Beef Production Research Articles

PSX-11 Behavior of Kentucky beef producers towards controlling internal parasites

Abstract Internal parasites can reduce production efficiency in livestock grazing systems. Increased concern has been expressed regarding the potential loss of efficacy of available products currently available to livestock managers to control internal parasites. A survey was conducted during the spring of 2023 of Kentucky beef producers participating in a Fecal Egg Count Reduction Test (FECRT) study to gain insight related to their behavior toward managing internal parasites. A total of 70 individuals completed or partially completed the survey instrument. Similar numbers of operations had a single calving season of either spring (35.8%) or fall (37.3%) with these being more prominent than having both spring and fall calving seasons or a year-round calving season. When asked if they had ever performed a FECRT within their herd previously, 96.9% of respondents indicated they had not. Administering an anthelmintic twice annually was reported most often at 69.2%, while 16.9% indicated once per year and more than twice annually being reported by only 6.2%. Sixty percent of beef cattle managers indicated that they rotated products. When asked about the frequency of product rotation, 33.9% indicated they rotated products at each application while 25.8% switched products annually with another 21% never switching products. It is unclear as to why these two questions yielded slightly different outcomes. As all anthelmintics dosage is based on body weight (BW), determination of dosage was asked. More than 75% estimated BW for dosage while 15.4% used a scale to set the dosage for each animal and 7.7% used a scale to obtain an average BW to set the dosage for all animals. Route of administration of product most frequently utilized was pour-on at 66.3% either alone or in combination with another product. Oral drench (17.5%) and injectable (13.8%) were the next most common routes of administration with a single report of product being provided in the feed. This information provides Extension educators with insight regarding beef cattle managers’ behaviors towards anthelmintic use and aid in developing educational programs focused on controlling internal parasites.

PSX-4 Exploring the impact of age and body condition score on the genetic analysis of mature cow weight in American Angus cattle

Abstract Selecting sires with optimal genetic merit for mature weight (MWT) is crucial for profitability of beef producers, ensuring cost-effective production and increased economic returns per animal. The main objective of this study was to determine how different statistical approaches [e.g., including the fixed effects (FE) of age and body condition score (BCS) in the statistical model and/or pre-adjusting the weights for these effects] affect variance components estimation and genetic parameters for MWT, and their impact in the posterior selection decisions. The dataset provided by the American Angus Association (AAA) comprised 80,296 MWT records from 37,934 cows aged 2 to 15 yr. Contemporary groups (CG) were defined by concatenating herd, year, and season of measurement. Model 1 analyzed unadjusted MWT with CG and BCS as categorical FE and age as a covariable (quadratic). Model 2 was model 1 without BCS, model 3 was model 1 without age, and model 4 considered CG as the only FE. In model 5, MWT was pre-adjusted for 6 yr of age and BCS of 6, and CG was the only FE included in the statistical model. Additive genetic and permanent environment (pe) random effects were included in all statistical models except model 5, which did not include pe (only one adjusted record per animal). Variance components were calculated using REML implemented in the BLUPf90+ family of programs. Sires with at least 10 offspring (n = 1,483) were ranked according to their breeding values (EBVs) predicted for MWT, and all and the top 10% sires were used to estimate the rank correlation across models. The heritability (± SE) estimated for MWT was 0.43 (± 0.011), 0.42 (± 0.011), 0.70 (± 0.008), 0.72 (± 0.082), and 0.37 (± 0.013) for models 1, 2, 3, 4, and 5, respectively. Repeatability values were 0.64, 0.67, 0.72, and 0.76 for models 1, 2, 3, and 4, respectively. The EBV ranks were highly correlated between models 1 and 2 (Top 10%: 0.96; All: 0.99), and models 3 and 4 (Top 10%: 0.99; All: 0.99). Inflated heritabilities in models 3 and 4 suggest that the effect of age is confounded with the additive genetic effect, which will not translate to greater genetic progress. Therefore, disregarding age in the genetic evaluation of MWT is not recommended. Similarities between models 1 and 2 suggest that BCS has a relatively small impact on MWT, probably related to the relatively low genetic correlation between these traits. Models 1 and 5 cannot be directly compared, as they use slightly different response variables (body weight vs. pre-adjusted weight) and may lead to slightly different selection decisions (correlation between Top 10%: 0.85; All: 0.95). Further investigations in this field are warranted.

