MITIGATING HEAT STRESS IN GRAZING BOS INDICUS-INFLUENCED BEEF CATTLE IN TROPICAL/SUBTROPICAL ENVIRONMENTS

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: ACTIVE
• Funding Source: AFRI COMPETITIVE GRANT
• Reporting Frequency: Annual
• Accession No.: 1027768
• Grant No.: 2022-67015-37087
• Cumulative Award Amt.: $640,000.00
• Proposal No.: 2021-07133
• Project Start Date: Jun 1, 2022
• Project End Date: Aug 31, 2026
• Grant Year: 2022
• Program Code: [A1231]- Animal Health and Production and Animal Products: Improved Nutritional Performance, Growth, and Lactation of Animals

Recipient Organization
UNIVERSITY OF FLORIDA
G022 MCCARTY HALL
GAINESVILLE,FL 32611

Performing Department
(N/A)

Non Technical Summary
Heat stress impairs animal performance and health, leading to annual losses of $1.2 billion for dairy, beef, and swine industries in the U.S. Current heat stress knowledge was obtained from studies using feedlot beef and dairy Bos taurus cattle, which has limited implications to an understudied but crucial animal population for the U.S. beef industry (Bos indicus-influenced cattle in grazing systems) due to differences in management and how this breed responds to heat stress. The rationale of our proposal is that the use of heat abatement (access to shade) during critical periods of production (gestation and early life) is expected to improve the performance of grazing Bos indicus-influenced beef cows and modulate the future growth, immune function, and reproduction of their offspring. Our primary hypothesis is that heat abatement of pregnant cows followed by heat abatement of their offspring after birth will have the greatest additive impacts on offspring growth, immunocompetence and reproduction. Our objectives are to: (1) identify metabolites that can be used to predict cow and calf heat stress responses; and (2) evaluate the individual and combined impacts of gestational and early life heat stress abatement on performance and metabolic responses of grazing beef cattle. We expect that: (1) multiple metabolites, physiological and performance responses will differ between pregnant cows provided or not access to heat abatement, and such differences will illustrate the precise impacts of heat stress in grazing Bos indicus-influenced beef cows; and (2) heat stress exposure during gestation will also alter multiple molecular, metabolic, and physiological mechanisms of the offspring, leading to impaired ability of the offspring to cope with heat stress during early life. This proposal will lead to a better understanding of the causes and provide the foundation to develop management practices tailored to improve the productivity of Bos indicus-influenced beef cattle in tropical/subtropical environments and address a fundamental step to meet the rising global demand for beef.

Animal Health Component

40%

Research Effort Categories

Basic

60%

Applied

40%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
306	3310	1020	60%
305	3310	1040	30%
305	3310	1090	10%

Knowledge Area
305 - Animal Physiological Processes; 306 - Environmental Stress in Animals;

Subject Of Investigation
3310 - Beef cattle, live animal;

Field Of Science
1040 - Molecular biology; 1090 - Immunology; 1020 - Physiology;

Keywords

beef

heat stress

indicus

metabolomics

transcriptomics

Goals / Objectives
Objective 1 - Identify top circulating metabolites of pregnant beef cows during heat stress abatement that predict postpartum cow and calf performance. The working hypothesis is that prepartum body weight gain and plasma metabolome of pregnant cows will differ when provided or not long-term access to heat abatement during gestation and lead to positive carryover effects on post-partum cow and calf performance.Objective 2 - Combine gestational and post-weaning heat stress abatement to alter calf muscle transcriptomics and blood metabolomics and promote their growth, immune function, and reproduction. The working hypothesis is that access to heat abatement during post-weaning phase will magnify the changes on calf muscle transcriptome, plasma metabolome, growth, immune response and reproduction previously programmed by gestational heat abatement exposure.

