Sustainable food systems provide food security while stewarding economic, social, and environmental bases in ways to meet future generations' needs. Sustainable food systems encompass the health of animals, people, and ecosystems. Healthy and productive ruminants can produce meat and milk products with fewer resources, and consequently, often fewer greenhouse gas emissions are produced. Ruminant livestock faces the dual challenge of being impacted by and contributing to climate change, while also experiencing increased demand for ruminant meat and milk products due to growing global population and increased incomes. This challenge presents different ways forward depending upon solutions and how one values certain aspects of sustainability, ranging from simply building upon past improvements in ruminant agriculture to dramatic reductions in ruminant livestock populations. Better understanding the concerns with ruminant's role in sustainable food systems is important, as is understanding the different viewpoints and interpretation of evidence both for and against ruminant agriculture. This review provides a brief overview of some of the key issues related to the role ruminant animals play in sustainable food systems, including greenhouse gas emissions, feed‐food competition and land use, and human nutrition. The review also highlights how improved animal health outcomes can enhance ruminants' role in sustainable food systems. Ultimately, ruminants make unique contributions to human flourishing via providing nutrition, livelihoods, and ecosystem services from forage resources and grassland landscapes. However, the status quo is unlikely to meet the challenges of the coming decades, thus investing in research and development into sustainable ruminant systems is required.

Data from three experiments was analyzed to determine the number of visits and days to assess gas flux (CH₄, CO₂, and O₂), dry matter intake (DMI), and average daily gain (ADG) from growing animals under confined conditions. In experiment 1, 213 animals (461 ± 91 kg initial body weight [BW]) were fed a backgrounding diet and evaluated for 60 d. In experiment 2, 169 steers (488 ± 37 kg initial BW) were fed a finishing diet and assessed for 70 d. In experiment 3, 64 steers (514 ± 42 kg initial BW) were fed a finishing diet and evaluated for 80 d. In each experiment, animals were placed in one pen with one Greenfeed and five SmartFeeds to collect gas flux and feed intake simultaneously. Gas flux was analyzed using data from 161 animals from the three experiments with 100 visits for 2 or more min or 3 or more min. Also, metabolic heat production (MHP) was estimated using the individual gas flux. Daily DMI was calculated as the daily feed intake corrected by the dry matter concentration. ADG was computed as the slope of the regression of the shrunk BW (96% BW) throughout each of the experimental periods. The mean gas flux and MHP were estimated for increasing or decreasing 5-visit intervals starting with the first or the last 5 visits and increasing or decreasing until the full 100-visit dataset was utilized, respectively. Intervals of DMI were estimated for increasing or decreasing 5-d intervals starting with the first or the last 5 d and increasing or decreasing until the end of the experimental period, respectively. Intervals of ADG were estimated for increasing or decreasing measurement period intervals until the end of the experimental period, respectively. Pearson and Spearman correlations were computed between the maximum visits or days and each shortened visit or day interval. The minimum number of visits and days was determined when correlations with the total visits were greater than 0.95. The results indicated that the minimum number of visits needed to quantify CO₂, O₂, and MHP accurately was 40, while CH₄ was 60. A visitation length of 2 min or more or 3 min or more did not modify the gas flux determination. Thus, based on the average daily visitation in these experiments, gas flux data could be collected for 25 d. Additionally, the required days to determine DMI was 30, while ADG could not be assessed in a shorter than 60-d period. The evaluation of sustainable practices and the selection of efficient animals requires assessing gas flux (CO₂, CH₄, and O₂) and animal performance (e.g., dry matter intake [DMI] and average daily gain [ADG]). Data from three experiments were used to determine the minimum number of visits and days to determine gas flux, DMI, and ADG from growing animals in confined conditions. The results indicated that the minimum number of visits needed to quantify CO₂ and O₂ accurately was 40, while CH₄ was 55. A visitation length of 2 min or more or 3 min or more did not modify the gas flux determination. Thus, based on the average daily visitation in these experiments, gas flux data could be collected for 25 d. Additionally, the required days to determine DMI was 30, while ADG could not be assessed in a shorter than 60-d period.