69 The Holos model for estimating greenhouse gases and soil carbon: Characterizing regionalized beef farm model systems

Abstract The objective of this work is to characterize regionally representative beef farm systems that represent dominant or typical surveyed management practices for 11 beef-producing regions across Canada. This work fulfills two further purposes 1) to improve and expand the Holos model interface; and 2) to facilitate the estimation of greenhouse gas (GHG) emissions and soil carbon (C) changes on beef farms in different regions of Canada. Holos version 4 is the whole-farm model of Agriculture and Agri-Food Canada’s to estimate GHG emissions and changes in soil C on Canadian farms in response to shifts in management practices. Holos can be implemented in all 10 Canadian provinces and accounts for GHG emissions from crop and livestock production [enteric and manure methane (CH4), manure and soil N2O emissions], farm machines and infrastructure [on-farm energy carbon dioxide (CO2) emissions], as well as from the upstream production of some farm inputs (synthetic fertilizer and pesticides). The model is designed to utilize data readily available on the farm to answer, ‘What if?’ scenarios, whereby the user can test the effect of changing management practices on their whole-farm GHG budget. To reduce the data input burden on the user, Holos V4 has built-in model livestock systems for beef, dairy, swine and poultry production that characterize the dominant features of these operations in Canada at the national scale based on relevant literature/data and expert opinion. Regarding beef production, we have characterized regionally specific model beef farms for incorporation into Holos, one for each of 11 Canadian beef-producing regions. General characteristics and management practices for each farm were based on the 2011 Beef Farm Survey (Sheppard et al., 2015), which summarizes management information from 1,009 Canadian beef farms, combined with data from the Canadian Cow-Calf Cost of Production Network (Canfax 2023). Each regional farm includes cow-calf, backgrounding in confinement, backgrounding on pasture and finishing components, and considers all the specific feed (e.g., forage, grains, by-products) required for each stage of the beef cycle. These 11 model farms are simulated within the current Holos V4 model to explore the impacts of variation in beef management practices on farm GHG emissions across Canada and on soil C stocks on lands used to produce feed and graze cattle. An overview of the national-level dairy, swine and poultry components in Holos will be presented along with a more detailed perspective of whole-farm GHG budget and multi-decadal soil C dynamics in regionalized beef farms. The impact of management and environmental factors that lead to differences in GHG emissions and soil C stocks in beef farms will also be explored.

171 Examining the role of vitamin E in ruminant livestock growth and production

Abstract Vitamin E is necessary for health, growth, and reproduction in livestock. However, vitamin E requirements and supplement strategies for optimal livestock production and performance are poorly understood, and the role that it plays in skeletal muscle growth has not been thoroughly explored. Ideal vitamin E requirements for optimal skeletal muscle growth have yet to be identified in beef cattle or sheep. Because skeletal muscle growth is important for meat production in livestock, a more thorough understanding of postnatal skeletal muscle growth and the relationship with vitamin E is necessary. The goal of this presentation is to discuss what we currently understand about vitamin E and the relationship it has with skeletal muscle growth in ruminant livestock. This presentation will discuss previous research relating to vitamin E supplementation in beef cattle and sheep, and the resulting impacts on growth and production. Additionally, emerging research using both in vivo and in vitro methods to further explore the relationship between vitamin E and skeletal muscle growth and production of beef cattle and sheep will be presented.

350 Awardee Talk: Beef cattle mineral nutrition: What do we know and where do we go from here

Abstract Trace minerals are pivotal in enhancing cattle growth and ensuring profitability in beef production. Historically, supplementation strategies have aimed at preventing deficiencies, significantly improving growth and reproductive performance. However, as cattle breeding has evolved to achieve remarkable growth rates, the challenges related to health and stress during the feeding period have intensified. This presentation explores refined trace mineral recommendations, focusing on zinc’s “stress requirement” for cattle undergoing transit and health challenges, and its impact on performance. The segmented nature of the beef industry, necessitating multiple transports, induces physiological stress and oxidative stress, highlighting the need for tailored mineral supplementation. Further, when recognizing feedlot cattle as the high-performing athletes they are, the potential benefits of adjusted trace mineral concentrations become apparent. Preliminary findings suggest that optimal zinc concentrations may exceed current National Academies of Sciences, Engineering, and Medicine (NASEM) 2016 recommendations, whereas for other minerals like copper and manganese, the existing guidelines remain appropriate. This presentation will explore the differential effects of increasing dietary zinc and copper in conjunction with various growth-promoting technologies. Preliminary data indicates that increasing zinc concentrations can linearly enhance average daily gain (ADG) and hot carcass weight (HCW), especially when using potent anabolic implants, while the response to increased copper concentrations exhibits a more quadratic relationship with performance. Building upon the foundational work of pioneering researchers in the field of mineral nutrition, this presentation advocates for the continuous refinement and optimization of trace mineral supplementation strategies. By integrating cutting-edge technologies and fostering collaborative research efforts, we aim to further enhance the sustainability of the beef industry. A deeper understanding of trace mineral requirements in the face of modern production challenges will pave the way for more precise and effective nutritional strategies.

371 Applying precision rangeland grazing management systems in western South Dakota

Abstract Western rangelands represent approximately 58% of the total arable land in the U.S. and are used primarily for cow-calf production, which has the largest greenhouse gas (GHG) emission footprint of all beef production phases. Further, beef production sustainability concerns involve climate mitigation (reducing GHG output) and adaptation (climate-resilient soil-plant-animals). Precision livestock farming (PLF) may help address sustainability concerns by providing innovative solutions and new opportunities for extensive rangeland production. The use of precision measurement and management tools with precision system models can connect measurement data to inform management capabilities. For example, real-time individual weighing and remote sensing (precision measurement tools) can be used to inform and implement dynamic rotational grazing management using virtual fencing technology (precision management; Menendez et al., 2022, 2023). Recent USDA investment in climate-smart agriculture (CSA) commodities has provided over $3 billion in funding to implement practices to reduce GHG emissions in agriculture production, for which PLF may be one approach to accomplish these goals. The overall purpose is to develop commodities produced using NRCS climate-smart practices (e.g., prescribed grazing, 528) and document reductions to provide market opportunities associated with inset GHG. Currently, South Dakota State University is leading two simultaneous programs, which include precision ranching (virtual fencing, precision weighing, and GHG evaluation) and a beef and bison CSA program (GHG evaluation; 7 producer-owned research ranches, representing more than 1.09 million ha). The scale of the CSA program has revealed that current PLF research has only been a prelude to providing the precision tools necessary to successfully implement CSA practices and document their impact through monitoring, measuring, reporting, and verification (MMRV). This presentation will include rangeland grazing case studies that cover the application of virtual fencing, animal location, behavior tracking, remote sensing, precision weighing, feeding, supplementation, and enteric emissions and soil moisture monitoring on extensive rangelands. Case studies will include an overview of big data processing and precision system model development methods. Increasing awareness of available PLF tools for optimizing grazing management, animal performance, productivity, and associated challenges (maintenance, costs) is essential for meeting livestock and sustainability goals. PLF and data-driven approaches aid in the creation of scalable, cost-effective MMRV protocols and models (soil carbon and enteric GHG) for extensive rangelands (20 to 70,000 ha areas) that allow producers to realize potential CSA market incentives. Further, MMRV will likely help guide management decisions by identifying CSA strategies that build climate-resilient landscapes for sustainable livestock production and other environmental synergies (soil microbiome, bird and insect habit, water retention).

