Kim Egan, DVM, Dairy Consultant Manager, Genex
Factors affecting how well our cows transition through the dry period, freshening and early lactation could arguably have the biggest impact on the profitability of our farms. Nutrient intake and mobilization, calving-related issues, stocking density and other factors, including genetics, all play a role in how well cows transition from dry to lactating.
Cows that do not transition well may become thin, experience anestrus and have an increased incidence of lameness. Thinner cows have a thinner digital cushion, as the thickness of this cushion in the hoof is highly associated with body condition (body condition is also included in the Ideal Commercial Cow index).
The two genetic indices we now focus on, Lifetime Net Merit (LNM$) and Ideal Commercial Cow (ICC$), incorporate traits that improve the ability of our cows to transition and stay in the herd. ICC$ includes Locomotion, Productive Life and Calving Ability. LNM$ includes Foot & Leg Composite, Productive Life and Calving Ability. So, let's take a look at lactating cows to see how genetically superior females are more profitable for the herd.
We looked at event data from 12,269 cow records. All cows freshened within one calendar year from November 2013 through October 2014. The percentage of those culled within 60 days in milk (DIM) declines as LNM$ parent average (LNMPA) increases. See the graph below:
On these same cows, we can also see the percentage of cows recorded as lame decreasing steadily with increasing LNMPA as illustrated in the graph below:
The financial impact of lameness has been reported to be $300 per event as published by the American Association of Bovine Practitioners in the 1995-1996 proceedings, and the cost of early culling has been reported to average $750 per cow culled prior to 60 days in milk according to Dr. Albert DeVries, University of Florida, in 2010. Therefore, we can see how the cows with better genetics are more profitable for the farm.