Evaluation of Temperament and Transportation Stress on Body Composition Traits and Meat Quality in Beef Cattle

Stressors can be psychological (restraint, handling, or novelty) or physical (hunger, thirst, fatigue, injury, or thermal extremes) (Grandin, 1997). Temperament has been associated with stress responsiveness in which higher concentrations of cortisol have been correlated with temperament of cattle (Curley et al., 2006; King et al., 2006). In addition, Smith and Grandin (1999) reported that appropriate handling of cattle and swine, as contrasted with improper or inappropriate handling, can result in improved productivity of live animals; in higher quality of slaughter livestock, carcasses, and cuts; and in greater profitability in the production and packing sectors. Voisinet et al. (1997) determined that feedlot cattle with calm temperaments have higher average daily gains than cattle with excitable temperaments. Additionally, over the past several years real-time ultrasound has provided a means in which to measure carcass traits (i.e., longissimus muscle area, rib fat, and intramuscular fat) in the live animal. For young cattle, quality grade is determined primarily by marbling, and ultrasound can provide an estimation of intramuscular fat which can be related to marbling in the carcass. Lipid deposition is believed to follow a set hierarchal pattern of omental, peripheral, subcutaneous, intermuscular, and intramuscular. However, certainly genetics, sex, health, implantation program, environment, stress, nutrition, and management all impact lipid deposition. Intramuscular fat is one of the last depot sites in beef cattle and also a fat that can be easily mobilized in times of nutrition or environmental stresses. For the past 4 years our research team has focused on elucidating the interactions between disposition and physiological stress on production performance in beef cattle. One aspect of this research involves the evaluation of the combined effects of transportation stress and animal temperament on real-time ultrasound body composition traits (primarily ultrasound intramuscular fat).