Extensive Beef Production Research Articles

The impact of rainfall on beef cattle growth across diverse climate zones

Genetics, animal husbandry and the feedbase all impact cattle growth. Australia’s cattle feedbase covers 40% of the continent and encompasses diverse climates and landscapes, making stocking rate decisions challenging. Of the factors contributing to climate change, rainfall is a primary determinant of feedbase growth and, with this, cattle growth. Understanding the interplay between rainfall and cattle growth across the diverse Australian landscape is thus critical to aid farmer decision-making. However, revealing such interactions between landscape and rainfall for cattle growth for such decision-making has until now been infeasible due to a lack of sufficient temporal and spatial cattle growth data. The Optiweigh (OW) system has been deployed across Australia’s extensive beef production systems as a voluntary weighing unit, opportunistically monitoring cattle liveweight (LW). This study determined the impact of rainfall on the temporal and spatial variability of beef cattle growth across three of Australia’s agro-climatic zones (grassland, subtropical and temperate), aiming to describe the diverse feedbase through patterns of LW variability. A total of 1.3 million cattle LW observations were collected from 82 026 cattle over 2 years (2020–2022). Rainfall data from the Australian Bureau of Meteorology were also collated for the closest meteorological station to each OW unit. Cattle LW average daily gain (ADG) was clustered by season and zone. A series of linear mixed models were used to examine ADG for each zone-season combination, with random effects for individual animals and farms, and fixed effects for climate zone and current and lagged rainfall. The overall mean ADG for the dataset was 0.68 kg/day, with greater growth variability between farms within a zone (SD: 0.349 ± 0.021 kg/day, estimate ± SE) than between cattle within a farm (SD: 0.229 ± 0.004 kg/day). This ADG variability can be partly attributed to the timing and amount of rainfall, with agro-climatic zones showing unique interactions between rainfall and ADG. Seasonal lagged rainfall effects were present in the grassland and temperate zones, while rainfall in the temperate zone had a year-round effect on cattle growth. Further, season-wise lagged rainfall had mixed effects on ADG, whereas rain occurring in a season reduced growth in the same season across zones (P < 0.001). These findings provide valuable initial insights into the variability of ADG across the landscape over time and markedly improve our understanding of the interplay between climate and Australia’s diverse feedbase, contributing to improved management strategies.

Assessing the Environmental Impact of Extensive Beef Production in Grazing Lands of Argentina

Assessing the Environmental Impact of Extensive Beef Production in Grazing Lands of Argentina

Climate and Biodiversity Credentials for Australian Grass-Fed Beef: A Review of Standards, Certification and Assurance Schemes

Extensive livestock production occupies 25% of the ice-free terrestrial surface of the Earth, and Australian beef production contributes about 10% of this total land footprint. Therefore, the management of cattle has major implications for natural vegetation, soils, biodiversity, and atmospheric greenhouse gases in Australia and globally. To meet global sustainability targets and consumer expectations, a variety of environmental Standards, Certification and Assurance (SCA) schemes are being developed and implemented to enable producers to verify claims relating to their products. Improved standardization and coordination are now needed to address the rapid proliferation of credentialing systems that use different frameworks, methods and levels of scientific verification. Using the Australian grass-fed beef industry as a case study, we identified the measures, metrics and methods that are currently used by SCA schemes for climate and biodiversity credentialing. From here, a co-design process with industry representatives was applied to develop recommendations for credentialing in extensive beef production, feedlots and meat processing. It was clear that the successful adoption of credentialing by beef producers will require flexible and user-friendly support tools that use scalable data sources such as existing producer records, agtech databases and remote sensing information. Substantive rewards and incentives will be required to support producer engagement with the SCA schemes. Overall, ’more needs to be done to ensure the transparency of schemes and to meet benchmarks for integrity such as determining uncertainty and support though peer-reviewed science.

