Weight Gain Of Steers Research Articles

The LTAR Grazing Land Common Experiment at the Central Plains Experimental Range: Collaborative adaptive rangeland management.

Semiarid rangelands throughout the western Great Plains support livestock production and many other ecosystem services. The degree to which adaptive multi-paddock (AMP) grazing management approaches can help achieve desired ecosystem services remains unclear. At the Central Plains Experimental Range in northeastern Colorado, a management-science partnership with a diverse stakeholder group is comparing collaborative adaptive rangeland management (CARM), designed to incorporate AMP principles, to traditional rangeland management (TRM), consisting of season-long grazing during the growing season. Each treatment was implemented on a set of 10, 130-ha pastures paired by soils, topography, and plant communities to evaluate how CARM affects vegetation (composition and production), livestock production (steer weight gain), and wildlife habitat (vegetation structure for grassland birds). For the first 5 years of the experiment, CARM cattle were managed as a single herd using AMP grazing with planned year-long rest in 20% of the pastures. Relative to TRM, CARM enhanced heterogeneity in vegetation structure across the landscape, benefiting two grassland bird species. However, this came at the cost of 12%-16% lower steer weight gains in CARM versus TRM and declining populations of a third bird species of conservation concern in both treatments. Here we discuss how increased understanding of ecological and social processes during the experiment's first 5 years led to changes in the CARM treatment and management objectives during the next 5 years. We also discuss how innovations in remote sensing, environmental sensors, ecosystem modeling, social learning, and economic analyses are being integrated into and supported by the CARM experiment.

Impacts of environmental feedbacks on the production of a Central Queensland beef enterprise in a future climate

CONTEXTUnderstanding climate change impacts on beef production enterprises in northern Australia is challenging due to the complexity of the system, which involves biophysical processes such as pasture and animal production, herd management, economics, emissions, and the interaction among these things. Modelling is a powerful tool to help the beef industry understand the impacts of climate change and to develop adaptation plans to help ensure enterprises remain economically viable over the long term. OBJECTIVEWe assess climate change impacts on a single specialised beef enterprise south-east of Moura (24.59°S, 150.09°E) in northern Australia's Central Queensland region. This is achieved by comparing enterprise performances during a 2030s climate and a 1975–2013 baseline period. METHODSWe used a calibrated pasture model called GRASP to simulate the farm's pasture growth under multiple scenarios for land conditions, grass basal areas and stocking rates for the baseline and 2030s climates and to construct pasture growth databases – known as datacubes. The datacubes provide a simplified representation of mean coupling between the herd dynamics and livestock production model (Crop Livestock Enterprise Model). The coupled whole-of-farm model was parameterised using enterprise data collected through interviews with the property owner and allowed for feedback between the pasture and livestock systems. The feedback capability allowed us to consider changes in land condition through stocking rates and their effect on pasture growth, animal weight gain, profit and CO2 emissions. RESULTS AND CONCLUSIONSWe found that warmer and drier climatic conditions during 2030s will reduce pasture growth in austral spring and summer but increase pasture growth in winter and autumn. Increased pasture growth in winter and autumn cannot compensate for the reduction in pasture growth in the warm seasons but can improve animal liveweight gain in winter and early spring. This leads to an overall increase in annual weight gain of steers (the cattle class that provides the main income source for this farm) while the CO2 emission intensity remains similar to the baseline period. Maintaining land condition under the 2030s climatic conditions considered will require a reduction in sustainable herd size, leading to lower beef production and lower profit under current pasture and herd management strategies. Impacts will likely differ from those described if a drier future is not realised. SIGNIFICANCEThis study provides a climate change impact assessment on a specialised beef enterprise (i) being distilled from individual ruminants, and (ii) considering environmental feedbacks in the interaction between pasture and livestock systems.