Project Methods
Experimental designThe study will be conducted at the University of Florida - Range Cattle Research & Education Center (Ona, Florida). Animals will be cared for in accordance to protocols reviewed and approved by the University of Florida Institutional Animal Care and Use Committee. The study will be replicated over 2 periods of 17 months each (Period 1 = July 2022 to November 2023; Period 2 = July 2023 to November 2024). Each period will cover important production stages (from second trimester of gestation until the start of the first breeding season of beef heifers) and will be divided into gestational (weaning to calving), pre-weaning (birth to weaning), and post-weaning phases (weaning to pre-breeding).Gestational phase: Within each 17-month period, 160 pregnant multiparous Brangus cows (5 ± 1 year of age; 480 ± 10 kg of body weight; 5.3 ± 0.3 of BCS; 320 cows over 2 periods) will have their calves weaned in July (four months before calving). Then, cows will be blocked by initial body weight, age and BCS, and randomly allocated into 1 of 16 bahiagrass pastures (10 cows and 4 hectares per pasture). Treatments will be assigned to pastures (8 pastures/gestational treatment) and will consist of 1 of 2 practices provided to cows from second trimester of gestation until calving (July to November; Figure 4): (1) No heat abatement (CONTROL) = No access to artificial shade; and (2) Heat abatement strategy (HAST) = unlimited access to artificial shade (3.7 m2 of shade per cow). Artificial shade will be provided to pregnant cows to decrease exposure to direct solar radiation. Our preliminary data demonstrated that all B. indicus-influenced cattle utilized the shade structure during the hottest hours of the day.Pre-weaning phase: Cows and calves will remain on their respective pasture from birth until calf weaning at 8-9 months of age (July of the subsequent year). One Brangus bull will be assigned to each pasture for natural breeding of cows from January to March. Bulls will be rotated among pastures every 2 weeks to avoid genetic makeup of a single bull and will be replaced by another Brangus bulls if needed. Cows will be provided 2.3 kg/day of sugarcane molasses + urea (75% TDN, 20% CP; DM basis) added with a trace mineral and vitamin mix from calving to the end of the breeding season. Pregnancy rates will be determined 45 days after the end of the breeding season via rectal ultrasound.Post-weaning phase: Immediately after weaning, all male calves will be sold and all cows will return to their original herd. Heifer calves will be transferred to a different set of 16 bahiagrass pastures (1 hectare/pasture) using their respective pre-weaning pasture distribution. Then, 4 pastures per gestational treatment will be randomly assigned to 1 of 2 strategies until November: CONTROL (no artificial shade) or HAST (3.7 m2 per heifer of artificial shade). Pasture will be the experimental unit and all 4 possible treatments combinations will consist of: CC = CONTROL strategy assigned to cows during gestation and their heifers during post-weaning phase; CH 2 = CONTROL strategy assigned to cows during gestation and HAST strategy assigned to their heifers during post-weaning phase; HC = HAST strategy assigned to cows during gestation and CONTROL strategy assigned to their heifers during post-weaning phase; and HH = HAST strategy assigned to cows during gestation and their heifers during post-weaning phase. Each treatment combination will contain a total of 4 pastures, 40 cows, and 18 to 20 heifers per period (total of 8 pastures, 80 cows and 36 to 40 heifers/treatment combination over 2 periods of 17 months). Heifers will be vaccinated against bovine respiratory disease pathogens (2 mL s.c.; Bovi Shield Gold One Shot; Zoetis Inc) and clostridium (2 mL s.c.; Ultrabac 7, Zoetis Inc.) at the time of weaning. All heifers will receive booster vaccines consisting of Bovi Shield Gold 5 (2 mL s.c.; Zoetis Inc.) and Ultrabac 7 (2 mL s.c.) at 14 days after weaning. All heifers will graze bahiagrass pastures and offered concentrate supplementation at 1.5% of body weight (DM basis) from July to November to attain 65-70% of their mature weight at breeding. Concentrate will consist primarily of soybean hulls and soybean meal (22% CP, 73% TDN; DM basis).Data collectionObjective 1: Evaluate the body temperatures (surface, rectal and vaginal) and implement untargeted metabolomic analyses (global detection and relative quantification of metabolism end products) of cow plasma samples to obtain in-depth physiological and molecular information on metabolic challenges induced by in utero heat stress management. Specific sample collection and data analysis: heat shock proteins mRNA in cow blood; cow plasma cortisol and metabolome: calf plasma concentrations of IgG (marker for passive immune transfer), cortisol (indicator of physiological stress) and haptoglobin (indicator of inflammatory response); growth measurements of cow and calves and indicators of heat stress levels of both cows and calves (body surface temperature, intravaginal temperature, rectal temperature, and respiration rate). Statistical analyses: Body weight change (cows and calves), body temperatures and respiration rates (cows and calves), and calf plasma data will be analyzed as a completely randomized design using the MIXED procedure of SAS (version 9.4). Pasture will be the experimental unit, whereas animal(pasture) and pasture(treatment) will be included as random effects in all analyses. Growth and thermoregulation data of cows will be analyzed as repeated measures, and tested for fixed effects of gestational treatment, month, period, and all resulting interactions, using the covariance structures with the lowest Akaike information criterion. Calf rectal temperature, body weight, and plasma data at birth will be tested for fixed effects of gestational treatment, period, and treatment × period.Objective 2: Evaluate for the first time the outcomes of combining heat abatement during gestation and post-weaning phase on body thermoregulation, plasma metabolome, muscle transcriptome, immune response following vaccination, and puberty attainment in beef heifer offspring. Specific sample collection and data analysis: growth measurements and indicators of heat stress levels of calves (body surface temperature, intravaginal temperature, rectal temperature, and respiration rate); puberty attainment and pregnancy percentage of heifers; heifer longevity; innate and humoral immunity of heifers following weaning and vaccination; blood metabolome and heat shock proteins of heifers; muscle tissue transcriptomics; and muscle gene coexpression network analyses. Statistical analysis: Growth, serum and plasma data will be analyzed as a completely randomized design using the MIXED procedure of SAS. Binary data (seroconversion and puberty attainment) will be analyzed using the GLIMMIX procedure of SAS. Pasture will be the experimental unit, whereas heifer(pasture) and pasture(gestational × post-weaning treatment) will be included as random effects. Growth, plasma, and reproduction data (puberty attainment and longevity) will be analyzed as repeated measures and tested for fixed effects of gestational treatment, post-weaning treatment, month, period, and all resulting interactions, using covariance structures with the lowest Akaike information criterion. Data integration: Date collected from different layers (transcriptomics and metabolomics) will be integrated following a systems biology approach. This approach will allow identification of potential networks which are disturbed in the absence of heat stress.