Estimating body dimensions and weight of cattle on pasture with 3D models from UAV imagery

Monitoring traits of cattle with an Unmanned Aerial Vehicle (UAV) could assist farmers in monitoring the status and health of their herd without actually visiting them. This feasibility study presents 3D methods to manually estimate body dimensions, such as height and weight, of individual Holstein Friesian cows with stereo RGB imagery, video and LiDAR data from UAVs. In total, 25 different cows over 3 years were monitored and 4,611 images, ∼10 videos, and a LiDAR dataset were analysed. The methods used were estimating weight by analysing 3D models made with RGB imagery and video from UAV, and estimating height and weight from LiDAR data. Software used in this study to process the UAV data and to extract 3D models are Agisoft Metashape Professional, CloudCompare, RiPROCESS 1.8.4 Riegl Software and Potree Desktop. LiDAR showed accurate results for estimating withers height (mean error 6cm) and weight (mean error 38 kg). Estimating weight with 3D models extracted with Structure for Motion (SfM) from overlapping RGB imagery resulted in less accurate results (mean error 62kg). The latter result improved to a mean error of 31 kg when three outliers were removed which exceeded twice the standard deviation. These results suggest that the use of UAVs is promising for estimating body dimensions in extensive beef production systems. The main challenge remains to record individual cows from all sides without too much movement or motion from the cow to enable 3D modelling. Another challenge was to decrease the mean error in weight estimations so that changes in body weight over time can be monitored. Future research should focus on improving the overall mean error of cattle weight estimation, finding solutions for moving cattle and shifting from manual to automated processing of UAV imagery into 3D models.

Detection, identification and posture recognition of cattle with satellites, aerial photography and UAVs using deep learning techniques

ABSTRACT To obtain specific information about cattle in extensive production systems, the usual labor intensive work done by the farmer to find and visit cattle herds in large pastures can be replaced by using UAVs. UAVs are capable of assessing traits in cows, like distinguishing individuals and postures. Although these traits and the detection of cattle, do not represent resilience and efficiency directly, these may contain information associated to resilience. We performed a feasibility study of remotely sensed imagery (using datasets from satellites, manned aircrafts, and UAVs), and deep learning techniques to detect, count, identify and characterize posture of individual cows in grassland production systems. With these techniques, we focused on : (1) automatic detection of cattle locations and animal counting; (2) cow postures like standing, grazing or lying; and (3) individual cow identification. Data were collected during three field trials in the Netherlands and Poland. Artificial Intelligence was used to classify the objects (cattle) in the drone imagery. Classification accuracies of >95% were obtained for detecting cows. Accuracies of ~91% were obtained for identifying individual cows, and accuracies of ~88% were obtained for cow postures. These results make camera-mounted drones a promising new technology for monitoring extensive beef production systems.

Sensor-based detection of parturition in beef cattle grazing in an extensive landscape: a case study using a commercial GNSS collar

Context Neonate management remains a key issue in extensive beef production systems where producers are faced with substantial environmental and management challenges that limit their ability to monitor and manage livestock in a timely manner. Parturition is a critical event and can affect the calf health and survival, particularly in the perinatal period (up to 48 h after birth). As such, monitoring parturition using precision livestock technologies may provide producers with additional tools to manage their cattle and mitigate the impacts of neonatal mortality in extensive beef systems. Aims The purpose of this study was to determine whether data from a global navigation satellite system (GNSS) collar could be used to detect parturition events in extensively grazed beef cattle. Methods Forty-eight Bos taurus cows (583.5 kg body weight ± 9.25 s.e.m.) were allocated to a 28 ha paddock between 8 January 2021 and 6 March 2021 during the calving season. Thirty of the animals were fitted with GNSS-equipped collars (Smart Paddock, Vic., Australia) that captured data at 10 min intervals. Parturition events were recorded daily by visual observation. Collected data were used to calculate key predictive features related to calving behaviour. Derived features were compared and assessed for changes in the period surrounding parturition. Key results Increases were observed in distance to nearest neighbour and to herd aggregate features, and decreases were observed in paddock utilisation and distance travelled features in the lead-up to calving (P &lt; 0.05). Furthermore, the number of animals within a 20 m radius decreased significantly (P &lt; 0.05) in the lead up to parturition, supporting known isolation behaviours. Conclusions With further development of predictive algorithms, on-animal sensors may be valuable in the prediction of calving events in extensive beef production systems. Implications Remote management and monitoring with on-animal sensor technologies, such as GNSS collars and tags, will provide producers with an additional means of monitoring their animals, while overcoming many of the management challenges associated with extensive grazing operations.

