Animal Sciences Commons^™

The Effectiveness Of Subjecting Bos Indicus Crossbred Beef Carcasses To Higher Temperatures To Improve Tenderness, Georgianna Whipple, Mohammad Koohmaraie, Michael E. Dikeman, John D. Crouse

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Many studies have evaluated changes that occur in muscle during the aging process and how they relate to meat tenderness. Other research has shown that subjecting carcasses to higher temperatures soon after slaughter speeds the aging process that ultimately results in improved tenderness. Several things may explain this effect. The higher temperature causes the pH (acidity) of the muscle to decrease faster. Also, the combination of lower pH and higher temperature could promote an earlier release of calcium into the muscle, which normally occurs in muscle tissue after slaughter. This increase in calcium concentration in turn activates the calpain enzyme …

Germplasm Utilization In Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch, Donald D. Lunstra

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Heterosis achieved through continuous crossbreeding can be used to increase weight of calf weaned per cow exposed to breeding by 20%. Comprehensive programs of breed characterization have revealed large differences among breeds for most bioeconomic traits. About 55% of the U.S. beef breeding population involving 93% of the farmers and ranchers who produce beef cattle are in production units of 100 or fewer cows. Optimum crossbreeding systems are difficult to adapt in herds that use fewer than four bulls. Further, fluctuation in breed composition between generations in rotational crossbreeding systems can result in considerable variation among both cows and calves …

Use Of Crossbreeding And Breed Differences To Meet Specific Targets For Production And Carcass Traits Of Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The specific requirements for effective use of breed differences to meet specific production and market requirements are: (1) accurate assessment of production resources in regard to availability and costs, (2) accurate assessment of market requirements; Le., value differences in carcass composition associated with yield grade and quality grade, and (3) accurate current characterization of breeds in regard to such traits as: (a) growth rate and size, (b) carcass composition, (c) milk production, and (d) age at puberty. This information is needed to identify contributing breeds to use in alternative mating systems to achieve specific targets for production and carcass traits. …

The Relationship Of Metabolic Hormones, Nutrition, And Postpartum Anestrus In Different Biological Types Of Cattle, Andrew J. Roberts, Russell A. Nugent Iii, Thomas G. Jenkins, John M. Klindt

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Restricted energy intake can suppress the overall productivity of cattle. Restricted energy intake can decrease overall productivity of beef cows through, among other traits, decreased milk production, calf performance, and reproduction. However, failure of a cow to conceive is the major component affecting the overall production efficiency of the cow herd. In a companion report included in this publication ("Postpartum Interval Is Influenced by Nutritional Environment and Biological Type"), we demonstrated that the postpartum intervals for breeds of cattle with different genetic potentials for growth and milk production were differentially affected by restricted energy availability. This report, along with numerous …

Relationships Of Thymic Peptides Thymosin Α1 And Β4 With Reproductive Status: Puberty And Estrus, Thomas H. Wise, Michael L. Day, James E. Kinder, Ralph R. Maurer

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The thymus gland has been analyzed in depth in relation to its immunological function, but new evidence is accumulating that the thymus and its endocrine secretions (interferons, interleukins, thymic peptides) may be required for normal reproduction. The thymus gland regresses at puberty and pregnancy, indicative of the effect of gonadal steroids on the gland. Steroidal interactions have been hypothesized to mediate the secretion of some thymic peptides. Thymosin β₄, a thymic peptide, seems to have an integrative role in gonadal function by promoting the release of gonadotrophin releasing hormone whereas thymosin α₁ causes the release of adrenocorticotrophin …

Superovulation Of Cows By Initiating Fsh Treatments During The First Few Days After Estrus, Andrew J. Roberts, Sherrill E. Echternkamp

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Superovulation of cattle is a technique being used in conjunction with embryo transfer to expedite the propagation of animals with genetic merit for desirable traits. Briefly, these techniques involve the induction of multiple ovulations during one estrous cycle by administering multiple injections of a hormone called follicle stimulating hormone (FSH). Under ideal conditions this treatment will result in multiple embryos. These embryos can then be collected from the cow and transferred to recipient cows of lesser value, which act as surrogate dams. These techniques allow the production of many calves from one cow within a year as opposed to the …

Effect Of Marbling Degree On Palatability And Caloric Content Of Beef, Tommy L. Wheeler, Larry V. Cundiff, Robert M. Koch

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The relationship of marbling to beef palatability has been the subject of numerous investigations and several review papers. A vast majority of the data on this subject indicate that there is a positive relationship between marbling degree (or percentage chemical fat) and tenderness, juiciness, and flavor intensity, and an inverse relationship with Warner-Bratzler shear force (a mechanical measure of tenderness). However, this relationship is weak at best. Generally, although tenderness may increase linearly as marbling increases, the increments are very small, particularly from one marbling degree to the next. A comparison of the extremes in USDA quality grade (e.g., Standard …

Effects Of A Β-Agonist On Muscle Protein Degradation, Enzyme Activity, And Meat Tenderness In Steers, Tommy L. Wheeler, Mohammad Koohmaraie

