|Vann, Rhonda - MISSISSIPPI STATE UNIV|
|Randel, Ron - TEXAS AGRILIFE RESEARCH|
|Welsh JR., Tom - TEXAS A&M UNIV|
|Willard, Scott - MISSISSIPPI STATE UNIV|
Submitted to: American Meat Science Association Conference Reciprocal Proceedings
Publication Type: Proceedings
Publication Acceptance Date: July 11, 2008
Publication Date: July 15, 2008
Citation: Vann, R., Randel, R., Welsh Jr., T., Willard, S., Carroll, J.A. 2008. Evaluation of temperament and transportation stress on body composition traits and meat quality in beef cattle. Proceedings of the 61st American Meat Science Association Reciprocal Meat Conference, June 22-25, 2008, Gainesville, FL. p. 1-5. Interpretive Summary: A collaborative study consisting of two experiments was conducted involving scientists from Mississippi State University, Texas AgriLife Research, Texas A&M University, and the Livestock Issues Research Unit to evaluate the combined effects of transportation stress and animal temperament on real-time ultrasound body composition traits (primarily ultrasound intramuscular fat). The first study evaluated the combined effects of transportation stress and animal temperament on real-time ultrasound body composition traits of beef steers. These results from our first study suggest that hauling stress has negative effects on body composition traits, specifically percentage of intramuscular fat and rib fat. The objective of the second study was to determine the influence of bovine temperament on ultrasound body composition traits in bull calves in response to transportation and endotoxin challenge. Results from our second study indicated that bull body weight and rib fat were reduced due to transportation and endotoxin exposure. Collectively, the results from these two experiments demonstrate that transportation stress and endotoxin exposure negatively impact body composition traits, especially intramuscular fat in young steers transported to the feedlot or bulls undergoing transportation and an endotoxin challenge. These changes are minimal in younger growing animals; however, the trend is evident and further research is needed to elucidate these changes. This would also indicate that fat cattle transported long distances to a harvest facility could undergo the same type of changes in percentage of intramuscular fat and thus could have an impact on cattle marketed on a grid system. The results from this study will be of particular interest to individuals engaged in beef production systems, whether private individuals or industry, as well as to scientists working in the area of beef cattle production, health, and overall well-being.
Technical Abstract: The objective of the first study was to evaluate the combined effects of transportation stress and animal temperament on real-time ultrasound body composition traits (primarily percentage of intramuscular fat) in Angus Crossbred (n = 68) and Brahman (n = 60) steers. Temperament scores (1 to 5 scale) were assigned at weaning, yearling, and before departure to the feedlot. Mean exit velocity (EV; m/s) was recorded at weaning, yearling, before departure to the feedlot, and at feedlot arrival. Three sets of steers were hauled 3 distances (644, 809, and 1,236 km) to a feedlot. Body weights were collected at the same times as the mean exit velocity. Real-time ultrasound measurements for ribeye area, rib fat and rump fat, and gluteus medius depth were taken on steers before departure to the feedlot and again upon arrival at the feedlot. An overall temperament score was used which combined temperament score at weaning and yearling. Correlation coefficients between temperament scores at weaning and yearling were highly correlated (r = 0.72, P = 0.001). Overall temperament score reflected (P = 0.001) exit velocity and pen temperament score before departure to the feedlot. Breed and the distance cattle were hauled affected (P = 0.007) exit velocity and percentage of intramuscular fat (P = 0.053) and rib fat (P = 0.02) at feedlot arrival. Angus crossbred steers hauled shorter distances had similar changes in percentage of intramuscular fat than Brahman steers. Brahman steers hauled the greatest distance had the greatest reduction in rib fat. As overall temperament score increased, cortisol concentrations also increased. These results suggest that hauling stress has negative effects on body composition traits, specifically percentage of intramuscular fat and rib fat. The objective of the second study was to determine the influence of bovine temperament on ultrasound body composition traits in response to transportation and endotoxin challenge. Brahman bulls (10 mo of age) were selected on temperament score. The bulls with the lowest (C; n = 8; 0.87 m/s and 1 PS), intermediate (I; n = 8; 1.59 m/s EV and 2.25 PS), and highest (T; n = 8; 3.70 m/s and 4.88 PS) scores were used in this study. Prior to transportation (departure), after transportation (770 km) and post-lipopolysaccharide (LPS) challenge body weights and ultrasound body composition measurements for longissimus muscle area (LMA), percentage of intramuscular fat, rib fat (RF), and rump fat were collected. Body weights decreased (average 18.6 ± 55 kg) for all temperament groups from date of departure through post-challenge LPS (P < 0.001). A temperament score × day interaction (P < 0.05) for LMA was evident in the T bulls (-2.62 ± 1.44 cm2) having a greater change in LMA from departure to post-challenge LPS compared with C (-1.54 ± 1.54 cm2) and I (-1.62 ± 1.44 cm2) bulls. There was a numerical trend for bulls classified as T (-0.15 ± 0.11) to have the smallest decrease in percentage of intramuscular fat compared with the C (-0.41 ± 0.11) or I (-0.43 ± 0.11) bulls due to transportation or post-challenge LPS. Rib fat thickness was reduced (average 0.03 ± 0.03 cm) due to transportation for bulls in all temperament classifications (P < 0.03). Bulls classified as T (0.004 ± 0.003) had the smallest reduction (P < 0.07) in RF compared with the C (-0.05 ± 0.03) or I (-0.04 ± 0.03) bulls post-LPS challenge. Minimal changes in rump fat occurred during this study. Bull body weight and RF was reduced due to transportation and post-challenge LPS. Although many of the changes in ultrasound body composition traits due to transportation and post-LPS challenge are minimal, there are some trends; however, more research needs to be done to further elucidate these changes.