No abstract

Grazing trials were conducted for 2 yr using weanling Brahman crossbred beef steers to evaluate graded levels of salinomycin (0, 50, 100 or 150 mg. head-1.d-1) for 161 d and to evaluate salinomycin in a free-choice mineral supplement (99 d). The 40 and 48 steers in trials 1 and 2 had average initial weights of 198 and 285 kg, respectively. In trial 1, steers were group-fed to consume either 0, 50, 100 or 150 mg of salinomycin.head-1.d-1 in .9 kg ground corn while grazing bermudagrass pastures. Both linear (P less than .01) and quadratic (P less than .05) effects were observed for steer performance as salinomycin level increased from 0 to 150 mg.head-1.d-1. Linear increases (P less than .01) in ruminal NH3-N (mg/100 ml) and in the molar proportion of propionate and decreases (P less than .01) in butyrate and acetate/propionate were detected. In trial 2, mineral supplements with and without salinomycin were fed free-choice to steers on bermudagrass pasture. The mean salinomycin intake of 38 mg.head-1.d-1 was lower than anticipated as a result of the instability of salinomycin in the mineral supplement and the slightly lower intake (65 g/d) than anticipated (75 g/d). Performance of steers was not influenced by salinomycin supplementation in trial 2. The ionophore salinomycin at intakes over 50 mg.head-1.d-1 appears to increase the performance of steers grazing bermudagrass pasture.

Cool‐season annuals can be used to extend the grazing season in the South and provide a high quality forage for grazing animals. Objectives of this study were to evaluate various forage mixtures for animal performance, grazing days, and carrying capacity. Four cool‐season annual forage mixtures planted in a prepared seedbed were grazed by weanling beef steers during a 4‐yr study. Forage mixtures included (i) rye (Secale cereale L.)‐ryegrass (Lolium multiflorum Lam.)‐arrowleaf clover {Trifolium vesiculosum Savi.), (ii) rye‐ryegrass‐ladino clover (Trifolium repens L.), (iii) ryegrass‐arrrowleaf clover and (iv) ryegrass plus N fertilizer. The grazing season was generally from mid‐November to mid‐May. Forage mixtures containing rye allowed more animal grazing days during December and January, a period when forage is usually most limiting, and allowed more (P < 0.05) total grazing days (157 vs. 149 d) but produced fewer grazing days in April and May than ryegrass pastures. Daily gains of steers ranged from 2.05 (ryegrass) to 2.21 lb/d (ryegrass‐ladino clover). Beef production/acre averaged 505 lb/acre with cost of gain ranging from $0.32 to $0.36/lb. Rye and clover were beneficial to forage mixtures for enhancing forage availability and animal gains, respectively.

No abstract

Fall sodseeding of annual forages into perennial warm‐season pastures offers a practical method of extending the grazing season and improving forage quality. A 2‐yr study evaluating the effect of sodseeding method and ryegrass‐clo‐ver mixtures on forage production, animal performance, and economics of sodseeded winter pastures for growing beef animals was conducted. Forage mixtures of either annual ryegrass (Lolium multiflorum Lam.)‐white clover (Trifolium repens L.) (R‐W) or ryegrass‐white clover‐crimson clover (Trifolium incarnatum L.) (R‐W‐C) were sodseeded into common bermudagrass [Cynodon dactylon (L.) Pers.] pastures in the fall by (i) drilling into the sod using a conventional grain drill equipped with a small seed attachment (Drill), or (ii) lightly disking (less than 1 in. deep) before broadcast seeding followed by lightly disking and harrowing (Broadcast). Pastures were grazed with weanling calves beginning in late November in Year 1 and late December in Year 2 through May. Sodseeding method had no effect on total yield. The addition of crimson clover into the mixture increased total forage production (P=0.10), monthly clover percentage (P<0.05) during February, March, and April, and animal grazing days (P<0.05) during April. Animal gains and beef production per acre were not affected by either sodseeding method or mixture averaging 2.15 lb/head/d and 460 lb beef/acre. Economic analysis showed the highest net returns for drilling R‐W mixtures ($93/acre). Bermudagrass hay production following the grazing season was similar for both sodseeding methods and both mixtures. The results of this study suggest that the easiest or least expensive method for fall sodseeding should be considered.