Submitted to: JOURNAL OF ANIMAL SCIENCE AND BIOTECHNOLOGY
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/23/2013
Publication Date: 6/20/2013
Publication URL: http://handle.nal.usda.gov/10113/56878
Citation: Mays, A.R., Looper, M.L., Williamson, B.C., Coffey, K.P., Coblentz, W.K., Aiken, G.E., Rosenkrans, C.F. 2013. Forage and breed effects on behavior and temperament of pregnant beef heifers. Journal of Animal Science and Biotechnology. 4:20. DOI:10.1186/2049-1891-4-20. Interpretive Summary: Cattle raised for beef spend a considerable amount of time on pasture and receive much of their nutrition from pasture. Breeds of cattle can behave differently on pasture and react differently to certain grasses. In this study, we widened the scope of traditional grazing research by including behavioral observations between two different breed-types grazing two types of tall fescue. Cattle used in the study were either 1/8 to 1/3 Brahman, a breed originally from India, or a cross of two European breeds, Gelbvieh and Angus. Brahman-influenced cattle are often more temperamental than cattle with European breeding. Much of the tall fescue in the U.S. is infected with a fungal endophyte that produces toxins. New varieties of tall fescue contain novel endophytes that do not produce toxic substances. The two pasture types compared in this study were toxic endophyte-infected or nontoxic endophyte-infected tall fescue; Brahman-influenced cattle are known to be more tolerant of the compounds produced from toxic endophyte-infected tall fescue. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was evaluated for each pasture. During the second year, exit speed from the weigh chute also was determined for each heifer as an indicator of temperament. Gelbvieh x Angus heifers assigned to toxic endophyte-infected pastures had the lowest percentage of animals grazing and the largest percentage of animals resting in the shade, suggesting they were less tolerant of toxic endophyte-infected fescue than Brahman-influenced cattle. When weighed, Brahman heifers had faster exit speeds from the weigh chute than Gelbvieh x Angus heifers, indicating there were inherent differences in temperament between breed types, but these differences were not affected by fescue type. At the end of the trial each year, average daily gains were greater for Gelbvieh x Angus heifers than Brahman-influenced heifers, and greater for nontoxic endophyte-infected pastures compared to toxic endophyte-infected pastures. Assessing animal behavior as part of grazing studies may lead to enhanced animal well-being, and more profitable forage-based cattle production systems.
Technical Abstract: Integration of behavioral observations with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems. Brahman-influenced (BR; n=64) and Gelbvieh x Angus (GA; n=64) heifers consumed either toxic endophyte-infected tall fescue (E+) or one of two nontoxic endophyte-infected tall fescue (NT) cultivars during two years. Heifers were weighed at midpoint and termination of grazing. Grazing behavior (grazing, resting in the shade, lying, or standing without grazing) was recorded (n=13 visual observations per year in June and July) for each pasture. During year 2, exit velocity and serum prolactin were determined. Grazing behavior was influenced (P < 0.05) by an interaction between fescue cultivar and breed type. Gelbvieh x Angus heifers assigned to E+ pastures had the lowest percentage of animals grazing and the largest percentage of animals resting in the shade. Brahman-influenced heifers had faster exit velocities (P < 0.001) than GA heifers (0.52 vs. 0.74 ± 0.04 seconds/meter, respectively). Bodyweight was affected (P < 0.01) by an interaction of tall fescue cultivar and day, and an interaction of tall fescue cultivar and breed type. Heifers grazing NT pastures were heavier (P < 0.01) than heifers grazing E+ pastures at midpoint and termination. Gelbvieh x Angus heifers grazing NT pastures were heavier (P < 0.01) than GA and BR heifers grazing E+ and BR heifers grazing NT pastures. An interaction of forage cultivar and breed type occurred for serum prolactin (P < 0.01). Collectively fescue cultivar, exit velocity, and concentrations of serum prolactin were associated with grazing behavior. Heifers grazing NT pastures were observed to be grazing more than heifers assigned to E+ pastures, regardless of breed type, which may have contributed to changes in bodyweight and average daily gain in heifers. Integration of behavioral observations along with traditional selection schemes may lead to enhanced animal well-being and more profitable forage-based cattle production systems.