By Kim Egan, DVM, Dairy Consultant Manager, Genex
There have been a lot of presentations, articles and discussion in the last few years about genetic improvement, genomic testing and breeding strategies based on genetic merit. Do you still have questions about the difference genetics can make in a herd or the difference it is making in your herd? Let's look at performance aspects at differing genetic levels both within individual herds and across several large herds.
In single herds, comparison by genetic values can show differences even when cows are eating the same ration and experiencing the same temperatures, milking routine, ventilation, crowding, etc.
Here is an example from an individual herd analyzed in 2013. In this 1,700-cow herd, 28.87% of cows with a Lifetime Net Merit Parent Average (LNMPA) under +$250 experienced metritis and/or retained placenta. In this same herd, for the same period of time, only 22.9% of cows with LNMPA over +$250 experienced metritis and/or retained placenta. Using figures from Overton & Fetrow published by the Dairy Cattle Reproductive Council in 2008, the average cost of a case of metritis is $225. In this example, the cows with higher LNMPA were $9,361 more profitable just in reduced cases of metritis or retained placenta in one year.
After looking at several individual herds and seeing similar results in each one, data was compiled and the findings are as follows. Data from 24,760 cows showed fewer displaced abomasums and fewer cases of metritis, especially in first lactation, with a reduction from 46.19% (with sire LNM less than +$200) to 14.75% (with sire LNM over +$600). The results are illustrated in the graph below.
Surprisingly, even the percent of fresh cows that experienced displaced abomasums were significantly reduced with improving sire LNM. See the graph below.
This shows that when it comes to fresh cow issues genetics do matter.