Beef Cattle Research Programs

Beef cattle research at Texas A&MĀ covers a wide spectrum of topics to provide scientific information to Texas beef producers. Current programs focus on production topics such as nutrition, management, breeding and selection, and reproduction. Our researchers are based in all geographic locations in Texas and also collaborate with other scientists across the nation. See a summary of some of our latest research projects below.

Also, theĀ 2009-2010 Beef Cattle Research in Texas publication is now available online. This publication features research articles on a variety of beef cattle research projects throughout the state. To request your free copy, please contact Dr. Andy Herring.

Selected Beef Cattle Research Abstracts

Effect of delaying implant and programmed rate of gain on performance and carcass characteristics of yearling beef steers: G. Scaglia, L. W. Greene, F. T. McCollum, N. A. Cole, and T. H. Montgomery

Performance and carcass characteristics of feedlot steers: Effects of delayed implanting and programmed feeding during the growing period: G. Scaglia, L. W. Greene, F. T. McCollum III, N. A. Cole, and T. H. Montgomery

Current Research Project Updates

McGregor Bovine Genomics Project

Objectives: To identify specific genest that influence fertility, feed efficiency, and growth.

Approach: Through embryo transfer, researchers will produce 400 animals in 10 families for the study. Researchers will collect DNA from each animal, as well as his parents and grandparents, and also document phenotypic information from each animal. Steer calves will be studied for feed efficiency, and heifer calves will be studied for fertility and cow productivity. After the genes are mapped, researchers will pool information from the human, mouse, rat and bovine genome sequencing projects to establish gene functions and look for associations between genes and phenotypic traits.

Results to date: In February 2003, researchers had collected 222 frozen embryos, with 88 confirmed pregnancies. Embryo transfer continues throughout the spring. A group of 256 recipient cows have been gathered for use in this project. This spring, the first group of calves were born, and a web-based database was built to maintain the project data. Researchers also completed a feeding regime pilot test and established the feeding protocols.

Heterosis Retention in Bos indicus/Bos taurus Crosses
Objectives: To evaluate female productivity in purebred and crossbred cattle and determine how well second-generation crossbreds retain their hybrid vigor.

Approach: Most cattlemen know the value of heterosis in a Brahman x British F1 female, however many of our Texas cattle are actually crosses of two crossbred parents, and have less heterosis than a true F1. Despite the wealth of information available on F1 Brahman x British crossbreds, there is little research to describe heterosis retention from the second-generation crosses. Recommendations for Texas optimum breeding herds cannot be established without research on this popular cross by Texas cattlemen. In 1995, herds were established at McGregor to evaluate heterosis retention in the Bos indicus / British crosses, including purebred cattle, F1 crosses, F2 crosses, first- and second-generation 3/8 / 5/8 crosses, and a four-breed composite. Cows from each group are retained to evaluate lifetime productivity.

Results to Date: In preliminary results, Brahman x Hereford crosses, indicate as much or more heterosis retention in the F2 than expected, and in the Brahman x Angus crosses show less than expected.

Evaluation of Tropically-Adapted Breeds
Objectives: To evaluate the productive lifespan of two groups of F1 cows out of British dams and sired by a variety of heat-tolerant sire breeds.

Approach: In the early 1980s, a group of Bos indicus cattle were imported from Brazil, and a need arose to compare these breeds to the Brahman. Calves were produced out of Hereford dams and sired by Angus, Gray Brahman, Gir, Indu-Brazil, Nellore, and Red Brahman bulls from 1982 to 1985. The heifer calves were kept and evaluated for reproductive traits, maternal traits and longevity. Any cows that received a severe injury, had poor health, or did not wean a calf in two years were culled. In the early 1990s, Boran and Tuli, two other heat-tolerant African sire breeds, were added to the study, and the heifer offspring were also evaluated.

Results to Date: Bos indicus-sired cows have been much more productive than Angus-sired cows. African-sired cows have been very productive as compared to Brahman-sired cows, which smaller mature size.

Genetic Regulation of Fat Deposition
Objectives: To study fat deposition and distribution in cattle from the individual gene level to carcass composition.