43 Approaches for improving nitrogen utilization efficiency and environmental sustainability of pork production systems

Abstract Nitrogen (N) is an essential element for life, but due to its inefficient utilization, N waste and emissions generated have exceeded the planetary boundaries and ability of the Earth to effectively overcome these environmentally detrimental effects. Global food animal production contributes 29 to 34% of total global N emissions, with pork supply chains contributing about 16% of these emissions. Life cycle N use efficiency (NUE) of U.S. pork production is only about 56%, which is similar to broiler (55%) and egg (50%) production, but greater than beef (10%) and milk (31%) production. However, only about 10 to 44% of dietary N is converted into edible pork products. While genetic improvement has increased NUE associated with improved lean growth rate, improvement in litter size has led to an increased proportion of low-birth-weight pigs that have reduced NUE. Although metabolic modifiers including porcine somatotropin, ractopamine, and immunocastration improve NUE, they are not feasible or acceptable to consumers in many countries. Separate sex feeding and reducing market weight can also improve NUE. Ultimately feeding program design and implementation have the greatest potential to improve NUE because feed is associated with 70% of N emissions in pork production systems. Multi-objective feed formulation using Life Cycle Assessment environmental impact data of feed ingredients, precision feed formulation and feeding practices to overcome variability in digestible nutrient content of feed ingredients and nutritional requirements of pigs fed in groups, feed processing to enhance energy and nutrient digestibility, and minimizing feed wastage offer the greatest opportunity to improve NUE and environmental sustainability. There are substantial differences in greenhouse gas emissions and embedded water and land use associated with growing-finishing feeding programs depending on the dietary proportions of corn, soybean meal, distillers dried grains with solubles (DDGS), and crystalline amino acids among U.S. geographic regions. Furthermore, addition of thermally processed supermarket food waste to corn-soybean meal (CSBM) diets can significantly reduce environmental impacts and diet cost without compromising growth performance and carcass composition compared with current commercial feeding programs. Although growing-finishing feeding programs using CSBM diets with minimal crystalline amino acids result in greater N intake, N retained, and urinary N excretion compared with feeding low protein, crystalline amino acid supplemented (LP) diets, and diets containing 30% DDGS, growth performance and carcass composition are optimized and impacts on climate change, marine and freshwater eutrophication, and fossil resource are reduced by feeding CSBM diets compared with feeding LP or DDGS diets. Sourcing and using feed ingredients with reduced environmental impact metrics along with precision diet formulation and feeding practices to ensure “getting the right amount of energy and nutrients in the right feed fed to the right pigs at the right time” can improve NUE and environmental sustainability of pork production systems.

453 Fluxes of greenhouse gases from pastures and methane emissions from beef cattle in Australia

Abstract The carbon footprint of beef cattle production may need to consider both the fluxes of greenhouse gases (GHG) of pasture ecosystems and cattle enteric emissions because these are the largest contributors to the carbon balance. The objective of the present study was to measure the fluxes of greenhouse gases from pastures and enteric methane (CH4) emissions from cattle throughout long periods of time under commercial conditions. The fluxes of CH4, carbon dioxide (CO2), and nitrous oxide (N2O) were measured throughout a period of 3 yr in multiple pasture types ranging from native to sown, and from temperate to summer pastures in New South Wales, Australia. A set of 8 dynamic chambers that automatically close for 10 min every 1.5 h were used for this purpose. The chambers measured the change in the concentration of GHG to allow for the estimation of emissions (positive flux) or sinks (negative flux). All data was then summarized to estimate daily fluxes and the global warming potential (CO2e) was calculated multiplying CH4 by 28 and N2O by 265. The final dataset contained 2,709 d of measurements across the 8 chambers. The GreenFeed system was used to measure CH4 production from cattle under varying conditions fed various diets throughout the same period. Cattle categories included weaners, heifers and steers, bulls and cows under both grazing or pen conditions. Cattle were fed a variety of diets ranging from low quality forages to high quality forages, grain supplementation, and grain-based diets. Data were averaged across many days for each animal and the final dataset contained 1,014 measurements. The CO2 flux from pastures ranged from -855 (uptake) to +339 kg CO2ּ ha-1ּ d-1 with a mean of -10.4 ± 2.19 kg CO2ּ ha-1ּ d-1. The minimum, mean and maximum CH4 fluxes were -192 (uptake), 0.015 ± 0.488, 434 g CH4 ּha-1ּ d-1, respectively, whereas NO2 values -146 (uptake), 17.1 ± 1.23, 1,293 g N2O ּ ha-1ּ d-1, respectively. These fluxes resulted in a GWP ranging from -855 (uptake), -5.83 ± 2.222, 445 kg CO2e ּha-1ּ d-1suggesting that pastures were on average a net sink of GHG throughout the present study. The CH4 production from cattle ranged from 43.6 to 404.6, with an average CH4 production of 192 ± 90.3 g CH4ּ animal-1ּ d-1, which is equivalent to 5.37 kg CO2eqּ animal-1ּ d-1. These results suggest that a hectare of livestock pastures offsets more than the CH4 produced by the average beef cattle in the present study. The fluxes of GHG from vegetation may need to be considered when estimating the contribution of livestock production to global warming.

