Improving heat detection rates and pregnancy rates in repeat breeders

There are several ways to economically evaluate better reproduction. Whatever economic indicator is used, research suggests that the more efficient our dairy producers become at getting their entire dairy herd pregnant, both first service cows and repeat breeders, the potential exists for increased profitability for the dairy enterprise.

INTRODUCTION

Over the last number of years, there has been a great deal of discussion and many educational programs dealing with improving heat detection rates and pregnancy rates in dairy herds. Many of the programs have dealt with the implementation of various synchronization programs to get the vast majority of the breeding herd (those cows who are eligible to be bred post voluntary waiting period) inseminated in a timely manner. These synchronization methods have helped a great deal in improving the likelihood of nearly all cows eligible for a first service being inseminated within the first 21 days (an average heat cycle) post voluntary waiting period.

In contrast, there appears, at least in my experience working with dairy producers, to be a problem area with regard to repeat breeders. The repeat breeding herd in realty is no different from the first service breeding herd when it comes to the importance of heat detection. And yet I continue to observe a large number of dairy producers who do not do a very good job of presenting the repeat breeding herd for insemination in a consistent manner. This lack of consistency for rebreeding non-pregnant cows reduces the overall heat detection rates and pregnancy rates on these farms.

A STUDY OF 9 LOCAL DAIRY HERDS IN NORTHEAST PENNSYLVANIA

In reviewing the DHIA reproduction information for 9 herds that I routinely work with, I found some interesting information exemplifying this concern.

Herd # Days to
1st service

Heat
detection rate

% of repeat breeders with
breeding interval ≥ 48 days 
between breedings
1 73 56% 8.2%
2 78 62% 23.1%
3 70 50% 23.3%
4 68 50% 24%
5 75 50% 27.2%
6 92 45% 29.6%
7 70 44% 34.1%
8 81 42% 42%
9 92 29% 45.4%

As you can see, days to first service varied in these 9 herds from 68 days to 92 days, and heat detection rates varied between 29% and 62%. What I found particularly interesting was the variation between herds in relationship to repeat breeders and the percentage of these cows not re-inseminated within 48 days (two heat cycles). In the herd with the lowest percentage of repeat breeders with a breeding interval ≥ 48 days (herd #1), only 8.2% of these non-pregnant cows were in the ≥ 48-day breeding interval group. From my personal experience in working with this herd, it is noteworthy that the herd owner is doing pregnancy diagnosis at around 28 to 33 days post breeding and immediately begins a resynchronization program with all cows diagnosed open.

On the other end of the spectrum, herd #9 had the highest percentage of open cows not re-inseminated within 48 days (45.4%) and the lowest heat detection rate at 29%. However, this herd does do a great job of getting cows to conceive as evidenced by a conception rate of 64%. These herds demonstrate, along with the rest of the herds included in the table above, that reducing the breeding interval between services can have a positive effect on heat detection rates, pregnancy rates, and ultimately can improve dairy profitability.

CONCLUSION

According to the University of Missouri Dairy Cattle Reproduction Manual published in February of 2009, an increase in days open can be valued at between $0.50 and $4.50 per day, a pregnant cow is worth $250 to $600 more than an open cow, and each percentage point increase in pregnancy rate is equal to roughly $35 per cow. Increasing the number of pregnant cows leads to the opportunity to do more voluntary culling and/or selling of excess breeding stock. Other studies show similar values or costs to dairy farms in delayed pregnancies.

There are several ways to economically evaluate better reproduction. Whatever economic indicator is used, research suggests that the more efficient our dairy producers become at getting their entire dairy herd pregnant, both first service cows and repeat breeders, the potential exists for increased profitability for the dairy enterprise.

Listed below are a few points to emphasize when attempting to reduce the percentage of repeat breedings that do not occur in a timely manner (for example, the percentage of cows with a breeding interval of ≥ 48 days or 2 heat cycles):

A consistent and early diagnosis of all inseminated cows to identify non-pregnant cows as early as possible is critical. Shortening the breeding interval on these cows improves reproductive performance (Giordano et al., 2011). This allows dairy producers to focus on repeat breeders either through focused heat detection or enrolling these cows in a resynchronization program.

If enrolling repeat breeders in a timed A.I. protocol, the proper timing and strict adherence to detailed protocols with the synchronization program being used is very important.

The most important considerations when using a resynchronization program are: the interval between first insemination and the resynchronized insemination; the conception rate to the resynchronized insemination; and the speed and accuracy of the pregnancy diagnosis method (chemical test, ultrasound test, or palpation) that is needed for the system (Lucy et al., WCDS Advances in Dairy Technology (2012) Volume 24: 95-109).

 

Author

Gary Hennip

Gary Hennip
1 articles

Penn State Dairy Extension Team Member

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Penn State University

Penn State University

Penn State is a multicampus public research university that educates students from Pennsylvania, the nation and the world, and improves the well being and health of individuals and communities through integrated programs of teaching, research, and service.

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