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Conversations: Monitor inbreeding

 

Ask a specialist to determine if your herd’s genetic make-up is costing you money

 

Some dairy challenges pose significant productivity and economic risks, even though day-to-day signs are undetectable. As producers and their advisors meet in the conference room (or kitchen), one conversation should lead to answers regarding inbreeding questions.

 

By Jeff Ziegler

 

Unlike other challenges that impact your herd, inbreeding isn’t something you can visually see on a day-to-day basis. But inbreeding poses significant risks to your herd. And, if not managed, could have a substantial economic impact.

All too real are the risks of lower milk production per lactation, reduced reproductive performance, decreased calf health and vigor, and an increased risk of recessive genetic disorders. 

For every 1% inbreeding, a herd experiences a decrease of 24 Lifetime Net Merit Dollars (-24 NM$), an increase in age at first calving (+.36 days), reduction in productive life (-13 days), reduced lifetime milk production (-790 lbs.), reduced lifetime protein production (-25 lbs.) and increased first calving interval (+.26 month).1 If you consider that the average inbreeding coefficient in the U.S. is 5.62%, the financial impact starts to multiply rapidly. 

Remember, the cost of each additional day a dairy cow is open, beyond the herd’s voluntary waiting period, can range from $3.19-$5.41/cow/year,2 further amplifying the economic blow that inbreeding can have.

To get a handle on inbreeding one has to know where your herd stands genetically. If you don’t have a starting point, you can’t begin to measure, manage, or avoid inbreeding, let alone reduce the impact of it. 

 

1) How do I start?

The best place to start is to identify the current genetic base and influence within the herd. This can be accomplished through a number of approaches, depending on a herd’s records, history, needs and resources available. 

Recognizing that every herd is going to be different, there are some common records that a trained inbreeding consultant could use to help determine the herd base. These efforts might include an evaluation of past semen purchases to identify common genetic influences, or a review and study of herd management records – assuming parentage is accurately captured. Genomic and/or parentage testing is another option – testing either a random cross segment of the herd or the entire herd, if resources permit. Or, with a commitment to change and manage inbreeding, a starter line of similar sires could help achieve the desired long-term results.

 

2) What is the best way to establish a herd base?

Depending on your individual herd situation, different options may be a better fit than others. 

For example, if you have pedigree information on all of your animals, a thorough evaluation of the pedigrees and breeding records will work. Another herd might not have the depth of information needed to evaluate pedigrees, so it may be better to evaluate semen purchases, or genomic and/or parentage tests.

 

3) How do I make it happen, once I know my genetic base?

Compliance to these programs is – perhaps – the greatest challenge. Designed to meet breeding goals, mating programs still require a specific cow or heifer to be bred to the right sire. This may seem simple, yet time and pressure to do more within the same day can challenge even the best herd managers to stay organized and precise.

Work with a herd genetic consultant knowledgeable and trained in inbreeding management programs to help find the right starting point and develop a plan that can deliver the herd improvements the individual dairy seeks.

 

4) Where can this insight take me?

Inbreeding management is much more than a single generation of mating; it is a long-term commitment. Not only should production and management traits of sires be carefully considered, the sequence and rotation of like-genetic sires should be carefully, consistently and thoughtfully rotated. 

When properly implemented, using groups of sires that are genetically very similar can provide performance improvement and minimal inbreeding from one generation to the next. However, it is important to remember that just because two sires may have similar parentage sequence in their pedigree, the actual genes they inherited and/or will transmit may be drastically different.

 

5) Is inbreeding management difficult?

Inbreeding management can be fairly easy, with a program approach. Sires that have been specially bred and/or genomic tested to fit into a few unique, intensely similar genetic make-up categories can be used in a simple rotational sequence, either changing sire categories with each generation, or even just every 12 to 18 months, depending on the degree of herd management. 

Regardless of which method you use to manage inbreeding, don’t let it go unchecked in your herd. Tools are available to help manage and avoid the economic impact of inbreeding.

1/ Cassell, B.G.; Effect of inbreeding on cow performance and mate selection in dairy cows; Proceedings of the Western Dairy Management Conference; 1999.

2/ DeVries, A; Determinants of the cost of days open in dairy cattle; Proceedings of the 11th International Symposium on Veterinary Epidemiology and Economics; 2006.

 

FYI

Jeff Ziegler, genomic program manager with Select Sires Inc. Contact him via phone: 614-733-3451; or e-mail: jhzieg@selectsires.com.

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