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Crossbreeding can help herds
this document web posted: Wednesday May 4, 2005 20050505p73
By Ian Bell
Brandon bureau
Inbreeding in dairy cattle is leading to fertility challenges that research suggests can be alleviated partially by crossing different breeds of dairy cattle.
Les Hansen, a dairy geneticist at the University of Minnesota, and two of his colleagues studied the issue of inbreeding. They presented their findings in February at a dairy extension seminar attended by producers from four American states.
They found that Holsteins have become more inbred over time and that two bulls now make up more than 30 percent of the gene pool of Holsteins in the United States. They noted the narrowing of the genetic base globally is almost as severe.
One of the first negative effects of inbreeding is reduced cow fertility, wrote Hansen and his colleagues in their report. An inbred embryo is more likely to be non-viable and sloughed, meaning that the cow remains open longer.
The dairy geneticists looked at the benefits of crossbreeding Holsteins with other dairy breeds to alleviate calving difficulties and fertility challenges. The Holsteins were crossed with the Normande, Montebeliarde and Scandinavian Red breeds.
Generally, the crossbreeding resulted in fewer calving difficulties and stillbirths in comparison to what was seen with Holsteins.
In a study of the number of days the cows remained open during their first lactation, it was found that the Holsteins remained open the longest, at an average of 150 days. With the Normande-Holstein crossbreds, the number of days open during the first lactation averaged 123.
The first service conception rate averaged 30-35 percent for the crossbreds, while it was 22 percent for pure Holsteins.
It was also found that the milk production from the crossbreds was not much different from that of the Holsteins.
"If you look across the breeds, including the Normande, there would be a slight loss of production, but nothing that's so extreme that the other traits can't make up for it," Hansen said.
Hybrid vigour is one of the bonuses producers can expect from crossbreeding.
However, he cautioned that dairy producers should not regard crossbreeding as a dairy genetic improvement program.
He said the performance of the crossbreds still relies on the quality of genetics within the individual breeds. Producers still need to look for genetics from bulls that are the best in their breed and progeny tested.
"Over time, if you're going to improve the cows for production and for health and fertility, that can only happen by using better and better bulls."
this document web posted: Wednesday May 4, 2005 20050505p73
By Ian Bell
Brandon bureau
Inbreeding in dairy cattle is leading to fertility challenges that research suggests can be alleviated partially by crossing different breeds of dairy cattle.
Les Hansen, a dairy geneticist at the University of Minnesota, and two of his colleagues studied the issue of inbreeding. They presented their findings in February at a dairy extension seminar attended by producers from four American states.
They found that Holsteins have become more inbred over time and that two bulls now make up more than 30 percent of the gene pool of Holsteins in the United States. They noted the narrowing of the genetic base globally is almost as severe.
One of the first negative effects of inbreeding is reduced cow fertility, wrote Hansen and his colleagues in their report. An inbred embryo is more likely to be non-viable and sloughed, meaning that the cow remains open longer.
The dairy geneticists looked at the benefits of crossbreeding Holsteins with other dairy breeds to alleviate calving difficulties and fertility challenges. The Holsteins were crossed with the Normande, Montebeliarde and Scandinavian Red breeds.
Generally, the crossbreeding resulted in fewer calving difficulties and stillbirths in comparison to what was seen with Holsteins.
In a study of the number of days the cows remained open during their first lactation, it was found that the Holsteins remained open the longest, at an average of 150 days. With the Normande-Holstein crossbreds, the number of days open during the first lactation averaged 123.
The first service conception rate averaged 30-35 percent for the crossbreds, while it was 22 percent for pure Holsteins.
It was also found that the milk production from the crossbreds was not much different from that of the Holsteins.
"If you look across the breeds, including the Normande, there would be a slight loss of production, but nothing that's so extreme that the other traits can't make up for it," Hansen said.
Hybrid vigour is one of the bonuses producers can expect from crossbreeding.
However, he cautioned that dairy producers should not regard crossbreeding as a dairy genetic improvement program.
He said the performance of the crossbreds still relies on the quality of genetics within the individual breeds. Producers still need to look for genetics from bulls that are the best in their breed and progeny tested.
"Over time, if you're going to improve the cows for production and for health and fertility, that can only happen by using better and better bulls."
