• Asian-Australasian Journal of Animal Sciences
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• v.16 no.7
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• pp.968-978
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• 2003

The effects of monensin, Tween 80 and exogenous fibrolytic enzymes on ruminal fermentation and animal performance were studied in vitro and in vivo. In Expt 1, the effects of the surfactant Tween 80 (0.2% wt/wt, DM basis) on ruminal fermentation of alfalfa, corn and orchardgrass silages were investigated using in vitro gas production techniques. Tween 80 did not affect (p>0.05) cumulative gas production at 24 h, but it reduced (p<0.05) the lag in fermentation of all three silages. With corn silage and orchardgrass silage, gas production rates and concentrations of total volatile fatty acids (VFA) were increased (p<0.05) by Tween 80; with alfalfa silage, they were reduced (p<0.05). Tween 80 increased (p<0.05) the proportion of propionate in total VFA, and reduced (p<0.05) acetate to propionate ratios (A:P) with all three silages. In Expt 2, exogenous fibrolytic enzymes (E; at 0, 37.5 or 75 g/tonne DM), monensin (M; at 0 or 25 ppm and Tween 80 (T; at 0 or 2 L/tonne DM) were added alone or in combination to backgrounding and finishing diets fed to 320 crossbred steers in a feeding trial with a $3{\times}2{\times}$2 factorial arrangement of treatments. The backgrounding and finishing diets contained barley grain and barley silage in ratios of 57.8:42.2 and 93.5:6.5 (DM basis), respectively. Added alone, none of the additives affected DM intake (p>0.1) in the backgrounding or in the finishing period, but interactive $M{\times}T$ effects were observed in the finishing period (p=0.02) and overall (p=0.04). In the finishing period, T without M tended to reduce DM intake (p=0.11), but T with M increased (p=0.05) DM intake. Monensin increased average daily gain (ADG) during backgrounding (p=0.07) and finishing (p=0.01), and this ionophore also improved overall feed efficiency (p=0.02). Warm carcass weight was increased (p<0.001) by M, but dressing percentage was reduced (p=0.07). In the backgrounding period, T increased ADG by 7% (p=0.06). Enzymes increased (p=0.07) ADG by 5 and 6% (low and high application rates, respectively) during backgrounding, but did not affect (p>0.10) ADG during finishing, or overall feed efficiency. Whereas T enhanced the positive effects of M on ADG during backgrounding (p=0.04) and overall (p=0.05), it had no impact (p>0.1) on the effects of E. Interactions between M and T suggest that the surfactant may have potential for enhancing the positive effects of monensin on beef production, but this requires further research.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.10
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• pp.1450-1454
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• 2006

Three hundred and seventy-five steers (approximately 7 mo of age and $239.0{\pm}10.4kg$) were utilized to determine the effects of trace mineral (TM) supplementation and source on performance during the on-farm backgrounding and feedlot receiving phases of beef cattle production. At their respective ranches, steers were stratified by body weight into six groups. Groups were then assigned to one of six pens and pens were randomly assigned to treatments. Treatments consisted of: 1) control (no supplemental Cu, Zn, Mn, and Co), 2) inorganic trace mineral ($CuSO_4$, $ZnSO_4$, $MnSO_4$, and $CoCO_3$), and 3) organic trace mineral (iso-amounts of organic Cu, Zn, Mn, and Co). Mineral treatments were fed in alfalfa pellets formulated to supply 360 mg of Zn, 200 mg of Mn, 125 mg of Cu, and 12.5 mg of Co per head per day from either organic or inorganic trace mineral sources. Control steers received alfalfa pellets with no additional Cu, Zn, Mn, or Co. Steers were allowed free access to harvested alfalfa-grass hay throughout the 30-d on-farm backgrounding phase. On day 30 post-weaning, steers were weighed and transported to the feedlot. Steers were blocked by treatment within ranch, stratified by initial body weight, and randomly assigned to one of 36 pens (9-12 head per pen; 12 pens per treatment). Steers remained on the same on-farm backgrounding trace mineral treatments, however, trace mineral treatments were included in the total mixed growing ration. Steers were fed a corn silage-based growing diet throughout the 28 d feedlot receiving period. There was no effect of TM supplementation on performance of steers during the on-farm backgrounding phase. By the end of the 28-d feedlot receiving phase, ADG was similar between control and trace mineral supplemented steers. Steers supplemented with organic TM had greater (p<0.05) ADG than steers supplemented with inorganic TM by the end of the 28-d feedlot receiving phase. Morbidity and mortality rates were similar across treatments.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.12
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• pp.1690-1698
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• 2011

Feedlot and in vitro ruminal experiments were conducted to assess the effects of saponin-containing surfactant applied during tempering of barley grain on cattle growth performance and on ruminal fermentation. In the feedlot experiment, treatments with three barley grain/barley silage based diets were prepared using barley grain at 7.7% moisture (dry, D), after tempering to 18% moisture (M), or after tempering with a saponin-based surfactant included at 60 ml/t (MS). Each treatment was rolled at settings determined previously to yield optimally processed barley. A total of 180 newly weaned British${\times}$Charolais steers were fed three diets in 18 pens for a 63-d backgrounding period and 91-d finishing period to determine feed intake, growth rate and feed efficiency. Cattle were slaughtered at the end of the experiment to measure the carcass characteristics. Tempering reduced (p<0.001) volume weight and processing index, but processing characteristics were similar between MS and M. Tempering increased (p<0.05) growth during backgrounding only, compared with D, but did not affect feed intake in either phase. During backgrounding, feed efficiency was improved with tempering, but during finishing and overall this response was only observed with the surfactant. Tempering did not affect carcass weight, fat content or meat yield. Surfactant doubled the proportion of carcasses grading AAA. In the in vitro experiment, barley (500 mg; ground to <1.0 mm or steam-rolled) was incubated in buffered ruminal fluid (40 ml) without or with surfactant up to 20 ${\mu}l/g$ DM substrate for 24 h. Surfactant increased (p<0.05) apparent DM disappearance and starch digestibility but reduced productions of gas and the volatile fatty acid and acetate:propionate ratio, irrespective of barley particle size. Compared with feeding diets prepared with non-tempered barley, tempering with surfactant increased the feed efficiency of feedlot steers. This may have arisen from alteration in processing characteristics of barley grain by surfactant rather than its direct effect on rumen microbial fermentation.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.6
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• pp.800-807
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• 2019

