Archive for Breeding Strategy

Sire vs. Dam – Which has a Greater Impact on Your Herd’s Genetic Improvement?

Too many people say that dairy breeding is an art. If they manage their herds this way, they will be unable to compete in an industry that grows with science. Art places value on the ‘family’ and sees both parents contributing equally shared value to their offspring. In practicing the science of dairy cattle breeding parents are not equal when it comes to which one is the most important when deciding upon a herd’s genetic improvement plan (Read more: What’s the plan? And Flukes and Pukes – What Happens When You Don’t Have a Plan, and Pick The Right Bull – Your Future Depends on The Decisions You Make Today!).

3 Factors Determine Genetic Advancement

On a simplified basis, the rate of genetic advancement in a dairy herd is primarily a function of three factors: 1) the superiority of parents; 2) the accuracy of the parent’s genetic indexes and 3) the generation interval expressed as the time between the birth of the parent to the birth of the calf. Dairy cattle breeders have, in the past, placed a priority on intense selection, but today with genomic information generation interval is necessary.

Four Pathways for Improvement

In a population of dairy cattle there are four groups, commonly called transmission pathways that are considered when determining the overall population rate of improvement. These pathways are: 1) the Sires of Bulls (SB); 2) the Sires of Cows (SC); the Dams of Bulls (DB); and the Dams of Cows (DC). Breeders do not have equally accurate information on each pathway and definitely do not apply equal selection intensity for each pathway.

Which Breeding Scheme is the Best?

The following table outlines the importance of the different pathways for three improvement schemes when animals are ranked and selected using total merit indexes like TPI, NM$ and LPI.

Comparison of Genetic Improvement Schemes

Pathway Selection % Accuracy Generation Interval Relative Emphasis
1. Traditional Progeny Testing Program
Sires of Bulls (SB) 5 0.99 7 44%*
Sires of Cows (SC) 20 0.75 6 22%
Dams of Bulls (DB) 2 0.6 5 31%
Dams of Cows (DC) 85 0.5 4.25 3%
Relative Total Merit Genetic Gain per Year = 100%
2. Genomic Testing Program
Sires of Bulls (SB) 5 0.75 1.75 34%
Sires of Cows (SC) 20 0.75 1.75 23%
Dams of Bulls (DB) 2 0.75 2 40%*
Dams of Cows (DC) 85 0.5 4.25 3%
Relative Total Merit Genetic Gain per Year = 185% to 200%
3. Genomic Testing Program with IVF
Sires of Bulls (SB) 5 0.75 1.75 30%
Sires of Cows (SC) 10 0.75 1.75 20%
Dams of Bulls (DB) 2 0.75 2 36%*
Dams of Cows (DC) 10 0.62 2 14%
Relative Total Merit Merit Genetic Gain per Year = 225% to 250%

* Pathway of most importance The Bullvine appreciates the assistance of Dr. Larry Schaeffer, University of Guelph, in providing information for the above  table. Further details can be found in Dr. Schaeffer’s 2006 paper “Strategy for applying genomic-wide selection in dairy cattle,” Volume 123 of Journal of Animal Breeding and Genetics.

Progeny Testing has Served Breeders Well

Breeders have been successful when they used the results of the traditional A.I. progeny testing programs. That is when only elite sires are used to produce bulls (SB) for progeny testing, each year newly proven sires are used to produce the heifer calves (SC), Dams of Bulls (DB) are elite indexing milking females and the bottom 10-15% of the cows in the herd are not used to produce replacement heifers. (Read more: Why you should get rid of the bottom 10% and  8 Ways DNA PROFILING Your Whole Herd Will Improve Your Breeding Program) most important pathway, by quite a distance, is the Sires of Bulls (SB) at 44%. Combined the sire pathways (SB & SC) account for 66% of the total genetic progress. That is opposite to what many breeders say ‘Sires are not as important as cow families. The cow family, in a herd, dominates.’

