Stocker cattle (Bos spp. L.) performance has been adversely affected on tall fescue (Festuca arundinacea Schreb.) pasture infected with the endophyte (Acremonium coenophialum Morgan‐Jones and Gams). Grazing results, however, cannot be completely evaluated until the carryover effects on the animal are evaluated through the feedlot phase to the final product, the carcass. In this study 60 Angus (B. taurus L.), Brahman (B. indicus L.)‐Angus, Angus × Braham‐Angus, and Simmental (B. taurus L.) × Brahman‐Angus, 12‐ to 19‐mo‐old steers in 1987, and 54 in 1988, were used to study effects of grazing ‘Kentucky 31’ tall fescue on subsequent feedlot performance. Steers had been grazing fescue pastures from November to May. The pasture treatments were: (i) high endophyte (HE) with 76% infected fescue; (ii) HE with 74% infected fescue interseeded with a mixture of clovers (HE + Clo); and (iii) low endophyte (LE) with 0.7% infected fescue. Steers were removed from these pastures in eastern Oklahoma on 21 May, held for 6 d on bermudagrass [Cynodon dactylon (L.) Pers.]‐ryegrass (Lolium multiflorum Lam.) pastures and shipped 450 mi to a feedlot in western Oklahoma. Steers were then fed for 117 or 113 d (years 1987 and 1988, respectively) and slaughtered. No treatment × year interaction was noted and data were pooled across years. The HE steers weighed 101 lb less than LE steers at the end of grazing, but HE steers gained 66 lb more during the feedlot phase than LE steers. The HE steers gained faster during the 6‐d holding period, tended to lose less weight in transit to the feedlot, and gained faster during the first 48 or 49 d (years 1987 and 1988, respectively) in the feedlot. Steers which had been grazing HE + Clo pastures gained similarly to LE steers in the feedlot. The HE + Clo steers had heavier final body and carcass weights than LE steers because of slightly greater gains on pasture and in the feedlot, plus greater gains during the 6‐d holding period. Rectal temperature was higher for HE than for LE at the end of fescue grazing and after the 6‐d holding period. Temperatures of steers that grazed HE + Clo were intermediate. No differences in rectal temperatures were noted the morning following arrival at the feedlot. Carcass weights were lighter and quality grade tended to be lower for HE steers. These results suggest that steers showing clinical signs of fescue toxicosis can compensate for up to 67% of the reduced gains resulting from grazing fescue.
The tall fescue (Festuca arundinacea Schreb.) endophyte (Acremonium coenophialum Morgan‐Jones and Gams) has been associated with poor stocker cattle (Bos spp. L.) performance, but more information about management techniques using clover (Trifolium sp.) in pastures and the effect of cattle breed may help managers reduce the losses associated with the endophyte. This 3‐yr grazing study from early November to late May each year with yearling steers on ‘Kentucky 31’ tall fescue pasture evaluated the pasture effects of: (i) high endophyte (HE) with 76% infected fescue, (ii) HE with 74% infected fescue interseeded with a mixture of clovers (HE + Clo), and (iii) low endophyte (LE) with 0.7% infected fescue. A total of 173 Angus (AN) (B. taunts L.), Brahman (B. indicus L.)‐Angus (BA), and Simmental (B. taurus L.) × Brahman‐Angus (S × BA) 7‐ to 12‐mo old steers were used to study effects of grazing tall fescue on weight gains and rectal temperatures. Steers of all three breeds gained significantly faster on HE + Clo and LE pastures than on HE pastures. The interaction of fescue pasture treatment × breed for steer gain, however, was significant for the 196‐d grazing season because the BA steers gained faster than AN steers on all three pasture treatments. The BA steers gained 0.62, 0.48, and 0.19 lb/d more than the AN steers on HE, HE + Clo, and LE, respectively. The greatest reduction in steer gain for the HE pastures occurred from mid‐March to late May. Rectal temperature was affected only in late May with a significant pasture treatment × breed interaction. Rectal temperature of BA steers was not affected by the endophyte while temperatures for the AN and S × BA steers were higher for HE pastures than for LE pastures with the temperatures of HE + Clo pasture steers intermediate. These results suggest that clover in HE fescue can help overcome the detrimental effects of the endophyte and that cattle differ in ability to tolerate the toxic effects of the endophyte.
Yield responses by native range to fertilization has often been disappointing in the tall grass prairie, and the results were confounded by changes in species composition. This study evaluated the response to N and P fertilizer by monocultures of three native species ‘Kaw’ big bluestem (Andropogun gerardi Vitman), ‘Caddo’ switchgrass (Panicum virgatum L.), and indiangrass [Sorghastrum nutans (L.) Nash] and an introduced grass, weeping lovegrass [Eragrostis curvula (Shrad.) Ness]. Rates of N fertilizer were 0, 45, 90, and 180 kg/ha in all combinations with P at 0 and 40 kg/ha. Forage production, crude protein, fertilizer N recovery, stand longevity, and soil fertility changes were evaluated. Excellent forage yield responses to N fertilization were obtained from the native species in monoculture. Switchgrass and weeping lovegrass were the most productive species at 180 kg N − 40 kg P/ha, but had different seasonal production. All native grasses produced one flush of growth and very limited regrowth when compared with weeping lovegrass. Indiangrass had significant reductions in stand at 90 kg N and 180 kg N/ha and was the first species each year to show visual symptoms of drought stress. Severe lodging of big bluestem at 180 kg N/ha limited its potential. Fertilizer N recovery of all species was most efficient at the 90 kg N − 40 kg P/ha treatment being 52 to 66% for native grasses and 84% for weeping lovegrass. Soil tests revealed P accumulations with P fertilization, decreased soil pH associated with N fertilizer and soil K changes in relation to forage removal. The native species have some characteristics which limit their potential for use in fertilized meadows.
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