Aromatic feed additives when phase feeding of steers

research results of some scientists indicate an increase in the average daily gain of live weight in steers by 17–20 % and a decrease in feed expenditures by 15–18 % with periodic changes in the nutritional content of ration from 80 to 120 % of the norm. The purpose of the research was to establish the infl uence of phase feeding when using aromatic feed additives on the feeding behavior, physiological state and beef productivity of steers of Simmental breed. The research was carried out in the Private agricultural farm “Agrofi rma Privolye” in the Troitsk area in the Luhansk region and the Peasantry farm “Tananov K. A.” in the Sukhinichi area in the Kaluga region. Three scientifi c and economic experiments were conducted to study a new way to increase the productivity of young cattle on fattening by organizing phase feeding of steers with periodic changes in the nutritional content of their rations from 80 to 120 % of the norm (without changing the structures) and using aromatic feed additives VANILLA 12033, ANIMAL FEED FLAVOR 08004168 and CITRO FENNEL 09005559. It has been established that beef production using the improved method of phase feeding of steers with the periodic use of VANILLA 12033 aromatic additive was more economically effi cient than traditional rearing of young animals. Thus, the profi t from the conditional realization of the weight gain of steers from the age of 12 to 18 months was higher by 3200–7800 rubles (per 1 head) with the increase in the level of profi tability of beef production.

Vegetation and Animal Performance Responses to Stocking Density Grazing Systems in Nebraska Sandhills Meadows

Management-intensive grazing, which is proposed to increase forage and animal productivity and maintain soil integrity and biodiversity, is seen as an alternative to meet 21st century agricultural and environmental challenges. The purpose of this study was to test the hypothesis that high levels of trampling of standing vegetation associated with mob grazing (a.k.a., ultrahigh stocking density) leads to increased plant diversity and productivity. A long-term experiment was established on a subirrigated meadow in the Nebraska Sandhills as a complete block design comparing three grazing treatments applied annually during the growing season for 8 consecutive yr (2010−2017): 120-pasture rotation with one grazing cycle (mob; 225 000 kg live weight ha−1), four-pasture rotation with one grazing cycle (4PR1; 7 000 kg live weight ha−1), and four-pasture rotation with two grazing cycles (4PR2; 5 000 kg live weight ha−1). All treatments were set at a moderate stocking rate (7.4 animal unit months ha−1) using yearling steers. Percentage trampling, plant production, species composition, and steer weight gain were estimated annually. We applied linear mixed-effect models to account for year and treatment effect on the response variables. Percentage trampling on mob pastures ranged from 40% to 55% over the 8 yr of the study, nearly double that of the 4PR1 and 4PR2 pastures. We observed that mob grazing had no overall effect on plant species composition, aboveground production, and root growth relative to low stocking densities. Average daily gain of steers in the mob pastures was less than gain of steers in 4PR2 pastures in all years, with intermediate weight gains for the 4PR1 steers. Overall, stocking density did not appear to be a driver of plant composition and productivity in rotationally grazed pastures on subirrigated meadows in the Nebraska Sandhills.

Can measurements of foraging behaviour predict variation in weight gains of free-ranging cattle?

Context Technologies are now available to continuously monitor livestock foraging behaviours, but it remains unclear whether such measurements can meaningfully inform livestock grazing management decisions. Empirical studies in extensive rangelands are needed to quantify relationships between short-term foraging behaviours (e.g. minutes to days) and longer-term measures of animal performance. Aims The objective of this study was to examine whether four different ways of measuring daily foraging behaviour (grazing-bout duration, grazing time per day, velocity while grazing, and turn angle while grazing) were related to weight gain by free-ranging yearling steers grazing semiarid rangeland. Methods Yearling steers were fitted with neck collars supporting a solar-powered device that measured GPS locations at 5 min intervals and used an accelerometer to predict grazing activity at 4 s intervals. These devices were used to monitor steers in four different paddocks that varied in forage biomass, and across two grazing seasons encompassing a wide range of forage conditions. Steer weight gain (kg/steer.day) was measured in each paddock during each of three ∼60 day time intervals, and daily foraging behaviours were measured during 15–21 days in each interval. Results A model based on only two daily measurements of foraging behaviour, mean grazing bout duration (calculated at a 5 min resolution) and mean velocity while grazing explained 62% of the variation in animal weight gain. Conclusions Daily measurements of foraging behaviour vary substantially in response to varying foraging conditions in space and time, and can effectively serve as indicators of variation in cattle weight gain. Implications On-animal sensors that monitor foraging behaviour have the potential to transmit indicators to livestock managers in real time (e.g. daily) to help inform decisions such as when to move animals among paddocks, or when to sell or transition animals from rangeland to confined feeding operations.

