Abstract:
Proc. Aust. Soc. Anim. Prod. Vol. 16 THE INFLUENCE OF DIETARY PROTEIN AND ENERGY INTAKES ON OVARIAN DEVELOPMENT IN PREPUBERTAL BRAHMAN CROSS HEIFERS F.M.N. AKARRO*, K.W. ENTWISTLE* and R.D. RANDEL** Little information is available on the dietary components influencing bovine ovarian development in the prepubertal period. The effects of protein (P) and energy (E) levels (High - H; Low - L) on ovarian development in prepubertal (14-16 mth) Brahman cross heifers were examined in a 2 x 2 factorial experiment (n=12/cell) after either six or twelve weeks of treatment. At both times, H levels of either P or E significantly (*P x0.05) stimulated ovarian development with L levels: Characteristic Protein level Energy level H L H L 2.42 Follicular fluid 6 wk 1.84* 1.95* 2.54 12 wk 2.23* 2.41* 3.07 2.89 wt. (9) Diameter largest 6 wk 10.1 6.7 * 10.6 6.1 * Follicle (mm) 1.2 wk 10.8 9.7 * 10.3 10.1 No. follicles >6 mm 6 wk 0.5 * 1.75 1.9 0.65* 12 wk 2.1 1.8 2.5 1.4 * The incidence of atretic follicles was also significantly higher in L P and E groups (25%; 50%) than in the corresponding H groups (18%; 7%). Three of four heifers which had ovulated by 12 weeks were from HP groups. Both P and E levels influenced prepubertal ovarian development and changes occurred within six weeks of commencing treatment. * Graduate School of Tropical Veterinary Science, James Cook University, Townsville Qld 4811. ** Texas A 6r M University, Texas Agric. Expt. Stn, Overton, Texas. CONTROL OF WIREGRASS (ARISTIDA RAMOSA) BY GRAZING MANAGEMENT K. A. ARCHER* and G.M. LODGE* Wiregrass is a poor quality native grass whose seed carcases. A grazing strategy to control wiregrass and to species such as Danthonia has been developed which matches season of grazing to their reproductive cycles (Lodge and effects of this system on livestock and pasture production farmlets. contaminates wool and encourage valuable the intensity and Whalley 1985). The are being studied in Treated plots are heavily grazed over summer and autumn at a rate of 12.5 sheep/ha and are then rested in winter by transferring the sheep to the remainder of the farmlet. The overall stocking rate is 5 sheep/ha, the same as that in the continuously grazed control plots. After two years of heavy summer grazing the mean dry matter yield of wiregrass was 410 kg/ha compared with over 5,000 kg/ha for the control plots. In the high summer stocking treatment liveweight declined by 8 kg/head and greasy wool production decreased by 1.2 kg/head compared to the control. Strategic grazing management can be used to control wiregrass within a farmlet system. The production losses would be offset against benefits of reduced vegetable fault and future higher stocking rates. Modified strategies using burning or supplementary feeding are being studied to reduce these losses. LODGE, G.M. and WHALLEY, R.D.B. (1985). Aust. Rangel. J. 7: 6. = Dept of Agriculture, N.S.W. Agricultural Research Centre, Tamworth, N.S.W. 2340. 403