Recently we've engaged in a couple of conversations about the value of genetic evaluation tools like our Canadian Lifetime Profit Index. It seems that some people equate animals who rank high on this listing - be they male or female - as being high production cattle only! It is interesting to speculate where this concept comes from and why it is so ingrained in some mindsets. In truth, animals are evaluated for their estimated transmitting abilities for fat and protein production and type or durability traits and health and fertility or fitness traits as components of the LPI. While we'll be doing some "technology transfer" on this topic in the pages of the Canadian Jersey Breeder in coming issues a few points are worth noting now.
Overall emphasis in the breed-specific formula for Jersey are 57% production, 33% durability and 10% health and fertility. In greater detail, the weightings within the production component for Jersey are (out of a total of ten) 5.1 protein yield, 0.9 protein percent, 3.4 fat yield and 0.6 fat percent. Our emphasis on yields is lower than the other breeds and our emphasis on percents is notably higher. Durability considers ratings for herd life, mammary system, feet and legs and dairy strength with the three type traits receiving descending emphasis in the order they are listed.
Within the health and fertility section, somatic cell score, udder depth, milking speed and daughter fertility are all considered. Again, Jersey varies from most other breeds by placing more emphasis on somatic cell score, udder depth and milking speed than daughter fertility. Part of the decision was based on the fact that Jerseys excel when compared to other breeds for daughter fertility.
The exact emphasis within the Jersey breed was developed by our Genetic Improvement Committee and recommended, as stated above, to the Board of Directors of Jersey Canada who approved it for implementation by Canadian Dairy Network, Canadian supplier of genetic evaluations.
In recent years the Genetic Improvement Committee have done pedigree studies of the high ranking LPI cows in Canada. The discovery was that most of the high-ranking cows come from deep pedigrees with numerous generations of high scoring cows or higher scoring cows for the herd of origin. There is usually good/above average production evident for generations and sometimes quite excellent performance for health traits.
While slavish devotion to the exact rankings of cows or bulls on these lists could end up being overly restrictive and cause narrowing of genetic bases they do serve as a terrific genetic direction tool. Canadians love balanced cows and balanced genetics. We want productive cows with strong type who are healthy and last a long time. It would be both prudent and wise to consider what the LPI lists tell us and to shrewdly consider what the true capabilities of high ranking cattle, male or female, really are. Take a look at the top few LPI bulls and think about what characteristics their proofs have.
Food for thought!
