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Vulpia species C.C. Gmel. are annual grass weeds that can reduce the productivity of perennial pastures throughout southern Australia. To develop more effective strategies to manage vulpia, a 3-year experiment was established in western Victoria (average annual rainfall: 625 mm) comparing different methods currently used to control this weed. Overdrilling perennial ryegrass (Lolium perenne L.) seed and simazine application treatments were applied to phalaris (Phalaris aquatica L.) pastures that were set-stocked or rotationally grazed (either as a four-paddock or strategic rotation) with Merino ewes. The content of vulpia, subterranean clover (Trifolium subterraneum L.) and other annual grasses as a proportion of total dry matter increased, and the proportion of phalaris decreased in most grazing treatments throughout the experiment. The mean vulpia content was lowest and the phalaris content was highest in the four-paddock rotation, whereas vulpia content was greatest and phalaris content was lowest under set-stocking. Simazine application in June with or without ryegrass overdrilling reduced the number of vulpia tillers/m2 in 2000 and 2001 and vulpia panicle production in 2000, although vulpia populations increased to pretreatment levels in herbicide-treated swards by 2002. The number of vulpia seeds in the soil seed bank was not affected by any of the treatments. The most effective treatment was a combination of ryegrass overdrilling and herbicide application in the four-paddock, rotationally grazed pastures. This experiment highlights the need for an integrated approach to manage vulpia since relying on herbicide application alone is ineffective. This is particularly the case when competitive pasture species are unable to adequately utilise available resources and prevent a recovery in vulpia populations. [ABSTRACT FROM AUTHOR]

Dark-cutting in muscles of the beef carcass is due to low muscle glycogen levels at slaughter and occurs particularly in autumn and winter in grass-fed cattle in southern Australia. The aim of these experiments was to investigate the effect of supplementary feeding of cattle grazing pasture during winter on muscle glycogen levels. The first experiment involved 70 cattle allocated to two stocking rates grazing improved perennial ryegrass and subterranean clover pastures [high stocking rate (HSR) v. low stocking rate (LSR)] by two pasture feeding regimes (control, pasture only v. pasture supplemented with a high-energy ration for 4 weeks) plus a feedlot treatment (fed high-energy ration in pens with no pasture for 11 weeks). Muscle biopsies were collected from the M. semitendinosus (ST) and M. semimembranosus (SM) muscles and analysed for muscle glycogen. The ST muscle glycogen content for supplemented animals increased (P 0.05) of supplementation on the muscle glycogen content of the SM or on the muscle glycogen content of the ST or SM of cattle in the feedlot treatment, relative to control cattle. HSR cattle tended to have lower muscle glycogen in the ST compared to LSR cattle across both feeding regimes. The second experiment used 60 cattle allocated to two treatments (control, pasture only v. pasture supplemented with a high-energy ration for 3 weeks). The treatments were applied to cattle grazing improved perennial ryegrass and subterranean clover pastures and muscle biopsies were collected weekly from the SM and ST. Supplementation resulted in a linear increase (P < 0.05) in muscle glycogen levels over the 3 weeks in both the SM and ST muscles. These results indicate that feed quality has a major impact on muscle glycogen levels in the SM and ST of cattle destined for slaughter. At times of the year when pasture quality is poor or quantity is lacking, supplementation with a high-energy supplement has the potential to dramatically increase muscle glycogen and reduce the incidence of dark-cutting beef. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the effect of genotype and age at slaughter (8, 14 and 22 months) on the retail display life of lamb chops [boneless loin (M. longissimus thoracis) and boneless leg steaks from the knuckle (M. rectus femoris)]. The genotypes represented were Poll Dorset Border Leicester Merino, Poll Dorset Merino, Merino Merino (M M) and Border Leicester Merino. The colour and retail shelf-life of lamb cuts were assessed objectively, using a HunterLab Miniscan, at 24 h postslaughter and at 0, 2 (midpoint of commercial retail display life) and 4 (endpoint of commercial retail display life) days for overwrapped product in a simulated retail display. M M had a higher ultimate pH (pHu) in the knuckle, but not the loin, at 8, 14 and 22 months of age relative to the other three genotypes. Generally, at 1 day postslaughter and over the 4 days of retail display, the loin from the M M genotype was lighter, less red and more brown with a lower oxymyoglobin:metmyoglobin (oxy:met) ratio, a faster time to discolouration and a higher percentage change in the oxy:met ratio during retail display. Conversely for the knuckle, the M M genotype was generally less brown (more red) and less yellow with a higher oxy:met ratio, a slower time to discolouration and a lower percentage change in the oxy:met ratio. There were few differences between the other genotypes in surface meat colour either at 1 day postslaughter or during retail display for either muscle. At 14 and 22 months of age, the loin was darker, redder and yellower with a higher oxy:met ratio relative to the previous age than meat from the 8- and 14-month-old sheep, respectively. In conclusion, the loin from Merinos was most susceptible to discolouration in retail display and thus would be least acceptable to the consumer. In spite of the higher pHu in the knuckle of the Merino genotype, the meat was less susceptible to discolouration during retail display compared with the other genotypes. [ABSTRACT FROM AUTHOR]

Eleven windbreaks (Monterey cypress, Monterey pine, tuart, sugar gum, black wattle and mixed native species) were studied in south-west Victoria. Windrun (U) was measured with cup anemometers set above ground (Z) at 1.5 m and 0.5 m (eight windbreaks), 1.5 m (two windbreaks), or 0.5 and 0.25 m (0.95 m mesh). The U pattern (U/U0, where U0 is open windspeed) was: (1) to windward, a shelter effect to at least ?3 H, (where H means windbreak height) with a reduction of 20% or more at ?1 H and (2) to lee, Xmin (position of minimum windspeed, Umin) from 1?7 H; Umin (minimum U/Uo) varied with windbreak density; and XS (distance where U/U0 is <0.8) varied from 8?25 H. Optical porosity (?O) was 0.16?0.53 compared with 0.24?0.61 for aerodynamic porosity (?A), obtained from the ratio of Umin and U0. ?A from present data and calculated for windbreaks of previous studies, showed a curvilinear effect of windbreak porosity (?A, %) on Xmin, but little effect on XS: Xmin (H) = 3.008Ln?A ? 6.6 (adjusted r2 = 0.33, P < 0.0001, r.s.d. = 1.8); XS (H) = 12.2+ 0.307?A ? 0.0047?A2 (adjusted r2 = 0.07, P < 0.08, r.s.d. = 4.1). Effective shelter is best obtained by establishing tall, dense windbreaks and excluding browsing livestock. [ABSTRACT FROM AUTHOR]