510 Utilizing python programming for modern genetic evaluation systems

Abstract Advancements in agricultural data collection and methodologies for data analysis offer opportunities for beef cattle producers to improve herd genetics. Genetic evaluation systems (GES) can benefit from modern programming approaches to keep up with these advancements. Python, a fast-developing programming language with scientific computing libraries such as NumPy and SciPy, offers flexibility that allows for quick adoption of superior algorithms and new data sources, as well as easy maintenance of the software over the long-term. This study evaluated the use of Python (v3.12.1) for developing a GES capable of executing all the necessary functions expected of modern implementation of GES. A simulated dataset was generated with the R package AlphaSimR to mimic characteristics of the Angus beef cattle breed. The dataset included pedigree information, phenotypic data, and true breeding values (TBVs) for each animal. Phenotypic traits included birth weight (BWT), weaning gain (WG), and post-weaning gain (PWG), with a total of 976,400 animals simulated across 15 generations. The GES software was developed in house, and included components such as data import, pedigree and data preprocessing, calculating inbreeding, constructing the inverse of the numerator relationship matrix, solver initialization, estimation of breeding value, and writing results. The genetic evaluation employed pedigree-based best linear unbiased prediction (BLUP) and a multiple-trait animal model, using a preconditioned conjugate gradient iteration algorithm to solve the mixed model equations. Convergence was assessed using the residual vector norm divided by the right-hand-side norm, with a threshold to declare convergence set to 1x10-5. The software was run on a Linux server with an Intel(R) Xeon(R) Gold 6242 CPU @ 2.80GHz, 96 GB of RAM, and eight cores. Accuracy was measured using Pearson correlation coefficient between TBVs and estimated breeding values (EBVs). To benchmark computing time and solutions, the same dataset and model were input into a commonly used commercial GES, MiXBLUP (v3.0.1). The solver was the most time-consuming component of the GES, with a run time of 27 min. However, the application of multiprocessing reduced the run time by 72% to 8 min. The Pearson correlation coefficient between EBV and TBV was 0.86, 0.79, and 0.73 (P < 0.01) for BWT, WG, and PWG, respectively. In contrast, MiXBLUP completed breeding value prediction in less than 1 min. The Pearson correlation coefficient between Python and MiXBLUP predictions was 1.0 (P < 0.01). While Python is an ideal language for modern GES, further updates are necessary to optimize performance and operations. Future research will focus on refining computational algorithms, exploring parallel processing techniques, and enhancing user interfaces to ensure easy integration with industry practices.

63 Impacts of protein supplementation frequency on animal performance, rumen fermentation and methane emission from growing beef cattle

Abstract Nutrient supplementation is one of largest expenditure in forage-based beef production systems, especially when forage quality is poor or limited. Decreasing supplementation frequency may have a role in improving sustainability by increasing animal performance and minimizing cost of labor and fuel. This study evaluated the impacts of protein supplementation frequency (canola meal pellet; CMP) on animal performance, rumen fermentation, and enteric methane production from beef cattle fed forage-based diet. A total of 60 crossbred backgrounding steers [body weight (BW) = 278 ± 10 kg) was randomly assigned to one of the three treatments (n = 20/treatment): i) control (no CMP supplementation), ii) control + everyday CMP supplementation (0.83 kg/d per steer), and iii) control + every other day supplementation of CMP. The study was comprised of 21 d of adaptation followed by three 21-d periods, with enteric methane measured for 7 d per period. Animals were fed grass hay-based diets once a day at 0800 h and remained on their respective diets throughout the 63-d study. Diets were formulated considering animal BW, feed nutrient density and environmental condition in accordance with the National Academies of Sciences, Engineering and Medicine. Each treatment group was assigned to a pen, with the cattle and diets rotated among pens weekly to allow the animals to access the GreenFeed system stationed in one of the pens for enteric methane measurement. For measurement of rumen fermentation products, three ruminally canulated steers (BW = 350 ± 20 kg) were allocated to the three treatments using a 3 x 3 Latin Square Design with 21-d periods so that one animal received all the treatments over the three experimental periods. Animals were adapted to the treatments for 17 d and rumen samples were collected between d 19 and 21 at 0700 h, 1000h, 1300 h, 1600 h and 1900 h. Data were analyzed using the Mixed procedure of SAS. Relative to the control treatment (9.9 kg/d), DM intake was 4 to 5% greater (P < 0.001) following CMP supplementation regardless of supplementation frequency. Similarly, average daily gain was greater (7 to 11%, P = 0.01) for CPM supplemented treatments as compared with control (1.04 kg/d) irrespective of supplantation frequency. Rumen fermentation was affected by treatments. Total VFA concentration was greater (P = 0.01) for the every other day supplementation of CMP as compared with control and daily supplementation treatments. Conversely, rumen ammonia concentration was not affected by treatments. The control group had greater acetate and reduced propionate molar proportions that resulted in a 5 to 6% greater acetate:propionate ratio (P < 0.01) as compared with the CMP supplemented groups. Enteric methane production (g/d) was greater for the daily CMP supplementation (P = 0.02) while yield (g/kg daily weight gain) was not affected by treatment. Our results indicated that reduction of protein supplementation frequency improved animal performance without negatively impacting rumen fermentation.

