As reported in Progressive Dairyman (Issue 17, Oct. 19, 2014) Heather White, Ph.D. at the University of Wisconsin – Madison, Department of Dairy Science “estimates that 20 to 45 percent of cows in U.S. dairy herds have or will be affected by ketosis – either clinical or subclinical -at some point in their lifetime.” In contrast a breed selected for increased resistance to ketosis and other diseases, the Norwegian Red, has a frequency of other diseases (combined ketosis, milk fever and retained placenta) of 2.4% in first lactation cows and between 4 and 5% in later lactation cows.
For those dairymen who are utilizing Norwegian Red as a complementary breed in their crossbreeding scheme for increased fertility and health, the good news about genetic improvement in lowering ketosis in the Norwegian Red population is impressive. Here’s a short history of the genetic selection in the breed* for less ketosis.
- Ketosis was included in the total merit index used for selection of Norwegian Red sires in Norway from 1978 to 1996. The relative weight on ketosis was <4% from 1978 to 1981 and was between 7 and 8.8% from 1982 to 1993.
- In Norway, the incidence of ketosis has decreased gradually since the mid-1980s. For first lactation cows, the mean frequency of ketosis decreased from 10.6% in 1987 to 4.3% in 1998 and to 1.0% in 2013.
- In 1994, the relative weight put on ketosis was reduced to 1.8%. Ketosis was replaced by “other diseases,” a trait that includes milk fever, ketosis, and retained placenta. In 1997 “other diseases” received a relative weight of 3%, today 2%, in the total merit index.
The “extra” good news is that the genetic correlations between mastitis and other diseases including ketosis indicates the existence of some general disease resistance factor with a genetic component (which is consistent with knowledge about the major histocompatibility complex).*
The extra “bad” news about ketosis, of which most dairyman are painfully aware, quoting Heather White, “ketotic cows are 50 times more likely to leave the herd in their 1st 30 days in milk, and those that are not culled are more likely to suffer from displaced abomasum (DA), lower milk production and reproduction challenges.”
Crossbreeding with Norwegian Red makes a boatload of sense for dairymen desiring healthier cows. Who doesn’t want increased resistance to ketosis, other transitional diseases and mastitis? The Norwegian Red breed is also likely the most fertile breed of dairy cattle in the world, with component production very close to that of the Holstein.
*Heringstad, B, Y. M. Chang, D. Gianola, and G. Klemetsdal. 2005. Genetic Analysis of Clinical Mastitis, Milk Fever, Ketosis, and Retained Placenta in Three Lactations of Norwegian Red Cows, Journal of Dairy Science 88: 3273–3281.
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