Objective: The aim was to evaluate backgrounding beef steers on oat + ryegrass pastures mixed with vetch and/or using energy supplementation. Methods: A randomized block design with three treatments and three replications was used. The treatments were: grass + supplement (oat + ryegrass + supplementation), legume + supplement (oat + ryegrass + vetch + supplementation) and grass + legume (oat + ryegrass + vetch). A continuous grazing system with a variable stocking rate was used. Twenty-seven intact crossbred steers (1/4 Marchigiana, 1/4 Aberdeen Angus and 2/4 Nellore) aged 7 months old and average weight of 190 kg were used. Steers were supplemented at 1% of the body weight of ground corn. The experiment lasted 84 days, between May and August 2014. Behavioral assessments were performed two times per experimental period, for 24 hours. Results: The forage mass was different between treatments, being greater for steers fed without legume. The accumulation rate, forage allowance, and stocking rate did not differ between treatments due to the adequate adjustment of forage allowance. The final weight of animals, as well as the dry matter intake (kg/d), did not differ between treatments. However, forage intake was higher for non-supplemented animals in relation to supplemented steers. Supplement intake did not alter the total digestible nutrient intake due to pasture quality. Animals fed grass + supplement had higher live weight gain per area than those fed grass + legume. Animals without supplementation spent more time in grazing. Conclusion: Feeding behavior was not altered by mixing with vetch or supplementation. Non-supplemented animals started the grazing peak earlier and spent more time in grazing than those supplemented; however, the average daily gain was similar between treatments. The live weight gain per hectare was 47% higher in pastures in which the animals received supplementation compared with those mixed with vetch, a consequence of the substitutive effect.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.7
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• pp.992-1006
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• 2018

Beef production extends over almost half of Australia, with about 47,000 cattle producers that contribute about 20% ($A12.7 billion gross value of production) of the total value of farm production in Australia. Australia is one of the world's most efficient producers of cattle and was the world's third largest beef exporter in 2016. The Australian beef industry had 25 million head of cattle in 2016-17, with a national beef breeding herd of 11.5 million head. Australian beef production includes pasture-based cow-calf systems, a backgrounding or grow-out period on pasture, and feedlot or pasture finishing. Feedlot finishing has assumed more importance in recent years to assure the eating quality of beef entering the relatively small Australian domestic market, and to enhance the supply of higher value beef for export markets. Maintenance of Australia's preferred status as a quality assured supplier of high value beef produced under environmentally sustainable systems from 'disease-free' cattle is of highest importance. Stringent livestock and meat quality regulations and quality assurance systems, and productivity growth and efficiency across the supply chain to ensure price competiveness, are crucial for continued export market growth in the face of increasing competition. Major industry issues, that also represent research, development and adoption priorities and opportunities for the Australian beef industry have been captured within exhaustive strategic planning processes by the red meat and beef industries. At the broadest level, these issues include consumer and industry support, market growth and diversification, supply chain efficiency, productivity and profitability, environmental sustainability, and animal health and welfare. This review provides an overview of the Australian beef industry including current market trends and future prospects, and major issues and opportunities for the continued growth, development and profitability of the industry.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.7
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• pp.1007-1016
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• 2018

USA beef production is characterized by a diversity of climates, environmental conditions, animal phenotypes, management systems, and a multiplicity of nutritional inputs. The USA beef herd consists of more than 80 breeds of cattle and crosses thereof, and the industry is divided into distinct, but ofttimes overlapping sectors, including seedstock production, cow-calf production, stocker/backgrounding, and feedlot. Exception for male dairy calves, production is predominantly pastoral-based, with young stock spending relatively brief portions of their life in feedlots. The beef industry is very technology driven, utilizing reproductive management strategies, genetic improvement technologies, exogenous growth promoting compounds, vaccines, antibiotics, and feed processing strategies, focusing on improvements in efficiency and cost of production. Young steers and heifers are grain-based diets fed for an average of 5 months, mostly in feedlots of 1,000 head capacity or more, and typically are slaughtered at 15 to 28 months of age to produce tender, well-marbled beef. Per capita beef consumption is nearly 26 kg annually, over half of which is consumed in the form of ground products. Beef exports, which are increasingly important, consist primarily of high value cuts and variety meats, depending on destination. In recent years, adverse climatic conditions (i.e., draught), a shrinking agricultural workforce, emergence of food-borne pathogens, concerns over development of antimicrobial resistance, animal welfare/well-being, environmental impact, consumer perceptions of healthfulness of beef, consumer perceptions of food animal production practices, and alternative uses of traditional feed grains have become increasingly important with respect to their impact on both beef production and demand for beef products. Similarly, changing consumer demographics and globalization of beef markets have dictated changes in the types of products demanded by consumers of USA beef, both domestically and abroad. The industry is highly adaptive, however, and responds quickly to evolving economic signals.