PSII-1 Weaning as prenatal stress: preliminary study on indicators of calf resiliency

Abstract Maternal stressors have been reported to alter fetal development in many species. During pregnancy beef cattle are subjected to different potential stressors, such as weaning their current offspring, as part of beef production practices. The objective of this study was to investigate the relationship between weaning method as a prenatal maternal stress and the effect on offspring resiliency. Multiparous cows were weaned of their calves in the fall of 2022 using either abrupt (A), fenceline (F), or nose-flap (N) weaning methods (n = 30 per group). Calves born from these cows the following spring (2023) were followed for birthweights, morbidity, and mortality. Mean estimated fetal age at exposure was 126 d (range 66 to 219 d) using breed averages for gestational length. Cognitive tests were performed at 2 mo of age using an outdoor arena to continuously monitor calves during 2 min of initial isolation, 2 min exposed to a novel object, and 1 min of exposure to a human in the arena. Tests were performed sequentially, and treatments were balanced across days. Prenatal exposure to A was associated with a 74.8 (2.5 to 2,237.3, P < 0.01) and 21.5 (1.2 to 385.7, P = 0.03) times increase in the odds of calves being stillborn or failure to thrive within 24 h of birth compared with F or N, respectively. There was no difference in morbidity or mortality during d 1 to 60. Birthweights were available on one-half of the calves from each group and showed no statistical difference; however, there was a 4.53 kg numerical difference between A and N groups. Behavioral data from a subset of 36 calves (A = 14, F = 11, and N = 11) was assessed for time spent standing, moving, exploring, duration in the open center vs. perimeter of the arena. There was a tendency for A exposed calves to spend more time in the perimeter after being confronted with a novel object compared with N exposed calves (mean difference of percent of total test time in perimeter from isolation to novel object test: A = 24.0 ± 23.9 %, N = -2.9 ± 22.1 %, P = 0.08). Fenceline exposed calves spent more time moving during initial isolation than either abrupt or nose-flap (69.3 ± 14.7 %, 50.6 ± 11.9 %, and 69.9 ± 17.8 % for A, F, N, respectively (P = 0.01 for A vs F and F vs N). These behavioral and physiological indicators support a potential divergence in survivability and coping mechanisms associated with prenatal exposure to different weaning methods. Future research will evaluate different dimensions of cognitive performance as well as increasing sample size.

72 Environmental impacts associated with the removal of productivity enhancing technologies from three different post-weaning feed management strategies in Saskatchewan: A case study

Abstract The purpose of this research was to examine the use of productivity enhancing technologies (PETs) and post-weaning management on the environmental impacts of beef steers in western Canada. The PETs considered in the current study included ionophores (i.e., monensin, 33 ppm) and hormone implants (i.e., Ralgro, 36 mg zeranol). The production management systems considered were direct finishing (Heavy), confined backgrounding prior to finishing (Medium), and confined and pasture-based backgrounding prior to finishing (Light). The objectives were to model and compare environmental outcomes [greenhouse gas emissions (GHG), ammonia (NH3) emissions, land requirements and water use] using a whole-farm perspective and better understand the environmental footprint of the Canadian beef industry. Compared with natural steers, PETs led to a 10 to 13% reduction in GHG emissions (CO2e kgּ boneless beef-1), a 10 to 32% decrease in NH3 emissions (kg NH3ּּ kg boneless beef-1), a 9 to 22% reduction in land use (haּ kg boneless beef-1) and 12 to 25% decrease in water (m3ּ kg boneless beef-1) use. Direct finishing compared with backgrounded, and 2-stage backgrounded steers reduced GHG by 32% and 39% kg CO2eּ kg boneless beef-1, NH3 emissions by 36% and 52% kg NH3ּ kg boneless beef-1, land requirements by 25% and 73% haּ kg boneless beef-1 and water use by 18% and 51% m3ּ kg boneless beef-1, respectively. Varying post-weaning strategies allows producers to value-add (additional weight through backgrounding) and maximize the use of available feed (grazing). The full environmental impacts of removal of PETs from Canadian beef production must consider a whole-systems approach including economic viability, ecosystem services, as well as consumer demand and social acceptance.

452 Data-driven strategic sustainability initiatives of beef and dairy genetics consortiums: A comprehensive landscape analysis for USA, Brazil, and Europe

