Efficacy of Endo-Fighter® for Cattle Grazing Endophyte-Infected Tall Fescue Pastures During Summer and Early Fall

Two 84-day grazing trials were conducted (Aug 24 – Nov 17, 2006; Jun 14 - Sept 7, 2007) near Spring Hill, TN to determine the efficacy of Endo-Fighter (R), an ADM Alliance Nutrition, Inc. product designed to be fed to cattle grazing or fed endophyte-infected fescue or hay and Prototype, an improved version of Endo-Fighter (R). Tall fescue pastures with >90% of pasture exhibiting infestation (E+), thus producing high concentration of ergot alkaloids in the grass, were grazed.

In 2006 sixty weaned crossbred heifers (325 ± 17 kg) (2007, steers, 267 ± 18 kg) were used in a randomized block design (2007, CRD), blocked by previous treatment and randomly allotted to pastures with four animals per 1.2-ha paddocks and five replications per treatment. Treatments were ADM Alliance Nutrition, Inc. mineral products: 1) Mastergain (R) mineral = Control; 2) Endo-Fighter (R) mineral; 3) Prototype mineral. Animals had free choice access to E+ grass, water and shade.

Heifers were weighed on d 0, 1, 28, 56, 83, and 84 (2006) and on d 0, 1, 22, 43, 64, and 85 (2007). In 2006 data collected were initial, d 28, d 56, and final weights, and ADG. In 2007 data collected were initial, d 22, d 43, d 64, and final weights, and ADG for each period. Blood serum was collected at each weigh date for prolactin analysis. Mineral consumption and animal grazing behavior were determined at 14-d intervals. Data were analyzed using the MIXED procedure of SAS. For all variables, contrasts were performed to compare Control to mineral supplements containing Endo-Fighter (R) or Prototype.

In 2006 total ADG (kg) and average daily mineral consumption (g) were: 0.61, 170*; 0.56, 122*; 0.50, 146; for Control, Endo-Fighter (R) and Prototype, respectively (*P < .09). In 2007 data were 0.61, 134; 0.57, 147; 0.56, 116; for Control, Endo-Fighter (R), and Prototype, respectively. For both years, serum prolactin was not different (P > 0.05) among treatments. Animal performance and prolactin levels were not significantly affected by the feeding of Endo-Fighter (R) or Prototype in these trials. However, lack of response to Endo-Fighter (R) and Prototype in 2006 may have been attributed to mild weather conditions. In 2007 lack of response may have been a result of extreme heat and drought conditions.