Heat Stress Mitigation Strategies in Feedyards: Use, Perceptions, and Experiences of Industry Stakeholders

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.

Bunk space requirements for growing beef cattle limit-fed a high-energy corn and corn co-product diet

Bunk requirements for optimal growth performance of growing calves limit-fed high-energy corn and corn co-product diets have not been widely evaluated. Three-hundred eighty-five crossbred steers (initial body weight = 215 ± 25 kg) were purchased in Texas, transported to the Kansas State Beef Stocker Unit, and weighed at arrival. Steers were stratified by body weight and randomly assigned to 1 of 28 pens containing 12 to 14 head. Within block, pens were randomly assigned to one of four bunk allotment treatments: 25.4, 38.1, 50.8, or 63.5 cm of bunk per head for a 58-d receiving period. Calves were fed at 0700 h once daily at 1.8% of bodyweight (dry matter basis) from February 2 to March 13, 2021; thereafter the daily feed allotment was increased to 2.0% of bodyweight. The diet contained (dry matter basis) 39.5% dry-rolled corn, 7.5% supplement, 40% wet corn gluten feed, and 13% prairie hay. Steers were individually weighed on days 29 and 58 and pen weights were measured weekly to determine feed offered for the following week. Body weights on days 29 and 58, dry matter intake, or gain-to-feed ratio during the receiving period did not differ (P ≥ 0.34) between treatments. During the first 29 d, average daily gain (ADG) increased linearly as bunk space increased (P = 0.03); however, no treatment effects were observed thereafter. In addition, ADG standard deviation from days 0 to 29 responded quadratically (P = 0.05) where ADG standard deviation tended to be greater in the 38.1-cm allotment and was greater in the 50.8-cm allotment compared to the 25.4-cm allotment (P = 0.07 and P = 0.04, respectively). Bunk score tended to decrease linearly as bunk allotment decreased (P = 0.06). Following the receiving period, steers were blocked by bunk treatment and randomly assigned to 1 of 18 pastures. Steers were grazed for 90-d from May to August at a targeted stocking density of 280 kg live-weight ˖ ha^–1. During the grazing season, ADG increased linearly with reduced (P < 0.01) bunk allotment; however, body weights did not differ (P = 0.91) between bunk treatments at the completion of the grazing period. In addition, overall total body weight gains and ADG from the receiving and grazing periods did not differ (P > 0.57) between bunk treatments. We interpreted our data to suggest that bunk space allotments of 25.4 to 63.5 cm per head had minimal impact on growth performance during a 58-d receiving period and did not affect final body weights following a 90-d grazing season.

Impacts of a post-transport/pre-processing rest period on the growth performance, anthelmintic efficacy, and serum metabolite changes in cattle entering a feed yard

A total of 80 crossbred, high-risk heifers (initially 250 ± 4.2 kg BW), were transported from an Oklahoma City, Oklahoma sale barn to the Kansas State University Beef Cattle Research Center. Cattle were unloaded and randomly placed into one of four receiving pens and provided ad libitum hay and water. Each pen was randomly assigned to one of the four rest times before processing: (1) immediately upon arrival (0); (2) after a 6-h rest period (6); (3) after a 24-h rest period (24); and (4) after a 48-h rest period (48). After all cattle were processed, heifers were allotted into individual pens with ad libitum access to a receiving ration and water. Heifers were weighed individually on d 0, 7, 14, 21, 28, and 35 to calculate average daily gain (ADG). Feed added and refusals were measured daily to determine dry matter intake (DMI). A fecal egg count reduction test and analysis of blood serum metabolites were also conducted. All data were analyzed using the GLIMMIX procedure of SAS (v. 9.4, Cary, NC) with individual animal as the experimental unit. Processing time did not impact (P > 0.05) heifer BW or ADG. From d 0 to 35, DMI decreased linearly (P = 0.027) as rest time increased. The number of days for heifers to reach a DMI of 2.5% BW was linearly increased (P = 0.023) as rest time increased. There was no evidence of differences (P ≥ 0.703) among rest times for feed efficiency. While morbidity did not differ between treatments (P > 0.10), mortality increased linearly (P = 0.026) as the time of rest increased. A significant processing time × day interaction (P < 0.0001) was observed for the prevalence of fecal parasites, where the percentage of positive samples was significantly lower 14-d after anthelmintic treatment, regardless of the processing time. Serum IBR titer for heifers processed at either 0 or 6-h upon arrival was significantly higher (P < 0.01) on d 35 compared to d 0. Heifers processed after a 48-h rest period had significantly higher glucose values (P < 0.01) on d 0 compared to heifers processed at 0, 6, or 24-h. In summary, rest time prior to processing did not impact receiving calf growth performance. A 6-h rest period upon arrival appeared to be most beneficial to DMI. Anthelmintic treatment at processing reduced the parasitic load in heifers processed at all times. Vaccine titer did not increase after initial processing in heifers processed 24- or 48-h after arrival, indicating the seroconversion of IBR antibodies during the longer rest period.

