Poor animal performance on tall fescue (Festuca arundinacea Schreb.) pasture may be associated with toxic products produced by the fungal endophyte Acremonium coenophialum Morgan‐Jones and Gams (previously identified and referred to as Epichloe typhina (Fries) Tulasne). The object of this study was to determine steer performance on ‘Kentucky 31’ tall fescue pastures which were either heavily infested or relatively free of the fungal endophyte. Replicated 1.2 ha paddocks were located in west central Alabama on three soils, Sumter clay (fine silty, carbonatic, thermic Rendolic Eutrochrept), Houston clay (very fine montmorillonitic, thermic Typic Chromudert), and Eutaw clay (very fine, montmorillonitic, thermic Entic Pelluderts). They were fertilized annually with 224 kg N ha−1 and grazed with yearling steers. The grazing season during the 4‐year period averaged from 23 October to 24 December and 26 February to 16 June. Tall fescue, averaging 94% of plants fungus infested, produced 768 animal days ha−1 and produced 384 kg beef ha−1 with an average daily gain (ADG) of 0.50 kg. Tall fescue with less than 5% of plants infested produced 593 animal days ha−1 and produced 492 kg beef ha−1, with an ADG of 0.83 kg. Rectal temperatures were 0.8 °C higher and hair coats much rougher on steers which grazed fungus‐infected grass rather than grass free of the fungus. Results of the study furnish further evidence that the fungal endophyte, A. coenophialum, is associated with low performance of steers on tall fescue pasture. In the absence of the fungal endophyte, ADG of steers on tall fescue is high and similar to that on small grain pastures.

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Anti‐quality components factors associated with poor animal performance on tall fescue (Festuca arundinacea Schreb.) pasture may include mycotoxins produced by the fungus Epichloe typhina (Pers.) Tul. The original objectives of this study were to compare steer performance on pastures of different grass species, but large differences in animal performance occurred among paddocks in different replications of the tall fescue‐dallisgrass (Paspalum dilatatum Poir.) treatment. The experiment was conducted in west central Alabama on replicated 1.2 ha paddocks containing two calcareous soils, Sumter clay (Rendolic Eutrochrept, fine silty, carbonatic, thermic) and Houston clay (Typic Chromudert, very fine montmorillonitic, thermic). The tall fescue‐dalligrass pastures were fertilized with 336 kg N/ha annually and grazed with yearling steers for 225 days annually for 3 years. The three tall fescue‐dallisgrass paddocks contained very little dallisgrass, but animal performance differed greatly on them. Steers averaged 453 kg gain/ha on two paddocks with an average daily gain (ADG) of 0.68 kg, while steers on the other paddock averaged only 360 kg gain/ha with an ADG of 0.45 over the 3‐year period. Dry matter digestibility of the forage averaged 63% for the high performance paddocks and 58% for the low performance paddock. Mineral content of the forage was similar on all paddocks. Tall fescue forage in the low performance paddock was heavily infested with Epichloe typhina fungus while the other two paddocks were lightly infested with the fungus. Results of the study suggest that this fungus may be associated with low performance of steers on tall fescue pasture.

This study investigated the effects of advancing stage of maturity and additive treatment on the fermentation characteristics of three common grassland species. Perennial ryegrass (PRG; Lolium perenne L., var. Gandalf), timothy (Phleum pratense L., var. Erecta) and red clover (Trifolium pratense L., var. Merviot) were harvested at three dates in the primary growth (11 May, 8 June and 6 July; Harvests 1–3) and ensiled with the following additive treatments: (1) control (i.e. no treatment), (2) formic acid‐based additive, (3) homofermentative lactic acid bacterial (LAB) inoculant and (4) heterofermentative LAB inoculant. Additive application to the PRG (irrespective of harvest date), the late‐harvest timothy (Harvest 3) and the red clover (Harvests 2 and 3) herbages had little impact on silage fermentation characteristics, where a lactic acid dominant fermentation already prevailed. However, the application of the formic acid‐based additive to the Harvest 1 and 2 timothy and Harvest 1 red clover herbages, where the silage fermentation characteristics were poorer, resulted in an increase in the proportion of lactic acid in total fermentation products and a decrease in pH. In contrast, the heterofermentative LAB inoculant had a negative impact on silage fermentation characteristics where a poor preservation prevailed in the corresponding control silage.