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).