Quality of Plant-Based Ground Beef Alternatives in Comparison with Ground Beef of Various Fat Levels

The objective of this study was to compare the quality characteristics of current plant-based protein ground beef alternatives (GBA) to ground beef (GB) patties of varying fat percentages. Fifteen different production lots (n = 15/fat level) of 1.36 kg GB chubs of 3 different fat levels (10%, 20%, and 27%) were collected from retail markets in the Manhattan, KS area. Additionally, GBA products including a foodservice GBA (FGBA), a retail GBA (RGBA), and a traditional soy protein–based GBA (TGBA) currently available through commercial channels were collected. Consumers (n = 120) evaluated sample appearance, juiciness, tenderness, overall flavor liking, beef flavor liking, texture liking, and overall liking. Additionally, samples were evaluated for color, texture profile, shear force, pressed juiciness percentage (PJP), pH, and fat and moisture percentage. All 3 GB samples rated higher (P &lt; 0.05) than the 3 GBA samples for appearance liking, overall flavor liking, beef flavor liking, and overall liking by consumers. Similar results were found with trained sensory panelists, which rated the GBA as less (P &lt; 0.05) juicy, softer (P &lt; 0.05), and lower (P &lt; 0.05) for beef flavor and odor intensity and higher (P &lt; 0.05) for off-flavor intensity than the GB. Moreover, the GBA had less (P &lt; 0.05) change in shape through cooking and a lower (P &lt; 0.05) percentage of cooking loss and cooking time than the GB. Also, the GBA all had lower (P &lt; 0.05) shear force and PJP values than the GB. The color of the GBA differed (P &lt; 0.05) from the GB, with the GB samples being more (P &lt; 0.05) red in the raw state. These results indicate that the GBA provide different eating and quality experiences than GB and should thus be considered as different products by consumers and retailers.

PSI-5 Effects of Bacillus and Lactobacillus in Milk Replacer on Calf Health

Stress in pre-ruminant calves can impact the functionality of the gastric epithelial lining, thereby impacting calf health during times of stress and potentially later in life. To mitigate this challenge, milk replacers frequently contain antibiotics to reduce the proliferation of harmful bacteria that may result in disease in pre-ruminant, milk supplemented calves. However, there is consumer and regulatory pressure to reduce the reliance on these antimicrobials and evaluate alternatives, such as probiotics, that may shift gut bacterial populations without impacting potential antimicrobial resistance. The objective of this study was to determine if supplementing calves with Lactobacillus and Bacillus species in milk replacer impacts pre-ruminant calf health. The project included 44 calves (50% Angus/50% Holstein) in a randomized complete block design, with calf serving as the experimental unit and age serving as a blocking factor. Calves were fed twice daily one of two treatments: 1) milk replacer with Lactobacillus and two Bacillus species at a total rate of 1.25 x 10^9 cfu/head/day; or 2) non-treated milk replacer. There were 22 replicates per treatment. To determine health status, calves were scored daily based on health indicators for fecal consistency or eye, nose, or ear normality. Health scores were ranked from 0 to 3, with 0 representing normal and 3 signaling severe symptoms, such as bilateral eye or nasal discharge, ear droop, or watery feces. Statistical analysis was performed using the GLIMMIX procedure of SAS. Overall, there was no evidence (P &gt; 0.05) that Lactobacillus and Bacillus inclusion impacted any measured health parameter. Notably, approximately 50% of calves had fecal scores indicating some level of watery stool, but this was not impacted (P &gt; 0.05) by probiotics. In summary, the inclusion of probiotics in calf milk replacer did not appear to impact calf health in the first 30 days.

