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Hereford and Red Angus Heifers Recruited for Genomics Research

The University of Missouri is recruiting 2,500 Hereford heifers and 2,500 Red Angus heifers to participate in a heifer puberty and fertility genomic research project. Heifers should be registered Hereford, registered Red Angus, or commercial Hereford or Red Angus. Hereford x Red Angus crossbred heifers targeted for the Premium Red Baldy Program would also be a good fit for the research project. Producers must be willing to work with a trained veterinarian to collect the following data: ReproductiveTract Scores collected at a pre-breeding exam 30 to 45 days prior to the start of the breeding season. PelvicMeasurements (height and width) collected at the same pre-breeding exam 30 to 45 days prior to the start of the breeding season. Pregnancy Determination Using Ultrasound reporting fetal age in days. Ultrasound will need to occur no later than 90 days after the start of the breeding season. In addition, heifers must have known birth dates and have weights recorded eithe

ARSBC 2018: General considerations for implementing an artificial insemination program or other reproductive technologies

George Perry
South Dakota State University

Criteria that heifers should meet:
What has the pregnancy rate in your heifers been over the past few years?
Have your heifer received growth promoting implants?
Have your heifers reached the target weight? Typically 65%.
What are the Reproductive Tract Scores of the heifers?

Heifers have to reach 55% of their mature weight to start reaching puberty. However, how well can we know what the mature weight will be? When targeting 55% at breeding, we are really walking on the knife's edge. By targeting 65%, we are hedging for uncertainty.

Heifers with Reproductive Tract Scores that are 1 or 2 not only have lower conception rates as heifers, they also have lower conception rates at 2-year olds.

Criteria that Cows Should Meet

What was the body condition score of your cows at calving? Should be greater than 5.
What is the current body condition score of your cows?
How many days postpartum will your bows be when estrus synchronization is started?

Animals that are not cycling (anestrous) cannot be breed.

Replacement heiferes should be vaccinated before and at weaning.
Both heifers and cows should be vaccinated at least 45 days before breeding.

40% of naive animals that were given a modified live vaccine had an abnormal cycle, which greatly reduces fertility. Even on second cycle, conception rate was only 30%.

Naive animals is dictated by vaccination program. If you didn't give the injection at weaning (purchased later), you can't guarentee it was given.

Cows that are vaccinated less than 45 days before the beginning of the breeding season had reduce conception rates.

There are several estrus detection aids out there. It is important that you use one you are familiar and comfortable with.

When comparing intense vs casual estrus detection systems, the intense estrus detection had a 71% pregnancy rate vs a 35% pregnancy rate with casual detection.

The timing of insemination is a balancing act of the lifespan of the semen and the aging of the ovum (egg). The balance point is typically 12 hours after the expression of estrus.

29% of females display heat from midnight to 6 am. Highlights the need for a detection aid!

Looking at over 10,000 head, there is a 27% improvement in fertility when animals express estrus. When selecting for higher fertility, we see increased expression of estrus.

When semen is deposited in the correct location at the correct time, fertilization occurs 95% of the time. There is a 10% decrease in fertility when semen is deposited in the cervix. No advantage to depositing semen deeper into the uterine, and there is a risk of scratching the uterus and causing bleeding when depositing too deep.

Maternal recognizition of pregnancy doesn't occur until day 15 to 17 of pregnancy. "What is the easiest thing to loose? Something you don't even know you have," Perry said. This can happen to cows that haven't yet recognize pregnancy.

Heifers put on a truck 1 to 4 days after insemination have pregnancy rates around 72%. There is a 12% loss in pregnancy for heifers shipped 8 to 12 days after insemination, a 9% loss for heifers shipped 29 to 33 days after insemination, and a 6% loss for heifers shipped 45 to 60 days after insemination.

Prior grazing exprience creates higher average daily gains compared to heifers that don't have grazing experience (have been in a dry lot). Pregnancy rates are also higher in those heifers that have prior grazing experience. Heifers that have been in dry lots travel around the pasture much more than heifers with previous grazing experience. Heifers from dry lots take 5 days to calm down and not walk too much.

Heifers on restricted diets have less mature embryos and lower quality embryos. A simple 6 day restriction of nutrition caused these differences.

Equation of Reproduction
1. Animals detected in heat and inseminated
2. Inseminator efficiency
3. Fertility level of the herd
4. Semen fertility level

What are the primary problems?

  • Cattle are not good candidates for an estrus synch/AI program (heifers too young, not reach puberty, too many anestrus cows)
  • Protocol compliance
  • Facilities
  • Shipping (trucking) stress
  • Cattle lose weight during breeding season 
  • Others...

See ARSBC Newsroom for more information. http://www.appliedreprostrategies.com/2018/newsroom.html

Note: this post was live blogged and may contain errors.


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