Abstract The past two decades have witnessed beef and dairy genetic consortiums implementing data-driven germplasm propagation programs in global cattle systems. These programs optimize for multi-dimensional economic, environmental, and animal welfare related sustainability goals and are driven by consumer demands and shifts in supply chains. To summarize these programs and gain insights into the sustainability journey of industry, we did a comprehensive landscape analysis of the strategic initiatives of key global genetics companies, their germplasm offerings, and data platforms offered in three major cattle producing geographies, namely the USA, Brazil, and Europe. Within these locales, they followed selection index-based genomic and reproductive management strategies for both beef, dairy, and beef-on-dairy production, tailored to relevant market and climatic conditions (Figure 1). While individual traits in selection indices ranged between 40 to 90 traits, all traits could be broadly grouped into three: namely production, longevity, health and reproduction. In the USA, companies like ABS Global, Select Sires, Genex Cooperative, STGenetics, Zoetis, Vytelle offer genomic selection programs encompassing germplasm products, and genetic and production data tracking platforms across the beef, dairy, and beef-on-dairy value chains. These companies have implemented reproductive management programs such as in-vitro fertilized embryo transfer, sexed semen, along with genomic selection with a focus on future replacements based on multi-trait sustainability indices. These initiatives are customized for each of the cow-calf, backgrounding, and feedlot sector of beef production. In dairy, these companies have diversified data-driven production programs customizable to conventional and organic production systems. In Europe, companies like CRV, Viking Genetics, and Alta Genetics prioritize traits related to resource efficiency, animal welfare and environmental impact. Semen companies also offer data management tools tailored to European market requirements, alongside services for on-farm semen production and storage to reduce transportation-related emissions. In Brazil, companies such as ABS Pecplan, CRV Brazil, and Semex Brazil, developed herd management solutions focusing on traits like heat tolerance, tropical environmental adaptability, and disease resistance. The landscape analysis revealed a dynamic industry, evolving to meet sustainability goals and market demands. These enterprises collaborate with stakeholders across the value chain, including producers, policymakers, and industry associations, to scale data-driven production systems that balance profitability and environmental footprint of cattle production. As such, they have positioned themselves to capitalize on the growing interest in sustainable livestock production practices worldwide by aligning scientific and technical strategies with evolving regulatory requirements and consumer demands. The global cattle industry is positioned to venture forward by leveraging niche carbon markets and new marketing channels propelled by emerging principles of environmental, social, and corporate governance. Strategic germplasm and data-tracking platform initiatives by these groups thus become an integral part of the livestock sustainability solution palette and will contribute its share to a climate-neutral Earth by 2050.

93 Ruminal archaea and bacteria metatranscriptomic responses to supplementation in steers fed low-quality forage

Abstract Forage comprises the majority of beef cattle diets globally, and its quality can vary. Supplementation presents a significant opportunity to improve the efficiency of production. Supplementation has been shown to increase ruminally available nitrogen, improve forage utilization, and reduce livestock methane (CH4) emissions. However, corresponding effects of supplementation on gene expression of rumen microbiota, in particular metabolic pathways involved in methanogenesis, have yet to be studied. This study aimed to evaluate the effect of supplement composition before and after feeding on rumen archaeal and bacterial gene expression in steers consuming a low-quality forage diet. Ruminal samples were collected from five ruminally cannulated Angus steers [body weight (BW) = 375 ± 45 kg] used in a 4 × 4 Latin square fed a basal diet of King Ranch Bluestem Hay (3.5% CP, 73% NDF), and one of four isonitrogenous (130 mg N/kg BW) supplements. Steers provided the two most divergent supplements (2% starch, 43% CP; 56% starch, 21% CP) were used for metatranscriptomic analysis. Rumen fluid samples were collected via rumen cannula 0 and 4 h post-feeding. Total RNA was extracted and sequenced. Differentially expressed genes (DEGs) were identified and functionally annotated. Pathway enrichment analysis was completed to determine enriched pathways (broad metabolic pathways) and modules (specific metabolic reactions). Only main effects are presented in this abstract. Archaeal hydrogenotrophic and methylotrophic methanogenesis reactions and tryptophan biosynthesis reactions were upregulated in the 2% starch supplement (P < 0.05). The 2% starch supplement resulted in fewer bacterial total upregulated carbohydrate-active enzymes compared with the 56% starch supplement (957 vs. 1,695 DEGs, respectively; P < 0.05), and an increased proportion of cellulose and hemicellulose-specific enzymes (35 vs. 29%, respectively; P < 0.05). The 56% starch supplement resulted in upregulation of the bacterial 3-Hydroxypropionate bi-cycle reaction (P < 0.05). Collection time exerted a larger effect than supplement composition on both archaeal and bacterial gene expression, with 83% and 63% of DEGs associated with time, respectively (P < 0.05). Archaeal hydrogenotrophic methanogenesis and carbon metabolism were upregulated 4 h post-feeding. In addition, 1,704 bacterial carbohydrate-active enzymes were upregulated 4 h post-feeding, as compared with 975 upregulated at 0 h (P < 0.05). However, these differences in DEGs did not correlate with significantly enriched pathways of bacterial carbohydrate metabolism. These findings demonstrate improvements to low-quality forage utilization, through CP and starch supplementation, can be correlated to relevant changes in gene expression of rumen microbiota. Furthermore, they demonstrate that supplementation influences the expression of methanogenesis reactions, suggesting an opportunity to affect CH4 production. Additional studies quantifying forage utilization, rumen microbiota gene expression and CH4 production are needed to further optimize supplementation strategies for improved efficiency of beef production whilst maintaining or reducing its carbon footprint.