47 Effects of Lactobacillus and Bacillus Probiotics on Pre-ruminating Calf Growth Performance and Efficiency

Lactobacillus and Bacillus probiotics may serve as an alternative to antibiotics in milk replacer for pre-ruminant calves by altering gastrointestinal microflora to prevent the proliferation of harmful bacteria. However, there are limited studies evaluating their impact on calf growth and efficiency. The objective of this trial was to discover the impact of probiotic-containing milk replacer on pre-ruminating calf growth performance. A total of 44 pre-ruminant calves (50% Angus/50% Holstein, average weight 39.3 kg + 7.5 kg) were fed milk replacer with either no probiotic or 1.25x10^9 colony forming units/head/day of a probiotic blending containing Lactobacillus and two different Bacillus species (Church & Dwight Animal Nutrition (Princeton, NJ). Calves were blocked by age and randomly assigned within block to one of two treatments in a randomized complete block design. Calf was the experimental unit, with 22 calves per treatment. Calf weight and hip height was measured on d 0 and 30 to calculate average daily gain (ADG) and average growth per day. Calves were offered 1.36 kg milk replacer [15% dry matter (DM)] twice daily and up to 0.5 kg starter feed (88% DM) once daily. Refusals were recorded to calculate average daily intake and gain to feed ratio (G:F). Initial weight differed (P = 0.020) between treatments, and was therefore used as a covariate in all response criteria. Calves fed milk replacer with probiotic had greater (P &lt; 0.05) ADG (0.53 vs. 0.42 kg/d, respectively) and G:F (0.50 vs. 0.41, respectively) than those fed the control. There was no evidence (P &gt;0.05) that probiotic inclusion impacted hip height on d 30 or daily intake. In summary, Lactobacillus and Bacillus probiotic inclusion in milk replacer improved calf growth performance without impacting intake. Subsequent research is warranted to elucidate mode of action and evaluate impact relative to an antibiotic-containing positive control.

PSI-6 Effects of rest period prior to processing on vaccine response and blood metabolites in feedlot heifers

It is common for feedyards to rest cattle after transport and prior to administration of their receiving vaccinations in an attempt to minimize transport stress and optimize vaccine efficacy and subsequent growth and performance. This study aimed to test how time of rest after feedlot heifer arrival impacts vaccine titer and blood metabolites indicating cattle health. Eighty mixed-breed heifers (250 ± 4.2 kg BW) were purchased at live auction in Oklahoma City, OK and transported to the Kansas State University in Manhattan. Heifers were allotted in a completely randomized design to one of four treatments processed at 0, 6, 24, or 48 hours after arrival. At the time of processing (d 0) and again on d 35, serum samples were collected and analyzed for infectious bovine rhinotrachitis (IBR) titer, large animal chemistry panel, and hepatic profile by the Kansas State Veterinary Diagnostic Laboratory. There were time × treatment interactions (P &lt; 0.02) for serum IBR titer, glucose, urea nitrogen, and bicarbonate. Specifically, heifers had greater (P &lt; 0.05) IBR titer on d 35 than d 0, as expected because they were vaccinated upon arrival. Upon arrival, cattle held for 48 hours prior to processing had significantly greater (P &lt; 0.05) glucose than those held for 24 hours (108 vs. 68 mg/dL, respectively), with no differences in processing treatment by d 35. Urea nitrogen levels in cattle held for 6, 24, or 48 hr prior to processing were greater (P &lt; 0.05) than those held for 0 hours on d 0 or for any length of time by d 35. Finally, cattle held for 0 or 48 hr prior to processing had lower (P &lt; 0.05) bicarbonate levels on d 0 than those held for 6 or 24 hours by d 35. These data show that while initial rest may be helpful to normalize blood metabolites, cattle should be placed within 24 hours of arrival. However, most blood metabolite levels normalize within 35 days.

