The Cow-Calf Manager

Livestock Update, November 2005

John B. Hall, Extension Animal Scientist, Beef, Virginia Tech

Impact of Novel Endophyte Fescue on Beef Cattle Performance

Fescue is the principal grazing forage over much of the MidAtlantic, Southeastern, and lower Midwestern states. Unfortunately, it also contains an endophyte (fungus that lives in plant cells) that produces toxins. These toxins, ergovaline and ergotamine, are well documented to reduce cattle growth, reproductive performance, and health. The reduction in cattle performance results in excess of $600 million in lost income for Eastern beef producers.

Until recently, the endophyte infected (E+) fescue problem could only be dealt with in the following ways:

• Avoid grazing fescue (not very practical)
• Plant endophyte free fescue (expensive and it didn't persist)
• Add clovers to pasture (a good solution)
• Change to fall calving season or run stockers in the fall (good option but not for everyone)

About ten years ago, plant breeders developed novel endophyte fescue by inserting an endophyte that did not produce toxins into endophyte free (E-) fescue. This novel endophyte conferred to the plant the drought tolerance and disease resistance that the normal endophyte imparts. However, since it didn't product the toxins that affect animals, the hope was that an animal friendly fescue that would persist under grazing conditions had been developed. Early reports under harsh grazing conditions indicate that novel endophyte fescue are equally or nearly equally persistent to endophyte infected fescue.

Animal performance trials with the two commercially available novel endophyte (NE+) fescues, MaxQTM and ArkPlusTM , have been conducted since 2000. Two Arkansas researchers (Gunter and Beck, 2004) reviewed the performance of growing cattle on NE+ fescue from studies in five states. Cattle grazing NE+ fescue gain weight 47% faster than cattle on E+ fescue and produce more pounds of beef per acre (Figure 1). Stockers grazing E+ pastures gained on average 1.35 lbs./day while stockers on NE+ or E- fescue pastures gained over 2.0 lbs./day.

The most common problem with grazing NE+ fescue is the tendency for animals to overgraze this fescue compared to E+ fescue. The toxins in typical E+ fescue reduce forage intake by the animal and this is the principal cause of decreased weight gain. In addition, the increased body temperatures and, perhaps, effects on growth hormones reduce weight gain. Like E- fescue animals increase intake of NE+ compared to E+ fescue.

The effects of NE+ fescue on reproduction in beef cattle are not as well investigated. Most studies suffered from having too few animals to make assessment of impacts on reproduction. Using small numbers of heifers grazing fescues during the winter development period before breeding, Ivy and coworkers (2001) found little difference in heifer growth except during hot weather in the last 21 days of the trial. During that time, heifers on novel endophyte or endophyte free pasture grew twice as fast as heifers on endophyte infected pastures.

However, all heifers were large enough to breed regardless of which fescue they grazed. This was most likely a result of heifers grazing these pastures during the cool part of the year. The number of heifers in each group was far too few to assess impacts on reproduction.

More cows grazing NE+ fescue were pregnant at pregnancy exam than cows grazing either E+ or E- pastures (Burke et al., 2004). However, there were no differences in the percentage of cows calving. Nursing calves grew faster on E- and NE+ pastures than E+ pasture during the summer.

Establishing NE+ fescue in old grass stands can be expensive. It has been estimated that based on increased calf gains, it would take about 7 years to pay back the cost of establishment and lost production (Gunter and Beck, 2004). If "fescue lookin" calves were discounted $15/cwt and calves from NE+ pasture did not receive a discount then the prediction is it would take 3 years to breakeven on establishing NE+ fescue. Using NE+ fescues when transitioning from cropland to timberland may be a more economical option. After recouping the cost of establishment, economists have estimated that a stocker operation could make $25 more per acre per year on NE+ fescue compared to E+ fescue. Strategic use of NE+ fescue in a beef operation looks promising.

New grazing study at Southwest AREC
In Southwest Virginia and other mountainous areas of the state, incorporating legumes in fescue has been an effective method to minimize the effects of E+ fescue on animal performance. Therefore, it is important to know if NE+ fescue with or without clover holds any advantage over E+ fescue.

The new grazing study will examine the impact of grazing E+ fescue, E+ fescue with clover, NE+ fescue, and NE+ fescue with clover on:

1. Growth and development costs of replacement heifers
2. Pregnancy rates in replacement heifers
3. Growth and cost of gain of steer during backgrounding

Stands were established this fall, so we will have the first data off these pastures next fall or spring 2007. Stop by the SWAREC for a tour of the pastures next spring or early summer.

This research is supported by a grant from the Virginia Agricultural Council and a gift of seed from Pennington Seed, Inc.

References
Bouton, J.H., G.C.M. Latch, N.S. Hill, C.S. Hoveland, M.A. McCann, R.H. Watson, L.L. Hawkins, and F.N. Thompson. 2002. Re-infection of tall fescue cultivars with non-ergot alkaloid producing endophytes. Agron. J. 94:567Ð574.

Burke, J.M., D.K. Brauer, and M.L. Looper. 2004. Use of novel endophyte-infected tall fescue for cow-calf production in Arkansas. J. Anim. Sci. 82 (Suppl. 1):91.

Gunter, S.A. and P.A. Beck. 2004. Novel endophyte-infected tall fescue for growing beef cattle. J. Anim. Sci. 82(E. Suppl.):E75ÐE82.

Ivy R.L., J.L. Howell, T.G. Best, J.E. Huston , R.R. Evans, and D.J. Lang. 2001. Evaluation of fungus infected, fungus free and novel endophyte fescues as forage sources for developing replacement heifers. Mississippi Report - 2001 Tall Fescue Toxicosis Workshop.

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