Livestock responses to winter pasture, bermudagrass pasture, and confinement feedin

This study compared the effects of winter pasture, summer pasture and confinement feeding on livestock production and livestock carcass parameters. Winter pastures consisted of Gulf ryegrass (GR) and/or Yuchi arrowleaf clover (AC) on clean-tilled seedbeds (CT) and overseeded on bermudagrass (SS). Fertility consisted of 112 kg ha$sp{-1}$ of nitrogen split in two equal applications for ryegrass alone while pastures of clover received 56 kg ha$sp{-1}$ of P$sb2$O$sb5$. Summer pastures consisted of bermudagrass alone (Ber) and bermudagrass that had been overseeded with Gulf ryegrass and/or Yuchi arrowleaf clover (SS). Ber and bermudagrass that had been overseeded with ryegrass received 224 kg ha$sp{-1}$ of nitrogen while pastures that had been overseeded with clover received no nitrogen fertilizer. All pastures were 0.4 hectare in size. Each treatment was replicated twice. Confinement feeding consisted of 56 and 84 days in 1983 and 89 days in 1985. Forage available to grazing animals was estimated from 10 height measurements and density estimates correlated with three 0.3m$sp{-2}$ hand harvested samples from each pasture every 14 days from 8 December 1982 until 17 October 1983 and from 23 January 1985 until 8 October 1985. In Vitro dry matter digestibility (IVDMD) was determined on hand harvested samples. Livestock were weighed every 28 days during each year.;Forage available for grazing was well correlated with ADG (r = 0.77) during the December-March portion of winter pasture when growth was limited and IVDMD was high. When rapid growth began in April, correlations of forage availability and ADG decreased and remained low throughout the summer pasture phase. CT treatments had higher ADG than SS treatments as a result of the residual bermudagrass causing a $>$50% reduction in usable forage on SS treatments. Nitrogen fertilized treatments in both winter pasture and summer pasture had consistently higher forage available to the grazing animal and tended to have higher ADG.;Carcass data indicated no significant differences in yield grade or fat color. The feedlot cattle had significantly higher fat thickness and quality grade than either the winter pasture or bermudagrass pasture cattle. Liveweight gain ranked feedlot $>$ winter pasture $>$ bermuda pasture with 88.8, 85.5, and 77.5 kg ha$sp{-1}$, respectively. Energy gain for treatment groups ranked feedlot $>$ bermudagrass pasture $>$ winter pasture with 236.5, 199.0, and 186.8 Mcal ha$sp{-1}$, respectively.