Rationing of non-degradable protein in diets for breeding steers

The paper provides the results of research on development of standards for non- degradable protein in diets for replacement steers of black-and-white breed. Studies were conducted in 3 groups of repair steers aged 12- 18 months, with an average initial body weight of 363-367 kg. Differences in feeding consisted in the fact that the amount of non-degradable protein in diet for steers in the control group was 10% lower than the accepted standard, in II group – corresponded to the accepted standard, in III group – 10% higher than standard. It has been determined that animals of II and III experimental groups, consuming diets with increased level of non-degradable protein, better digested dry and organic matter, and protein by 6.4 and 6.9; 6.4 and 7.1; 5.6 and 5.5 p.p. However, there was an increase of total protein by 4%, total and protein nitrogen – by 4-5% in blood of steers of the II experimental group, while in young animals of III experimental group these indicators increased respectively by 6.5 and 7%. The average daily weight gain of steers of the experimental groups increased by 3 and 5%, ejaculate volume – by 11-14%, sperm cells count – by 9-12%, amount of energy deposited in weight gain – by 4.1-9.0%, diet energy consumption per 1 MJ deposited in weight gain decreased by 4-5 %.

Forage production and steer performance in fertilized smooth bromegrass and smooth bromegrass–legume pastures

AbstractSmooth bromegrass is a commonly used cool‐season pasture grass that responds favorably to annual spring fertilization, but annual fertilizer applications require annual inputs of both time and expense. This study was conducted to determine if interseeding legumes into established smooth bromegrass pasture is a viable alternative to spring fertilization. Steers (Bos taurus) were rotationally grazed in either fertilized smooth bromegrass pastures or smooth bromegrass pastures interseeded with legumes. Data were collected on forage production, forage available at the beginning of each grazing rotation, steer weight gain, and the number of grazing days. Total forage production for the growing season was not different between the pasture types, but fertilized pasture had greater available forage early in the growing season and interseeded pasture had greater forage production late in the growing season. Season‐long average daily gain of steers was not different between pasture types, but daily gains were greater in interseeded pasture late in the growing season and may be linked to proportionally greater abundance of legumes late in the season. Beef production ac–1 was higher in interseeded pastures, largely due to increased days of grazing. We found that interseeding legumes into established pasture can be a viable alternative to annual spring fertilization and may outperform fertilized pasture depending on the metric and growing conditions.

Isoflavone supplementation, via red clover hay, alters the rumen microbial community and promotes weight gain of steers grazing mixed grass pastures.

Biochanin A, an isoflavone present in the pasture legume red clover (Trifloium pratense L.), alters fermentation in the rumen of cattle and other ruminants. Biochanin A inhibits hyper-ammonia-producing bacteria and promotes cellulolytic bacteria and fiber catalysis in vitro and ex vivo. Consequently, biochanin A supplementation improves weight gain in grazing steers. Red clover contains biologically active isoflavones that may act synergistically. Therefore, the objective was to evaluate the effect of two levels of red clover hay on growth performance and the microbial community in growing steers grazing mixed grass pastures. A grazing experiment was conducted over 2 early growing seasons (2016 and 2017) with 36 cross-bred steers and twelve rumen-fistulated, growing Holstein steers for evaluation of average daily gain and rumen microbiota, respectively. Steers were blocked by body weight and assigned to pastures with one of four treatments: 1) pasture only, 2) pasture + dry distillers’ grains (DDG), 3) pasture + DDG + low level of red clover hay (~15% red clover diet), or 4) pasture + DDG + high level of red clover hay (~30% red clover diet). DDG were added to treatments to meet protein requirements and to balance total protein supplementation between treatments. All supplementation strategies (DDG ± red clover hay) increased average daily gains in comparison to pasture-only controls (P < 0.05), with a low level of red clover supplementation being the most effective (+0.17 kg d-1 > DDG only controls; P < 0.05). Similarly, hyper-ammonia-producing bacteria inhibition (10–100-fold; P < 0.05), fiber catalysis (+10–25%; P < 0.05) and short chain fatty acid concentrations were greatest with the low red clover supplement (+~25%; P < 0.05). These results provide evidence that lower levels or red clover supplementation may be optimal for maximizing overall microbial community function and animal performance in grazing steers.

