Steer Performance in Fescue‐Clover Pastures with Different Levels of Endophyte Infestation

Abstract

A 3‐yr study was conducted at Ames Plantation, Grand Junction, TN to determine the effects of fungal endophyte (Acremonium conenophialum Morgan‐Jones & Gams) infestation (E+) levels in ‘Kentucky 31’ tall fescue (Festuca arundinacea Schreb.) pastures on steer (Bos taurus L.) performance. Two replications were used of 1.2‐ha pastures overseeded yearly with ladino white clover (Trifolium repens L.) on a fine‐silty, mixed, thermic Typic Hapludalf soil. Yearling tester steers (three per pasture) and additional steers of similar size maintained available forage at heights of 2.5 to 7.5 an. Botanical composition, available forage, average daily gain (ADG), grazing days, and gain per hectare were determined every 21 d; serum prolactin, haircoat roughness, rectal temperatures, and E+ levels were measured at longer intervals. Results were computed using a generalized linear mixed models procedure. Generalized least squares means and standard errors for the broad inference space were estimated (BLUE) and differences for specific linear contrasts were predicted (BLUP). Steer ADG was depressed from over 800 to about 450 g in spring and from about 700 to 400 g during the entire grazing season as A. coenophialum increased from 3 to 81%. Animal grazing days were not different among treatments. Gain was about 65 kg ha−1 more with 22% E+ (379 kg ha−1) than at higher endophyte levels, but it was almost 500 kg ha−1 at 3% E+. Serum prolactin (125 ng mL−1 in steers grazing 3% E+) was halved with 22% E+ and was depressed further at higher E+ levels (41 to 18 ng mL−1). Results suggested that the effect of the endophyte on animal performance in tall fescue‐clover pastures is not linear, with greater depression per unit infestation at lower levels than at higher levels.

Biochanin A (an Isoflavone Produced by Red Clover) Promotes Weight Gain of Steers Grazed in Mixed Grass Pastures and Fed Dried‐Distillers’ Grains

“…To verify that the tall fescue remained endophyte free, single tillers were collected on 10 June from 25 randomly chosen plants within each pasture to determine the ergovaline concentrations. Averaged over pastures, the ergovaline concentrations were negligible (0.06 ± 0.03 mg g −1 DM) and posed no potential effect on animal performance from fescue toxicosis (Fribourg et al, 1991). Tillers were placed in ice and subsequently freeze dried in a Botanique Model 18DX48SA freeze drier (Botanique Preservation Co., Peoria, AZ), ground through a 1-mm screen, and assayed for ergovaline by high-performance liquid chromatography with fluorescence detection, using a modification of the procedure of Yates and Powell (1988) as described by Carter et al (2010).…”

“…Tillers were placed in ice and subsequently freeze dried in a Botanique Model 18DX48SA freeze drier (Botanique Preservation Co., Peoria, AZ), ground through a 1-mm screen, and assayed for ergovaline by high-performance liquid chromatography with fluorescence detection, using a modification of the procedure of Yates and Powell (1988) as described by Carter et al (2010). Averaged over pastures, the ergovaline concentrations were negligible (0.06 ± 0.03 mg g −1 DM) and posed no potential effect on animal performance from fescue toxicosis (Fribourg et al, 1991).…”

Journal of Range Management, Volume 53, Number 4 (July 2000)

“…Other alkaloids detected were isolysergic acid amide, 8-hydroxylysergic acid amide, ergonovine, chanoclavine-1, and Nformylloline. We suspect that the endophyte or its associated alkaloids may be responsible for avoidance of robust needlegrass, based on findings with other grasses (Garner and Cornell 1987, Fribourg et al 1991, Miles et al 1996. Kaiser et al (1996) isolated N e o t y p h o d i u m from robust needlegrass seed collected from 10 New Mexico and Colorado populations.…”

“…Steers preferred clover in mixed E+ tall fescue (Festuca arundin a c e a Schreb. )/white clover (T r i f o l i u m repens L.) pastures, but they preferred Etall fescue in mixed E-tall fescue/white clover pastures (Fribourg et al 1991). Eleven of 12 heifers avoided diets with 60% E+ tall fescue seed in favor of diets with 60% E-tall fescue seed (Garner and Cornell 1987).…”

Endophyte Infected Tall Fescue and Small Ruminant Production: Do We Have a Problem?

“…1) that produces ergot alkaloids, which can cause fescue toxicosis in cattle (2,3,5,6,28,29,34). Symptoms of the malady are reduced prolactin concentrations, elevated body core temperature, and a reduction in feed intake, weight gain, pregnancy, and calving rates (4,16,20,26,33,38). Fescue toxicity has been estimated to cost the United States beef industry $800 million in annual losses (37).…”