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Fescue and spring breeding

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Column by Doug Shepherd, Hardin County Extension agent

Good old KY31 Fescue. It “holds most of this part of the world together” by preventing soil erosion, etc., and provides an excellent, high-yielding, high-quality durable forage for nearly all species of livestock. Unfortunately, it comes with baggage. mainly in the form of an endophyte or fungus that lives in the plant and provides it protection from natural biological predators. It can cause real problems to some livestock species during certain periods of their life.

The endophyte found in most fescue fields causes cattle and other species to run elevated body temperatures, eat less, constricts blood vessels decreasing blood flow to extremities and affects reproduction and the birthing process. However, if fescue fields are managed properly, many of these effects can be lessened or removed completely.

Many Kentucky and local beef producers have spring-calving cow herds that graze fescue pastures which have high endophyte levels. Getting a high percentage of cows bred in May, June and July to calve in March, April and May can be a real challenge. As a result, many prefer fall calving, but there are many who believe they can have successful breeding performance in the spring.

Keys to getting a high percentage of cows pregnant for a spring calving season were developed by Dr. Roy Burris, University of Kentucky Extension beef specialist at the UK Research and Education Center outside Princeton, Ky. According to Burris, the most general problem is winter feeding programs aren’t adequate to support required body condition for early rebreeding. Cows should enter the breeding season in a good body condition (BCS 5) which doesn’t always follow winter feeding programs. It seems we sometimes try to “rough them” through the winter and hope spring grass “straightens them out.” That’s a sure formula for delayed breeding or open (not bred) cows. Spring-calving cows need to conceive before late June for best results.

Burris conducted a trial several years ago at the research center in which similar cows were separated into three breeding periods of 45 days each on high endophyte fescue. The first breeding period was from April 21 to June 5, second was from May 21 to July 6, and the third from June 19 to August 4. Percent bred were 89.2 percent, 78.4 percent and only 59.3 percent respectively for the three breeding groups. Typically at Princeton, which is in Western Kentucky, the average maximum daily temperature reaches 90 degrees by about June 20. This elevated air temperature, coupled with the endophyte that is present in most fescue pastures, likely contributed to that decreased reproductive performance.

They also measured alkaloid levels in high-endophyte fescue pastures. Since the primary culprit in toxicity of high endophyte fescue pastures seems to be ergovaline, an alkaloid that affects animal performance, they looked at ergovaline levels across the growing season. The research data showed that ergovaline levels were basically flat from May through mid-June, then increased slightly through mid-July. They nearly tripled going into August and steadily increased in September. So what does this tell us? That the increased toxicity, coupled with high temperatures, appears to mean that breeding will not occur at acceptable rates in July, August or September due to increased body temperatures that interfere with conception. Therefore, your cows need to be pregnant by the end of June for best results.

There are several other keys to a successful breeding season. Obviously, fertile bulls are extremely important and breeding soundness exams on those bulls are essential. See your veterinarian about getting one of these exams. Think fertile bulls and cycling cows.

A complete mineral supplement needs to be available on a year round basis. Artificial insemination brings on a need for managing the details of insemination and estrous synchronization protocols. Don’t let cows lose condition as the breeding season nears. Lush, watery grass might not support regaining condition after calving, peak milk production and rapid re-breeding. Just do whatever it takes to get them bred and bred early.

The effects of the fescue endophyte can be decreased tremendously in established pastures by incorporating other grasses and legumes in those fields. Red and white clovers typically are used to renovate fescue pastures as are alfalfa and other recommended legumes. These all help dilute the effect of the endophyte and improve the quality of the forage being produced on that field. New improved novel and endophyte-free fescue have been developed that can be used in new stands or sown in existing stands. The endophyte only can be transmitted via seed from an infected plant, so non-infected and infected plants can grow side by side.

Doug Shepherd is a Hardin County Extension agent for agriculture and natural resources. Reach him at 765-4121 or at www.hardinag.org.