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♦ Strategies For Successful Heifer Repro
♦ Strategies For Successful Heifer Repro

Strategies For A Successful Heifer Reproduction Program

Kristi Fiedler, Associate Vice President of Technical Services, Genex

Today’s outstanding dairy reproduction programs are creating a new environment for farmers. The traditional mentality has been to raise every heifer because she will be needed as a replacement. Now dairy producers are changing their strategies because of more opportunity to raise the best replacements – they have more heifers than needed to maintain herd size. Raising healthy replacements is still a high priority for dairy farmers, but now they can choose which calves will be the most productive on their farm. This article will summarize strategies commonly used to raise the highest quality heifers in an economical fashion.

Healthy Calves
A cow’s or heifer’s transition affects the health and reproductive status of the resulting calf. The dam not only needs to be able to deliver a healthy calf, but also produce quality colostrum to build calf immunity. Newborns need clean high-quality colostrum equal to 10% of their body weight within 8 hours of birth (Leadley, 2009). The Attica Veterinary Associates website, http://bit.ly/H6z8GF, includes several educational articles on colostrum management. With adequate colostrum, healthy newborn calves will have fewer illnesses, higher growth rates, increased fertility and improved production over their lifetime.

Disease Prevention
Preventing disease is essential for successful and profitable reproduction programs as many diseases have a strong impact on reproduction. For example, calves with respiratory disease are twice as likely to leave the herd and first calving will be delayed approximately six months when compared to calves that didn’t experience respiratory infections (Bailey, Murphy, and James, 2009). Additionally, calves with scours will calve at 30 months of age or greater (Bailey, Murphy, and James, 2009).

According to the Virginia Cooperative Extension website, the key areas of disease prevention management include parasite control; coccidiosis; infectious diseases like Infectious Bovine Rhinotracheitis (IBR), Bovine Viral Diarrhea (BVD), Parainfluenza-3 virus (PI-3) and Bovine Respiratory Syncytial Virus (BRSV); and others such as pinkeye, foot rot and mastitis. The Virginia Cooperative Extension website, http://bit.ly/GOlMfc, provides good background, explanations and suggestions for vaccination protocols. It is important to note the prevalence of some diseases may vary by region. Seek advice from a local veterinarian or animal health consultant to set up a proper vaccination and treatment protocol.

Growth Rate & Nutrition
Ideal growth rates for dairy calves are 1.7 to 2.0 pounds per day (“Dairy Calf & Heifer Association”, 2012). As they grow and mature, calves also need different protein ratios in their feed. Work with a nutritionist and veterinarian on rations that best fit each age group.

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Table 1 is from a 3,200-cow herd that tracks daily gain on all heifers from birth to post freshening. The data shows the replacements with average daily gain (ADG) greater than 1.71 calved earlier (AvAGEFR = average age at freshening) and produced more milk (Av M305 = 305-day mature equivalent milk production, Av305PR = Actual 305-day milk production). As the ADG from birth to post freshening increased so did milk production in the first lactation.

By 13-15 months of age, Holstein heifers should weight 850 to 900 pounds, and possess a hip height of greater than 50 inches and a whither height of 48 inches (“Dairy Calf & Heifer Association”, 2012). According to the American Jersey Association (2012) the target weight for breeding age Jersey heifers should be 55 percent of mature weight. Therefore if mature cows are 1,000 pounds the target breeding weight is 550 pounds.

Breeding
A good goal is to breed all heifers within 21 days of the set artificial insemination (A.I.) date. If the herd’s breeding age is 12 months or 365 days, then all heifers should be inseminated by 386 days of age. During this 21-day period, several methods can be used to detect estrus including KAMARs®, tail paint, visual observation, activity monitors or a combination of methods.

A common heifer breeding protocol is to inject prostaglandin and utilize a heat detection method the day the heifers are moved to the A.I. pen. Observe and breed heifers displaying estrus activity. Give a second prostaglandin injection 10 to 12 days later to heifers that are not yet inseminated. Heifers not inseminated during the period of giving prostaglandin injections may not be cycling. Two approaches can be taken with this group; enroll them into a five-day CIDR® synchronization program or have the veterinarian check them for other issues such as freemartins.

Re-enrolling in Breeding Program
Pregnancy check all bred heifers 29 to 42 days since last heat through rectal palpation or DG29 blood pregnancy testing. Heifers that are not pregnant should be injected with prostaglandin or enrolled into a five-day CIDR program.

Virgin heifer abortion rates average 3%, so it is necessary to follow up with a pregnancy check at 60 to 90 days since last heat to confirm heifers are still carrying a calf. This step is more important for heifers that are first confirmed pregnant less than 32 days since last heat because they are at a higher risk for early embryonic loss. Finally, perform another confirmation pregnancy check at 180 to 200 days carried calf.

