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The 1995 National Beef Quality Audit reported that dark cutting beef (dark cutters) cost $6.08 per animal harvested in the United States. Feedlot data were obtained over a 3-yr period from nine commercial feedyards (15,439 pens of cattle; 2,672,223 total cattle). Feedyard, sex, implant treatment, days from final implant to harvest, maximum and minimum daily temperatures, and temperature fluctuations from 2 d before harvest to the day of harvest all contributed (P < .05) to the incidence of dark cutters. Heifers yielded a higher (P < .05) percentage of dark cutters per pen and, when reimplanted a second time with an estrogenic implant, produced greater (P < .05) mean percentages of dark cutters per pen than heifers reimplanted with either androgens or combination (androgen and estrogen) growth promotants. Furthermore, heifers produced higher (P < .05) mean percentages of dark cutters per pen than steers during periods of hot (> 35 [degrees] C) weather 2 to 1 d before harvest. Steers, when treated with a combination (androgen and estrogen) implant when entering the feedyard and as a reimplant, produced higher (P < .05) mean percentages of dark cutters per pen when compared to other moderate growth-promoting implant strategies. When producers opted to implant steers with estrogenic growth promotants, either as the cattle entered the feedlot or as a final reimplant before harvest, the occurrence of dark cutters was reduced from 9.2 per thousand cattle shipped to 2.0 and .5 per thousand cattle shipped, respectively. Producers that reimplanted heifers before harvest with products that were not primarily estrogenic reduced the occurrence of dark cutters from 10.4/1,000 cattle shipped to 5.2/1,000 cattle shipped when androgen-based growth promotants were used and to 3.5/1,000 cattle shipped when combination (androgen and estrogen) implants were administered. In addition to implant selection, those producers that held cattle on-feed over 100 d past reimplantation reduced the incidence of dark cutters per pen by an average of 38% among heifers and 69% among steers. By reducing the occurrence of dark cutters, there is an opportunity for beef producers to realize large economic savings. Key Words: Beef, Quality, Management, Values

This study was conducted to assess the effect of temperament on the average daily gains of feedlot cattle. Cattle (292 steers and 144 heifers) were transported to Colorado feedlot facilities. Breeds studied included Braford (n = 177), Simmental x Red Angus (n = 92), Red Brangus (n = 70), Simbrah (n = 65), Angus (n = 18), and Tarentaise x Angus (n = 14). Cattle were temperament rated on a numerical scale (chute score) during routine weighing and processing. Data were separated into two groups based on breed, Brahman cross ([greater than or equal to]25% Brahman) and nonBrahman breeding. Animals that had Brahman breeding had a higher mean temperament rating (3.45 [+ or -] .09) or were more excitable than animals that had no Brahman influence (1.80 [+ or -] .10); (P < .001). These data also show that heifers have a higher mean temperament rating than steers (P < .05). Temperament scores evaluated for each breed group also showed that increased temperament score resulted in decreased average daily gains (P < .05). These data show that cattle that were quieter and calmer during handling had greater average daily gains than cattle that became agitated during routine handling. Key Words: Beef Cattle, Temperament, Weight Gain, Breeds, Sex Differences

Fear is a very strong stressor, and the highly variable results of handling and transportation studies are likely to be due to different levels of psychological stress. Psychological stress is fear stress. Some examples are restraint, contact with people, or exposure to novelty. In many different animals, stimulation of the amygdala with an implanted electrode triggers a complex pattern of behavior and autonomic responses that resemble fear in humans. Both previous experience and genetic factors affecting temperament will interact in complex ways to determine how fearful an animal may become when it is handled or transported. Cattle trained and habituated to a squeeze chute may have baseline cortisol levels and be behaviorally calm, whereas extensively reared animals may have elevated cortisol levels in the same squeeze chute. The squeeze chute is perceived as neutral and non-threatening to one animal; to another animal, the novelty of it may trigger intense fear. Novelty is a strong stressor when an animal is suddenly confronted with it. To accurately assess an animal's reaction, a combination of behavioral and physiological measurements will provide the best overall measurement of animal discomfort. Key Words: Handling, Restraint, Welfare, Anxiety, Stress, Slaughter

A course is described in which students are taught principles of livestock behavior and how an understanding of behavior can facilitate handling. Some of the principles that are covered in the course are livestock senses, flight zone, herd behavior during handling, and methods to reduce stress during handling. To teach problem solving and original thinking, the students design three different types of handling facilities. Design of restraint equipment and humane slaughter procedures are also covered. Both existing systems and ideas for future systems are discussed. Students are provided with infor-mation from both scientific studies and practical experience.

Casual observations indicated that some cattle are more sensitive to sudden movement or intermittent sound than other cattle. Six commercial livestock auctions in two states and a total of 1,636 cattle were observed to assess the relationship between breed, sex, and temperament score on the response to sudden, intermittent visual and sound stimuli, such as the ringman swinging his arm for a bid and the sound of him briefly yelling a bid. A 4-point temperament score was used to score each animal while it was in the ring. The scores used were 1) walks and(or) stands still, with slow, smooth body movements; 2) continuously walks or trots, and vigilant; 3) gait is faster than a trot (runs even a couple of steps), with fast, abrupt, jerky movements, and very vigilant; and 4) hits the ring fence, walls, partitions, or people with its head. Animals were observed for flinches, startle responses, or orientation toward sudden, intermittent sounds, motions, and tactile stimulation, such as being touched with a cane or plastic paddle. The cattle observed were mostly Bos taurus beef breeds and Holstein dairy cattle. Holsteins were more sound-sensitive (P = .02) and touch-sensitive (P [is less than] .01) than beef cattle. Sensitivity to sudden, intermittent stimuli (e.g., sound, motion, and touch) increased as temperament score (excitability) increased. Cattle with a temperament score of 1 were the least sensitive to sudden, intermittent movement and sound and those with a temperament score of 4 were the most sensitive (P [is less than] .01). This same relationship was sometimes observed for touch but was not statistically significant. Motion-sensitive cattle were more likely than nonsensitive cattle to score a temperament rating of 3 or 4 (P [is less than] .01). Steers and heifers were more motion-sensitive than the older bulls and cows (P = .03). Beef cattle urinated (P [is less than] .01, n = 1,581) and defecated (P [is less than] .01, n = 1,582) more often in the ring than did dairy cattle. Cattle that became agitated during handling in an auction ring were the individuals that were most likely to be startled by sudden, intermittent sounds and movements. Reactivity to sudden, intermittent stimuli may be an indicator of an excitable temperament. Key Words: Cattle, Responses, Sounds, Temperament