How much do we really understand the TPITM and LPI system? Do we really know what they mean and what their limitations are? Earlier this week CDN General Manager Brian VanDoormaal posted an informative an interesting article, ‘Canadian Pride of the Canadian Kind!’, on the CDN website comparing and contrasting TPI™ and LPI, the national indexes for the USA and Canada. This got us here at the Bullvine thinking, maybe it’s time to revisit just what these indexes mean, why we have them and what their limitations are.
A New Tool was Needed
These indexes started in Canada and the USA for a number of reasons. In 1984 Holstein Canada had adopted its breeding strategy whereby equal emphasis was to be placed on type and production yet almost two animal generations later breeders often continued to practice single trait selection – for show type, for conformation, for fat percent, for other traits. Marketers were all claiming to the #1 bull for this that or the other thing. In short the strategy was not being followed and the benefits of moving the population forward were not being achieved.
Setting the Standard for Continuous Improvement
TPI and LPI were introduced at relatively the same time and their primary achievement was to set a common base for breeders to rank their animals. Both indexes were first used over twenty years ago and have been continuously improved. Since starting as a way of combining type and production TPI™ and LPI have been enhanced by attaching economics to the traits. This relates back to the breeders bottom line. The indexes have been adjusted to norms and standard deviations. For instance, milk yield is a big number and conformation is a single number, but their relative importance may be more closely related than the numbers alone would indicate. Having said that, it was a good move to remove milk yield in favour of fat plus protein. We don’t need to be shipping water or forcing cows to producing more and more low component milk. Next conformation traits used in the indexes was limited over time to those of most economic importance on the farm. More recently the indexes have added health and fertility traits.
These are all worthwhile enhancements. Yes these indexes have been dynamic over the past two decades but have not been changed so frequently that they have lost the trust and support of the users
How to Use the Indexes
Today we make multiple uses of TPI™ and LPI:
- to select parents especially bulls to be used,
- to market both males and females,
- to follow the breed’s breeding strategy specifically indentifying the animals that best combine the traits and weightings in the strategy
- used as culling tools within a herd or population primarily for proven bulls. Cows are most often culled for one or two economically limiting factors they have.
And the most important use of TPI™ and LPI
- To rank animals based on the breeding strategy.
Moving the Population Forward!
It is the breeder’s and breeding companies that use the rankings to move their herd of the population forward. Since the traits in these indexes frequently have zero or negative correlations with each other, the indexes are a way to rank animals and come up with what is often referred to as ‘balanced breeding’. Animals with show type and production well below average or high production and low type, do little to improve herds or breeds.
Indexes Go Beyond the Numbers
Wouldn’t it be great, if you could just combine this LPI or TPI number with this trait you’re trying to improve and , “Voila!” you have the progeny that will improve your breeding program? In 2012, when we are using, TPI™ and LPI we must be mindful that they include composite and predictive traits that are independent or negatively associated with each other. This means that the number in the index cannot be seen in the milk pail, in the eye of the breeder or in the bottom line of the farm. For instance a cow or bull with 3000 LPI – where do you see that number? It’s the combination of factors that is important. Simply stated, the indexes are a way of comparing the merits of animals. The significance is in the comparison not in the number itself.
So what are the Results?
Since the adoption of both TPI™ and LPI, breeders and breeding companies have been able to significantly improve their herd and move the breeds forward according to the breeding strategies. The results can be seen in the udders in the barns and the volumes of fat and protein in the bulk tanks to name just three components of these indexes. Less obvious are the results for less heritable traits like feet and legs, SCS and the more recently added traits for female reproduction and longevity. Measuring the results of breeding is not easy or free of complication. Variables on each farm such as nutrition, housing, labour, management and environment can all impact the breeding results.
Annually CDN publishes the changes in many traits for the Canadian dairy cattle populations. These changes are estimates of the genetic gains made in the previous year. In 2012 the published changes for Holsteins include LPI +160, fat +3.4 kgs, protein +2.4 kgs. Conformation+1.05, Mammary System +0.93, Feet & Legs +0.81, Herd Life +0.50, SCS -0.03 and Daughter Fertility -0.27. As you can see progress was not made for all traits. This happens because animals in the population are the result of breeder decisions and not the result of having a national breeding strategy. We do not have access to the results for the USA however we expect that they would mirror those in Canada.
Are There Limitations?
Yes there are two limitations. First, as mentioned, TPI™ and LPI points cannot be seen by the human eye, measured in the bulk tank or on a farm’s financial statement. Secondly TPI™ and LPI function as if breeders are mating animals evenly rated for all components in the index. In actual fact, every bull and every cow has both strengths and limitations. Neither the absolute average nor the perfect animal in the population has ever been achieved. Each time a breeding decision is made, breeders must consider the attributes and limitations of both the male and the female in the population along with the objective of that particular mating and not just take the TPIs™ or LPIs of the parents, add them together and divide by two to get the resulting progeny!
The Bullvine Bottom Line
Even though TPI™ and LPI have limitations, they are beneficial tools to use in improving the genetics of North America’s dairy cows. There is no doubt that these indexes will be refined and improved in the future. The dairy cow of the future will be even better. Genetics does make a difference!