The Relationship between Satellite-Derived Vegetation Indices and Live Weight Changes of Beef Cattle in Extensive Grazing Conditions

The live weight (LW) and live weight change (LWC) of cattle in extensive beef production is associated with pasture availability and quality. The remote monitoring of pastures and cattle LWC can be achieved with a combination of satellite imagery and walk-over-weighing (WoW) stations. The objective of the present study is to determine the association, if any, between vegetation indices (VIs) (pasture availability) and the LWC of beef cattle in an extensive breeding operation in Northern Australia. The study also tests a suite of VIs along with variables such as rainfall and Julian day to predict the LWC of breeding cows. The VIs were calculated from Sentinel-2 satellite imagery over a 2-year period from a paddock with 378 cattle. Animal LW was measured remotely using a weighing scale at the water point. The relationship between VIs, the LWC, and LW was assessed using linear mixed-effects regression models and random forest modelling. Findings demonstrate that all VIs calculated had a significant positive relationship with the LWC and LW (p &lt; 0.001). Machine learning predictive modelling showed that the LWC of breeding cows could be predicted from VIs, Julian day, and rainfall information, with a Lin’s Concordance Correlation Coefficient of 0.62 when using the leave-one-month-out cross-validation. The LW and LWC were greater during the wet season when VIs were higher compared to the dry season (p &lt; 0.001). Results suggest that the remote monitoring of pasture availability, the LWC and LW is possible under extensive grazing conditions. Further, the use of VIs and other readily available data such as rainfall can be used to predict the LWC of a breeding herd in extensive conditions. Such information could be used to increase the productivity and land management in extensive beef production. The integration of these data streams offers great potential to improve the monitoring, management, and productivity of grazing or cropping enterprises.

Accuracy of genomic breeding values and predictive ability for postweaning liveweight and age at first calving in a Nellore cattle population with missing sire information.

The multiple sire system (MSS) is a common mating scheme in extensive beef production systems. However, MSS does not allow paternity identification and lead to inaccurate genetic predictions. The objective of this study was to investigate the implementation of single-step genomic BLUP (ssGBLUP) in different scenarios of uncertain paternity in the evaluation for 450-day adjusted liveweight (W450) and age at first calving (AFC) in a Nellore cattle population. To estimate the variance components using BLUP and ssGBLUP, the relationship matrix (A) with different proportions of animals with missing sires (MS) (scenarios 0, 25, 50, 75, and 100% of MS) was created. The genotyped animals with MS were randomly chosen, and ten replicates were performed for each scenario and trait. Five groups of animals were evaluated in each scenario: PHE, all animals with phenotypic records in the population; SIR, proven sires; GEN, genotyped animals; YNG, young animals without phenotypes and progeny; and YNGEN, young genotyped animals. The additive genetic variance decreased for both traits as the proportion of MS increased in the population when using the regular REML. When using the ssGBLUP, accuracies ranged from 0.13 to 0.47 for W450 and from 0.10 to 0.25 for AFC. For both traits, the prediction ability of the direct genomic value (DGV) decreased as the percentage of MS increased. These results emphasize that indirect prediction via DGV of young animals is more accurate when the SNP effects are derived from ssGBLUP with a reference population with known sires. The ssGBLUP could be applied in situations of uncertain paternity, especially when selecting young animals. This methodology is shown to be accurate, mainly in scenarios with a high percentage of MS.

Intravaginal Devices and GNSS Collars with Satellite Communication to Detect Calving Events in Extensive Beef Production in Northern Australia