Performance, body composition and net requirements of protein and energy for weight gain in steers supplemented with or without addition of lipids

This research aimed to evaluate the performance, body composition and net requirements for protein and energy in grazing Nellore steers supplemented with or without addition of lipids. Twenty-eight steers, 301 ± 5.8 kg BW, were used in the experiment. The comparative slaughter method was used, with four steers used as references. The remaining 24 steers were randomly distributed into four groups, during 180 days, according to treatment: only Panicum maximum cv. Mombasa grass; Mombasa grass with concentrated supplementation based on soybean meal; Mombasa grass with concentrate containing lipids from soybean oil; and Mombasa grass with concentrate containing lipids derived from soybean grains. The total DMI of the steers fed only the pasture did not differ (P &gt; 0.05) from the average intake of the treatments with or without addition of lipids. There were no differences (P &gt; 0.05) between treatments for total daily gain, carcass and non carcass for protein, energy and fat. The requirements of protein and energy did not differ (P &gt; 0.05) among the treatments. When the pasture is of good quality, supplementation does not alter the body composition or the net requirements of protein and energy for weight gain. The supplementations with higher concentrations of lipids (oil and grain) were not enough to promote greater gains in fat and energy in carcass.

Impacts of reduction of phosphorus in finishing diets for Holstein×Zebu steers

In Brazil, commonly males of dairy herd are destined to beef production. However, little is known about the mineral requirements for dairy males. Therefore, the objective of this experiment was to evaluate the calcium (Ca) requirements of Holstein×Zebu steers by determining Ca body tissue concentrations, true absorption and retention coefficients, as well as the requirements for maintenance and weight gain of steers fed diets containing or not containing dicalcium phosphate. Twenty-eight Holstein×Zebu steers with an average initial body weight of 377.5±49.4kg were utilized. The experiment was conducted as a completely randomized design with a 2×2 factorial arrangement of treatments. Factors included 1) two concentrate levels (30% or 60%); and 2) two levels of dicalcium phosphate (DP), 0 or the amount necessary to attend the estimated dietary requirements. Absorption and retention coefficients, maintenance and gain requirements were estimated. The feedstuffs, refusals, feces, urine, blood and bone were sampled for Ca and phosphorus (P) analysis. Phosphorus intake was improved by the addition of concentrate and presence of DP. There were no variations in the daily fecal and urinary phosphorus excretion as a function of DP. The serum level of inorganic phosphorus was lower in non-supplemented animals, although it was within adequate concentrations for all treatments. Dry matter and organic matter intake, organic matter digestibility, performance, and efficiency were not affected by treatment. Absorption and retention coefficients, and the net requirements for maintenance are similar across treatments. Therefore, the lack of inorganic supplementary Ca and P in diets of feedlot finishing cattle does not change the concentrations of these minerals in bone. The dietary requirements of calcium and phosphorus obtained for cattle were lower than those described by the nutritional requirement systems from Brazil, USA, and UK.

Modeling weather and stocking rate effects on forage and steer production in northern mixed-grass prairie

Stocking rate (SR) is the primary management factor that influences livestock gains, plant community changes and forage production, as well as economic returns for livestock producers. More effective stocking decision making by ranchers in the semi-arid northern mixed-grass prairie requires clearly understanding forage production and yearling steer weight gain (SWG) responses to SR and high weather variability. The objectives of this study were to: (1) test the Great Plains Framework for Agricultural Resource Management-Range (GPFARM-Range) model for predicting forage production and SWG under three experimental SR treatments and long-term weather conditions on semiarid northern mixed-grass prairie in southeast Wyoming, USA; and (2) quantify the threshold responses of forage production and SWG to SR and the yearly weather variability across years using long-term simulations with SR higher than those experimentally evaluated. We improved upon the GPFARM-Range model to simulate peak standing crop (PSC) and SWG for three experimental SR treatments (low, moderate and high; 0.20, 0.33 and 0.44steerha−1, respectively) from 1982 to 2012 at Cheyenne, Wyoming, USA. The improved model accurately predicted the effects of SR on PSC and SWG across years (root mean square errors from 355 to 387kgha−1 for PSC and from 12.8 to 14.2kghead−1 for SWG). We ran the model with long-term weather data and 50–300% higher SR (0.66–1.76steerha−1) than the high SR experimental treatment. Differential responses of predicted total intake of digestible nutrients (quadratic increase) and metabolic maintenance (linear increase) to these higher SR resulted in a quadratic increase of predicted SWG with SR and high yearly variability at high SR levels. The financially-optimum SR with highest profits was reduced to 0.33steerha−1 for dry or normal seasons and 0.44steerha−1 for wet seasons. Such reduced SR can also benefit land conservation with high PSC and low harvest efficiency. The moderate SR with 25% harvest efficiency was determined between 0.22 and 0.33steerha−1 for dry or normal seasons, or between 0.33 and 0.44steerha−1 for wet seasons. These results provide useful direction for selecting an effective SR to achieve high economic net return with lower yearly variability (risk) and reduced likelihood of rangeland degradation.

