“Success isn’t always about greatness. It’s about consistency. Consistent hard work leads to success. Greatness will come.” -Dwayne “The Rock” Johnson
This quote from “The Rock” especially resonates in the area of genetic selection in beef cattle. But goals are one thing. Putting in place a plan to meet those goals, and sticking to this plan, is what yields results.
To this end, researchers from Agriculture and Agri-Food Canada and UAlberta conducted a breeding and selection program for residual feed intake (RFI) in the crossbred cattle herd at UAlberta’s Roy Berg Kinsella Research Ranch. The 1st years of selection were supported by grants from the Alberta Livestock and Meat Agency, and the Beef Cattle Research Council. To start, the main crossbred herd was split in two based upon cattle age, and calving date the previous year, to yield equal herds. Then one herd was subjected to a traditional selection scheme, which was growth from birth to one year of age for both replacement heifers and bulls, including a cut-off for birthweights. This was the “Control” herd. For the other herd, replacement breeder selection was based on a selection index that included EPDs for maternal weaning weight, and genomically-enhanced breeding values for RFI (but still including the cut-offs for birth weights). This herd was named the “Efficient” herd.
Even after project funding ended, researchers maintained these Control and Efficient herds, and continued selection for RFI in the Efficient herd though their replacement bulls. They also continued testing all potential replacement breeding animals for RFI through funding from other projects. Replacement heifers in the Efficient herd have slowly decreased their RFI values, and in winter 2019-2020, Efficient heifers consumed 4.8% less feed than the Control heifers during their RFI test. This is an improvement of 0.7%/year for RFI, which is in line with the 0.5%-0.8%/year improvement rate as reported at the end of the formal projects.
To put this in an economic context, we can compare the difference in feed costs for these heifers:
For example, a crossbred heifer at Kinsella consumes on average 8.71 kg DM (dry matter)/day. The difference in intake between the Efficient vs Control heifers is 0.42 kg DM/d or 4.8%. Therefore, feed savings would be $0.15/kg DM x 365 days x 0.42 kg DM/day = ~$23/heifer/year.
Would any cattle producer like to save $23/head/year in feed costs? Of course, they would! Multiply that by 100 head of cattle, the savings could reach $2,300. And the savings increase as more feed efficient cattle are fed.
Now, what about environmental benefits? Well, a heifer of the same size and genetic background as the above Efficient heifers at Kinsella emits ~179 g CH4/day as measured by Manafiazar et al (2020). The same study found that heifers with a difference in DMI of 8% also had a difference in CH4 emissions of 2.5%/day. Therefore, a difference in DMI of 4.8% as a result of selecting for RFI as described above would be associated with a difference in daily CH4 emission of 1.5%. This equates to 2.69 g CH4/day, or 0.98 kg/year. The global warming potential of methane is its grams emitted multiplied by a factor of 28, which, in our example, equals a difference of 27.4 kg CO2e/year. Thus, enteric CH4 emissions from an Efficient heifer would be predicted to be 27.4 kg CO2e/year lower than from a Control heifer. Multiply that by 100 heifers and now you have a difference of 2,740 kg, or 2.74 tonnes. So what?
To put this in context, we will compare these emissions to GHG emissions from an average car, which emits ~404 g of CO2/mile. The reduction in enteric methane emissions brought about by selection for RFI in these 100 cattle is equivalent to a car driving 6,782 miles. Whoa! Can we do that? Yes, we can. 🙂