The newest genetic measurement is DPR or Daughter Pregnancy Rate.   It is calculated by measure of the calving intervals after a cow has her second (and later) calvings.   Keep in mind the USDA data set only uses the first five lactations, so there would only be three "calving intervals" measured, and most weight will be on that interval between second and first lactation, with a default value of 250 days open assigned a cow who is culled in lactation.   (At 2.4 lactations per cow national average, only half of DHIA cows would have two measured and then a third default value calving interval.    The other half would have only one measured calving interval at best). 

Is lower cow fertility mostly a "management" problem?

The figure assigned for DPR is a percentage of cows pregnant at a certain "average" point, not a representation of actual days open.   Data from New Zealand, where cow fertility has been tracked for years, is expressed as an actual calving interval in days.   On USDA data DPR is considered of fairly low (4%) heritability, with scientists still insisting most fertility loss is the fault of "management" and "higher production", but in the Moorepark trials in Ireland, results to date show the North American and the European Holstein to be lower in fertility than the New Zealand Friesian under a standardized Irish feeding regime that has neutralized most of the yield variation, and that the difference in calving intervals has increased with each additional calving.  In New Zealand, heritability estimates on Calving Interval are considered much higher.   Given the importance of cow fertility to successful seasonal production as practiced in new Zealand, their cow population has endured generations of culling against lower fertility, with the result that selection for the trait over time increased the heritability of response. In the USA, therefore, with only a 4% heritability measurable, we know we are starting with a cow population that has been randomly "selected" for fertility over time, with the trend going in the wrong direction.

Accepting this 4% heritability measurement at face value, many AI geneticists are suggesting to look at Productive Life (PTA- PL) instead or along with DPR data.   PL is assumed to be 7% heritable which is still fairly low (production yield PTAs are 25% heritable; component percentages 50% heritable) but at that rate nearly twice the heritability of DPR.   My only caution is that neither figure is anything but an estimate (based on parent averages and correlated linear type traits)  until a bull is old enough to have mature-age daughters, so we find ourselves trusting a "parent average" on a low heritable trait.   Obviously, you want to look at all sources of information that might help you, in this situation.

Sire conception rate is not the same genetics as cow fertility rate 

This conclusion is supported by a retired veterinarian who worked thirty years within a large AI stud system and tells us that, based upon reported breeding slips from their inseminators, the Holstein cow has suffered a 1% per year loss in first-service conception rate between 1966 and 1995, when he retired.    This was occuring in spite of his ongoing efforts to eliminate from their system sires with low conception rates.  This AI system has been one of the leading proponents of "production genetics" as measured by USDA- PTA values alone, and it has been established through a data review by NCSU that we have developed prominent sire lines that are measurably lower than average for cow fertility, while among the highest for PTA milk values.   

NCSU has calculated sire conception rates for years on all cows whose records come through their Raleigh DRPC.   Dairymen have been using this data for years to avoid low conception sires, and yet their cow herds often continue to decline in fertility rate.   This is evidence supporting the conclusion that semen conception rate is not highly correlated with cow calving interval.   DPR calculations are a step in addressing this observation.

To summarize, previous genetic selection practices emphasizing PTA pounds of milk as primary and all other considerations secondary, have led us to "breed" increasingly infertile cows.

Longevity of production is highly correlated to cow fertility rates

I was struck by an article written by Dr Dave Selner for a recent issue of Midwest Dairy Business in which he provides a table of selected recent Holstein AI sires with over 5000 daughters in their latest USDA summaries.   At the top of the list were Robthom Infinity (at +3.2) and Iona Farms Camaro (at +3.1)    When you look at their pedigrees you will find that "Infinity" is from a multiple generation "EX" high lifetime production family at Thompson's in Missouri, while "Camaro" is from a cow scored "EX95" with a 266,000m lifetime production who lived over 16 years of age.   Both of their dams' pedigrees include the 1960s sire NoNaMe Fond Matt who was recognized as a leading sire of high lifetime (200,000+m) daughters.   "Camaro" was often below-average on sire conception rate, yet we now know daughters of  "Camaro" have above-average fertility.

Speaking of "Fond Matt", here was a bull sired by Lakefield Fond Hope (a Michigan-bred bull who travelled to Kansas, then Canada, and finally to NOBA).   "Fond Hope" was sired by a Canadian show type bull, from a dam who ended up as half of the Holstein breed's two-generation lifetime production champion pairing: Lakefield Fobes Delight (EX) and Minnow Creek Eden Delight (EX), between the two producing over 575,000 pounds milk in their combined lifetimes.   "Fond Hope" has a younger maternal brother Carnation Royal Master (EX95) born in 1957, who is at or near the top of the DPR summaries.  These bulls were popular in an era before "index" was the only breeding selection tool used.   I think we can start to build a case here for the higher heritability of "cow fertility" than scientists find looking at current commercial cow data, and that strong clues can be found from pedigrees giving you a full lifetime of performance (not just the first five lactations that USDA stores).