Observing calves at birth may help to identify risk factors for, and reduce, calf loss in extensive beef systems. The objectives of this study were to: (1) evaluate two commercial satellite birth alert systems to enable the observation of newborn calves and (2) assess behavioral changes of cows around calving. Vaginal Implant Transmitters (VIT) paired with Global Navigation Satellite System (GNSS) collars were worn by 20 cows in Trial 1 and 10 cows in Trial 2 to identify birthing events. The VIT and GNSS collars contained a temperature sensor, accelerometer, and very high frequency (VHF) to communicate with a handheld tracker, and ultra-high frequency (UHF) for communication between the VIT and GNSS collar, which had two-way communication using Iridium satellites. A change (Brand 1) or drop (Brand 2) in temperature of more than 3 °C and inactivity triggered the VIT to communicate an expelled alert to the collar, which transmitted the birth alert information via Iridium (device ID, date, time and geolocation of the GNSS collar at expulsion). Cows and calves were tracked in the paddock following a birth alert to assess their health and status. Overall, true birth alerts occurred in only 27.6% of devices. Cows remained active on the day of calving travelling 5.54 ± 4.11 and 5.00 ± 2.80 km/day compared to 6.45 ± 2.79 and 6.12 ± 2.30 km/d on days when calving did not occur for Trial 1 and 2, respectively (mean ± SD). Average activity of the accelerometer X- and Y-axis on calving day was reduced by 15%–20% compared to other days in Trial 1 (p &lt; 0.05) but not in Trial 2 (p &gt; 0.05). Results suggest that these two birth alert systems are not suitable for use in extensive systems and the further development of the technology is required. Cows in the current trials remained active on the day of, and after, calving, indicating that a faster, real-time alert system and communication protocol would be required to achieve the aim of finding newborn calves.

Is it possible to accurately estimate lactation curve parameters in extensive beef production systems?

ABSTRACT Objective The objective was to characterize the lactation curve applying 3 different models using multiparous grazing beef cows. Materials and Methods Milk production data from 99 British crossbred multiparous cows grazing native pastures were analyzed. Lactation was assessed 15 d postpartum and then monthly until weaning (180 d postpartum) using a milking machine after an oxytocin injection. Total milk production and lactation curve were characterized using Wood (WD) and Wilmink (WIL) models, and both were compared with spline functions. Comparison was made applying adjusted coefficient of determination (R2adj) and MSE. Results and Discussion Cubic splines with 5 equally spaced knots (CS5) presented the best adjustment (lowest Akaike information criterion and Bayesian information criterion). The R2adj values were 0.55, 0.54, and 0.53 (the greater the better) and MSE values were 2.54, 2.59, and 2.47 (the lower the better) for WD, WIL, and CS5, respectively. Estimated milk production for the lactation period was 1,277, 1,255, and 1,195 kg for WD, WIL, and CS5, respectively. Milk peak was predicted to happen at 32, 25, and 36 d postpartum, with a production of 8.74, 8.21, and 8.40 kg for WD, WIL, and CS5, respectively. No differences were evident in the lactation curves (95% CI). Implications and Applications The proposed method and frequency used to assess grazing beef cattle milk production accurately estimate the lactation curve. The Wood model, used worldwide, was a precise estimator of the lactation curve, which in our case was verified applying splines. These results provide key information to calculate grazing beef cow requirements.

Effect of controlled breeding on performance of beef cattle in Central Bushveld bioregion

In most extensive beef production systems in South Africa, calves are weaned at specific dates. This implies that cows that calve late in the season wean younger and lighter calves. In the current study, Bonsmara cows were mated naturally after synchronization over six years (2009 - 2014) in an extensive production system on natural veld in the Central Bushveld bioregion. Within the herd, 50% of cows were synchronized prior to the commencement of the summer breeding season and they were mated naturally for 90 days. The results indicated that calving rate did not differ significantly between cows that were synchronized and non- synchronized. However, there was a significant difference between years in calving rate. Oestrous synchronization prior to natural breeding influenced the average days to conception. The difference in percentage of cows that calved within 293 days of the onset of the breeding season between those that were oestrous synchronized and non-synchronized was 15% in favour of the synchronized cows. Although calves from synchronized cows achieved higher average weaning weights, the cost implications of synchronization offset the benefit of higher calf weights.&#x0D; Keywords: calving rate, oestrous synchronization, natural breeding

Infrequent dietary supplementation feeding in beef cattle: animal responses and factors affecting its success