PSI-5 Effects of rest period prior to processing on anthelmintic response during the receiving period in feedlot heifers

A major stressor affecting feedlot cattle performance is transportation. Knowing when to process cattle and how much rest to provide prior to processing may improve cattle health and response to processing, such as anthelmintic administration. The goal of this project was to determine the impact of time of rest prior to initial processing on parasite prevalence during the receiving period. Eighty mixed-breed heifers (250±4.2 kg BW) were purchased at live auction in Oklahoma City, OK and transported to the Kansas State University Beef Cattle Research Center in Manhattan. Heifers were allotted in a completely randomized design to one of four treatments processed at 0, 6, 24, or 48 hours after arrival. At processing (d 0), fecal samples were collected, and cattle were subcutaneously injected with 1.0 ml/50 kg BW moxidectin (Cydectin®, Bayer Animal Health, Shawnee Mission, KS) and orally dosed with 1.0 mL/50 kg BW oxfendazole (Synanthic®, Boehringer Ingelheim, St. Joseph, MO). Fecal samples were collected again on d 14. Fecal samples were analyzed by the Kansas State University Veterinary Diagnostic Laboratory for qualitative and quantitative fecal float. Time of processing did not impact (P &gt; 0.05) any measured response criteria. On d 0, there was a high prevalence of fecal parasites, which was significantly reduced by d 14 (94.5% vs. 23.1% of cattle with detected fecal parasites on d 0 vs. 14, respectively). On d 0, semi-quantitative density showed the highest concentration of strongyle and eimeria parasites, which were significantly reduced (P &lt; 0.05) by d 14 (315 and 155 vs. 2 and 6.5 eggs/g of feces detected for strongyle vs. eimeria, respectively). In summary, time of rest prior to processing had no detected impact on anthelmintic response, but the dual injection/oral protocol used in this experiment was highly effective at reducing parasite levels within 2 weeks of administration.

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57 Effects of rest period prior to processing on growth and performance during the receiving period in feedlot heifers

Cattle feeders work to decrease the severity of transport stress. The objective of this experiment was to determine how the time of rest prior to processing impacts subsequent performance in feedlot heifers during the receiving period. Eighty mixed-breed heifers (250 ± 4.2 kg BW) were purchased at live auction in Oklahoma City, OK and transported to the Kansas State University Manhattan. Heifers were allotted in a completely randomized design to one of four treatments, then processed at 0, 6, 24, or 48 hours after arrival. After all cattle were processed, they were placed in individual pens, where daily DMI, refusals, and health outcomes were evaluated twice daily. Cattle were individually weighed on d 0, 14, and 35. Data were analyzed using the GLIMMIX procedure of SAS (v. 9.4, Cary, NC). Time of processing did not impact (P &gt; 0.10) heifer body weight or ADG. Overall, there was a linear inverse relationship between DMI and time at rest (P = 0.027) from d 0 to 14. The same pattern was observed overall, from d 0 to 35 (P = 0.027). Time of rest prior to processing impacted (P = 0.038) the proportion of heifers that reached a target of 2.5% DMI per BW by 14 days after arrival (25, 60, 53, and 24% of cattle with 0, 6, 24, or 48 hours of rest, respectively). While G:F and morbidity did not differ among treatments (P &gt; 0.10), mortality increased linearly (P = 0.026) with increasing time of rest. This study suggests that allowing feedlot heifers to rest after arrival for more than 24 hours before processing may negatively affect subsequent DMI, but without substantially altering body weight or ADG in calves fed in individual pens; additional research in traditional feedlot group-housed pens and environment is warranted to further evaluate these effects.

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