The objective of this study was to investigate the effectiveness of early weaning fall-born calves on heifer and calf performance in Florida. Over two consecutive years, 3-yr-old Braford and Brahman x Angus first-calf heifers were assigned randomly to one of two treatments; early-weaned (EW, n = 20 and 30 for yr 1 and 2, respectively) and normal-weaned (NW, n = 20 and 38 for yr 1 and 2, respectively). Calves were EW on January 23 and 3 for yr 1 and 2, respectively. Following EW, all first-calf heifers were returned to bahiagrass (Paspalum notatum) pastures with the mature cowherd. Early-weaned calves were maintained on annual ryegrass (Lolium multiflorum) pastures at 8.2 and 10.7 calves/ha for yr 1 and 2, respectively, and were provided supplemental grain mixture (14% CP) at 1.0% of BW daily. Normal-weaned calves remained with their dams in the mature cowherd on bahiagrass. Final calf BW was collected on April 17 (d 84) and April 24 (d 111) for yr 1 and 2, respectively. Early-weaned calves had a greater (P < 0.001) ADG (0.17 kg/d) in yr 1, but a lower (P < 0.001) ADG (-0.24 kg/d) in yr 2 compared with NW calves. Early weaning resulted in heavier first-calf heifers with greater BCS at the time of normal weaning (August 1; 491 vs. 452 kg, with BCS = 6.34 vs. 4.75 for EW and NW heifers, respectively; SEM = 5.0 and 0.07). Heifers with EW calves had a higher (P < 0.07) pregnancy rate during both years than normal-weaned heifers (89.5 vs. 50.0 and 96.7 vs. 80.0% pregnant during yr 1 and 2, respectively). Early-weaned, first-calf heifers also had a lower (P < 0.05) calving interval in yr 2 (384 vs. 404 d; SEM = 6.0). These data suggest that EW will improve body condition of first-calf heifers resulting in an increased pregnancy rate. Early-weaned calves maintained on winter ryegrass provide producers with the ability to optimize early-weaned calf performance, while capitalizing on low cost of gain and favorable spring markets.
Stargrass (Cynodon nlemfuensis Vanderyst) is an important tropical forage, but the interaction of stocking rate (SR) and N fertilizer rate on stargrass pastures is not well understood. The objective was to determine the effects of three SR (2.5, 5.0, and 7.5 bulls ha−1) and three N rates (112, 224, and 336 kg ha−1 yr−1) on stargrass pasture characteristics and performance of Jamaica Red Poll (Bos taurus × B. indicus) weanling bulls at St. Ann, Jamaica. Soil was a bauxitic clay loam, and pastures were rotationally stocked (7‐d grazing and 21‐d rest period). Pregraze herbage mass increased as SR decreased (2.0‐4.8 Mg ha−1 in Year 1 and 3.3‐8.3 Mg ha−1 in Year 2). Herbage crude protein (CP) and in vitro digestible organic matter (IVDOM) generally increased with increasing SR and N rate. Bull daily gain decreased curvilinearly from 0.70 to 0.26 kg in Year 1 and 0.65 to 0.35 kg in Year 2 as SR increased from 2.5 to 7.5 head ha−1 Daily gain increased linearly as N rate increased from 112 to 336 kg ha−1 The N fertilizer rate had little effect on gain per hectare at the lowest SR, but gain increased with fertilization up to 224 kg N ha−1 for a SR of 5 head ha−1 and up to 336 kg N ha−1 for a SR of 7.5. In conclusion, economic return from N fertilization of stargrass pastures is dependent upon SR, with greater N rates more likely to be profitable if SR is high.
Tbe botanical composition of the diets of 5 esophageal-fistulated steers in summer (June to August) and winter (January to March) on a south Florida range was studied in order to point out those plants or groups of plants that warrant management. Diets of steers grazing 3 ecosystems were compared: pine palmetto (Typic and Arenic Haplaquod soils), freshwater marsh (Terric Medisaprist soil), and transition area around the marsh (Spodic Psammaquent soil). In addition we wanted to know if diets of steers regrazing a summer-grazed pasture in the winter were the same as diets from a pasture grazed only in the winter. A total of 320 diet samples were analyzed microbistologlcally, and out of 109 species, steers were found to eat 42 species. Steer diets were significantly different between summer and winter, while diets were similar on tbe regrazed-winter and winter-only pasture. Differences between summer and winter diets were mainly a decrease inPanicum hemitomon on the marsh and a decrease in Lachnanthes caroliniana in the winter diets on the pine-palmetto area, an increase in the proportion of shrubs in the winter diet on the pine-palmetto area, and an increase in Xyris spp. and Solidago jistuIosa in the latewinter on the marsh and the transition area around the pond. These diet changes were the result of changes in plant availability or palatability, which was the case with P. hemitomon. These data indicated that Andropogon spp. and Schizachyrium stoloniferum were major components of the pine-palmetto area diet of cattle and should receive management to increase their yields. Forbs, though seasonally available, should be encouraged by shrub control, careful use of selective herbicides, and promotion of natural reseeding. Shrubs, especially Serenoa repens and Ilex &bra should be available as winter foods. Florida's southern range is primarily a flatwoods site, which is a broad flat area interspersed with 1 to IO-ha saucer-shaped depressions which form freshwater marshes or maidencane (see Table 2 for Latin binomials) ponds. Hilmon (1964) described southern Florida rangeland and its vegetation, and indicated that the pinepalmetto ecological type comprised 75% of the range, and the fresh-marsh type made-up 15% of the range. The remaining 10% was in wet-prairie, which is a transition between pine-palmetto and fresh water marsh. As an important part of the total pasture system, range is frequently interfaced with improved pastures, and most ranching operations use range in the winter as a source of roughage for dry-pregnant cows (Kalmbacher 1978). Unlike most cultivated pastures where 1 or 2 forages are grazed, range pastures often have over 100 indigenous plants from which livestock can select. Many range plants are available seasonally and others, while available throughout the year, are only eaten seasonally. Ranchers need to know which species cattle select in order to determine supplementation needs, make best use of different pastures, and manage important plants. A review of literature pertaining to botanical .comp...
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