The Genomics for Commercial Angus Cattle Producer Demonstration Site (PDS) project with funding support from MLA involves a group of breeders in Victoria’s North East trialing the HeiferSELECT product to assist in their selection of replacement heifers. Six core-producers will test 100% of their heifer crop over five years. The core-producers DNA sampled their first heifer progeny in Spring 2020 and have recently collected samples on their 4th cohort.
In the early stages of the project, the participants made numerous observations that were not expected. These include:
- Liveweight did not correlate with genetic merit as the impact of environmental factors was largely underestimated by the producers.
- Selecting replacement heifers with genomics adds significant market-value to cull/surplus heifers by the inclusion of heavier and visually appealing animals which increased returns in most markets.
- Selecting lighter heifers did not significantly impact conception rates.
The project has also reinforced the basic fundamentals of the role of genetics in beef herds. The most stark of these is the importance of producers selecting bulls that meet their breeding objective. Many producers had some bulls that were not taking their herd in the desired direction. These were typically deployed under duress (following breakdowns) or selected only for birthweight for use over heifers.
As the revelations slowed down a little during this middle phase of the PDS, the group took the opportunity to consider some related topics. Angus Australia gave us the opportunity to trial the equivalent genomics tool for angus steers, and we engaged respected livestock consultants MacKinnon Group to use GrassGro to evaluate our production system profitability against alternative target markets.
SteerSELECT
SteerSelect is a genomics tool developed by Angus Australia and CSIRO. It predicts the genetic merit of commercial Angus steers and facilitates the drafting of Angus steers into production systems that are suited to their genetics. While the tool is not yet commercially available, our genomics group was given the opportunity to trial it, and two of our producers used it on their entire steer crop.
The fundamental questions around a genomic tool for commercial steers is around which parts of the supply chain can benefit from genetic predictions, and who might be willing to pay for it. Our producers were keen to see if they could put the tool to use in the on-farm link of the supply chain.
The Tool
Like HeiferSELECT, SteerSELECT evaluates a DNA sample of an individual animal and provides a number of genetic predictions.
- On Farm
- Yearling Weight
- Feedlot
- Average Daily Gain
- Daily Feed Intake
- Carcase
- Carcase Weight
- Eye Muscle Area
- Rib Fat
- MSA Marbling
- Ossification
- Resiliance
- ImmuneDEX
- Angus Content
- Angus Y/N
- Angus %
- Non-Angus Breed Content
- British %
- Indicus %
- European %
- Other %
The tool also identifies the registered Angus sire.
SteerSELECT for On-farm Selection
There may be seasonal scenarios where a breeder wishes to sell off the least profitable stock. Could genomic predictions for yearling weight (YW) be used to identify which steers are most suitable to retain and grow to feedlot specification?
The first lesson we learnt at the beginning of the Genomics PDS was that environmental factors largely determine actual yearling weights in our heifers. Factors such as age (born early or late in the calving season) and nutrition (milk yield of dam) being the most obvious of these. Similarly in our steers, genomic predictions for YW don’t correlate with actual yearling weight. See Figure 1: YW Actual vs YW Prediction.
Another way of considering the genetic merit of the steers being retained to grow out to feedlot spec is to look at their Average Daily Gain (ADG) genomic prediction versus actual. Using the same steer cohort in the previous graph, we looked at ADG for the 58 days prior to measuring their YW. See Figure 2: ADG Actual vs ADG Prediction.
There does not appear to be any opportunity to select the most profitable steers (on-farm) using genomics, on the basis of yearling weight and average daily gain. Marbling ability is obviously another key indicator of genetic merit and we look forward to comparing genomic predictions with the eventual carcase feedback on this cohort of steers.
In most commercial enterprises, whether it’s steers or heifers, typically only a very small percentage of outliers a.k.a. ‘runts’ or ‘rats and mice’ are unsuitable to join or are left off the truck. These animals often have good genetic merit so it can be assumed they have been subjected to extreme environmental pressure such as dam abandonment or teat failure and/or disease.
