Committee Technical Sessions:
Cow Herd Efficiency & Selection Decisions
Fertility in Beef Cows
BOZEMAN, Mont. (June 2, 2011) — The problem: embryonic mortality of single-service efforts [estrus synchronization followed by artificial insemination (AI)]. The solution: determine the factors that improve fertility and consequently lessen instances of embryonic mortality, or abortions. According to Tom Geary, USDA-ARS Fort Keogh Livestock and Range Research Laboratory, Miles City, Mont., on average, 38% of heifers synchronized and AIed will be open upon pregnancy check 42 days following the breeding date.
The significant economic impact of a “missed cycle” or an early abortion is not something often talked about. But according to Geary, if 25% of heifers are open after the first breeding effort, even if they become bred in their next cycle, the industry loses the potential for $800 million per year. “A missed pregnancy ultimately means lighter calves, later puberty of calves, and more diversity in meat and carcass composition,” he said. All of these factors spell out financial hardship to the cow-calf producer.
Geary’s goal was to determine whether or not follicle size affects pregnancy establishment and maintenance. His research on donor cows and recipient cows suggests that the follicle size only matters in the recipient cow, so the effect of the follicle size acting through the maternal environment prepared the cow for a successful pregnancy.
Additional findings indicated that estradiol concentration at the time of breeding was the most important factor relating to fertility, followed by the presence of progesterone on Day 7 following breeding. Other factors, in order of effectiveness, are presence of progesterone prior to breeding, ovulatory follicle size, embryo quality and days postpartum at breeding.
Geary and his research his team are also studying bull fertility. A new piece of equipment, the EasyCyte Flow Cytometer effectively analyzes several factors in semen that are difficult or impossible for researchers or veterinarians to see under a microscope. The Cytometer should help quickly identify bulls that should be culled due to infertility.
They have also used magnets to “sort” ubiquitin-affected sperm, thought to be ineffective. After the removal of the poor sperm, fertilization rates increased 2 to 4 times.
“We learned that fertility is much more complicated than we had hoped,” Geary said.
He concluded that the most important variable related to pregnancy success was estradiol concentration at the time of breeding.
Additionally, progesterone is obligatory to a successful pregnancy, as is blood flow to corpus luteum (CL).
Geary presented his findings to a joint technical session of BIF’s Cow Herd Efficiency and Selection Decisions committees. To listen to this presentation and to view the PowerPoint that accompanied it, visit the Newsroom at www.BIFconference.com.
BIF’s 43rd Annual Research Symposium and Annual Meeting was hosted June 1-4 on campus at Montana State University, Bozeman, Mont.
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