198 Discovery of key functional SNP markers associated with feed efficiency in beef cattle

Abstract Beef production contributes to approximately 2.4% of the total Greenhouse Gas emissions in Canada. Improving beef cattle feed efficiency (FE) may lead to improved energy partitioning and resource use, thereby improving the sustainability of the beef industry. Our objective was to identify differentially expressed key regulatory genes and associated novel functional SNP markers linked to FE in Canadian beef cattle using RNA-Sequencing (RNA-Seq) of rumen tissue collected from 48 beef cattle [n = 16 Angus, n = 16 Charolais, n = 16 Kinsella (Composite Hybrid including Angus, Charolais, Galloway, Hereford, Holstein, Brown Swiss, and Simmental)] selected for extreme FE phenotypes. In total, 11 key regulatory genes (MYH1, MYL2, MYLPF, TNNC2, EIF4B, RHOD, TCEANC, CKM, ENSBTAG00000040518, SERPINB2, and USP43) were significantly differentially expressed (DE) between extreme Residual Feed Intake (RFI) groups (low-RFI n = 8, high-RFI n = 8 per breed) using CLC Genomics Workbench (FDR < 0.05; |FC| >2). Using an optimized RNA-Seq variant calling pipeline using STAR and BCFtools, a total of [total (unique to low-RFI, unique to high-RFI)] 75 (36, 39), 78 (42, 36), and 53 (35, 18) uniquely fixed functional SNPs were located within coding regions of these 11 functional candidate genes, in low- and high-RFI animals in the Angus, Charolais, and Kinsella breeds, respectively. Considering all functional SNPs uniquely identified in low- or high-RFI groups for all breed comparisons, the majority of SNPs were identified in MYH1, EIF4B, and SERPINB2 genes, which function together in metabolically demanding biological processes (P < 0.05) related to muscle contraction, muscle system, and muscle filament function processes. Additionally, EIF4B and SERPINB2 genes were found to have a role in signaling pathways that coordinate cell growth and immune function, respectively. Using RNA-Seq to identify key regulatory genes and associated functional SNPs linked to FE may uncover important genetic markers that influence the regulation of FE in beef cattle.

347 Quantifying phenotypic and genetic variation for cow fertility phenotypes in American Simmentals using total herd reporting data

Abstract Inefficiencies in reproduction are the largest drivers of loss in United States beef production. Nearly all reproductive traits are at least modestly heritable, making genetic selection and improvement possible over the long term. Cow-centric reproductive traits present unique challenges, as they are not expressed in male animals and will not be observed until later in the productive life of a female, if at all. This makes cow-centric fertility traits ideal candidates for selection with Expected Progeny Differences (EPDs). We used a commercially generated dataset from the American Simmental Association (ASA) to explore the phenotypic and genetic variation in these traits. The dataset comprised Total Herd Enrollment (THE) records, which required unbiased reporting of enrollment, calving, and disposal for 303,158 females (132,403 cows and 170,755 heifers). Using the THE data, we calculated three continuous and two discrete traits that are indicators of heifer and cow fertility and rebreeding ability. These traits were: 1) calving date (calving date of the cow relative to the start of the calving season), 2) calving interval (days between calves), 3) first calving interval (calving interval observation between the first and second calving record for a female), 4) heifer pregnancy (did the animal calve as 2-yr-old?), and 5) discrete early calving (did animal calve in the first 30 d of the calving season?). We observed a significant difference in calving date in mature cows that calved in the first 30 d of the calving season of their contemporary group as heifers compared with those that calved later (Table 1). Early calving heifers averaged a nearly 10 d sooner calving date throughout their productive lives compared with those that calved after 30 d as heifers (29.9 d vs. 40.2 d, P-value < 0.01). We used a combined pedigree and genomic approach, implemented in GIBBSF90+, to estimate genetic, environmental, and permanent environmental variance components. We estimated heritabilities of 0.24 (± 0.037215) for heifer pregnancy, 0.06 (± 0.009265) for calving date, 0.07 (± 0.015451) for discrete early calving, 0.04 (± 0.003954) for calving interval, and 0.04 (± 0.009604) for first calving interval. We observed positive phenotypic and genetic correlations between these traits, ranging from 0.01 to 0.96 (Table 2). This work provides an extensive population survey of phenotypic trends in reproductive performance and management in a large seedstock population. The heritable nature of the inspected traits motivates further work in understanding their genetic architectures and how they are affected by heterosis in crossbreeding programs.

263 Public perspectives of calf handling: A survey of Canadians

Abstract In North American beef production handling and restraint of young calves is integral to animal welfare and management practices. This study used a mixed method approach to gather public perceptions of three handling and restraint methods common on beef operations in western Canada (RW - Roping and Wrestling, NF – roping and NordForks, and TT – Tilt Table). Canadian participants (n = 551) recruited by CloudResearch to represent the national demographics participated in an online survey that included videos of each handling method to ascertain preferences and acceptability. Prior to watching the videos, participants were given industry information about handling and restraint or generic information regarding hay as a control information statement within the topic of agriculture. The survey also collected information about knowledge of the beef industry, animal welfare, and empathy toward animals. The reasons for preferences were described as presence of a perceived positive attribute and absence of a perceived negative for most preferred methods, and inversely when explaining least preferred method. The findings focused on calf’s experience, perception of handler actions, and pragmatic balancing of handler needs and a good life for the calf. Methods were rated as more acceptable for participants that ate meat consistently, knew more about the beef industry, and, to a lesser extent, if the individual had a lower animal empathy score (Table 1). Acceptability was not affected by providing information about the practices; however, information about handling and restraint did elicit more pragmatic reasoning. Most participants preferred TT over NF and RW (P < 0.001) and found TT more acceptable as well (P < 0.001). The TT was the most preferred method due to calf experience and human handling, notably the absence of dragging a calf, which was predominant in why participants selected NF or RW as their least preferred method. Consistency of themes highlights that the Canadian public has a fundamental expectation of value for the quality of life of the calf, humane handling, and pragmatism which aligns with beef sustainability initiatives and represent points of connection for building trust between industry and the public.