Information that is useful for selection beyond DPR and PL

We never use any bull, evaluated or not, without having first a pedigree record of the lactation history for his dam, as well as two nearest grandams.   His dam especially has to show either many lactations OR a close to annual calving interval on lactations to-date.   Your ideal bull mother would have both (many lactations and tight calving intervals).   If the dam has both, we are more easily satisfied if only one grandam has both (you will look a long time in current pedigrees to find three nearest dams all with long lifetimes and good calving intervals, even before you consider what is superior production under those restrictions).  

Believe it or not, the sire analysts who built the dynamics of commercial AI (John Hecker at MABC Select Sires, Archie Nelson at All-West Select Sires, Ted Krueger at Curtiss, Bryce Weiker at Noba, Marlowe Nelson at TriState Breeders, Lloyd Ebersole at Sire Power, Dick Witter of Taurus, among others) were men who admired high-production, long-lifetime breeding cows and bought their sons.  It is their generation of sires whose daughters provided the data that said "high PD bulls' daughters are higher in total lifetime production".   As a result of loss of fertility, accelerated as newer sire analysts focused exclusively on buying bulls from high-indexing first-lactation cows, this is arguably no longer the case (which also explains why a high plus PL has little correlation with level of PTA milk today).  The mature cow with the high lifetime total is passed over today as "old genetics"-- as if that was a negative trait, the ability to still be productive when matured-- but there is no other way to verify a cow family's ability to be superior for fertility characteristics.

How to read a pedigree for cow performance

Here are some examples of Jersey cows that are high profile in recent breed genetics:

This cow shows a 74,040 pound lifetime over a 76 month lifelength.   This calculates to 33 pounds "per day of life" (Bob Miller of Mil-R-Mor Holsteins and Jim Pappas of Stardust Jerseys argue this is the most accurate way to evaluate a dairy cow's productive ability).   That big third lactation was made over a 480-day calving interval (only 105 days carrying calf from the first 305) so she proves to be a cow whose productivity per day "peaked" only in second lactation-- clearly a fast-maturity short herdlife cow with test% levels no better than a good Holstein.   Oddly, her only son "Boomer Sooner" proved to sire the same sort of cows.   Fertility, however, was not a problem; and in certain crosses (for example, against "QS Magic") "Sooner" made profitable, long-lifetime cows.

Where is the three year old lactation on this cow?   It seems that on her second calving at 3-03, she was not placed on test.   (An explanation of this is in the "TopBrass" issue of Jersey Journal back in 1989.   I will have to look it up.).

As a result "Faustine" only made three recorded lactations, with a lifetime total of 61,230 pounds over a 75 month life-- which works out to only 27 pounds per day of life.   But in reality her lifetime total is much higher.  Can we depend on such a cow for fertility?  Knowing there was a 3 year old calving helps, and we can calculate from that an average 13.3 month calving interval.  The more important question is, "How often are cows managed in noneconomic ways to develop a large, promotable lactation?"   In the case of "Faustine" the attempt to make a national record actually killed the cow.

Her son "Top Brass" was noted for nice uddered, smaller cows that milked well while they lasted, which was, again, not always to very old age, usually because their crooked legs and flat feet gave out, but fertility was not a problem; strength of physique was the more frequent downfall, reflected in her own premature demise.

The Ogston herd actually practiced a selection process by which no bull was ever used whose dam did not maintain a near-annual calving interval at least up to a full physiological maturity.   Mr Bishop believes the high fertility they enjoyed over a multi-decade dairy career relates to this practice.   As a way of keeping focused upon the need for fertility, Mr Bishop only considered 305 day lactations in making his decisions regarding breeding worth of cows.

Likewise, Mayfield Dairy under Paul Sparrow focused upon two great sires who came from longer lifetime production cows: Lindale Beacon Bas (sire of "Little Lady" and "Patience") and, to follow him, Marlu Milestone (sire of "Generator") whose dam had 188,737 pounds lifetime (*3x milking) and full sister had 199,508 pounds lifetime...  Again, regular calving, regular breeding cows.

This is the combination of blood behind "Faustine", so you might assume she would transmit better fertility.   (In the case of her son "Top Brass" the paternal grandam Chocolate Tristram May has a six lactation lifetime with 14 month calving interval average.   We may be seeing some slippage in fertility through his sire, Observer Chocolate Soldier given his pedigree involves a high degree of close linebreeding.   His two grandams average 13 months on 8 lactations and 15.4 months on 11 lactations, acceptable but maternally at least on the "slippery slope").   As you ponder the subject you start to realize how complex the issue of predicting "cow fertility" really becomes.

  "Frida" was the dam of HL Pompey Frederick who was born rather late in her life (1965) after she was purchased as one of three "teenage" daughters of Lilacs Remus Unrivalled at the Brigham Farm dispersal in 1962, by High Lawn.   (Note the "Zephyr" cow we reviewed earlier was sired by the bull Lilacs Remus Pilot who is paternal brother to "Unrivalled".   High fertility and long life do follow cow family lines.)

