Fescue Forages

Does the fescue endophyte negatively impact bull fertility?

Roughly 25% of US beef originates from areas in which fescue forages are predominant. Losses associated with the fescue endophyte are estimated at a whopping $1 billion annually. Within this area of the US, 95% of the calf crop is achieved via natural service, making bull exposure to endophyte toxins a major issue.



We always talk about how the fescue endophyte affects cow fertility, but rarely talk about the negative impact on bulls. Studies have shown that grazing infected fescue forages can reduce sperm quality vs bulls consuming non-infected forages. Effects range from lowered sperm motility to increases in morphology defects (misshapen spermatozoa) to decreases in prolactin levels (a hormone thought to play a part in male fertility); however, results were inconsistent.  The problem is that even if we do breeding soundness exams (BSE), we cannot always detect these problems.

So the take home message is that bulls on fescue forages may be subfertile, even if they pass a BSE. The fescue endophyte impacts semen quality at least some of the time. Given how important your bulls are to your bottom line and economic growth, can you afford to take a chance on their fertility?

Short of removing bulls from fescue pastures or not feeding them fescue hay, what can you do to safeguard their fertility? One way is to combat known nutritional issues found in fescue forages with strategic supplementation.



Research has shown that copper levels are lower in endophyte-infected fescue vs. endophyte-free fescue when grown under identical conditions. Additionally, cattle grazing endophyte-infected fescue exhibit decreased copper status as opposed to cattle grazing endophyte-free fescue. However, the magnitude of this decrease was greater than the difference between the forages.  What this means in a nutshell is that the endophyte not only decreases the total amount of copper present in the fescue, but also, negatively affects bioavailability of copper inside the animal. This makes sense when you consider that the typical symptoms for fescue toxicosis closely resemble those for copper deficiency. For all of these reasons, lowered copper status plays a large part in the fescue toxicosis syndrome. Proper supplementation with a high copper supplement can help alleviate some of the fescue toxicity symptoms.

While proper levels of all minerals are important, two key trace minerals with a direct effect on bull fertility are copper and zinc.  Bulls deficient in copper may have reduced libido and poor semen quality. If the deficiency is severe, the bull can become sterile due to testicular damage. Zinc nutrition is also vital for development and maintenance of testicular tissue. Research has shown that bulls receiving supplemental zinc produce more and better quality semen than bulls that are not supplemented. Either organic or inorganic forms of zinc produced positive results in terms of semen volume, sperm concentration, percent live sperm and sperm motility. But it was found that bulls receiving organic zinc displayed higher numbers of sperm per ejaculate and better motility compared to those receiving inorganic zinc sulfate. Additionally, we know that the body utilizes copper better in the presence of zinc.

The SWEETLIX Solution

SWEETLIX Fescue Balancer products have been scientifically formulated to take into account factors associated with the fescue endophyte. Supplement bioavailablity is crucial, especially in areas with high levels of antagonists like sulfur or iron in soils. For this reason, SWEETLIX Fescue Balancer products contain Bioplex® organic sources of copper, zinc, manganese and cobalt and Sel-Plex® organic selenium as well as inorganic sources for optimum bioavailability and performance. SWEETLIX Fescue Balancer products also contain FEB-200™ to help support overall performance and help cattle attain maximum genetic potential on fescue forages.

SWEETLIX Fescue Balancer products have all been designed to deliver enhanced magnesium levels and deliver NRC recommended levels of essential trace minerals. Due to the mineral factors described, these products deliver twice NRC levels of copper and zinc to help combat issues caused by fescue endophyte and assure that bulls get what they need to be productive.

To see full benefit, feed SWEETLIX Fescue Balancer products at least 60 days prior to expected breeding to impact sperm production. (The process of sperm formation and maturation takes 60 days in the bull.) Continue feeding at least through the end of the breeding season.


The fescue endophyte can affect bull fertility too. Given the importance of bulls to your future calf crop, can you take the chance of suboptimal fertility decreasing your calving percentage? Cattle producers who utilize fescue pastures who also observe rough, discolored hair coats (red tinge on black hair or loss of pigment around the eyes); winter coats that are slow to shed; decreased conception rates; increased days open; hoof problems and/or depressed immunity should consider use of one of the SWEETLIX Fescue Balancer products. 

Ask for SWEETLIX by name at your local SWEETLIX dealer or call 1-87-SWEETLIX to speak with a SWEETLIX nutritionist.


Bioplex®, Sel-Plex® and FEB-200™ are registered trademarks of Alltech