Improving heifer reproduction
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By Todd Bilby
Dairy producers often overlook their heifer reproduction program due to the assumption that their heifer reproduction is doing good. When compared to lactating dairy cattle, this assumption is probably correct; however, heifer reproduction can be improved on most dairies and save dairies a substantial amount of money.
First thing you should assess is if your heifers are being bred at the optimal time for improved profitability. Dairy heifers should be at 60% of mature bodyweight by first breeding. Goals should be to get all heifers pregnant between 14 - 16 months of age so that they calve between 23 - 25 months of age. Strive for at least a 60% conception rate.
Heifers that calve at 23 months versus 26 months of age can result in substantial economic benefits. Heifers cost a producer on average $1,200 to raise from birth to calving so the later the heifers age at first calving the higher the cost. In addition by extending the age at first calving research has shown that a greater number of replacement heifers would be needed to maintain herd size, again increasing costs.
To get heifers bred on time, they need to be moved to the breeding pen in a timely fashion. Move heifers weekly to the breeding pens or at least bi-weekly to ensure heifers are bred as soon as they reach target height and weight requirements.
Utilize an injection of prostaglandin at the time they are moved into the breeding pens and again 10 - 12 days later for heifers not yet inseminated. This would allow by 28 days, or 6 days after the 3rd prostaglandin injection, after entering the breeding pen that > 95% of heifers are inseminated. With the remaining heifers you can decide to either give another injection of prostaglandins 10 -12 days from previous injection or enroll them into an Ovsynch + CIDR timed AI program to ensure all heifers get inseminated.
Routine pregnancy checks should occur weekly or bi-weekly at minimum. All pregnancies should be reconfirmed as early as 60 to 90 days carried calf. Move pregnant heifers out of the breeding pens to make room for new heifers moving in. Any heifers diagnosed open at pregnancy check, administer prostaglandins or enroll into Ovsynch + CIDR timed AI protocol.
Lastly, evaluate your heifer reproductive performance. DO NOT just look at average age at first calving, average conception rate and number pregnant at pregnancy check as these metrics DO NOT reflect current performance. Instead evaluate Voluntary Period Compliance (are heifers being moved into the AI pens often enough and according to plan?), distribution of first breedings (how long after the VWP is it taking to get first insemination into heifers?), Pregnancy rate, Insemination Risk (Heat Detection Rate), and Conception Risk.
Pregnancy rate is often overlooked in heifer reproduction as dairy farmers tend to look at conception risk and (or) insemination risk. The reason pregnancy rate is probably the number one key metric to evaluate on heifer reproduction is due to the equation that is used to come up with a pregnancy rate. This is the number becoming pregnant in a 21 day period divided by the number eligible to become pregnant in a 21 day period. This is important because pregnancy rate has two major components: conception risk and insemination risk.
Pregnancy rate will help determine the speed at which heifers become pregnant.
In conclusion, there is a substantial economic opportunity to get heifers bred successfully and in a timely manner. Reducing the age at calving from 26 months to 23 months will improve profitability despite the incremental costs to achieve better pregnancy rates.
For further information, please visit: http://texasdairymatters.org/
FYI
■ Contact Todd Bilby, call 254-968-4144 or e-mail trbilby@ag.tamu.edu.
