B.FLT.1014 - Australian optimal carcase endpoint and sorting system development

Summary

The objective of this project is to develop the Australian Optimal Carcase Endpoint and Sorting System (AOCESS) to predict the carcase endpoint that achieves the maximum profit for Australian feedlot cattle. This project entails the evaluation, development, and calibration of animal growth and economic models, and the integration of these models with feedback data from different technologies and carcase grading. The decision support tool will allow predictions at critical points in time and near real-time such as induction and re-implant performing forward predictions for different target carcase endpoints considering the length of the feeding period, economic, diet and animal characteristics from induction to slaughter.

The optimal carcase endpoint of feedlot cattle can be defined as the carcase weight and specifications that maximises profit of the slaughtered animal, which is largely determined by carcase value and cost of production. Body fatness influences both beef quality and cost of production affecting the amount of feed and time required to achieve a particular carcase endpoint depending on factors such as genetics, induction weight, nutrition, and management. The present project completed a serial slaughter trial with three genetic biotypes of steers (Angus, Brahman, and Charolais) slaughtered at 0, 50, 100, 150, and 200 days on feed. Feed intake and body composition were measured. These data were then used to evaluate currently available nutrition models that predict animal performance and cost of production. A number of sensor technologies including ultrasound, biometrics, smart tags, RFID at feedbunk, walk-on-weighing and computed tomography were examined for their utility to improve prediction of feedlot cattle performance, body composition and carcase traits. Finally, two commercialisable systems were developed 1) to predict forward and 2) to predict in real time the optimal carcase endpoint to maximise profits.

Objectives

1. Evaluate the precision and accuracy of growth models to predict feed intake and carcase characteristics of Australian feedlot cattle.
2. Evaluate the precision and accuracy of sensor technologies to predict feed intake and carcase characteristics of Australian feedlot cattle.
3. Develop the first version of the Australian Optimal Carcase Endpoint and Sorting System.
4. Make recommendations of potential value to the Australian lot feeding industry and next steps for evaluation of the adapted Australian model.

Key findings

Body composition analysis revealed important breed, days on feed and breed x days on feed interactions for model development.
- Ultrasound predicted carcase grading with moderate to low precision and accuracy being best for rib fat, followed by intramuscular fat. Ultrasound kidney fat (mm) could predict kidney pelvic and heart fat (kg) with modest precision.
- Breed specific equations for rate of empty body weight (EBW) change per unit of empty body fat (EBF) accretion were developed.
- Equations to predict chemical EBF of live animals were developed from EBW, ultrasound measures; and also retrospectively from carcase characteristics.
- The in-pen weighing system was accurate to measure body weight and predict dry matter intake (DMI) with high precision and accuracy doing the back-calculation of energy and protein required for the observed BW and ADG. It has great potential for integration into feedlot sorting models, dependent on capital cost.
- Computed tomography of 28 carcases of different weights and breeds showed high precision and accuracy to predict physically separable fat and lean tissues.
- Prediction of carcase fat and empty body fat were also precisely predicted by CT, however the regression coefficient was lower than one, likely due to CT-derived fat containing moisture in each voxel unlike chemical fat.
- These results suggest that CT-derived carcase and body composition could replace the labour-intensive processing and chemical analysis with the equations presented in the present study, with appropriate linear bias adjustments.
- Two commercialisable feedlot sorting products have been developed, one based in real-time monitoring of BW and another to perform forward predictions of body composition. Further evaluation and development of both products is highly recommended.

Benefits to industry

Accurate projection of costs of production and sales revenue has the potential to sort cattle into dispatch marketing groups with maximum profitability. Further research is required to understand the value proposition of sorting systems developed in this project versus traditional marketing methods (body weight sorting at induction, or at drafting prior to slaughter).

MLA action

MLA presented results of this project to the October 2023 MLA Feedlot Research Symposium with consulting nutritionists and veterinarians.

Phase 3 of the research program is currently being considered by MLA.

Future research

It is recommended to start evaluating and refining both products developed in the present project under commercial conditions, namely the ‘live performance and carcase predictor’ and the ‘forecasting Australian Optimal Carcase Endpoint and Sorting System model’. Collecting new information in a serial slaughter trial with Wagyu cattle is also recommended due to its unique fat metabolism.