|Carter, Jessica -|
|Dougherty, Charles -|
Submitted to: American Forage and Grassland Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 1, 2009
Publication Date: June 21, 2009
Citation: Carter, J., Dougherty, C., Aiken, G.E. 2009. Performance and physiology of yearling steers grazing toxic tall fescue as influenced by feeding soybean hulls and implanting with steroidal horomones. American Forage and Grassland Conference Proceedings. CD-ROM. Interpretive Summary: Tall fescue is a versatile forage species that has become extremely favorable to producers because of its agronomic qualities, including ease of establishment, tolerance of heat, drought, and insects, as well as providing erosion control. However, cattle grazing tall fescue infected with a fungal endophyte that produces ergot alkaloids may have an unthrifty appearance and perform poorly. Cattle grazing toxic tall fescue typically do not achieve targeted growth rates (<1.0 lb/d). However, cattle could be implanted with steroidal hormones and fed concentrate or by-product feeds to restore growth rates. An experiment was conducted with steers grazing endophyte-infected tall fescue to determine if combining feeding of pelleted soybean hulls with steroidal implantation have additive effects on weight gain and severity of toxicosis. Combining feeding of soybean hulls with implantation provided a 71% increase in average daily gain over the control treatment, whereas feeding SBH without implantation and implantation without feeding SBH provided increases of 32 and 13%, respectively, over the control treatment. Results indicated that steers on endophyte-infected tall fescue can be fed soybean hulls and implanted with steroid hormones to substantially improve performance.
Technical Abstract: Ergot alkaloids produced by an endophyte (Neotyphodium coenophialum) that infects tall fescue (Lolium arundinaceum) adversely affect cattle weight gain and physiology. Sixty-four steers were grazed on endophyte-infected (E+) KY-31 tall fescue for 77 days in 2007 and sixty steers were grazed for 86 days in 2008 to evaluate the combined effects of implantation of steroidal implants and feeding of soybean hulls (SBH) on performance and physiology. With or without feeding pelleted soybean hull (SBH) treatments (5.0 lb/steer/day) were randomly assigned to 6, 7.5-acre pastures. Treatments of with or without ear implantation with steroid hormone (200 mg progesterone – 20 mg estradiol) were assigned to groups of five or six (4 pastures in 2007) steers within each pasture. Average daily gain (ADG), rectal temperature, serum prolactin, and hair coat rating responses to SBH and steroid implants were measured. Feeding SBH and steroid implants had additive effects on ADG. Rectal temperature was highest with feeding SBH, but rectal temperatures were reduced when SBH was combined with steroid implants. Implanting did not affect serum prolactin or hair coat ratings, but steers fed SBH had higher serum prolactin and also had greater frequency of sleek hair coats. The results indicate that SBH in conjunction with implants may increase steer weight gain. In addition, SBH may aid in shedding of rough hair coats of fescue cattle.