Progress 06/01/24 to 05/31/25

Outputs
Target Audience:Graduate students in the animal science field, livestock county agents, industry personnel, and cow-calf producers. Delivered 14 local/regional/national webinars/seminars and 5 international webinars/seminars on beef cattle nutrition-related topics. The total number of people outreached was 500 at the local/regional/national presentations and >2,200 people at the international webinars/seminars on beef cattle nutrition-related topics. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?A total of 19 presentations (webinars and seminars) were delivered in this reporting period. Partial results of our project were shared during these presentations. INTERNATIONAL (total = 5) Moriel, P. 2024. Webinar. Fetal Programming and calf performance. In: International Beef Academy Webinar Series, January 2024, College Station, TX. 10 students. Moriel, P. 2024. Webinar. Metabolic Imprinting and calf performance. In: International Beef Academy Webinar Series, January 2024, College Station, TX. 10 students. Moriel, P. 2024. Webinar. Post-weaning heifer development. In: International Beef Academy Webinar Series, January 2024, College Station, TX. 10 students. Moriel, P. 2024. Webinar. Probiotic supplementation for cow-calf herds (Phibro Team). In: NOVONESIS Webinar Series, October 4, 2024, Sao Paulo, Brazil. 12 attendees. Moriel, P. 2024. Seminar. Nutritional management of beef heifers. In: Consorcio de Ganageros para Experimentación Agropecuaria (CEA), April 25th, 2024, Asunción, Paraguay [In Portuguese] 60 attendees NATIONAL (total = 4) Moriel, P. 2024. Cow herd nutrition during pregnancy: impact on subsequent fertility and offspring performance. Proceedings 2024 Applied Reproductive Strategies in Beef Cattle, September 4-5, 2024, Athens, GA. 200 attendees. Moriel, P. 2024. Seminar. Ruminant nutrition symposia: Overview of probiotic supplementation and opportunities to improve cow-calf production. 2024 American Society of Animal Science, Calgary, Canada. Jul 23rd, 2024. 200 attendees. Moriel, P. 2024. Seminar. Animal Behavior and Well-being Symposia: Short- and long-term effects of heat stress in cow-calf adapted to tropical and subtropical regions. 2024 American Society of Animal Science, Calgary, Canada. Jul 22nd, 2024. 100 attendees. Moriel, P. 2024. Seminar. ASAS-WSASAS Beef Species Symposia: Impacts of supplementing sulfate vs. hydroxychloride sources of Cu, Mn, and Zn on heifer growth performance and physiology during feed restriction and high-starch challenge periods. 2024 American Society of Animal Science, Calgary, Canada. Jul 22nd, 2024. 200 attendees. STATE (total = 3) Moriel, P. 2024. Seminar. Probiotic supplementation for replacement beef heifers. 73rd Florida Beef Cattle Short Course, University of Florida, Gainesville. May 10th, 2024. 200 attendees. Moriel, P. 2024. Seminar. Nutritional management to optimize cow-calf production in the Southeast - 2024 Florida Ruminant Nutrition Symposium. Feb. 28, 2024. Gainesville, FL. 300 attendees. Moriel, P. 2024. Seminar. Nutritional impacts on female reproduction. Ona highlight, University of Florida, Ona. May 21st, 2024. 25 attendees. LOCAL (total = 7) Moriel, P. 2024. Seminar. Heat stress in pregnant Bos indicus-influenced beef females. Florida Cattlemen Association - Quarterly Meeting. Dec. 5, 2024. Wauchula, FL. 22 attendees. Moriel, P. 2024. Seminar. Nutrition for beef females. Deseret Ranch visit. Sep. 20, 2024. St. Cloud, FL. 15 attendees. Moriel, P. 2024. Seminar. By-product supplementation. Winter Supplementation - South Florida Beef and Forage Program. Sep. 19, 2024. Kenansville, FL. 33 attendees. Moriel, P. 2024. Seminar. Impacts of BCS and probiotics on cow-calf production. Ona in-service training, Range Cattle REC, University of Florida, Ona. May 23rd, 2024. 11 attendees. Moriel, P. 2024. Seminar. Nutrition for reproduction. 2024 Reproductive Management School. April 16th, 2021, Clewiston, FL. 20 attendees Moriel, P. 2024. Seminar. Fetal programming and importance of body condition score. 2024 Reproductive Management School. April 16th, 2021, Clewiston, FL. 20 attendees Moriel, P. 2024. Seminar. Managing cow body condition score - Cattlemen's Roundtable. Feb. 21, 2024. Okeechobee, FL. 40 attendees. How have the results been disseminated to communities of interest?Partial results were briefly mentioned in webinars and seminars, but with the solely goal of updating the audience on the project progress, and not to generate discussion or inform about new management practices at this point. We will provide final analyses, outcomes, and recommendations upon finalzing this multi-year project. What do you plan to do during the next reporting period to accomplish the goals?Submitt all manuscripts generated in this multi-year project. Disseminate all information learned with this project to audiences in local, state, national, and international meetings.