Genomics gives 185 – 200%

Over the past five years, breeders have become familiar with the program whereby the genomic indexes on young animals are used for animal selection.  Even though this program is much discussed, it has been implemented on less than 10% of the farms in North America. In Holsteins, less than 7% of calves registered are genomically tested. Breeders are obviously not confident with the lower accuracies and the much shorter generation intervals. So let’s dig deeper to see what the facts are when it comes to rates of genetic improvement. With the genomics program the relative importance between pathways shifts to where the Dams of Bulls (DB), at 40%, is the most important followed next by the Sires of Bulls (SB) at 34%. Again in this program, as in progeny testing, very limited selection pressure is applied to Dams of Cows (DC), pathway resulting in only 3% of the total progress. The relative ratios of improvement from sire and dam pathways is 57:43. The telltale important fact is that by using a genomic program the rate of annual genetic gain is 185% to 200% of what can be achieved by using the traditional progeny testing program. Another important difference between these two programs is that considerable money can be saved by only having to progeny test less than half as many young bulls with the genomic testing program.

Adding IVF gives 225 – 250%

Some breeders add IVF to their genomic selection program however due to costs and the challenge of mating carefully to avoid inbreeding it is not for everyone. The accuracies of this program match those of the genomic testing program, but the selection intensities are increased for the Sires of Cows (SC) pathway and greatly increased for the Dams of Cows (DC) pathway. For all pathways the generation intervals are short, something many breeders state as being a concern.  These farms use IVF on maiden heifers to produce all of the next generation of animals. Again the most important pathway is the Dams of Bulls (DB) at 36%.  However, the differences between emphasis on the pathways is narrowed. The ratio of emphasis sires to dams is 50:50. Farms employing this program can have annual rates of genetic gain of 225% to 250% compared to what is possible for herds using a progeny testing program. To fund this more expensive program breeders often sell surplus embryos or animals.

The Bullvine Bottom Line

Determining which parent pathway is the most important rests with which testing and selection program a breeder wants to follow. For breeders using the traditional progeny testing program by far the most important animals are the sires of the young bulls (SB) that enter A.I. progeny testing programs. For breeders wanting to advance their herds at a faster rate by using the less accurate genomic information and shorter generation intervals, the dams of the bulls (DB) is the most important pathway. No matter which program a breeder chooses it is important to have a plan and always use the best available animals.



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Who Said You Can’t Breed For Higher Fertility?

If you were to describe the perfect program to achieve top female fertility in your herd, what would it be? Would your program include heifers calving at 22 months of age and every 11-13 months thereafter until lifetime production reaches 275,000 lbs (125,000 kgs) of milk? For decades breeders have heard that they can’t breed for fertility. It’s all management and nutrition. Well that story is changing. Let’s examine how genetics can play a role in improved fertility in a herd.

The Current Scenario

The CDCB (Council on Dairy Cattle Breeding) has summarized the following current reproduction information on the current US dairy cattle.

  • Holstein cows take 2.5 breedings per conception. Jerseys take 2.2.
  • Holstein cows average 80 days in milk before they are bred. Jerseys average 77 days.
  • Average calving interval for Holstein cows that calve back is 13.8 months. Jerseys average 13.0 months.
  • Average conception rate for Holstein cows is 32%. Jerseys average 41%.
  • Average age at first calving in Holsteins is 26 months. Jerseys average 23.5 months.

These stats for Holsteins and Jerseys are provided for breeders to benchmark their herds, not to start a breed war. In five years’ time even if a Holstein herd was able to achieve the current Jersey average it will not be good enough. The three biggest factors that stand out from these stats and that are in need of correction are: 1) days to first breeding; 2) number of breedings before conception; and 3) age at first calving.

As it turns out the reproductive performance of North American dairy cows and herds reached their lowest level in 2007 and since then there has been minor genetic improvement.