The purpose of this study was to: (1) understand heat mitigation strategies currently used and recommended by feedyard operators, veterinarians, and nutritionists, (2) understand their perceptions of heat mitigation strategies related to cattle health, performance, welfare, and carcass quality, (3) quantify the frequency of extreme heat events, and (4) understand industry needs associated with heat stress mitigation strategies. An online survey was shared via 11 industry association listservs. Descriptive statistics were performed on 56 responses (n = 22 operators, 26 veterinarians and eight nutritionists). Thematic analysis was performed on free-response questions. Sixteen (72.7%) operators, 23 (88.5%) veterinarians and eight (100%) nutritionists utilized at least one heat mitigation strategy. “Changing processing and shipping hours” (n = 42, 75%) had the most “strongly agree” responses when asked about strategy effectiveness. The majority of respondents agreed that heat stress negatively impacts cattle health, performance, and welfare (Mean ± SD; ≥7.8 ± 2.6 for all roles). Forty-two (75%) respondents experienced cattle death loss from extreme heat events. Thematic analysis indicated that respondents perceived pen infrastructure and water/feed management as important considerations for better mitigating heat stress impacts. When asked what resources would be helpful, respondents indicated research and data regarding the effectiveness of various strategies.

The objective of this experiment was to demonstrate the effectiveness of a commercially available tannin product (Silvafeed^® ByPro, 70% tannic acid) as an enteric methane (CH₄) mitigation and preventative animal health strategy in Holstein heifers (BW = 219 ± 17 kg; 9 mo), reared under organic production system requirements. Twenty heifers were randomly assigned to one of four commercial tannin supplementation treatments as follows: 0% (0 g/hd/d; CON), 0.075% (~5 g/hd/d; LOW), 0.15% (~10 g/hd/d; MED), and 0.30% (~21 g/hd/d; HIG) of dry matter intake (DMI). Heifers received their treatment in individual animal feeding stanchions and were fed a basal total mixed ration (TMR) through four SmartFeed Pro intake measurement bunk systems (C-Lock Inc., Rapid City, SD, USA) for 45 d. An automatic head chamber system (AHCS; i.e., GreenFeed, C-Lock Inc., Rapid City, SD, USA) was used to continuously evaluate enteric CH₄ production. No effect was observed among the treatments for CH₄ emissions (p ≥ 0.55), animal performance (p ≥ 0.38), or oxidative stress biomarker concentration (p ≥ 0.55). Superoxide dismutase (SOD) and reduced glutathione (GSH) concentrations exhibited a linear response to increasing tannin dose (p = 0.003), indicating a potential tannin effect on the antioxidant status of dairy heifers. This observation may encourage future tannin research relating to animal health, which may be of particular interest to organic dairy systems. The results of this study suggest that tannin supplementation at 0%, 0.075%, 0.15%, and 0.30% of DMI, did not alter CH₄ emissions, animal performance, or oxidative stress biomarker concentration in organic Holstein heifers when assessed under an on-farm research approach. Further, the results of this study affirm the challenges associated with on-farm research and the development of climate-smart strategies that are capable of mitigating climate impacts in less controlled environments under standard working conditions.

There is limited information regarding the effect of beef cattle enteric methane (CH4) classification during the backgrounding and finishing phases and the impact of using metabolic modulators such as growth-promoting implants. This experiment aimed to determine how CH4 and residual CH4 emission (RME) classification impact gas flux and whether implanted or non-implanted growing steers maintain the same CH4 and RME classification during the backgrounding and finishing phases. A total of 46 Angus steers (approximately 8 mo of age and 244 ± 11.1 kg of initial body weight [BW]) were enrolled. During the finishing phase, 23 steers were implanted, while 23 did not receive an implant. Individual animal growth performance and gas flux (CH4 and carbon dioxide [CO2] production and oxygen [O2] consumption) were determined during the backgrounding and finishing phases. In addition, RME was individually determined using metabolic BW and dry matter intake (DMI). In the backgrounding and finishing phases, steers were ranked in ascending order according to their CH4 production (g/d), CH4 yield (g/kg of DMI), CH4 intensity (g/kg of average daily gain), and RME. Consequently, steers were classified as low, medium, and high emitters based on the quartile distribution. Then, gas flux was analyzed using a completely randomized design for each phase. The relationship between the initial CH4 and RME classification during the backgrounding and the subsequent classification during finishing was analyzed using Fisher’s exact test. Steers classified as low CH4 or RME had lower (P < 0.05) CH4 production than high emitters during the backgrounding and finishing phases. The production of CO2 varies among classification groups regarding the growing phase and the use of growth-promoting implants. The consumption of O2 was lower (P < 0.05) in steers classified as low CH4 emitters during the backgrounding but not (P > 0.05) during the finishing phase. In addition, between 35% and 83% of the steers re-ranked according to CH4 and RME classification from the backgrounding to the finishing phase. In conclusion, the classification of growing steers using CH4 production, yield, intensity, or RME results in animals with lower CH4 production during the backgrounding and finishing phases. However, CH4 or RME classification should be conducted in each phase because growing steers re-ranked when changing from the backgrounding to the finishing phase.