Understanding heat stress in beef cattle

Thermal stress is the result of a misbalance between heat produced or gained from the environment and the amount of heat lost to the environment. The level of thermal stress can range from minor or no effect to death of vulnerable animals. Under summertime conditions, thermal stress results in hyperthermia or heat stress. Heat stress in feedlot cattle is a common summertime occurrence in cattle-producing parts of the world (USA, Australia, Brazil, etc.). Effects on animals experiencing heat stress include decreases in feed intake, animal growth, and production efficiency. During these extreme events, animal losses can exceed 5% of all cattle on feed in a single feedlot. Luckily, these extreme events are generally very localized and last only a day or two. However, these losses can be devastating to individual producers within the affected area. The level of heat stress an individual animal will experience is a result of a combination of three distinct components: environmental conditions, individual animal susceptibility, and management of the herd. Environmental components include temperature, humidity, wind speed, and solar radiation. Several indices have been developed to summarize the different components into a single value. Individual animal susceptibility is influenced by many different factors including coat color, sex, temperament, previous health history, acclimation, and condition score. Finally, management greatly influences the effects of thermal stress. Management factors can be broken into four distinct categories: feed, water, environmental influences, and handling. Understanding these risk factors and how each one influences animal stress will aid in the development of management strategies and how to implement them. Management strategies that can be employed at the right time and to the correct groups of animals will increase benefits to the animals and limit costs for the producers

Evaluating Ventilation Rates Based on New Heat and Moisture Production Data for Swine Production

Heat and moisture production (HMP) rates of animals are used for calculation of ventilation rate (VR) in animal housing. New swine HMP data revealed considerable differences from previously reported data. This project determined new design VRs and evaluated differences from previously recommended VRs. The swine production stages evaluated included gestation, farrowing, nursery, growing, and finishing. The ranges of ambient temperature and ambient relative humidity (RH) evaluated for VR were -25°C to 15°C in 10°C increments and 15% to 75% in 15% increments, respectively. Indoor set points for temperature and RH were, respectively, 15°C, 20°C, 25°C and 60%, 70%, 80% for all five ambient stages. The results showed that the old VR for moisture control was 54%, 30%, 69%, 31%, and 53% lower than the new VR for the gestation, farrowing, nursery, growing, and finishing stages, respectively. Updated recommendations for ventilation are necessary for designing and managing modern swine facilities

Design of University Small-Scale Dairy Processing Facility

This project was assigned to research the feasibility and value of implementing a dairy processing facility on the campus of the University of Nebraska-Lincoln. The facility would process milk produced from cows under the same roof and will serve as an educational experience for Nebraska dairy farmers, UNL students, and K-12 students in the Lincoln-Lancaster County area. If the project is successful and replicated across the state, this facility could have a significant impact on the reduction of milk transportation costs in the Nebraska dairy industry. The project began with researching milk processing methods and steps from production to consumption. Shortly after this step, information on milk consumption patterns was collected from UNL Dining Services to determine demand on campus. Every unit operation requires certain equipment to effectively ensure the safety and quality of the final product, and mass balances from UNL milk consumption data were used to size equipment and storage capacity. Engineering firms were then consulted to gather information on equipment specifications and prices. Equipment costs and operating costs (estimated with the help of Dr. Howell and other university dairy operations) were entered into a Monte Carlo simulation to analyze return on investment and a breakeven point. The results from the costs section showed that the fixed costs (equipment and engineering) for the milk processing would be about $1.2 million. The Monte Carlo simulation showed that the project would not turn a profit for 10-12 years, and approximately 2.25 million gallons of milk would need to be processed and sold to recover initial costs. Overall, the project successfully displays data that can be interpreted by the client to decide whether to move forward with the project and the appropriate scale for the project at UNL

AGEN/BSEN 112 Final project: Moving and Temperament of Cattle

Cattle movement and weather may affect the body temperature of cows which in turn affects their natural behavior and can influence their metabolism. Cattle take several days to resume their normal eating patterns after being overheated, and that can affect dairy production. This project was assigned to study the effect of temperament (calm vs excitable) and evaporative cooling on the body temperature of moving animals to optimize the environmental conditions around the cattle and consequently, dairy production. The project began with processing of a data set from Dr. Tami Brown-Brandl who was the client/adviser for the group. The data contained the body temperature of six heifer cows recorded every minute for 24 hours. During the recording period the cows were moved around from their pen, and either had water sprayed on them to aid in their cooling, or left dry. The cows were classified by their temperament as calm or excitable, depending on their reaction to the presence of humans. The results from the analysis showed movement of cattle had a consistent effect on their average body temperature. As time went on during the movement process, all cattle saw an increase in body temperature with excitable cows reaching a higher maximum temperature than calm cows. Unaided cooling (dry treatment) was also affected by temperament of the cows. Calm heifer’s temperature dropped 0.1 °C about every 2 hours, while excitable heifer’s temperature dropped 0.1 °C about every 6 hours. Evaporative cooling or wet treatments help the heifers shorten excess periods of elevated body temperature with no notable difference due to temperament. Based on the analysis it is recommended to treat all heifers with a wet treatment after movement in an effort to keep heifers calm and therefore easier to corral and handle

Evaluating a New Shade for Feedlot Cattle Performance and Heat Stress

Heat stress in cattle results in decreased feed intake, lower daily gain, and potentially death in susceptible animals under intense conditions. A study was carried out during the summer of 2013 at the USDA-ARS U.S. Meat Animal Research Center feedlot evaluating the impact of shade on environmental conditions and cattle performance. A novel two-tiered shade was used in half of the 14 pens, each holding 30 animals. The shades were designed to reduce solar heat load by 40% to 60% and to provide traveling shade across the pen, providing varied amounts of shade area as well as varied solar reduction potential. The objective of this study was to determine if the shade was effective at improving performance (evaluated as average daily gain, feed intake, and feed to gain ratio) and reducing environmental conditions that cause heat stress. A group of mixed-breed cattle with varied genetics including both and were selected, penned on the basis of sex, and blocked by color. Production parameters of pen feed usage were measured daily, and individual body weights were taken monthly. Environmental conditions including air temperature, relative humidity, wind speed, ground temperature, and black globe temperature with and without shade were measured. Solar load on the pens was reduced when shade was provided, with both ground temperature and black globe temperature showing reductions. Cattle showed nominally better performance; however, no significant differences were found in gain or feed intake. Panting scores were significantly lower with shade provided; slopes of cattle respiration rate versus ambient temperature were significantly lower with shade during the afternoon period