Effect of rate of weight gain of steers during the stocker phase. III. Gene expression of adipose tissues and skeletal muscle in growing–finishing beef cattle1

The objective of this study was to determine the impact of stocker production systems differing in growth rate on differential adipogenic and lipogenic gene expression of intramuscular (IM), subcutaneous (SC), and perirenal (PR) adipose tissues. Angus steers were assigned to 4 stocker cattle production systems in 2 consecutive years: 1) cottonseed meal-based supplement while grazing dormant native range (CON), 2) ground corn/soybean meal-based supplement while grazing dormant native range (CORN), 3) grazing wheat pasture at a high stocking rate for a low rate of BW gain (LGWP), and 4) grazing wheat pasture at a low stocking rate for a high rate of BW gain (HGWP). Steers were harvested during the stocker phase at similar age (different carcass weight) in Exp. 1 (3 steers/treatment) or at similar carcass weight in Exp. 2 (4 steers/treatment). Adipose tissues were analyzed for mRNA expression of adipogenic (peroxisome proliferator activated receptor γ [PPARγ], sterol regulatory element binding factor 1 [SREBF1], CAATT/enhancer binding protein β, and delta-like homolog 1) and lipogenic (glycerol-3-phosphate dehydrogenase [GPDH], fatty acid synthase [FASN], and diacylglycerol acyltransferase 2 [DGAT2]) genes. Multivariate analysis was used to evaluate the expression of adipogenic or lipogenic genes collectively. There was not a treatment × adipose tissue interaction (F-test, P > 0.15) when steers were harvested at similar age, but a treatment × adipose tissue interaction (F-test, P < 0.05) was evident when steers were harvested at similar carcass weight. At similar carcass weight, treatment had no effect (P > 0.10) on the canonical variate of adipogenic or lipogenic mRNA expression in IM adipose tissue, but faster rates of gain of LGWP and HGWP steers increased (P < 0.10) the canonical variate of adipogenic and lipogenic mRNA expression in SC and PR adipose tissue compared with CON and CORN steers. Strong positive correlations (P < 0.05) of PPARγ, SREBF1, GPDH, FASN, and DGAT2 mRNA expression with the canonical variate indicate that these genes strongly influenced differences between treatments and adipose tissues. These results suggest that contrary to our hypothesis rate of gain has little influence on differentiation and lipid synthesis of IM adipose tissue at similar carcass weight but faster rates of gain increase differentiation and lipid synthesis of SC and PR adipose tissue even at similar carcass weight.

Effect of rate of body weight gain in steers during the stocker phase. I. Growth, partitioning of fat among depots, and carcass characteristics of growing-finishing beef cattle1

