Health Traits and Breakfast
By Lloyd Simon, Sire Procurement Manager, Genex
When we take a walk through the grocery store to purchase breakfast "fixins" we understand the items we may want are priced by different measures. Eggs are by the dozen, bread is by the loaf, fruit and ham is by the pound, cereal is by the box. Confusing if it is your first time to shop, but we now think nothing of it.
Shopping for health traits is a similar experience. Productive Life is measured in months, Daughter Pregnancy Rate (DPR) is measured by percent, and Somatic Cell Score (SCS) is measured by log. But we have not had too many years to become as familiar with the process and values. When looking closer some obvious questions arise - Is the higher number always better? What are the practical implications? And lastly, what is the value to me?
Reading the Ingredients
Where does the health trait data originate? The data for SCS, DPR and Productive Life evaluations are gathered from producers' Dairy Herd Improvement Association (DHIA) records, edited for accuracy and then summarized each evaluation period.
SCS is the oldest of these three traits. SCSs are familiar to us as we see each cow's SCS on the monthly herd DHIA results. The SCS summary of a bull is a direct reflection of these monthly herd results and includes the level of somatic cells per milliliter of milk for each of his daughters. The bull's proof is recorded as a log score with 3.00 being average for all breeds. Above 3.00 relates to a higher SCS, while lower than 3.00 relates to an improved SCS.
The newest of these traits is DPR. DPR is a direct reflection of the ease or difficulty of a bull's daughters to become pregnant relative to the average. Again, DHIA breeding records account for the data summarized. As one would anticipate, the first significant actual DPR data on a sire actually occurs when his daughters are about 225 days in milk.
Zero is average for this trait. Positive numbers mean the bull's daughters are more likely to become pregnant relative to the average. Negative numbers mean the bull's daughters are less likely to become pregnant.
Productive Life is a direct measure of how long a bull's daughters actually are productive in the herd. Productive life is measured in months and it predicts the number of months, either more or less, that the daughters of a particular sire will stay in the herd relative to the average. The obvious question is if it measures or predicts how long they are in the herd, is the early information valid? Fortunately, SCS and Udder Depth are reasonably correlated to Productive Life and occur early in a bull's proof timeline. Additionally, DPR is also highly correlated to Productive Life which allows USDA to predict with reasonable accuracy the Productive Life of most sires. This should make sense to most dairymen; cows that breed back easily, have low SCS and shallow udders generally stay in the herd the longest.
Shopping for Health Traits
From a practical standpoint, shopping for health traits (SCS, DPR and Productive Life) is a relatively new experience. While doing so, the dollar values to keep in mind are $15, $21 and $29. These are dollar values which relate to each unit of measure for SCS, DPR and Productive Life, respectively.
For each 0.1 above or below 3.00 (average SCS log score for all breeds) each bull has a value entered in the Lifetime Net Merit (LNM$) formula. USDA values each 0.1 log at $15. If a bull's SCS summary is +2.80, his actual SCS dollar value in his LNM$ proof is +$30 ($15 x 0.2 = $30). If his SCS is +3.20, the dollar value would be -$30 ($15 x -0.2 = -$30).
The value of each unit (percent) in DPR is $21. Each positive percent is four less days open. Each negative percent is four more days open. Zero is average. If a bull has a DPR of +2.0%, his DPR dollar value in his LNM$ proof would be +$42 ($21 x 2 = $42).
USDA presently values each month of Productive Life at $29. A bull with a Productive Life of +3.0 (months) would have a Productive Life dollar value of +$87 ($29 x 3 = $87) in his LNM$ summary.
LNM$: The Sum of the Parts
Most of us are comfortable buying eggs by the dozen and bread by the loaf. Likewise, most dairymen know the price per hundred weight they receive for their milk and probably their feed cost per hundred. Within the LNM$ formula, DPR, SCS and Productive Life account for 35 percent or about one-third of a bull's LNM$ proof. While health and fitness traits do not express themselves as dramatically as pounds of milk in the tank, they do impact cash flow and net worth just as surely. Health, production, conformation and calving ability are all also weighted in LNM$ to rank sires on their net profitability.
Looking at the larger picture, genetically your herd is also a sum of these parts. Using the LNM$ index when making sire selection decisions can help to raise the genetic base and profitability of your herd. As always, the best advice is to start at the top of the LNM$ list and sort from there. But just like shopping for breakfast, it is important to know the value of the ingredients.