Source: CDN – March 2010 – A Look at Fertility from Two perspective

Source: CDN – March 2010 – A Look at Fertility from Two perspective

Breeders Must Address Fertility

An attitude shift is needed. We must move from tolerance of fertility to awareness that genetics plays a role. Not all breeders have accepted the need for change. The Bullvine analysed the sires with the most progeny registered with Holstein US over the past two weeks and found that nine, yes nine, of the top twenty had negative genetic ratings for Daughter Pregnancy Rate (DPR). In fact two sires had significant negative ratings of -2.5 and -3.5. In addition four of the twenty had only slightly positive ratings. In total 13 of the top 20 sires were not breed improvers for DPR. That is significant!

Some breeders have paid attention to the management side of fertility and have increased their pregnancy rate by aggressive heat detection, by using professional A.I. reproduction specialists (Read more: Artificial Insemination – Is Doing It Yourself Really Saving You Money?) by installing heat detection devices or by using hormone level monitors (Read more: Better Decision Making by Using Technology). However from the latest reports from milk recording, half the herds have a pregnancy percent of less than 15%. And only 10% of herds have a pregnancy rate of 21% or more. Clearly more attention needs to be paid to getting cows and heifers pregnant.

Genetic Tools to Aid with Fertility

Daughter Pregnancy Rate (USA) and Daughter Fertility (Canada) are the primary genetic evaluation ratings to use when selecting for improved female fertility. These indexes are created using data from insemination, milk recording and type classification.

However there are eleven other genetic ratings that have some influence on reproduction. Individually they may not be significant but collectively they can contribute to reproductive problems or solutions.

  • Calving Ease – difficult births delay cows coming into heat
  • Maternal Calving Ease – normal delivery benefits – cow, calf and staff
  • SCC – cows with mastitis are less likely to conceive
  • Feet – problem cows are not mobile and do not show heats
  • Rear Legs Rear View – cows that toes out are not as mobile
  • Milk Yield – high milk yield stresses cows. Breed for high fat and protein yields on lower volumes of milk.
  • Body Condition Score – high yielding cows that retain body condition are more fertile
  • Persistency – high lactation yielding cows that have flatter lactation curves put less strain on their bodies
  • Inbreeding – inbreeding negatively affects reproduction
  • Haplotypes – information is now coming available to show that certain haploids hinder reproduction
  • Semen Conception Rate – although not a genetic rating, low fertility semen should be avoided

Those are the tools available today. We can expect that, with the current research into genomics and reproduction, there will be new ratings to assist with breeding more reproductively sound animals in the future.

Selection Matters

The Bullvine recommends that after breeders short list the sires they intend to use that they eliminate sires that do not have a DPR over 1.0  or a DF over 103. Yes, female fertility is included in TPI, NM$ and LPI but the emphasis on fertility in these total merit indexes is not high enough to result in major genetic improvement for fertility. The following lists of bulls are examples of bulls that significantly improve total merit as well as female fertility.

Table 1 Top Ranking US Sires by Daughter Pregnancy Rate

Top Ranking Sires by Daughter Pregnancy Rate

Table 2 Top Ranking CDN Sires by Daughter Fertility

Top Ranking CDN Sires by Daughter Fertility

Action Plan

It is important for both herd viability and sustainability that the following steps be followed.

  1. Do not use bulls that are genetically inferior for reproductive traits.
  2. Genomically test heifer calves. Eliminate reproductively inferior cows and heifers.
  3. Include genomic reproductive information when correctively mating females.
  4. Use heat detection devices, hormone level monitoring equipment or intensive staff heat detection.
  5. Use herd management software and herd protocols to assist with reproductive management.
  6. Ensure that animal housing and animal grouping result in healthy animals
  7. Feed cows and heifers according to their performance and reproductive needs
  8. Employ staff training and education program for reproduction.

The Bullvine Bottom Line

The genetic attention starting to be given to female reproduction on dairy farms is long overdue. The first step for breeders is to include reproduction in your herd genetic improvement plan (Read more: What’s the plan?). In as little as five years, by following a progressive proactive plan, breeders will significantly reduce their losses due to reproduction.



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