Two experiments were conducted to examine the effect of growth rate to similar age or BW on fat deposition in stocker cattle grazing dormant native range (DNR) or winter wheat pasture (WP). In each experiment, fall-weaned Angus steers were randomly allotted to 1 of 4 stocker production programs: 1) control, 1.02 kg/d of a 40% CP cottonseed meal-based supplement during grazing of DNR (CON); 2) corn/soybean meal-based supplement fed at 1% of BW during grazing of DNR (CORN); 3) grazing WP at a high stocking rate to achieve a low rate of BW gain (LGWP); and 4) grazing WP at a low stocking rate to achieve a high rate of BW gain (HGWP). In Exp. 1, a subset of steers (3 steers per treatment) was harvested after winter grazing (138 d) at similar age. The remaining WP steers were transitioned into the finishing phase, whereas DNR steers were allowed to graze the same native range pastures for another 115 d without supplementation before entering the feedyard. In Exp. 2, steers grazed their respective pastures until each treatment reached an estimated HCW of 200 kg (262, 180, 142, and 74 d, respectively, for the CON, CORN, LGWP, and HGWP treatments), at which time a subset of steers (4 steers per treatment) were selected for intermediate harvest before finishing. In both experiments, the remaining steers were fed a finishing diet to a common 12th-rib fat thickness of 1.27 cm. In Exp. 1, winter grazing ADG was 0.19, 0.52, 0.68, and 1.37 ± 0.03 kg/d; and in Exp. 2, winter/summer grazing ADG was 0.46, 0.61, 0.83, and 1.29 ± 0.02 kg/d, respectively for CON, CORN, LGWP, and HGWP treatments. At intermediate harvest in Exp. 1, HGWP steers had greater (P < 0.01) 12th-rib fat thickness and marbling scores, compared with the other treatments. However, in Exp. 2, LGWP steers had greater (P < 0.01) marbling scores compared with HGWP steers, which were greater than DNR steers. At final harvest in Exp. 1, LGWP steers had greater (P < 0.01) 12th-rib fat thickness and smaller LM area, compared with the other treatments; however, there were no differences (P = 0.99) in final marbling scores. In Exp. 2, CON steers had lower (P < 0.05) 12th-rib fat thickness and tended (P = 0.10) to have greater marbling scores, compared with the other treatments. These data suggest that changes in the partitioning of fat among depots during the stocker phase may not be reflected after finishing when steers are fed to a common 12th-rib fat thickness.

Temperature and Precipitation Affect Steer Weight Gains Differentially by Stocking Rate in Northern Mixed-Grass Prairie

Cattle weight gain responses to seasonal weather variability are difficult to predict for rangelands because few long-term (>20 yr) studies have been conducted. However, an increased understanding of temperature and precipitation influences on cattle weight gains is needed to optimize stocking rates and reduce enterprise risk associated with climatic variability. Yearling steer weight gain data collected at the USDA-ARS High Plains Grasslands Research Station at light, moderate, and heavy stocking rates for 30 years (1982–2011) were used to examine the effects of spring (April–June) and summer (July–September) temperature and precipitation, as well as prior-growing-season (prior April–September) and fall/winter (October–March) precipitation, on beef production (kg · ha−1). At heavier stocking rates, steer production was more sensitive to seasonal weather variations. A novel finding was that temperature (relatively cool springs and warm summers) played a large predictive role on beef production. At heavier stocking rates, beef production was highest during years with cool, wet springs and warm, wet summers, corresponding to optimum growth conditions for this mixed C3–C4 plant community. The novelty and utility of these findings may increase the efficacy of stocking rate decision support tools. The parsimonious model structure presented here includes three-month seasonal clusters that are forecasted and freely available from the US National Oceanic and Atmospheric Administration up to a year in advance. These seasonal weather forecasts can provide ranchers with an increased predictive capacity to adjust stocking rates (in advance of the grazing season) according to predicted seasonal weather conditions, thereby reducing enterprise risk.

Effect of rate of body weight gain of steers during the stocker phase. II. Visceral organ mass and body composition of growing-finishing beef cattle