485 Impact of annual and perennial forage systems on forage biomass and quality, steer performance, and enteric methane emissions

Abstract Beef producers require forage options that provide adequate yield and high nutritive value, optimizing the production and sustainability of grazing operations. Few multiple year studies within Canada compare novel perennial and annual grass legume blends under grazing. This study evaluated the effects of perennial and annual forage systems on forage biomass and quality, grazing animal performance, and enteric emissions. Forage treatments included 1) AC Success hybrid bromegrass (Bromus riparius Rehm. × Bromus inermis Leyss.) + PS3006 alfalfa (Medicago sativa L.; HBG-ALF), 2) AC Armada meadow bromegrass (Bromus riparius Rehm.) + AAC Mountainview sainfoin (Onobrychis viciifolia Scop.; MBG-SF), 3) AC Hazlet fall rye (Secale cereale L.) + Frosty berseem clover (Trifolium alexandrinum L.; FR-CLOV), and 4) Winfred forage brassica (Brassica oleracea L.× Brassica rapa L.) + Gorilla forage brassica (Brassica napus L.) + 4010 pea (Pisum sativum L.) + CDC Austenson barley (Hordeum vulgare L.; BR-PE-BRAS). Yearling beef steers [n = 120, body weight (BW) = 397 ± 10 kg] were randomly allocated to 1 of 4 replicated (n = 3) forage systems for an average of 65 d grazing period amongst the 12 paddocks. Dry matter yield (DMY) was similar (P = 0.33) between BR-PE-BRAS (2,170 kg/ha) and HBG-ALF (1938 kg/ha), which were greater (P < 0.0001) than both MBG-SF (1030 kg/ha) and FR-CLOV (700 kg/ha) systems. Total digestible nutrient content (TDN) of FR-CLOV (63.6%) and BR-PEA-BRASS (62.0%) was greater (P < 0.0001) than both MBG-SF (51.7%) and HBG-ALF (49.3%) forages. Crude protein (CP) was greatest in FR-CLOV (15.2% P = 0.0012) intermediate in BR-PEA-BRASS (10.0%) and HBG-ALF (8.5%), and least in MBG-SF (6.6%). Steer performance was greatest when grazing HBG-ALF (87 kg/ha) paddocks, which was similar (P = 0.31) to FR-CLOV (62 kg/ha) and similar (P = 0.10) MBG-SF (51 kg/ha), but greater (P = 0.01) than BAR-PEA-BRASS (26 kg/ha). Enteric methane concentration from steers was the least when grazing BR-PE-BRAS (19.7g/kg DMI), followed by FR-CLOV (22.4g/kg DMI), MBG-SF (23.4g/kg DMI) and finally HBG-ALF (28.1g/kg DMI). In summary, BR-PE-BRAS and HBG-ALF forage systems provided the greatest DMY, while steer average daily gain (ADG) grazing HBG-ALF forage outperformed steers on BR-PE-BRAS paddocks. Forage energy and protein was greater in annual forage systems FR-CLOV and BR-PE-BRAS, compared with perennial forage systems. Enteric methane levels were the lowest in the steers grazing BR-PE-BRAS forage.

161 Development, deployment, and calibration of genomic selection tools to improve performance traits for Canadian beef cattle

Abstract Genomic selection has the potential to accelerate the genetic improvement rate for difficult/expensive to measure traits such as feed efficiency and fertility traits in beef cattle. To develop genomic selection tools for Canadian beef cattle, we collected or sourced phenotypic data of feed efficiency along with other traits including carcass merit, female feed intake and fertility related traits, and their genotypes from both research and commercial herds. The phenotypic data were consolidated and recorded for contemporary groups, leading to the development of data sets including 11,292 beef cattle with residual feed intake, dry matter intake, average daily gain, metabolic body weight, 7,299 to 8,081 cattle with carcass merit traits, and 1,802 to 2,792 cows with feed intake and fertility traits after quality controls. Genotype data of the animals from various single nucleotide polymorphisms (SNP) panels were merged to the same allele format of 50K, and then imputed to 770K SNPs, and eventually to whole genome sequence variants. The refined Canadian beef cattle data sets have not only allowed us to investigate genetic architectures of the beef performance traits but also enabled the development of genomic selection tools including molecular breeding values and multiple trait selection indexes with a moderate to moderately high accuracy for the traits through a cross-validation of within reference data set. The genomic selection tools have been successfully deployed to over 10,415 breeding candidates submitted by Canadian beef producers through multiple demonstration projects. The average accuracy of the molecular breeding values and multiple trait selection index of the commercial beef cattle ranged from 0.38 to 0.49 for feed efficiency and carcass merit traits, and from 0.26 to 0.38 for female feed intake and fertility traits. Current research is focusing on calibrating the genomic selection tools with larger data sets and with more advanced genomic prediction methods.

The Overall Situation of the Livestock and Evaluation of the Quantity of Beef Production in Batna City (Algeria)

Background: This study aims to determine the evolution of beef production during the last five years (2019-2023) in Batna city (Algeria) Methods: For the realization of this work we carried out an investigation at the municipal slaughterhouse of the city. During this investigation, we also took slaughter data. These include the weight of the carcasses and the classification of the slaughterhouse according to the categories of animals slaughtered. Moreover, a study was conducted to gather data from the Directorate of Agricultural Services (DSA) and the Ministry of Agriculture and Rural Development (MADR) regarding the number of cow herds in the studied city. The goal of this strategy is to comprehend the general state of the city’s livestock, including those destined for fattening and slaughter. Result: The animals intended for slaughter are mainly male cattle; of the young bulls and calves, the females admitted are cull dairy cows ( greater than 8 years). The results of this investigation showed that the beef production has experienced a remarkable drop from 1262560 kg in 2019 to 473430 kg in 2022, a slight change observed in 2023 but which still remains weak.