Author
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Aiken, Glen |
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Submitted to: Cow Country News
Publication Type: Popular Publication Publication Acceptance Date: 3/30/2016 Publication Date: 4/1/2016 Citation: Aiken, G.E. 2016. From the Lab Bench: Soy Hulls: A Special Feed for Cattle on Toxic Endophyte Fescue Pasture. Cow Country News. Pgs 55-56. Interpretive Summary: Our research in the past has shown benefits of feeding soy hulls and ear implantation with estradiol on performance of steers grazing toxic endophyte-infected tall fescue. A question from this research was if feeding soy hulls and ear implantation could be combined to provide even greater increases in weight gain efficiency. A two-year grazing experiment was conducted using steers that grazed toxic endophyte Kentucky 31 and evaluated the following treatments: 1) pasture-only control, 2) implanting with an estradiol-progesterone ear implant without soy hull feeding, 3) soy hull feeding (5 pounds/head/day) without ear implants, and 4) a combination of ear implants and soy hull feeding. Compared to the pasture-only treatment, ear implants only, soy hull feeding only, and a combination of the two treatments provided 13, 31, and 71 percent increases in average daily weight gain, respectively. The combined effects of implants and soy hulls were considerably higher than what was expected. Both treatments, particularly soy hulls, were indicated to reduce the severity of toxicosis and improve steer ADG. Subsequent research determined that soy hulls contain isoflavones, which are phytoestrogens that mimic the estradiol contained in most ear implants. Combining ear implantation of estradiol in combination with feeding soy hulls has potential as a management approach to enhance body weight gain and well-being for cattle producers interested in backgrounding calves for feedyard finishing. Technical Abstract: Soy hulls have a nutritive value that is comparable to a moderate quality hay and is often fed as a hay substitute. However, based on results of published research we conducted, it may offer more than the typical hay if fed to cattle grazing toxic endophyte tall fescue. A grazing experiment was conducted using steers that grazed toxic endophyte Kentucky 31 fescue to evaluate the following treatments: 1) pasture-only control, 2) implanting with an estradiol-progesterone ear implant without soy hull feeding, 3) soy hull feeding (5 pounds/head/day) without ear implants, and 4) a combination of ear implants and soy hull feeding. Daily weight gain averaged over the two years was 1.59 pounds/day for the control treatment, 1.79 pounds/day for ear implant only, 2.09 pounds/day for soy hulls only, and 2.71 pounds/day for the combination of ear implant and soy hull treatments. The 13 percent increase in ADG with the ear implant only treatment was expected, but a 31 percent increase with the soy hulls only treatment was higher than expected. Both treatments, particularly soy hulls, were indicated to reduce the severity of toxicosis and improve steer ADG. Combining the two treatments could relieve the adverse effects of toxicosis on cattle, but we were not sure how until we evaluated other ingredients in soy hulls that could benefit the cattle. Subsequent research showed that soy hulls contain isoflavones, which are phytoestrogens that mimic the estradiol contained in most ear implants. Soy hulls have estrogenic activity that, when combined with implantation with estradiol can have very positive effects on weight gain and well-being of calves that graze toxic endophyte tall fescue. |
