Feed Efficiency
We have always been conscious of both the cost/input side of beef genetic selection as much as the revenue/output side, which has tended to dominate selection in most other breeding programmes. We have been weighing and condition scoring our cows for more than 30 years as an indirect measure of efficiency, and for almost 15 years, we have been using sires that have been tested for feed intake. Then in 2017, we worked with partners Vytelle (then GrowSafe) to build our own facility to test our young bulls primarily and some specific lines of progeny. We have more data than anyone else in NZ on this essential economic and environmental characteristic. As part of the Leachman Cattle $Profit Global Genetic Evaluation, we combine our data and genomic testing with more than 40,000 other tested animals. Like all traits we measure, accuracy is vital to get the best predictions; hence we have a small dedicated research facility to carry out the testing and development of our young bulls.
Why single out this trait?
Firstly, it is highly relevant for both the profitability of our farmer partners and customers but also importantly allows us to positively select for animals with a lighter environmental footprint. Historically we couldn’t measure this characteristic but in recent decade or more the technology has become more widely available and accurate. While it is expensive to measure we have always believed that you can’t manage what you don’t measure. What we have found is significant variation and size is a poor indicator of efficiency.
Secondly, there is almost always unintended consequences from any selection. Moreover, these consequences are almost always negative.
For this very reason, we must measure EVERY economically relevant trait. We must be on the watch for unintended consequences. In this case, we should be particularly careful that our efficiency selection does not result in production of animals that are leaner (have less back fat) or that are too large (have large mature cow weights) or that have poor fertility (have a lower number of calves produced in a cow's lifetime). Fortunately, we measure each of these traits and actively select to ensure that we don't get unintended consequences.
If we measure feed efficiency when animals are getting very fat (i.e. when there are big differences in fat deposition from animal to animal), then efficiency selection favours the leaner animals. However, most beef cattle deposit very small amounts of fat during the age period of 7 to 11 months of age -- which is when we do our efficiency testing. At this age, the primary driver of efficiency is differences in metabolic requirements. Literally, we are measuring if the animal is burning up feed efficiently. Low metabolic cattle tend to need less energy to keep the same body condition. They are also better at depositing fat when provided with excess feed.
Ultimately, you get what you select for in animals. If you select for the female most prone to deposit fat reserves, you will ultimately decrease growth rate, decrease carcass weight, and reduce milk production. The resulting females might even tend to be LESS fertile. The only way to ensure fertility is actually to measure it and then utilise a fertility EBV. Preferably, this EBV would be genomically enhanced. This is exactly what the Rissington herd does by using the FRT EBV from Zoetis.
We do not believe that farmers can simply improve via single trait selection or, worse yet, through no selection at all. No modern farmer can survive without continuous improvement. Genetic improvement is part of that improvement puzzle.
At Rissington, we do not single trait select. We measure everything. We calculate genomically enhanced EBVs on every relevant trait. We search out unintended selection consequences. We are finding genetic lines that are both feed-efficient AND highly fertile. These lines maintain sufficient fat reserves to breed back consistently under pasture conditions while growing more efficiently in confinement. Make no mistake, they are not easy to find. However, the result is that Rissington is developing cattle that actually do more with less.