Single big lactation promotion for bull dams is deceptive

Unlike the Holstein breed, which early on in the AI era got lured into selecting their bulls on the basis of a single big lactation record, the Jersey breed's production progress has been underpinned by the sort of cows we exhibit above, valued by their Breeders as annual calvers and capable of extended life production.   Today, we see one of the reasons dairymen get interested in Jerseys is (1) they calve easier, (2) they breed easier, (3) they usually live longer.

[To support my comparison to the Holstein breed: Pawnee Farm Arlinda Chief's dam has five lactations and a 433 day calving interval, equal to 160 days open per 305-day lactation; Carlin M Ivanhoe Bell's dam has only four lactations and a 506 day calving interval, equal to 230 days open per 305-day lactation.   75% of ranking sires for "Net Merit" descend from these two AI heavy-hitters.   A large number of current ranking sires come from ET dams who only show one or two big early-age lactations.   Should we be surprised at fertility problems??]   

 As I read this, I am struck that the cows I use to demonstrate a high level of fertility and consequent longevity come from the 1950s and 1960s, whereas the cows who are more questionable for fertility and longevity come from the 1970s and 1980s... in spite of their larger lactation records, the pounds per day of life is only maybe five pounds higher.   Certainly our feeding strategy changes in Jerseys during the 1970s and after can account for most if not all that difference.   Now that a majority of Jersey young sires are being picked by sire analysts using "index" theory, will the Jersey breed fertility decline in the same way we have seen Holsteins deteriorate?   Certainly the risk is there.   It is up to Breeders to demand more than just the "minimum" in cow lifetime performance to protect this breed advantage.

It is in longevity (dependent on fertility) that dairy profitability depends.   Dairy is, like all other animal husbandry vocations, a reproduction business; before you get any production, there has to first be reproduction.    Why did the genetics industry ever lose sight of such a primary economic factor?? 

{modpagebreak title=Potential sources of longevity among "current" Jerseys} 

Potential sources of longevity among "current" Jerseys

Polled Jersey breeders are quick to point to Maplerow Mercury Aron-P (EX95%) who has the unique distinction of being both a Louisville National Show Champion and a Breed Lifetime champion with over 311,000 pounds in lifetime credits.   Think about it: that is the equivalent of fifteen lactation records of 20,000 pounds each.   Such cows are rare and deserve all the recognition they get.   She had three polled sons by "Duncan" that were sampled, and all generated low pluses for milk, a good level of component %s, low SCC scores, and high ratings for Productive Life.   Now that these sires are unavailable, many breeders have decided they deserved more usage than they received.

One of the most successful USA sires used by Canadian breeders was Schultz Performing Legend whose dam was an Ogston-bred cow sired by "Zev" with a lifetime around 160,000 pounds.   He is now recognized as a sire of long-life "brood cows".   A "Legend" daughter was recently honored as the current living lifetime production champion, exceeding the 250,000 pound mark.   Here again is a sire who never had a high enough PTA to be a first choice for siring sons for sampling, but has a good reputation for the cows he left us: easy breeding, low SCC, maturable type.

Another Louisville champion worth mentioning is C Tops Impressive (EX95%) who may be the highest producing cow to ever win the Jersey Jug.   Her lifetime credits reached 173,000m before she became a permanent embryo donor, and she has 23 registered offspring through 10/10/03.   On her first three lactations she calved 1-11, 2-11 and 3-11 producing 71,730 pounds of milk in 305 day lactations, after which frequent embryo transfer lengthened her calving intervals.   Everyone faces the dilemma of estimating calving intervals around cows from whom embryo production is desired, and that keeps the "art" of pedigree analysis alive (and the need for DPR calculations reinforced).

This year's Premier Performance Sire at Louisville, WF Brook Bomber (76J119) combines three cow families that have above-average longevity: old "Flower" (dam of "Brook"), "QS Babe" (grandam of "Barber") and WF Justin Bits EX95%, his direct maternal grandam, who shows 154,000m lifetime.  It is hard to prove the "Babe" family longevity because of extensive embryo transfer on young cows, but the PL and DPR ratings on bulls from the family are acceptable.

There is no "longevity" without first having fertility

I lean personally to the notion of paying more attention to lifetime production totals when selecting sires to be used to improve genetic potential for fertility.   It is not possible to generate a significant lifetime production total (150,000 pounds plus in Jerseys) without having the ability to breed back.   Those cows like "Aron-P" who have the extraordinary totals we always find bred back regularly.

No matter what your herd average, 150,000 pounds is an achievement.   To the breed average herd (around 15,000 pounds) it takes ten lactations.   To the breed leading herds (over 20,000 pounds) it still takes seven lactations.   To the NZ style low-input grazing herds (around 12,000 pounds) we are talking teenage cows.   In either cases, high lifetime totals indicate we beat the averages by a factor of 3 times normal "herdlife".   If you accumulate this ability in the pedigrees of the sires you use, you will have a better chance of breeding high-fertility cows than if you ignore it.