Editor's Note: Corey Geiger has not only been Howard's Dairyman's executive editor for years, he has also held the position of president of the Holstein Cattle Association since last year. Over the past four years, he has given six lectures in Beijing, Tianjin, Baoding and Harbin, mostly centered on the comfort and genetic selection of cows. Recently, the editorial board of Cattle Raising learned that the Holstein Dairy Cattle Association of the United States will update the Holstein Dairy Cow Comprehensive Performance Index (TPI) formula in April, so the Editorial Department of China and the United States has made a detailed interpretation of this adjustment.
Corey said: "In the interpretation, not only the recent update and changes of the TPI are introduced, but also some of my thoughts on the significant progress that Holstein cows have made in genetic selection in the past five years. ”
At present, the formula update has been officially recorded in April this year along with the genetic progress of the past 5 years.
Since 1980, the "genetic base" has been adjusted every five years. Starting in April 2020, all cows will be compared to the average cows born in 2015.
When measuring recent genetic progress based on changes in the level of genetic base, Holstein cows are among the top six major dairy cattle breeds in the United States.
Milk production: Although all breeds have made genetic advances, the genetic progress of Holstein cows is particularly impressive, as their milk production predicted heritability (pta) increased by 223 kg, milk fat changes by 11 kg, and milk protein by 8 kg.
Milk quality: With the exception of Holstein cows, changes in somatic scores (scs) were small, with only a 0.08 drop through genetic improvement.
Longevity: Holstein cows achieved in production lifespan (PL), which improved in just five years.
Survival rate: Are cows easy to survive? This is measured by the cow survival rate (CA). The indicator, published in August 2016, has improved in three of the six breeds, with Holstein cows topped with 0.74.
Health: Until now, only Holstein cows have evaluated 6 major diseases (true stomach displacement, ketosis, mastitis, uteritis, milk production fever and fetal dress). In April 2020, the genetic assessment of Juan ShanNiu also added a disease content. In addition to milk-producing fever, Holstein cows have made genetic progress in 5 other diseases.
Breeding: Of the 18 predicted values for the three main reproductive traits (daughter pregnancy rate, dpr; reserve cow fertility rate, HCR; adult cow fertility rate, ccr) in all herds (including six breeds), 13 were less than ideal changes, with only Holstein cows improving on all three traits.
Body shape: Almost all traits have been improved, some of which remain stable with fewer variations. It is a good thing that some traits are "stable", because some traits, such as the posterior torso, are optimal only when they are in the middle. More difficult to deal with are the characteristics of the nipples, and the current genetic trend is that the nipples are getting shorter and shorter, and they are getting closer and closer to each other. Such genetic progress affects "milk production power". When it comes to body shape, everyone has a different perspective. At present, cows are getting taller and taller in terms of genetic selection. While some breeders want to breed cows with these traits, this scheme may increase the risk of death in cows.
01 tpi formula variation
ptap: pta protein milk protein amount pta
ptaf: pta fat milk fat amount pta
fe:feed efficiency Feeding efficiency
ptat: pta type body shape pta
UDC:UDDER composite breast composite index
FLC:feet & legs composite limb and foot composite index
pl:pta productive life production life pta
ht:health trait index Health trait index
liv:pta cow livability cow survival rate pta
SCS:pta somatic cell score somatic cell score pta
fi:fertility index fecundity index
DCE:pta daughter calving ease daughter calbirth difficulty pta
DSB: PTA daughter stillbirth daughter still calving stillborn rate PTA
The formula has a constant, five years ago it was 2187, and this April it began to change to 2370. This constant can be thought of as a benchmark that can help breeders directly compare bull performance.
Making the most of genetics is one of the best ways to reduce production costs and achieve profitability, and the new TPI formula in April 2020 will help breeders achieve this goal.
According to the U.S. Department of Agriculture's (USDA) economic benefit assessment, on average, the offspring of the top 100 bulls in TPI will generate $486 (about $3,448) more in their lifetime than the offspring cows of the average bull.
More than half of these benefits come from the production of milk, fats and proteins, followed by the offspring benefits they produce.
Milk prices have changed a lot in recent years. Since studies have found that saturated fat can increase the content of high-density cholesterol (HDL) that is beneficial to the human body, milk fat has become popular again in the market. This has prompted excessive consumer demand for butter, whole milk, and all the animal fats associated with it, and in the U.S., the gains from milk fat began to outpace milk protein from 2016.
02 Where does the future go?
There may be more genetic choices in milk fat and milk proteins in the future. With this in mind, the milk protein amount pta and the milk fat amount pta in the formula are now similar in the April 2020 tpi formula, accounting for 19% of the weight, respectively. Previously, the proportion of milk protein PTA was 21%.
Other changes to the tpi include:
Feed efficiency is updated to align with THE USDA's economic benefits
Add the Health Traits Index to the tpi formula with a weight of 2%.
The comprehensive index of limbs and hooves was slightly adjusted to list some of the above-mentioned posterior torso traits as a two-way effect, and the median value was considered to be the best. This adjustment reflects the fact that some traits in the posterior body may be too late.
The trait first calving day old (efc) was added to the fecundity index. However, the total weight of the fecundity index remains unchanged at 13% of the tpi formula.
The weight of production life was increased from 4% to 5%, and the increase of 1% was transferred from the removed dairy characteristics (df).
03 Genetic selection is important
In terms of Holstein dairy cattle breeding, the tpi formula is the most widely used and relatively recognized indicator in the world, and it represents the vision of the Holstein Dairy Cattle Association of the United States to improve Domestic and foreign Holstein dairy cows.
This improvement helped drive domestic frozen concentrate sales to 21.8 million units in the United States in 2018.
Even more impressive is the 24.6 million frozen concentrate sold by the United States to international trading partners. This is not only a new record, but also represents the first time that the number of frozen semen exports exceeds the number of domestic sales.
04 About the Composite Index
Currently, in the TPI formula, production traits account for 46%, health and reproductive traits account for 28%, and body shape traits account for 26%. This is shown in the following table:
Table 1. Distribution of the proportion of the comprehensive index