Impacts
What was accomplished under these goals? Objective 1 = All samples were analyzed within this reporting period June 2024 to May 2025. Statistical analyses of all results are currently ongoing. Manuscripts will be submitted for publication in the next reporting period. Currently, all data collection occurred as planned and no issues were encountered. Partial results seem promissing and will help understand the performance data obtained in this study. Objective 2 = All final data will be collected within this reporting period June 2024 to May 2025. We are combining all data collected since 2022 and performing all statistical analyses.Manuscripts will be submitted for publication in the next reporting period. The performance data is outstanding with unexpected results. we anticipate a significant impact of our studies on cow-calf management in tropical/subtropical environments. Partial results were shared in national and international meetings and the excitement of the audience was clearly evident.

Publications

Progress 06/01/23 to 05/31/24

Outputs
Target Audience: Graduate students in the animal science field, livestock county agents, industry personnel, and cow-calf producers. Delivered 7local/regional/national webinars and 10 international webinars/seminars on beef cattle nutrition-related topics. The total number of people outreached was 709 at the local/regional/national presentations and >2,200 people at the international webinars/seminarson beef cattle nutrition-related topics. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?7 local/regional/national presentations for county faculty and producers. 10 international webinars for consultants, students, and producers. How have the results been disseminated to communities of interest?Partial results were briefly mentioned in webinars and seminars, but with thesolely goal of updating the audience on the project progress, and not to generate discussion or inform about new management practices at this point. We will provide final analyses, outcomes, and recommendations upon finalzing this multi-year project. What do you plan to do during the next reporting period to accomplish the goals?Final data collections will be performed between July 2024 and July 2025.

Impacts
What was accomplished under these goals? Objective 1 = all samples were finally collected and submitted for laboratory analyses, which are underway. Data will be analyzed in 2024. Objectiev 2 = Final year of our study was inititated in 2023. Last maternal data collection is scheduled for July 2023. Thereafter, we will combineall years of data and perform all statistical analsyes. Maternal results expected to be deliverd during the second semester of 2024. Heifer offspring are currently with their moms and will be weaned in July 2024. Thereafter we will start the last year of data collection on heifers. Final data on heifers to be collected in June 2025. Data will be summarized in July 2025.