Two experiments were conducted to examine the effect of rate of BW gain during the stocker phase on visceral organ mass and body composition of growing-finishing cattle that had grazed dormant native range (DNR) or winter wheat pasture (WP). In each experiment, fall-weaned steers were allotted randomly to 1 of these stocker production programs: 1) control, 1.02 kg · steer(-1) · d(-1) of a 40% CP cottonseed meal-based supplement during grazing of DNR (CON); 2) corn/soybean meal-based supplement fed at 1% of BW during grazing of DNR (CORN); 3) grazing WP at a high stocking rate to achieve a reduced rate of BW gain (LGWP); and 4) grazing WP at a low stocking rate to achieve an increased rate of BW gain (HGWP). In Exp. 1, 3 steers per treatment were harvested after winter grazing (138 d). The remaining WP steers were transitioned into a finishing phase and DNR steers were allowed to graze the same pastures for another 115 d before entering a feedyard. In Exp. 2, steers grazed respective pastures until each treatment reached an estimated HCW of 200 kg (262, 180, 142, and 74 d, respectively, for CON, CORN, LGWP, and HGWP treatments), at which time 4 steers per treatment were randomly selected for intermediate harvest before finishing. At the end of the finishing period, 4 additional steers from each treatment were randomly selected for final carcass measurements. All steers were fed to a common 12th rib fat thickness of 1.27 cm. After winter grazing in Exp. 1, HGWP steers had the greatest (P < 0.01) mesenteric/omental fat, total viscera, total splanchnic tissue mass, and carcass and empty body fat, compared with the other treatments. In Exp. 2 at intermediate harvest, WP steers had greater (P < 0.03) mesenteric/omental fat, total viscera, and total splanchnic tissue mass, compared with CORN steers, with CON steers being intermediate. Also, the WP steers had greater (P < 0.02) carcass and empty body fat, compared with CORN steers, with CON steers being intermediate. At final harvest in Exp. 2, LGWP steers had the least total viscera and total splanchnic tissue mass, compared with the other treatments. However, there were no differences (P > 0.53) among treatments for carcass or empty body fat. Stocker systems using WP or DNR result in cattle with differences in body fat and visceral organ mass before finishing; this may influence feedlot efficiency, even though there were no differences in body fat and visceral organ mass at the end of the finishing period.

Produção animal em pastagem de capim-braquiária adubada com nitrogênio

O experimento foi realizado em dois anos para avaliar o potencial de produção de bovinos em pastagens de Brachiaria decumbens adubadas com nitrogênio (N). Foram determinadas as massas de forragem total (MFT) e de forragem verde (MFV), a composição morfológica e o valor nutritivo da forragem potencialmente consumível, bem como o desempenho animal e a taxa de lotação (TL) das pastagens. Os tratamentos consistiram de quatro doses de N - 75, 150, 225 e 300kg/ha.ano -, em delineamento de blocos ao acaso, com duas repetições. Nos dois anos, as MFT e MFV aumentaram linearmente em função da aplicação de N. A composição química da forragem potencialmente consumível foi pouco alterada pela aplicação de N. A adubação nitrogenada não influenciou o ganho de peso individual dos novilhos, mas aumentou a TL - de 3,6 para 5,3 e de 3,7 para 5,2UA/ha no primeiro e segundo ano, respectivamente - e a produção animal por área da pastagem - de 404,2 para 737,9 e de 619,7 para 1008,4kg/ha no primeiro e segundo anos, respectivamente.

Heavily stocked 5-paddock rotational grazing effect on cross-bred Afrikaner steer performance and herbaceous vegetation dynamics in a semi-arid veld of Zimbabwe

A ten-year high stocking rate trial, mimicking communal areas was initiated at Matopos Research Station, Zimbabwe. Afrikaner steer crosses grazed continuously or rotationally at a high stocking rate (0.4 LU.ha-1) in two 45 ha areas, with one fenced into five 9 ha camps each for the rotational grazing sites, with 30 animals per site. It was hypothesized that, heavily stocked rotation will not improve herbage biomass, decreaser species abundance, basal cover or animal performance. Biomass, basal cover and decreaser species abundance were not (P > 0.05) significantly different between the grazing systems, save for Themeda triandra, Setaria incrassata and Panicum novemnerve, but were significant (P < 0.05) in terms of annual variation. Mean maximum steer weight gain was higher (P < 0.05) under continuous grazing. It was concluded that, the creation of rigid rotational grazing schemes in communal areas without proper stocking rates will not improve animal performance, herbage production, basal cover, but might have an effect on species abundance. In higher rainfall years, heavy stocking has no adverse effects on performance. Hence, any plans of grazing interventions on livestock management in communal areas, should consider stocking rate and rainfall, with a rapid stock reduction strategy in projected low rainfall years. Key words: Basal cover, communal areas, grazing system, herbage biomass, stocking rate, weight gain.