In today’s high feed cost environment, it is extremely cost effective to calve heifers around 23 months of age. Heifers that calve at greater than 25 months continue to consume feed longer versus returning a profit through milk production. Also, as mentioned previously, they are more likely to have calving issues and leave the herd earlier (Leadley, 2009).

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Culling Strategies
Over the past five years, the bar has been raised for reproduction management in the dairy industry. It is not uncommon for herds to have a pregnancy rate for cows greater than 25%. The Genex Reproductive Profit Manager (RPM) program benchmark for the average Holstein herd was 16.6% in 2008; in 2011, it increased to 19.7%. Jersey herds went from 20.1% to 21.9% respectively. In 2011, the Jersey RPM benchmark averages 18% sexed semen use in cows and 55% in heifers. The average Holstein herds used 7% in cows and 35% in heifers. The point is dairy herds have improved reproduction performance and implemented sexed semen use, resulting in more replacements than ever before.

The Genex RPM benchmark also indicates the average Holstein herd has a 97% replacement rate or 0.97 heifers for every cow in the herd, up from 84% in 2008. The average Jersey herd had a 60% replacement rate in 2008 and now has a 106%, or 1.06 heifers for every cow. Knowing these statistics, the question becomes: does a herd need to raise every replacement?

The simple answer to the question is no. A herd does not need to raise every replacement. Taking that into consideration, how does one determine a breeding strategy that will result in the highest dairy profits? Here are some basic steps to follow to develop an appropriate breeding strategy.

1. The first step is to know your herd goals. Are you planning to expand? By how much? Do you still need all your replacements from a previous expansion? Do you want to sell bred heifers? Do you want to cull calves early? Do you want to sell beef crosses? What is your ideal cull rate?

2. Then determine how many replacements are needed each year to achieve herd goals. Calf Math, available at http://calfmath.crinet.com, is a simple calculator with individual herd inputs that can help you to determine the number of replacements needed annually. The calculator also offers options for breeding strategies. For instance, through Calf Math, a dairy producer may determine if they increase sexed semen usage in heifers by 10%, they would have enough replacements and be able to breed the bottom 10% of their herd to beef semen to take advantage of high beef prices.

3. Next, decide how animals are to be sorted. Today, many options are available to sort herd data, such as herd software programs, dairy herd improvement record processing centers and genomic testing. When sorting animals, remember parent averages are about 45% accurate versus genomic data at nearly 70% reliable.

An example of how one might sort cows is by the desired traits. For example, sort the cows by those that calve every 13 months, have above average milk production and have low somatic cell scores or few mastitis events.

A 1,200-cow Holstein herd in Wisconsin uses the Genomic Selection Guide from AgSource Cooperative Services to determine the Lifetime Net Merit averages on the milking herd and 6K genomic tests all Holstein heifer calves at birth.

4. One of the most important steps is to decide what to do with the sort information. The strategies can be as simple as culling any calf with more than three health events or culling heifers that are not pregnant after four insemination attempts. Strategies can also be as complicated as genomic testing all animals, selecting the elite few for flushing and transferring their embryos into bottom-end cows.

The 1,200-cow herd mentioned previously uses the AgSource Genetic Selection Guide to determine the top and bottom 15% of the cows. Those cows in the top percentages are “cherry picked” to be bred to Holstein sexed semen. Those in the bottom percentiles are bred with Angus semen. The cows bred to Angus bulls remain in the milking herd as long as they calve and produce enough milk to be profitable. The crossbred calves are then sold at a premium price or some are raised as steers on the home farm. With this strategy, the herd maintains a 25% pregnancy rate and still has more replacements than needed. In fact, together with the vet it was decided the herd could cull four additional heifer calves per month. The bottom four calves based on the 6K genomic test results will be culled each month.

5. After thinking through the entire process, make a plan. Write down the plan, indicating how everything will be implemented and who will be responsible for each step along the way. Ensure everyone involved knows their role and monitors the results.

In summary, the priorities in developing replacement strategies are as follows:

• Good dam health and transition
• Quality and quantity of colostrum
• Disease prevention
• Growth rates greater than 1.7 pounds per day
• A structured and well-planned breeding program

Once these essential priorities are in place, a dairy has more options to raise the highest quality replacements in both health and genetics.

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References

Bailey, Tom, Julia Murphy, and Robert James, eds. "Dairy Heifer Health, Disease Control, and Vaccinations." Virginia Cooperative Extension, 01052009. Web. 2 Apr 2012. .

"Every Jersey Heifer a Quality Heifer." American Jersey Cattle Association. US Jersey, 2012. Web. 2 Apr 2012. .

"Gold Standards II." Dairy Calf & Heifer Association. n.p., 2012. Web. 2 Apr 2012. .

Leadley, Sam. "Antibody Absorption." Calf Facts by Sam Leadley. Attica Veterinary Associates, 2011. Web. 2 Apr 2012. .


April 2012


 
 
 
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