The long-term goal of Dr. Perry’s research program has been to discover, develop, and disseminate management practices that improve reproductive efficiency in cattle around the world.

The beef industry makes up roughly 22-24% of total meat produced worldwide, and with the estimated increase in the world’s population, food production must more than double to meet the growing world demand. The greatest benefit for the beef industry is its ability to convert low quality forage (which is not usable for human food) into a high-quality food source for humans.  However, as the world population increases, resources available for beef production become even more limited.  Therefore, the efficiency of beef production must increase to meet the rising demand.  Furthermore, it has been estimated that a 5% increase in the number of cows that conceive in the first 21 days of the breeding season would increase the pounds of beef weaned by 1,550 pounds per every 100 cows.  Thus, to enhance the sustainability of cattle production, further efforts to understand reproductive efficiency are essential.

In line with the rationale above, my research program has focused on incorporating both basic and applied research aspects to address questions that will impact reproductive efficiency in the beef industry.  More specifically my program has focused on four main areas: 1) the role of estrus (preovulatory estradiol concentrations) in regulating the uterine environment for pregnancy establishment and maintenance, 2) the impact of herd health management practices on reproductive efficiency, 3) factors that regulate sperm longevity and male fertility, and 4) the development of management practices to increase reproductive efficiency and decrease embryonic loss in cattle.

1) The role of estrus (preovulatory estradiol concentrations) in regulating the uterine environment for pregnancy establishment and maintenance

Our laboratory has demonstrated how changes in the hormone estradiol around the time of insemination can impact pregnancy success.  Data collected on over 10,000 cows/heifers synchronized with recommended fixed time AI protocols identified a 27% improvement in conception rates among animals with elevated concentrations of estradiol. Those results mean estradiol prompted the opportunity for an extra 27 calves out of every 100 cows.

2) The impact of herd health management practices on reproductive efficiency

We have demonstrated that the use of a modified live viral vaccine within 45 days prior to breeding can decrease AI conception rates by 5 to 8% compared to an inactivated viral vaccine.  Recently, the American Association of Bovine Practitioners developed Vaccination Guidelines to utilize when designing vaccination protocols.  This is the first time a food animal veterinary group has developed official vaccination guidelines, and work from our laboratory is highlighted in the impact of vaccinating during the prebreeding period. These new guidelines demonstrate the impact of my program on the cattle industry, and the potential to change the current dogma thus will have a tremendous long-term impact on the cattle industry.

3) Factors that regulate sperm longevity and male fertility

This current research is evaluating what factors may influence sperm survival and fertilization. As new information is gleaned from this research, improved technologies to store semen and increase conception rates through AI may be developed. These potential findings could be a game changer.

4) The development of management practices to increase reproductive efficiency and decrease embryonic loss in cattle

We have developed management strategies that have had a tremendous impact on beef cattle reproductive efficiency.  In collaboration with beef cattle producers and other laboratories, we have developed an estrous synchronization protocol (PG 6-day CIDR protocol) that increased control of follicular development and improved conception rates compared to other commonly used protocols (9% increase in first service conception rates).  We have further demonstrated that changes in diet immediately after AI can result in an up to a 15% decrease in AI conception rates.

ACADEMIC BACKGROUND