Abstract Infrequent supplementation (IS; i.e., feeding supplement to animals at frequency less than daily) as opposed to frequent (i.e., daily) could be used as a management tool to improve economic returns of extensive beef production systems by reducing costs associated with the delivery of supplement to cattle. However, previous reports on the effectiveness of IS on production responses in beef cattle are ambiguous and the factors affecting responses to IS by beef cattle are poorly known. The objective of this study was to summarise available data related to the success of IS in beef cattle fed a low quality diet. Additionally, we aimed to identify other potential factors, such as supplement type and composition, forage quality, supplemental degradable intake protein, breed of cattle and environment, which may influence the animal’s response to IS. The results of our study suggest that no single factor could fully explain the discrepancies among studies and, therefore, each of these factors should not be treated in isolation. Cattle maintained with IS appear to be more efficient using the urea recycling mechanism to maintain level of ruminal ammonia during the non-supplemental feeding days. Systematic approaches compiling all potential factors affecting responses of beef cattle to IS are required to determine the likelihood of success with IS for a given farming system.

Managing for the middle: rancher care ethics under uncertainty on Western Great Plains rangelands

Ranchers and pastoralists worldwide manage and depend upon resources from rangelands (which support indigenous vegetation with the potential for grazing) across Earth’s terrestrial surface. In the Great Plains of North America rangeland ecology has increasingly recognized the importance of managing rangeland vegetation heterogeneity to address conservation and production goals. This paradigm, however, has limited application for ranchers as they manage extensive beef production operations under high levels of social-ecological complexity and uncertainty. We draw on the ethics of care theoretical framework to explore how ranchers choose management actions. We used modified grounded theory analysis of repeated interviews with ranchers to (1) compare rancher decision-making under relatively certain and uncertain conditions and (2) describe a typology of practices used to prioritize and choose management actions that maintain effective stewardship of these often multi-generational ranches. We contrast traditional decision-making frameworks with those described by interviewees when high levels of environmental and market uncertainty or ecological complexity led ranchers toward use of care-based, flexible and relational frameworks for decision-making. Ranchers facing complexity and uncertainty often sought “middle-ground” strategies to balance multiple, conflicting responsibilities in rangeland social-ecological systems. For example, ranchers’ care-based decision-making leads to conservative stocking approaches to “manage for the middle,” e.g. to limit risk under uncertain weather and forage availability conditions. Efforts to promote heterogeneity-based rangeland management for biodiversity conservation through the restoration of patch burn grazing and prairie dog conservation will require increased valuation of ranchers’ care work.

A novel agroecosystem: Beef production in abandoned farmland as a multifunctional alternative to rewilding

In much of Europe policy is challenged by the abandonment of crop and pasture land and its replacement by natural forest regrowth. Rewilding is one option. An alternative, multifunctional, strategy is extensive beef farming coupled with carbon storage in herbage and naturally regenerating trees. An economic model is developed in the context of Estonia, where many of the constraints and opportunities relating to natural forest regrowth are in particularly sharp focus, but the approach will be widely applicable. Production of niche market beef, carbon sequestration, and other ecosystem services can proceed in parallel. A novel concept of support payments is proposed. Net present value assessment, with cash credits for carbon storage, demonstrates that the model is viable. A 100 ha tract of abandoned land, stocked with 35 beef cows, would produce beef profitably. Provisioning, regulating and cultural ecosystem services would be delivered, including a net storage of carbon, and rural regeneration would be promoted. The study provides further scientific underpinning for a policy discussion on abandoned land, which represents a growing proportion of Europe's land area. Extensive beef production is compatible with net carbon storage and can provide sustainable ecosystem services together with rural regeneration.

Climate mitigation by dairy intensification depends on intensive use of spared grassland.