Stochastic dominance analysis of returns to stocker grazing on conservation tillage winter wheat forage in Arkansas

Grazing cattle on winter wheat is a common income-generating practice in the Southern Great Plains, but few Arkansas cattle producers utilize this practice. Many areas in the state with potential to benefit from this practice are highly erodible, and conservation tillage may be needed to best ensure the existing natural resource base is not degraded over time. This study evaluates the profitability and return variability of grazing stocker steers on conservation tillage winter wheat pasture using simulation and stochastic dominance analysis. Average daily gains are simulated for steers grazed on conventional tillage, reduced tillage, and no-till winter wheat pasture using seven years of steer weight gain data from a conservation tillage winter wheat forage study near Batesville, Arkansas. Steer prices and prices for key forage production inputs such as diesel, fertilizer, and glyphosate are also simulated to account for their stochastic impacts on return variability. Steer net return distributions are generated for each tillage system, and first and second degree stochastic dominance are used to rank each tillage system according to specified producer preferences. The results indicate both conservation tillage systems are more profitable and less risky than the conventional tillage system. The conventional tillage system is dominated by no-till based on first degree stochastic dominance and by reduced tillage based on second degree stochastic dominance. Thus both conservation tillage systems would be preferred by risk-averse cattle producers to the conventional tillage system based on this analysis.

Steer Responses to Feeding Soybean Hulls on Toxic Tall Fescue Pasture

<h2>ABSTRACT</h2> A grazing experiment was conducted in 2004 and 2005 to evaluate effects of feeding pelleted soybean hulls (SBH) on weight gain, hair coat rating, rectal temperature, and serum prolactin of steers grazed on toxic tall fescue [Schedonorus arundinaceus (Schreb.)]. Forty steers [initial BW in 2004=257 ± 22 (SD) kg; initial BW in 2005=348 ± 27 kg] were assigned to five 3-ha pastures of toxic tall fescue that were randomly assigned either with (n = 2) or without (n = 3) pelleted SBH (2.3 kg/d per steer, as fed) feeding. Grazing was initiated in early June and was terminated at 112 d of grazing in 2004 and at 102 d of grazing in 2005. Feeding pelleted SBH increased (P < 0.05) ADG. Although the response to SBH was not different (P > 0.10) between the 2 yr, ADG was less in 2005 when there was drier weather. Cost of additional ADG from feeding pelleted SBH was below (P < 0.05) a breakeven of $170/ton pelleted SBH for a cattle price of $2.43/kg BW, and was below a breakeven of $120/ton pelleted SBH for a cattle price of $1.76/kg BW. Percentages of steers with rough hair coat rating averaged 93% and were not different (P > 0.10) between treatments at the conclusion of grazing in both years. Rectal temperatures were not different (P > 0.10) between years and treatments. Prolactin concentrations were not different (P > 0.10) between treatments in 2005, but tended to be lower in SBH steers in 2005. Results indicated that feeding pelleted SBH can cost-effectively increase steer weight gain, but will not alleviate or reduce severity of toxicosis.

A Wheat Grazing Model for Simulating Grain and Beef Production: Part II—Model Validation

Computer models must be thoroughly evaluated before being used for decision‐making. The objective of this paper is to evaluate the ability of a newly developed wheat grazing model to predict fall–winter forage and winter wheat (Triticum aestivum L.) grain yield as well as daily weight gains of steer (Bos taurus) grazing on wheat pasture in Oklahoma. Experimental data of three independent field studies were used. The first was a variety trial in which fall–winter forage and grain yields were harvested. The second was a planting date experiment in which forage in the fall–winter period and grain yields were harvested. The third was a steer grazing experiment in which standing wheat biomass and steer weight gain were monitored. For the variety trials, the model efficiency (ME), which reflects how well model predictions match measured data (1 means a perfect match), was 0.102 for fall–winter forage prediction and 0.367 for grain yield. For the planting date experiment, the ME was 0.615 for predicting fall–winter forage yields and 0.409 for grain yields when a root downward extension rate of 20 mm d−1 was used. In the steer grazing experiment, the relationship between average daily weight gain and forage allowance was adequately represented by the model. For the total steer weight gains in a wide range of stocking rates and grazing durations, the ME was 0.616. Overall results show that the model, if well calibrated, has the potential to predict fall–winter forage and grain yields as well as mean daily weight gain per steer.