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

Students’ Knowledge of and Attitudes Toward Dairy Production: A Survey Methodology Report

This report presents findings from a pilot survey conducted among undergraduate and graduate students (N = 410) at the University of Nebraska-Lincoln about students’ perspectives on technology usage, consumption, and sustainability in dairy production systems. An interdisciplinary research team developed the survey instrument and report. The main purpose of this pilot study was to create and administer survey items to support further research on experiential education and outreach opportunities related to robotics in small-scale dairy production and rural economic development. Descriptive findings indicated that most students had some familiarity with dairy production and the nutritional aspects of dairy products but expressed a desire to learn more. The majority of participants agreed that “The sustainability of our food system is important to me personally.” Among three statements about technology usage in dairy production, the statement “technology will improve the livelihoods of people working in agriculture” received the highest mean score, indicating that students largely agreed with this statement. Regarding animal welfare, students believed that caretakers should ensure the health of dairy cows. Many indicated that they think small dairy farms can be financially viable. Notably, most students agreed with the statement “I enjoy learning through immersive experiences (hands-on or virtual reality).” Half of the students expressed a high or moderate level of interest in agricultural-related careers, 80 percent showed a high or moderate interest in technology-related careers, and 82 percent demonstrated a high or moderate interest in careers in sustainability

Effects of decreased dietary roughage concentration on energy metabolism and nutrient balance in finishing beef cattle

The optimal roughage concentration required in feedlot diets changes continuously for many reasons such as source, availability, price, and interaction with other ingredients in the diet. Wet distillers grains and solubles (WDGS) are common in finishing diets and they contain relatively high amounts of fiber compared with other grains they replace. Therefore, concentration of roughage could be altered when WDGS are included in feedlot diets. There has been very little data published regarding the effects of roughage concentration on energy metabolism and nutrient balance in beef steers. Therefore, the effects of roughage concentration in dryrolled corn (DRC)–based diets containing 25% WDGS were evaluated in 8 steers (BW = 362 ± 3.71 kg) using a replicated Latin square. Data were analyzed with the fixed effects of dietary treatment and period and random effects of square and steer within square were included in the model. Diets consisted of 25% WDGS and the balance being DRC and coarsely ground alfalfa hay (AH) replacing corn at 2% (AH-2), 6% (AH-6), 10% (AH-10), and 14% (AH-14) of dietary dry matter. As a proportion of GE intake, fecal energy loss increased linearly (P = 0.02), and DE decreased linearly (P = 0.02) as dietary level of AH increased. Methane energy loss, as a proportion of GE intake, increased linearly (P \u3c 0.01) and ME decreased linearly (P \u3c 0.01) as dietary concentration of AH increased. Heat production tended (P = 0.10) to decrease reaching a minimum of 10% AH and increased from 10 to 14% AH inclusion. Moreover, as a proportion of GE intake, retained energy (RE) decreased (P \u3c 0.01) as AH level increased in the diet. Reasons for the decrease in RE are 1) the increase in fecal energy loss that is associated with decreased ruminal digestibility of NDF when AH replaced DRC and the shift in ruminal VFA produced, 2) the decreased energy available for animal retention when NDF increased linearly as AH increased in the diet, and 3) the methane and heat energy associated with digestion of the fibrous portion of the AH. Neutral detergent fiber and OM excretion also increased linearly (P \u3c 0.01) with increasing AH in the diet. The increased NDF and OM excretion were likely caused by the difference in digestibility of AH and DRC

Effects of decreased dietary roughage concentration on energy metabolism and nutrient balance in finishing beef cattle

The optimal roughage concentration required in feedlot diets changes continuously for many reasons such as source, availability, price, and interaction with other ingredients in the diet. Wet distillers grains and solubles (WDGS) are common in finishing diets and they contain relatively high amounts of fiber compared with other grains they replace. Therefore, concentration of roughage could be altered when WDGS are included in feedlot diets. There has been very little data published regarding the effects of roughage concentration on energy metabolism and nutrient balance in beef steers. Therefore, the effects of roughage concentration in dryrolled corn (DRC)–based diets containing 25% WDGS were evaluated in 8 steers (BW = 362 ± 3.71 kg) using a replicated Latin square. Data were analyzed with the fixed effects of dietary treatment and period and random effects of square and steer within square were included in the model. Diets consisted of 25% WDGS and the balance being DRC and coarsely ground alfalfa hay (AH) replacing corn at 2% (AH-2), 6% (AH-6), 10% (AH-10), and 14% (AH-14) of dietary dry matter. As a proportion of GE intake, fecal energy loss increased linearly (P = 0.02), and DE decreased linearly (P = 0.02) as dietary level of AH increased. Methane energy loss, as a proportion of GE intake, increased linearly (P \u3c 0.01) and ME decreased linearly (P \u3c 0.01) as dietary concentration of AH increased. Heat production tended (P = 0.10) to decrease reaching a minimum of 10% AH and increased from 10 to 14% AH inclusion. Moreover, as a proportion of GE intake, retained energy (RE) decreased (P \u3c 0.01) as AH level increased in the diet. Reasons for the decrease in RE are 1) the increase in fecal energy loss that is associated with decreased ruminal digestibility of NDF when AH replaced DRC and the shift in ruminal VFA produced, 2) the decreased energy available for animal retention when NDF increased linearly as AH increased in the diet, and 3) the methane and heat energy associated with digestion of the fibrous portion of the AH. Neutral detergent fiber and OM excretion also increased linearly (P \u3c 0.01) with increasing AH in the diet. The increased NDF and OM excretion were likely caused by the difference in digestibility of AH and DRC

Heat and Moisture Production of Growing-Finishing Gilts as Affected by Environmental Temperature

Heat and moisture production (HMP) values are used to size ventilation fans in animal housing. The HMP values that are currently published in the ASABE standards were from data collected in the early 1950s. This study is one of a series of studies being conducted to update the HMP values for the ASABE and ASHRAE (American Society of Heating, Refrigeration, and Air Conditioning Engineers) Standards. This study focused on the HMP measurements on growing gilts in the weight range of 60 to 120 kg over a temperature range of 16 to 32°C. Thirty gilts selected on the basis of weight and health status were placed in one of five environmental chambers and in one of six pens in each chamber. Heat production rate (HP) was determined using indirect calorimetry methods after the animals were acclimated for 2 weeks to a particular temperature. Each measurement was made on an individual animal over a 21-hr period. It was determined that HP decreased, feed intake decreased, and moisture production (MP) increased as environmental temperature increased. HP was directly affected by the level of feed consumption. Dynamic measurements showed a diurnal HP pattern in that it was higher during light period than during dark period, with an immediate increase as the lights were turned on. Results on nursery age animals will be reported in a companion study

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

High frequency magnetic permeability of nanocomposite film

The high frequency magnetic permeability of nanocomposite film consisting of the single-domain spherical ferromagnetic particles in the dielectric matrix is studied. The permeability is assumed to be determined by rotation of the ferromagnetic inclusion magnetic moments around equilibrium direction in AC magnetic field. The composite is modeled by a cubic array of ferromagnetic particles. The magnetic permeability tensor is calculated by solving the Landau-Lifshits-Gilbert equation accounting for the dipole interaction of magnetic particles. The permeability tensor components are found as functions of the frequency, temperature, ferromagnetic inclusions density and magnetic anisotropy. The obtained results show that nanocomposite films could have rather high value of magnetic permeability in the microwave range