Quality Genetics

Published on Wed, 01/06/2010 - 12:18pm

Genetic backlash is breeding some concern in dairy barns about the fertility and stamina of the world’s Holsteins. Leslie B. Morse Alumni Distinguished Teaching Professor of Animal Science at the University of Minnesota has been at the forefront of genetic research related to Holsteins. He says selective breeding practices over the last 20 years focused on developing a highly productive cow and ignored some fertility and health characteristics that are now affecting resilience and fertility in dairy herds.

"It's pretty incredible, what we've done to genetically improve dairy cattle," Hansen says. "Prior to about 1965, we weren't making any genetic improvement. When progeny testing was developed in the 80s and producers started using DHI milk recording methods to test the performance of a bull's daughters in many herds, genetic improvement really took off."
Since the Holstein was a very vigorous, fairly fertile dairy cow that was disease resistant, the breed tended to take over the dairy industry. During the 1960s, dairy producers were looking for sound udders, strong legs and healthy feet in their dairy herds. Those traits dominated genetic breeding plans for a long period of time.
"Dairy producers still want a sound udder for that milk to come through," Hansen says. "Solid feet and legs are very functional traits of a cow because they have to walk to the feed bunk and to the milking parlor. In the 1980s, we had very robust, fertile Holsteins that were consistently bred to improve productivity. The result was a cow with a tremendous will to milk and a sound udder too."
A New Plan
Since the 1980s, dairy producers are beginning to rethink the breeding plan that has dominated Holstein genetics for the past 20 years. First signs of fertility issues began to surface about 1990 when conception rates of lactating cows decreased from 60 to 70 percent to the current levels of 35 to 40 percent.
"If you talk to dairy producers today, they'll tell you that they are amazed at how much will to milk their cows have," Hansen says. "However, they will also tell you that they can't get their cows pregnant. They'll say the cow wants to get sick and sometimes wants to die on them. What's happened is that we kept selecting heavily for productivity and ignored fertility and the health of the Holstein."
Dairy producers are now looking at ways to recapture the vitality and fertility of the Holstein breed while they retain the productivity.
"There's tremendous interest in getting fertility and survival rates improved," Hansen says. "The frequency of getting Holstein dairy herds pregnant has recently taken a dive. There's been a pretty remarkable decline in the length of time a dairy cow remains in the herd. It's averaging somewhat more than two lactations per cow. The death rate on the farm is probably about ten percent, which is a catastrophic loss for dairy farmers."
The length of time it will take to redirect the genetics of the Holstein breed is difficult to predict. Around the world, two Holstein bulls make up about 30 percent of the gene pool, so inbreeding is an added concern.
"What we've done, because we had information on the bulls and the performance of their daughters, we've essentially bred the best to the best as fast as we could," Hansen says. When you do that year after year, the animals start being related to each other. One bull can produce 150,000 units of semen every year, which can be distributed globally. So there's no difference between America's Holsteins, German Holsteins or other Holstein dairy herds around the world."
Crossbreeding Program
Because there is no outcross Holstein genetics available, breeders are exploring some crossbreeding plans in order to re-establish the vitality of the Holstein breed. Hansen, along with Tony Seykora who is also from the University of Minnesota, has been monitoring the results of a crossbreeding program of seven large California dairy farms. Because research has demonstrated that crossbreeding improves vitality and fertility characteristics, the farms' high producing Holstein base was crossed with Scandinavian Red, Normande, or Montbeliarde bulls.
Scandinavian Red cattle are descendants of native cattle with infusions of Ayrshire and other breeds. They possess health and fertility traits as well as milk production. Montbeliarde originates in the French Alps and shares distant ancestry with Brown Swiss and Simmental.
"Obviously, the question is, is it time to see if cross breeding is the way to go," Hansen says. "That's the standard for all other livestock species so we're one of many universities now conducting research, comparing cross-breeds to pure Holsteins."
Milk quality has not declined, in either fat content or protein content, even though the Holstein breed is experiencing some difficulty. The percentage of solids in the milk of crossbred dairy herds is higher, but shouldn't be an issue in a crossbreeding program.
"Over 80 percent of the milk in the Midwest is used to make cheese anyway," Hansen says.
The big shift in the dairy industry is coming with the focus on cow health.
"Dairy farmers try very hard to take good care of their cows," Hansen says. "A healthy cow is a highly productive cow so dairy producers want her in the herds for a long time. There's no profit in the first two years of a Holstein heifer's life. The longer she's in lactating form, the more profit there is for the producer. All these incentives will keep the focus on the cow. Genetically we've made some mistakes by ignoring fertility and health and now we have some mop up to do to improve cow health."