For generations dairy cattle breeders have had reasons to explain why their cows did not quickly conceive or why the show cows needed to stay open and then calve at a particular time of the year in order to look their best for the show season. Well those are not reasons. They are excuses. We buy equipment, use drug therapy, manage groups, ask the vets to perform miracles and yes even lose sleep in attempts to raise our herd’s conception and pregnancy rates and lower our day’s open and extra days in the dry pen. But then we tell ourselves and fellow breeders that at only 5% heritability there is nothing we can do about genetically improving fertility in our dairy cattle.
If it was anything else, like a broken tractor, we’d go about getting it repaired even though it was a costly undertaking. Enhancing the genetics of dairy cattle fertility however falls into that ineffective area where – we keep doing things the same old way but expect different results. The truth is we must do things differently. Until we revamp the genetics of the dairy cows, we can not expect to reduce the costs and lost revenue associated with infertility.
What Oman Has Shown Us
Mention the name Oman to a Holstein breeder and you can expect a reaction. He is categorized as either the best sire to come along in years or he has ruined the breed. This icon does not inspire fence sitters. On the like side both Don Bennick (Read More – North Florida Holsteins: Aggressive, Progressive and Profitable!) and Chris Buchner (who I recently visited with at Elmwold Farms) extol Oman’s virtues. Don’s favourite cow is an Oman daughter. Chris put it this way – “We just loved our Omans. Sure they would not win a show but the Omans did it for us as we are in the business of efficient profitable production measured by maximizing fat and protein in the tank per cow per day of course at reasonable input costs’. This raises the question “Does function follow form or does form follow function?”. For Don and Chris, it is form that follows function
Oman did many things right when it comes to fertility. Calves are born easily, able to be productive cows before two years of age, able to breed back quickly while yielding a high volume of solids and able to do it year after year. And they do it in any environment. Oman showed us that calving ease, reproduction and longevity can all fit into a package and that cows do not have to be tall, dairy, flat boned or angular. In fact what Oman did was to show that there are genetic differences between sires when it comes to female fertility and it stimulated breeders to measure all traits independently instead of trying to define the model perfect cow. One size does not fit all.
Both phenotypic and genetic trends for female fertility have spiralled downwards as production increased in the past forty years. We put our focus on milk production and picture perfect conformation, using what is often called a combined production and type index. But the amount and quality of data captured and stored relating to female reproduction has been sadly lacking. For the milking herd that situation has been reversed in the past half decade due in part to the great expansion in herd management software programs with the data uploaded to central data bases where genetic analysis and evaluations are performed. But the same can not be said for heifer information. Any data that does exist for heifers remains on farm so, except in education or research herds, we can not correlate, on a population basis, the heifer stage of development with lifetime performance.
Where once we relied on what we called “cow sense” we now have genetic evaluations, for cows and bulls, for the following traits that correlate well with female fertility:
For years breeders felt that calves had to be large at birth to develop into large framed cows. Today commercially oriented breeders want live calves that are born unassisted and cows, especially first calvers, that deliver a live calf without assistance. Two genetic indexes are published – one for the birth of the calf (Calving Ease / Calving Ability) and one for the mother’s ability to deliver ( Maternal Calving Ease / Daughter Calving Ability). Sires rated above 7 in the USA or below approximately 97 in Canada for either calving ease index should be avoided unless breeders are prepared to attend and assist the birth. The cost of a difficult calving is significant when you consider the risk of death of calf and mother, vet and drug costs, an anestrous period, a longer time in the dry pen and less yield for both the lactation and lifetime.
Pregnancy Rate – No pregnancy, no calf, no lactation!
That says it all. Getting a pregnancy when a cow is lactating at a high level is no mean feat but is the reality of dairy cattle farming. Sires that rate below +1.0 for Daughter Pregnancy Rate (USA) and 105 for Daughter Fertility (Canada) will not improve the genetic merit of a herd for pregnancy rate. Correlated positively with sire ratings for Daughter Fertility in Canada is Body Condition Score (BCS). Correlated negatively is Dairy Form (USA) and Angularity (Canada). Bulls that have a rating above 105 for BCS have daughters that get pregnant whereas bulls above average for Dairy Form and Angularity are more difficult to get in calf. Using all these indexes assists breeders to get the overall picture so wise decisions can be made when selecting sires to use.
Length of Life
Some breeders prefer to select only for Productive Life (USA) or Herd Life (Canada) instead of selecting for the fertility traits. Additional factors beyond fertility go into calculating the length of herd life including SCS and udder depth. Therefore selecting for longevity may not get the boost in female fertility a breeder may be looking for. Again, as with the other indexes sires will need to have high ratings for Productive Life (over +3) and Herd Life (over 105) to positively impact the genetic merit of a herd.
have been a major step forward in ranking bulls for female fertility traits. Accuracies of genomic indexes are more than double what they were with Parent Averages alone. The general recommendations on using genomic sires applies when addressing daughter fertility – use many sires not just one or two.
So what is improved female fertility worth?
A definitive answer may not be available, but considering that for the average cow it starts when she is bred as a heifer and finishes when she has completed about three lactations. This, on average, covers about 54 months, and the total can mount up to a considerable amount from loss of revenue and added expense. If improving the genetics for female fertility in a herd could give you an added profit in a cow’s lifetime equivalent to the value of milk for half a lactation would it be worth putting more selection pressure of female fertility? I think it would.
A.I organizations go to considerable effort to package the semen from each sire so the optimum conception rates can be achieved from that bull. High semen fertility is not a genetic measurement for male fertility but it has a very positive effect on herd profit. Dr Bob Welper of Alta Genetics estimates that in a 500 cow herd using somewhat below average bulls for Sire Conception Rate (SCR) compared to using bulls that are above average for SCR costs the breeder a minimum of $35,000 per year. Having six more pregnancies every twenty-one days, higher herd average production, less semen cost, less labor required and more calves in a year are where the added profits come from.
Perhaps a breeder’s semen tank should have a warning label that reads – “Warning- Semen put in this tank must be above average for conception rate and able to produce fertile female offspring”.
The Bullvine Bottom Line
Female fertility can no longer be ignored when selecting sires to use or cows that are to be the mothers of heifer calves. Many tools exist that assist with female reproduction on a farm however the use of genetically inferior animals for female fertility as the parents of the next generation is costing much more than we care to admit. In time there will no doubt be additional female genetic fertility index. The time to start using the current indexes is now. Big dividends await breeders who make the effort to use the current genetic tools for female fertility.