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1508 PD: Improving reproductive performance on commercial dairies

Neil Michael Published on 16 October 2008

High reproductive success is fundamental to a dairy operation’s sustainability and growth in today’s dairy industry.

Over 95 percent of reproductive outcomes can be attributed to the environment of the cow and related management factors – which highlights the need for effective evaluation and monitoring of reproductive performance indicators. This [article] will highlight several fundamental opportunities to improve reproductive programs on commercial dairies and the preferred methods of measurement and monitoring their success.

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Economics of reproduction
Regardless of location within the world, improving reproductive efficiency has a significant influence on profitability. A recent review of financial results for U.S. dairies revealed milk revenue accounted for 93 to 95 percent of farm revenues and replacement animals represented 9 to 11 percent of total gross expenses (second only to feed costs), both of which are impacted by pregnancy production. Specifically, improved reproductive efficiency has a positive impact on milk flow (by placing more animals in the efficient and profitable portion of the cycle) and subsequently increase youngstock numbers that fuel herd replacements and overall growth opportunities.

In addition, genetic gain is hastened due to the ability to cull voluntarily (less reproductive culls) and the tendency to utilize higher genetic merit animals when reproductive numbers are good. Current reports estimate each incremental increase in pregnancy rate (PR) percentage point (within a range of 13 to 20 PR) return an estimated $15 to $18 per cow per year net of expenses.

Reproductive measures
PR is defined as the rate at which eligible animals become pregnant during a specified period (usually 21 days) and is the preferred metric by which reproductive programs are measured. Although the U.S. average PR is estimated to be 13 to 14 percent, many herds now consistently achieve 20 to 25 percent which gives them a distinct economic advantage over average PR herds.

Conception rate (CR) is represented as the total number of known pregnant animals divided by the total number of inseminated animals with known outcomes. We now see CR on many commercial dairies exceeding 35 to 40 percent, which is in sharp contrast to the continual decline of fertility of the U.S. cattle population that has been commonly cited in recent years.

Insemination risk (IR), formerly known as heat detection rate, is the percent of eligible animals that are detected and inseminated each measured period (usually 21 days). U.S. average IR is estimated to be 35 to 55 percent although 60 to 70 percent IR is possible when programs, cows and facilities are optimized and managed correctly.

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Other measures such as pregnancy inventory (PI) are utilized by many commercial herds to monitor the number of pregnancies produced each week in relation to required numbers to sustain a constant herd size. Although useful in stable situations, PI has limitations in herds with extreme seasonality or expansion dynamics. The inadequacies of previously popular measures such as days open (DOPN) and calving interval (CI) have been described by others and should not be used to manage reproductive programs proactively.

Reproductive opportunities and compliance measures
Determining whether PR, IR or CR performance meet the current goals of the dairy is quite simple – the more difficult but valuable component for the dairy management team is identifying a short list of profitable opportunities that the dairy commits to improve. Once a list has been determined, key measures should be identified to allow evaluation and monitoring of the implemented change.

The pregnancy production system is impacted by multiple influences that must all be managed to consistently produce quality pregnancies. Producers should ensure that fundamental areas are functioning well before attempting to implement the “newest protocol” on their dairy. Below is a partial list of fundamental influences of PR the author commonly finds on commercial dairy operations and the suggested compliance monitoring techniques:

1. Postpartum health events
Poor transition periods can influence the incidence of retained placenta, displaced abomasums, metritis and subsequently delay days to conception. Mastitis is similarly related to reduced fertility and increases the risk of abortion if pregnant. Focusing on consistent ration delivery, dry matter intake and stable rumen health both pre and postpartum are sound objectives to avoid excessive body condition loss and postpartum health events.

2. Insemination risk (IR)
Getting semen in eligible animals represents the largest opportunity to improve PR on most commercial dairies today. IR for the first breeding should be monitored to ensure greater than 95 percent of animals are inseminated within a desired breeding window of 25 to 30 days from the voluntary waiting period (VWP).

3. Technician performance
Time, temperature and hygiene are the hallmarks of consistent technician performance. Accepted A.I. technique is to thaw semen for 45 to 60 seconds at 95 to 98.6ºF and accurately deposit in the body of the uterus within 15 minutes of removal from liquid nitrogen. In addition, it is highly suggested that semen tanks are secured with padlocks to limit access and contain thaw monitors to detect possible semen damage.

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4. Cow observations and activity charting
Multiple studies have shown high-producing healthy cows should spend 12 to 14 hours per day lying comfortably. Research studies estimate each additional hour lying translates into 2 to 3.5 increased pounds of milk per day. In another study, researchers showed that animals will reduce eating activity in favor of resting activity when time allotments are restricted by daily management activities.

Additionally, extended time standing or long distances in transit to parlors can increase locomotion scores which have been associated with decreased fertility and expression of heats. The author’s field experience indicates that extended time on feet is currently one of the largest limiting factors to achieving high production, reproduction and long-lived cows on commercial dairies today, resulting from long holding times, overcrowding or inadequate facilities.

5. Synchronization efficiency
Although there is a wide range of synchronization protocols utilized within commercial dairies, the majority of commercial herds utilize a combination of both heat detection methods and synchronization to optimize IR and drive pregnancy production. Timed insemination (TAI) programs are designed to reduce heat detection errors, but concurrently introduce several variables including cyclicity, administration technique, drug storage and efficacy, and timing of injections that require routine monitoring. To optimize fertility, our current suggestion is that animals should not be inseminated before 50 to 55 days for detected heats or 70 to 80 days for timed inseminations.

6. Re-enrollment of open animals
Quickly returning open animals to the breeding pool improves PR. Resynch programs that ensure all open animals found on herdcheck are reinseminated within 10 days are optimal. In addition, extended herdcheck intervals and days carried calf at pregnancy check fundamentally increase the time until open animals may be detected, which often present opportunities to improve PR.

7. Heat stress
Management has become more critical in recent years as milk production continually increases in commercial herds, resulting in higher intakes and BTUs produced by lactating animals. Wiltbank and coworkers showed reduced embryo quality of lactating animals compared to heifers during heat stress. Holding pens appear to be a major contributor to heat stress loads on many commercial dairy operations, resulting in significant temperature spikes at milking that lead to decreased intakes, slug feeding and potential for early embryonic loss. Obviously, providing adequate sources of clean high-quality water within pens and in transit from the milking parlor is fundamental to minimizing the above effects of heat stress.

8. Evaluation of insemination type
[Evaluation] is an effective tool to highlight opportunities to improve reproductive performance. During data entry, different insemination types are assigned codes and subsequently compared for the same time period. Commonly used codes include natural or chalk, TAI, requested, dirty, blood and others as applicable to specific reproductive programs. Note: When evaluating CR, it is suggested that a minimum of 250 to 300 observations for each insemination type be evaluated to avoid making incorrect decisions due to normal binomial variation.

Summary
Achieving a consistently high rate of pregnancy production is profitable and achievable on commercial dairy operations through systematic evaluation of fundamental inputs to the production system. Improving fundamental processes including transition period, insemination risk, technician performance, activity charting, synchronization efficiency, re-enrollment of open animals and heat abatement can contribute to increased pregnancy rates on many commercial dairies. Once optimized, establishing routine compliance monitoring programs to detect aberrations and drift in system are necessary to minimize variation. PD

References omitted but are available upon request at
—Excerpts from 3rd Annual I-29 Dairy Conference Proceedings

Neil Michael
DVM MBA
Director of Technical Services
ABS Global, Inc.

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