Performing Department
ANIMAL SCIENCE
Non Technical Summary
Modern livestock production has experienced catastrophic losses due to global climate change. Sudden, extreme temperature spikes have increased in frequency and can be fatal to animals not routinely exposed to heat stress. In a single example, in the summer of 2022, a sudden temperature spike from moderate temperatures of about 80°F to over 100°F led to at least 2,000 deaths of finishing cattle in southwest Kansas. Because these incidents are expected to increase in frequency with climate change, it is critical that we define the biological mechanisms and genetic factors associated with the thermal stress response in cattle for the development of greater thermotolerance.Extreme heat exposure can disturb the counterbalance between metabolic heat production and dissipation, altering the animal's metabolism and cellular functions. However, there are limited data on how HS affects skeletal muscle, adipose tissue growth, and meat quality, and previous findings are contradictory. Our lack of understanding regarding how heat stress affects major tissue growth and meat attributes impedes our ability to counteract more frequent climate extremes and promote profitability in the beef cattle industry. Among meat-producing animals, beef cattle are more likely to be exposed to ambient and radiant heat extremes as they are typically raised outdoors. Furthermore, most preferred U.S. cattle breeds have black coats, which increases heat absorption. Unlike other meat-producing animal species, few studies have attempted to estimate the effects of heat exposure on beef cattle.With our preliminary study from cell culture, we hypothesize that acute heat stress regulates muscle and adipose tissue and results in altering overall growth and meat quality.Therefore, we set three aims:AIM 1: Determine signaling pathways related to animal growth potential driven by HSAIM 2: Assess skeletal muscle characteristics under heat stress.AIM 3: Estimate HS effects on meat quality for growing-stage cattle.Thirty-two black Angus-based steers will beused for a 28-day heat exposure trial.Steers will be randomly assigned to one of two groups:Thermoneutral pair-fed (TNP, THI1)72 or less, n=16), 2) heat stress (HS, THI 84-86, n=16).For yearling cattle,thermoneutral (TN2)) is between -10 and 20°C (14 and 68°F).Animals in the HS group will be exposed to heat during the daytime (09:00-17:00, 8 h/d) via the atmosphere heating method. During 12:00-15:00 (3 h/d), a carbon fiber heater (600W- bulb) will be located on the dorsal side of the animal (near the 13th rib area) to mimic the radiant heat exposure.THI for HS cattle will reach a maximum of 85 (severe stress) during the daytime. At night (18:00-09:00), THI will be kept below 72 to facilitate the animal's recovery and feed intake. Body temperature, growth performance, skeletal muscle and adipose tissue metabolism and, molecular changes, blood parameters will be examined. Animals will be harvested approximately 6 months after the trial at MSU Meats Laboratory and loin muscle will be analyzed to obtain meat quality attributes.Outcomes from this work will generate foundational research on a better understanding of the molecular response of skeletal muscle and adipose tissue and its potential impact on beef quality attributes. The effects of heat stress on the growth of beef cattle and its impact on meat quality and characteristics are of great value to scientists and the cattle industry. However, no data on beef cattle exist due to experimental challenges regarding animal health and welfare. Indeed, this is a significant obstacle. Incorporating the HS experimental condition in large animals is technically complex. Beef cattle in the finishing stages are particularly vulnerable to HS and can encounter dangerous conditions with a THI over 78. Because only a few studies have been conducted on beef cattle, our data from this seed grant will facilitate new opportunities to study the effects of HS across age ranges and breeds to fully understand its relationship with meat production in beef cattle.1)The temperature-humidity index (THI) is used to measure the combined effect of temperature and relative humidity.2)Temperatures above thisrange are regarded as heat stress (HS), asanimals must expend additional energy or modifybehavior to maintain body homeostasis.
Animal Health Component
0%
Research Effort Categories
Basic
80%
Applied
20%
Developmental
(N/A)
Goals / Objectives
Extreme heat exposure can disturb the counterbalance between metabolic heat production and dissipation, altering the animal's metabolism and cellular functions. However, there are limited data on how HS affects skeletal muscle, adipose tissue growth, and meat quality, and previous findings are contradictory. Our lack of understanding regarding how heat stress affects major tissue growth and meat attributes impedes our ability to counteract more frequent climate extremes and promote profitability in the beef cattle industry.With our preliminary study from cell culture, we hypothesize that acute heat stress regulates muscle and adipose tissue and results in altering overall growth and meat quality.Therefore, we set three aims:AIM 1: Determine signaling pathways related to animal growth potential driven by heat stressAIM 2: Assess skeletal muscle characteristics under heat stress.AIM 3: Estimate HS effects on meat quality for growing-stage cattle.
Project Methods
The results of our study will be distributed in peer-reviewed journals (i.e., Journal of Animal Science). We expect to produce two papers in peer-reviewed journals and train one postdoctoral scholar. This research will also be shared during scientific meetings such as the Reciprocal Meat Conference (RMC), the American Society of Animal Science (ASAS), and the ASAS Midwest annual meeting.