Milk and beef production cause 9% of global greenhouse gas (GHG) emissions. Previous life cycle assessment (LCA) studies have shown that dairy intensification reduces the carbon footprint of milk by increasing animal productivity and feed conversion efficiency. None of these studies simultaneously evaluated indirect GHG effects incurred via teleconnections with expansion of feed crop production and replacement suckler-beef production. We applied consequential LCA to incorporate these effects into GHG mitigation calculations for intensification scenarios among grazing-based dairy farms in an industrialized country (UK), in which milk production shifts from average to intensive farm typologies, involving higher milk yields per cow and more maize and concentrate feed in cattle diets. Attributional LCA indicated a reduction of up to 0.10kg CO2 e kg-1 milk following intensification, reflecting improved feed conversion efficiency. However, consequential LCA indicated that land use change associated with increased demand for maize and concentrate feed, plus additional suckler-beef production to replace reduced dairy-beef output, significantly increased GHG emissions following intensification. International displacement of replacement suckler-beef production to the "global beef frontier" in Brazil resulted in small GHG savings for the UK GHG inventory, but contributed to a net increase in international GHG emissions equivalent to 0.63kg CO2 e kg-1 milk. Use of spared dairy grassland for intensive beef production can lead to net GHG mitigation by replacing extensive beef production, enabling afforestation on larger areas of lower quality grassland, or by avoiding expansion of international (Brazilian) beef production. We recommend that LCA boundaries are expanded when evaluating livestock intensification pathways, to avoid potentially misleading conclusions being drawn from "snapshot" carbon footprints. We conclude that dairy intensification in industrialized countries can lead to significant international carbon leakage, and only achieves GHG mitigation when spared dairy grassland is used to intensify beef production, freeing up larger areas for afforestation.

Using temporal associations to determine maternal parentage in extensive beef herds

The assignment of maternal parentage, although time-consuming and expensive using traditional methods, is essential for genetic improvement. Within the sheep industry the recording of time-based (temporal) associations without human intervention has been routinely used to derive maternal parentage, however it has not been researched in extensive beef production systems. To determine whether temporal associations could be used to assign maternal parentage, cows and calves had their identity recorded as they walked to water over a 27-day trial. Two methods of association were investigated, being the half-weight index and the time difference between a cow and calf having their identity recorded. The half-weight index, which is a measure of the number of times two individuals are recorded together, correctly assigned greater than 90% of maternal pairs. When investigating the duration of data recording it was shown that 85% of maternal parentage could be achieved within only 21 days. Further work is required to determine the effect of calf age, herd and paddock size; however, the results showed that the half-weight index method of determining maternal associations is a labour-saving and accurate alternative to traditional methods used to identify maternal parentage.

Rangeland profitability in the northern Gulf region of Queensland: understanding beef business complexity and the subsequent impact on land resource management and environmental outcomes

The farm-gate value of extensive beef production from the northern Gulf region of Queensland, Australia, is ~$150 million annually. Poor profitability and declining equity are common issues for most beef businesses in the region. The beef industry relies primarily on native pasture systems and studies continue to report a decline in the condition and productivity of important land types in the region. Governments and Natural Resource Management groups are investing significant resources to restore landscape health and productivity. Fundamental community expectations also include broader environmental outcomes such as reducing beef industry greenhouse gas emissions. Whole-of-business analysis results are presented from 18 extensive beef businesses (producers) to highlight the complex social and economic drivers of management decisions that impact on the natural resource and environment. Business analysis activities also focussed on improving enterprise performance. Profitability, herd performance and greenhouse emission benchmarks are documented and discussed.

Assessing the carbon footprint of beef cattle in Brazil: a case study with 22 farms in the State of Mato Grosso

In order to meet the predicted growth in world population and increasing demand for food, the offer of animal products, especially in developing countries will also have to increase. Cattle-farming for beef production is one of the most important agricultural activities in Brazil. The country has the major commercial herd in the world and has achieved the position of leading beef exporter. The Brazilian beef sector has been under constant pressure from the international community to reduce the greenhouse gas (GHG) emissions and meet international sustainability standards. There are few studies regarding the GHG emissions associated with the Brazilian cattle production. The aim of this study was to evaluate the main sources of GHG in beef cattle production in the State of Mato Grosso, Brazil. We evaluated 22 farms distributed throughout the state in the year of 2011, accounting for approximately 60,000 ha of pasture area. The results indicated that the largest source of GHG in extensive beef production comes directly from the animals (89–98%). From these, 67–79% are from enteric fermentation, followed by manure decomposition (20–33%). Fuel combustion for farm operations, use of agricultural inputs and electricity consumption where other evaluated sources. The carbon footprints of the farms with herd size limited to 2000 head ranged from 4.8 to 8.2 kg of CO2eq per kg of live weight gain. For the farms with more than 2000 head, the carbon footprints ranged from 5.0 to 7.2 kg of CO2eq per kg of live weight gain. This study contributed to identify the main sources of GHG in the extensive cattle production and indicate mitigation priorities in Brazil.

