A primary objective of this study was to determine whether the binary traits heifer pregnancy (HP) and subsequent rebreeding (SR) were heritable in an experimental population of Angus cattle. A second objective was to determine the nature of the additive genetic relationships among HP, SR, and stayability (S(5/1)) in the same population. Heifer pregnancy was defined as the observation of a heifer conceiving and remaining pregnant to palpation at 120 d, given exposure during the breeding season. Subsequent rebreeding was defined as the observation of a 2-yr-old conceiving and remaining pregnant to palpation at 105 d, given pregnancy as a yearling and exposure during the breeding season. Stayability was defined as the probability of a female having at least five calves, given she becomes a dam as a 2 yr old. Data were analyzed using a maximum a posteriori probit threshold model to predict breeding values on the liability scale and Method R procedures to estimate variance components in the determination of heritability (h2). Additive genetic groups were used in determining the additive genetic relationships among these fertility traits. Additive genetic groups were formed on one trait's breeding values and used in the prediction of another trait's breeding values. Analyses yielded h2 estimates that were out of the parameter space 8.5 and 46.3% for HP and SR, respectively, and 5.9% for the reestimation of S(5/1). The majority of point estimates outside the parameter space for SR converged toward 0, whereas those for HP and S(5/1) primarily converged toward 1. From the subsamples producing h2 estimates within the parameter space, average h2 for HP, SR, and S(5/1) were .21, .19, and .15, with standard deviations of .12, .14, and .08, respectively. The estimates of h2 indicate that HP and S(5/1) were heritable and should respond favorably to selection; however, SR did not appear heritable due to the large number of subsamples producing h2 estimates out of the parameter space. Fixed effect estimates for age of dam were significant for HP. From the analyses using additive genetic groups, the relationship among HP and S(5/1) appeared to be nonlinear. This potential nonlinear relationship seen between HP and S(5/1) indicates that selection for improved female fertility would be most effective by having predictions on both traits.
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, gender, 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 < .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 < .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 < .01). Steers and heifers were more motion-sensitive than the older bulls and cows (P = .03). Beef cattle urinated (P <.01, n = 1,581) and defecated (P < .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.
No abstract
Any thorough examination of the present and future of agricultural education must certainly begin with a look into its past. Since the creation of the United States, many leading American philosophers have viewed a strong agrarian culture as the bedrock of American vigor. These same philosophers repeatedly noted the significance of comprehensive agricultural education to a nation rich in agricultural wealth. The signing of the Agricultural Colleges Act legitimized the concept of formal education in the agricultural sciences and provided funding for such education. The Act, which came to be known as the Morrill Act, after one of its primary authors, stressed the importance of comprehensive education. In fact, the inclusion of liberal studies was specifically mentioned in the Morrill Act and was defended repeatedly by Morrill himself. Comprehensive education prevented graduating technically trained students who were lacking in the basic outcomes of education--critical, comprehensive problem solving, cohesive thought, and effective communication. However, throughout history, the demands of a growing population coupled with rapid advancements in scientific knowledge led to a gradual move away from comprehensive education in agricultural sciences toward increasing specialization, resulting in more narrowly trained students. Today's agricultural students are technically well versed but often lack the skill and knowledge required for cohesive thought and critical problem solving. Addressing the multitude of challenges facing leaders in the future of agriculture requires much more than technical skill. These challenges require quick, yet careful thinkers and communicators who can respond to changing market structure and consumer demand in a dynamic way. Students who are a product of a conscious move toward amalgamation of burgeoning scientific knowledge and technical prowess with an integrative education emphasizing relationships between disciplines would better serve tomorrow's agriculture.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.