Sunny Day Zev Bishop
The Outcross package of Champions
Available at Select
Sires 7JE538
Inbreeding results from the mating of related individuals. These related individuals have a larger percentage of their genes identical than individuals from unrelated parents. Inbreeding is becoming a serious problem in all of the dairy breeds as the practice of mating the best to the best continues.
Inbreeding causes many obvious and serious problems along with others of a more subtle nature. Research has shown anywhere from a 46-65 pound milk loss per 1% of inbreeding. Butterfat and protein pound losses will move accordingly. Calf mortality rates will increase and reproductive efficiency will decrease as inbreeding percentages rise. One study showed that 50 percent more calves died from birth to two years of age in animals that were 12.5 percent inbred. Inbred cows will not live as long and will have a marked increase in fertility and overall health problems. Early embryonic death and other less measurable problems occur more frequently with inbreeding. In quoting Dr. Ben McDaniel from his presentation at the 1993 AJCC Annual Meeting, "My own personal feeling is that one percent inbreeding is close to the equivalent of one percent loss in net economic value. Now that is higher than many people will estimate. But when I look at other species, I see the heterosis effect we get which is the inverse of inbreeding. It appears to me that when we consider reproduction, health, and survival, that the inbreeding is going to hurt us there so much that the 50 pounds of loss in milk is only a small part of the net effect." As inbreeding percentages move higher, overall profitability of the cow decreases at an increasing rate.
As referenced in the August 1998 AJCA Green Book, the average percent of inbreeding when mating the top 21 active A.I. PTI sires to the 30 most common sire-maternal grandsire combinations found in registered Jersey females from 1993-July 1997 is 7.5%. An alarmingly high level of inbreeding when considering that in reality it is 20-25% higher when adding the influence of the maternal lines. Therefore, when mating these
30 most common sire-maternal grandsire combinations in the breed to these top PTI bulls, the resulting offspring will have an average level of inbreeding of 9.3%. It is also important to recognize that 13 of the these top 21 PTI bulls on the August 1998 Active A. I. list originate from only 5 cows on the maternal side of the bull's pedigree. Eight of these bulls have one of these 5 cows as their dam while five bulls have one of these 5 cows as their maternal grandam. This illustrates the relative ease of additional inbreeding when using the top bulls with only their sire as a mating reference.Published research shows a milk loss ranging from 46-65 pounds for every 1% of inbreeding, an average of 55.5 pounds. By multiplying 55.5 times the above 9.3 equals a 516 pound milk loss per cow. Take into account this milk and component loss and add to that the numerous other negative factors - such as higher semen costs due to lower fertility, fewer heifers to merchandise or bring into the herd due to lower calf livability, the cost of treating less healthy animals and decreased longevity - and inbreeding gets quite expensive.
Solutions
Of course, the easiest solution to inbreeding is to find that superior outcross sire. This is easier said than done. I like to think of a viable outcross sire as one who can add more to my cows and herd than just being different. This sire needs to contribute economically important traits to the gene pool and also be an outcross.
To again quote Dr. Ben McDaniel, "So when we find that good unrelated line, we want to keep it, or at least the bulls in it, linebred. Then we always have something that is not related closely to the cow population to cross back on them to minimize the inbreeding."
Sunny Day Zev Bishop is the prescription filled. He is linebred to outcross superior genetics that can add more than just being different.
This document was last updated September 14,
1998
Copyright 1998 Huffard Dairy Farms
165 Huffard Lane, Crockett, VA 24323
Barn & Fax 540-686-5201; James S. Huffard III (540) 686-5838; John B. Huffard
(540) 686-6310;
e-mail: jhuffard@naxs.com
