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Morphological and chemical characteristics of 11 warm season pasture weed species were defined. Goldenrod (Solidago altissima L.) was significantly taller and common ragweed (Ambrosia artemisiifolia L.) had the largest canopy diameter of the 11 species studied. Species ranged from 14 to 134 cm in height with canopy diameters of 25 to 70 cm. No direct correlation was found between individual leaf size and total leaf area. Macro- and micromineral content varied widely among species but all values obtained were considered high enough to meet the requirements of ruminant animals. Redroot pigweed (Amaranthus retroflexus L.) and horsenettle (Solanum carolinense L.) contained potentially toxic levels of nitrate. Five of the 11 species contained sufficient crude protein for ruminants and six of the 11 species were more than 50% digestible. Digestible energy values averaged 1.9 Mcal/kg for the 11 weeds evaluated.

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.

Information on pasture productivity and forage quality of various adapted species and combinations that support rapid animal gains is needed for successfully backgrounding yearling steers in the humid southeastern USA prior to feedlot placement. To evaluate productivity and quality of pasture combinations for growing beef steers, a grazing experiment was conducted near Memphis, Tenn., in 1975 to 1977 on a Typic Hapludalf. The 1.2 ha pastures were Midland (Cynodon dactylon (L.) Pers.) + (Trifolium repens L.) clover, Midland + N, 1/3 Midland + N plus 2/3 fescue (Festuca arundinacea Schreb.) + N in separate pastures, Midland overseeded with fescue + N, common (C. dactylon var. dactylon) + N, fescue + clover, and orchardgrass (Dactylis glomerata L.) + clover (OG + clo). Nitrogen was applied at 224 kg ha−1 y−1 on bermudagrass and at 67 kg ha−1 y−1 on fescue. Pastures were grazed using a modified put−and−take system maintaining orchardgrass at 7 to 14 cm high and the other grasses at 5 to 8 cm. Forage growth and consumption were determined by the cage−and−strip method. Yearling steers weighing 230 kg in the spring grazed 123 to 150 days; they were weighed at 21−day intervals and visual estimates of species composition were made at that time. Forage yield was 8.3 t/ha for Midland + fescue and ranged between 4.0 and 5.7 t/ha for the other treatments. Estimated forage consumption was 80% or more of the forage growth. Forage crude protein (122 to 152 g/kg) was sufficient for meeting the minimum requirements for growing 250− to 300−kg steers. Stocking rates were between 4 and 6 steers/ha. Average daily gains were about 475 to 575 g for all treatments, except for OG + clo (825 g/day). Pasture productivity ranged between 520 animal grazing days/ha for OG + clo to 1190 for Midland + fescue. The productivity of the other pastures was between 730 and 880 grazing days/ha. Daily forage dry matter (DM) intake was 5 to 7 kg/steer. Steers grazing OG + clo, fescue + clover, and Midland + N pastures had feed efficiencies of about 9 kg DM/kg gain; steers on the other treatments required 11 to 13 kg DM/ kg gain. Beef production was 321, 339, 375, 400, 416, 424, and 593 kg/ha for fescue + clover, common + N, 1/3 Midland − 2/3 fescue, Midland + clover, OG + clo, Midland + N, and Midland + fescue, respectively.

Performance of cattle grazing tall fescue (Festuca arundinacea Schreb.) is depressed when the grass is infested (E+) with the endophytic fungus Acremonium coenophialum Morgan‐Jones and Gams. Steer performance can be improved when clover (Trifolium spp. L.) is overseeded into tall fescue pastures, and beef production/acre can be increased when bermudagrass [Cynodon dactlyon (L.) Pers.] is grown in combination with tall fescue. The objective of this study was to compare effects on steer performance of including ladino clover (T. repens L.), ‘Midland’ bermudagrass, or a combination of both in E+ and noninfested (E−) tall fescue pastures. Three tester steers (Bos taurus L.) per pasture grazed between April and September from 1983 through 1985. Additional cattle were used in a modified put‐and‐take management system to maintain similar quantity and quality of forage among pastures. Forage growth and consumption were measured by cage‐and‐strip methodology. Pastures with bermudagrass treatments averaged 18 and 53% bermudagrass in spring and summer, respectively. Clover content of pastures overseeded with clover was variable among treatment combinations and years and ranged from 6 to 53%. Greater average daily gains (ADG), beef production per acre, and forage dry matter consumption, and lower rectal temperatures and hair coat scores, were observed when cattle grazed E− rather than E+ tall fescue. Steer ADG was higher on E+ pastures when bermudagrass was present. Clover was equally effective in increasing ADG on E+ and E − tall fescue pastures. Bermudagrass and clover were both effective in improving steer performance and/or production on both E+ and E− tall fescue. Additionally, bermudagrass reduced somewhat the detrimental effects of E+ tall fescue.