectively after the disease event. Prior to a case of lameness or pneumonia, lambs were significantly heavier than unaffected lambs suggesting a possible trade-off between growth and immune function. Overall, the study provides evidence that that a combination of ewe and lamb characteristics and disease events play an important role in determining lamb growth rate and that heavier lambs may be more susceptible to disease.