The profitability and production of a beef herd on transitional Cymbopogon- Themeda veld, receiving three different levels of lick supplementation - Preliminary results

The importance of containing costs through the optimal utilization of feed emphasizes the need to optimize, rather than maximize, the rate of reproduction. It is, however, unknown which lick supplementation regimen, provided to an extensive beef herd on mixed veld, could bring about the most profitable and efficient farming enterprise. The aim of the study was thus to determine what lick supplementation regime would be most profitable in an extensive beef production system maintained on transitional Cymbopogon-Themeda veld. The different lick supplementation regimens offered differed in crude protein (CP) content, percentage non-degradable protein (NDP), metabolisable energy (ME) content, and recommended daily intake. A herd of Drakensberger cows and heifers was divided into three treatment groups (Treatment A, Treatment B and Treatment C), with 70 animals (n = 70) per treatment group. The CP, NDP, ME content of the licks provided in Treatment A were higher than those provided in Treatment B and C, while the CP, NDP, ME content of the licks provided in Treatment B were higher than those provided to Treatment C, but lower than those provided to Treatment A. The first two years’ (2011 - 2012 and 2012 - 2013) preliminary results indicate no significant differences in parameters that affect cow herd performance (weaning weight, cow herd pregnancy rate, intercalving period) between treatments. However, substantial cost differences in the lick supplied between treatments was recorded; thus, affecting profitability. Significant differences between treatments in the pregnancy rates of the first-calf heifers was recorded in the second year, and indicated that providing protein in a drought during summer to first calf heifers may increase the calving rate and hence profitability.Keywords: Beef cattle, cow herd production, extensive farming, lick supplementation, profitability

Early weaning in Northern Great Plains beef cattle production systems: II. Development of replacement heifers weaned at 80 or 215 d of age

Studies were conducted to evaluate effects of weaning and subsequent heifer development treatments within two herds located in the Northern Great Plains, USA. Heifer calves from predominantly Angus×Hereford dams were stratified within dam age and calving date (Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, MT, USA; n=328) and randomly assigned within study and strata to one of three weaning treatments. Heifer calves from Angus and Angus×Simmental dams (n=167; Judith Gap (JG), MT, USA) were stratified within breed group by age, calving date, and AI sire. Heifer calves either remained with their dams until time of normal weaning (NW; approximately 213d of age) or were early weaned (approximately 80d of age) onto one of two early weaning (EW) diets. Heifer calves assigned to EW treatments received one of the following diets: (1) 17.5% CP (69% RDP and 7.53MJ/kg NEm or (2) 17.5% CP (57% RDP and 7.69MJ/kg NEm). At the time of normal weaning, heifers from LARRL (2005 and 2006) were further divided into two heifer development (HD) diet treatments that differed only in proportion of RDP: (1) 12.5% CP (83% RDP and 6.28MJ/kg NEm); or (2) 12.5% CP (72% RDP and 6.28MJ/kg NEm). Heifers from JG were fed a common heifer development diet. Heifer BW at time of normal weaning revealed that EW heifers were heavier, regardless of type of protein delivered by EW treatments (P<0.10). Heifer BW at the end of the development period was greater for EW heifers at LARRL (P<0.01) and similar for JG heifers (P=0.35) regardless of weaning treatment. Heifers at LARRL that received EW treatments had a greater percentage pubertal (P<0.06) from 39 to 2d before breeding compared to NW heifers. Pregnancy rates were not influenced by early weaning or heifer development treatments at LARRL (P>0.05); however, a greater percentage of EW heifers became pregnant throughout the breeding season at JG (P=0.03). These experiments demonstrate early weaning is a viable option to develop and breed heifers in extensive beef production systems in the Northern Great Plains, USA. When production may be jeopardized by environmental conditions (e.g., drought), early weaning calves will not impair a heifers opportunity to be retained as replacement females as early weaned heifers have similar or greater reproductive success than heifers that are normal weaned.