Publications

Progress 06/01/22 to 05/31/23

Outputs
Target Audience: Graduate students in the animal science field, livestock county agents, industry personnel, and cow-calf producers. Delivered 12 local/regional/national webinars and 6 international webinars on beef cattle nutrition-related topics. The number of people outreached per event was 872 (158 YouTube views) and 798 for the local/regional/national and international webinars on beef cattle nutrition-related topics, respectively. Changes/Problems:Changes: No changes. Problems: Hurricane Ian that occurred between September 23-30, 2022, was our major obstacle. The research center was hit directly for 2 consecutive days. Power was lost and all buildings flooded, which prevented any laboratory work to be completed. Fortunately, no samples were lost or affected and no animals were lost. Data collection continued as planned. Hence, our year 1 data was not jeopardized despite the hurricane challenges. What opportunities for training and professional development has the project provided?12 local/regional/national presentations 6 international webinars How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Cow data collection from year 1 will be finalized in August 2023 and will be available for analyses prior to the next reporting period. Heifer data collection from year 1 begins in August 2013 and will be finalized in November 2024. Hence, partial heifer data will be available in the next reporting period.

Impacts
What was accomplished under these goals? Impact: Environmental heat stress losses are currently over $1.2 billion in the U.S. and are projected to increase if the climate of the Earth continues to warm. Most human population growth is expected to occur in tropical/subtropical areas, which contain nearly 80% of the global cattle population. Bos indicus-influenced cattle predominate in these regions. Preliminary data indicated that Bos indicus-influenced cattle had altered physiological responses and greatest growth improvement when provided access to shade compared to Bos taurus cattle. In-utero heat stress programmed the dairy calf for a similar or opposing postnatal environment. Hence, a fundamental step to meet the rising global demand for beef include determining the specific impacts of gestational and post-weaning heat stress mitigation on grazing cow-calf productivity in tropical/subtropical regions. ACCOMPLISHMENTS: The study and data collection initiated in August 2022 and is currently in progress. Cow assigned to no shade during precalving phase had intravaginal temperatures of almost 1C higher and body condition score at calving of 4.5 (scale 1 to 9) whereas those that were provided shade access during precalving period achieved lower intravaginal temperature and a body condition score of 5 at calving. Breeding season of cows initiated in January 2023, and we expect that cows provided no access to shade will have lower pregnancy rates (to be determined in June 2023) and conceive late during the breeding season compared to cows that received precalving access to shade due to differences observed for body condition score at calving. Calves will be weaned in July 2023, and then, heifers will be assigned to their treatments for the post-weaning phase. Blood samples collected in year 1 (August 2022 to July 2023) will be analyzed once year 2 (August 2023 to July 2024) is also collected. So far, the limited number of preliminary results that we were able to collect confirm our hypothesis. Objective 1 - Identify top circulating metabolites of pregnant beef cows during heat stress abatement that predict postpartum cow and calf performance. 1) Activities completed: Blood samples were collected from August to November 2022 and stored in -80C freezers. 2) Data collected: August, September, and November 2022 3) Summary statistics and discussion of results: Plasma data has not been analyzed. Blood samples collected from August to November 2022 will be combined with samples to be collected in August to November 2023, and then sent to metabolome analysis. 4) Key outcomes: We expect that once all metabolome data is obtained (November 2023), we will be able to identify the key changes to circulating metabolites following precalving heat stress. Such data will also help explain future cow and calf performance and increase our knowledge on impacts of gestational heat stress in grazing beef cattle. Objective 2 - Combine gestational and post-weaning heat stress abatement to alter calf muscle transcriptomics and blood metabolomics and promote their growth, immune function, and reproduction. 1) Activities completed: Cow body weight and body condition score were collected from August to November 2022. Intravaginal temperatures of cows were also collected. Calves were born in November/December 2022. Cow breeding season started in January 2023 and will end in April 2023. Pregnancy rate of cows will be obtained in June 2023. Calves will be weaned in July 2023. 2) Data collected: Cow body weight and body condition score, cow intravaginal temperatures, cow behavior on pasture, cow plasma, and calf body weight at birth. Calf body weight will continue to be collected during Spring and Summer 2023. 3) Summary statistics and discussion of results: Cow body condition score at calving (November 2022) was greater (P≤ 0.01) for cows provided vs. not provided access to shade during precalving phase (4.5 vs. 5, respectively; Scale of 1 to 9). Cow intravaginal temperatures in September were the lower (P ≤ 0.03) for cows provided vs. not provided access to shade (approximately 1°C). Cow intravaginal temperature fin November (near calving) did not differ (P = 0.99) between treatments. Cows provided no access to shade had greater respiration rates in September (P ≤ 0.0007) and their calves were lighter birth BW (P = 0.05; approximately 5 lb lighter). So far, these preliminary results of year 1 confirm our hypothesis. However, additional data remains to be collected. 4) Key outcomes: We expect that precalving heat stress will be detrimental to future offspring performance, particularly when offspring is exposed to similar maternal treatments. These data will be available in the next reporting cycle. Once these data are collected, changes in knowledge and action are expected to occur.

Publications