Approach: Angus and American Wagyu (originally from Japan), cattle will be fed on either a high energy or a high roughage diet, then slaughtered at 4-month intervals beginning at 8 months after weaning. At harvesting, researchers will evaluate fat tissue samples and RNA from specific genes.

Results to Date: Presently, cattle are on feed. Previous investigations indicate that marbling from Wagyu cattle will be more abundant than in Angus cattle and will have greater levels of expression of several fat regulating genes.

Factors Affecting Number of Calves Sired by Bulls in Multi-Sire Pastures

  • Objectives
    • Determine the influence of semen traits, social interactions and mating behavior on reproductive performance of bulls in multi-sire herds
    • Develop criteria for selection of bulls that will increase reproductive rate in natural service matings
  • Approach
    • Conduct conventional breeding soundness evaluations (sperm motility and morphology and scrotal size)
    • Determine serving capacity (high or low) and social rank (dominant or submissive)
    • Determine presence or absence of specific proteins on sperm which are associated with fertility
    • 90-day breeding season with a bull to female ration of 1:25. 5) Sire of each calf determined by DNA analyses
  • Results
    • Most calves were sired by dominant bulls with the higher percentages of normal sperm and the presence of the fertility-associated antigen
    • Percentage of normal sperm is positively associated with the ability to sire calves that are born early in the calving season
    • Bulls that were more efficient in their mount to service ration sired the highest number of calves
  • Summary – Bulls that are capable of siring more calves in multi-sire pastures can be identified by combining a breeding soundness evaluation with:
    • assessment of dominance rank
    • determination of service efficiency
    • analysis of sperm fertility protein classification

Methods to enhance pregnancy rate to a timed insemination in beef females

  • Objectives
    • Develop treatments to increase synchrony of ovulation and eliminate the need for estrus detection
    • Increase pregnancy rate to a timed insemination
  • Approach
    • Utilize a conventional CIDR treatment (vaginal insert) to achieve synchronization of estrus
    • Evaluate hormone treatment combinations with the CIDR to increase synchrony of ovulation
    • Identify female traits which account for variation in pregnancy rate to timed A.I.
  • Results
    • Breed type, age and parity significantly influence pregnancy rate to timed AI.
    • Pregnancy rate to timed AI varies across herds due to body condition and skill of AI technician
  • Summary
    • Studies are in progress to develop estrous synchronization strategies specific for breed type, age and parity to achieve optimum pregnancy rates to timed AI.

Use of Net Feed Intake (NFI) to Improve Feed Efficiency

  • Objectives
    • To examine the relationships between NFI and performance traits in growing cattle
    • To determine if observed differences in NFI were associated with differences in ultrasound measures of carcass composition
    • To identify physiological measures that are predictive of NFI

Approach: Historically, the beef industry has not attempted to select cattle for improved feed efficiency because of the difficulty and expense of measuring feed intake in cattle, and because the traditional measure of feed efficiency (feed-to-gain ratio) is inversely related genetically to growth and size. Net feed intake is a new feed efficiency trait that quantifies genetic variation in feed intake beyond that related to differences in growth and body weight. Similar to a golf score, an animal with a negative NFI is more efficient because it eats less feed then expected, whereas a positive-NFI animal is less efficient because it eats more feed then expected.

Individual feed intake of growing steers (Study 1; N = 180) and bulls (Study 2; N = 60) were measured using electronic gate feeders, and NFI determined as actual intake minus expected intake from multiple linear regression analysis. Performance traits and ultrasound measures of carcass composition were measured and blood samples collected to measure various metabolites and hormones.

Results to Date:
Net feed intake was not correlated with body weight or ADG but was positively correlated with feed intake and feed conversion ratio (FCR). In the first study, steers identified as having low NFI (more efficient) had similar body weights and ADG, but ate 17% less feed and had 19% lower FCR compared to steers with high NFI (less efficient). The high NFI steers had greater back fat thickness, but similar ribeye areas compared to low NFI steers, suggesting that low NFI steers were slightly leaner. These results demonstrate that NFI is an alternative measure of feed efficiency that may provide opportunities to identify more efficient cattle independent of growth traits, and it should be investigated further for increasing U.S. beef cattle production efficiency.

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