Roman L. Hruska U.S. Meat Animal Research Center: Reports

It is generally accepted that muscle proteins are under continual degradation during normal growth. It has been estimated that 15 to 22% of the animal's total energy expenditure is for this muscle protein turnover. Regulation of the rate of muscle protein degradation could cause dramatic changes in rate and efficiency of muscle growth. Despite their importance in muscle growth, the mechanisms and control of skeletal muscle protein degradation are unknown. It has been hypothesized that several enzyme systems are involved at different stages of degradation, and that the calpain enzyme system (which occurs naturally in muscle) may initiate protein degradation …

Use Of Calcium Alginate To Immobilize Antimicrobial Agents On Beef Tissue, Gregory R. Siragusa, James S. Dickson

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Even under the best of slaughtering and processing conditions, beef carcasses will become naturally contaminated with some bacteria from the animal's hide, hair, hooves, and the abattoir environment. This contamination is mostly composed of bacteria which are harmless, but which can ultimately cause spoilage of the beef. The shelflife of raw beef is largely determined by the numbers and types of these bacteria. Since some bacterial contamination will always be present on beef, it is desirable to reduce these numbers to decrease the rate of spoilage, increase refrigerated shelflife, and further ensure the microbiological safety of raw beef before consumption. …

Roman L. Hruska U.S. Meat Animal Research Center (1993): Overview, D. B. Laster

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The Roman L. Hruska U.S. Meat Animal Research Center (U.S. Meat Animal Research Center) is part of the U.S. Department of Agriculture's Agricultural Research Service. U.S. Meat Animal Research Center was authorized by Congress on June 16, 1964, thereby creating a single facility that provides an unusual opportunity for making contributions to the solution of problems facing the U.S. livestock industry. The 35,000-acre facility and the otficelaboratory buildings provide a physical plant for about 80 scientists and about 200 support personnel. In addition, the University of Nebraska's Great Plains Veterinary Educational Center (GPVEC) provides a facility for four university faculty …

Estimates Of Genetic And Phenotypic Parameters Of Pelvic Measures, Weight, Height, Calf Birth Weight, And Dystocia In Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Based on requirements for assistance at first parturition as two-year-olds, experimental results document the importance of dystocia in major breeds of Bos taurus cattle. In addition to the greater labor and managerial requirements associated with dystocia (calving difficulty), experimental results show that dystocia results in reduced perinatal calf survival and reduced conception rate in females in the subsequent breeding season when dystocia is experienced. There is not agreement on the value of pelvic measures as a predictor of dystocia at first parturition. Information is limited on the genetic relationship between pelvic measures and other factors that may be genetically associated …

Factors Influencing Fetal Growth And Birth Weight In Cattle, Calvin L. Ferrell

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Fetal growth, as indicated by birth weight, has important influences on animal production. Birth weights lower than optimum are associated with reduced energy reserves, lowered thermoregulatory capability, and increased calf deaths at or near birth. In addition, low birth weights are related to low rates of growth after birth and decreased mature size. Conversely, birth weights greater than optimum are associated with greater calving difficulty. Primarily because of the increased calving difficulty, calf losses at birth and difficulties if rebreeding the cow are increased.

Fetal growth, hence birth weight, is influenced by numerous factors including number of fetuses, sex, parity …

Contributions Of Ovum Cytoplasm And Uterine Environment And Postnatal Environment To Maternal Effects In Beef Cattle, Keith E. Gregory, Ralph R. Maurer

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Any contribution or influence on offspring phenotype attributable to its dam, exceeding the inherited sample half of the dam's nuclear genes, is a maternal effect. Maternal effects can be classified into prenatal (e.g., cytoplasmic and uterine components) and postnatal [e.g., lactation, method of rearing (early weaning), plus other postnatal maternal components]. This experiment was designed with two objectives. The first objective was to determine the relative contributions of ovum cytoplasm and uterine influences on prenatal maternal effects by use of embryo transfer (ET). The second objective was to estimate breed differences in prenatal and postnatal maternal effects combined by evaluating …

A Simple Method For Freezing Bovine Embryos, Sherrill E. Echternkamp, Donald Elliott

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Deep freezing (cryopreservation) of bovine embryos provides an efficient economical method for storing embryos until suitable recipient cows (surrogate mothers) are available, or for transporting embryos to recipient cows at a distant location (e.g., exportation or importation of embryos between continents or geographic areas). Pregnancy rates achieved with frozen bovine embryos have increased steadily during the past five years and are approaching those obtained with fresh bovine embryos. However, acceptable pregnancy rates are only achieved when Grades 1 and 2 quality (excellent and good quality) embryos are frozen; survivability of Grade 3 (fair quality) embryos is considerably higher if the …

Beef Ribeye Muscle Glycogen And Color Response As Affected By Dietary Regimen And Postmortem Electrical Stimulation In Young Bulls, Mark R. Miller, H. Russell Cross, Marietta J. Buyck, John D. Crouse

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Utilization of the intact male by the beef industry has been the focus of much research in recent years. Advantages of bulls compared to steers in production efficiency, performance, and carcass leanness have been well documented. Disadvantages include aggressive behavior, darker postmortem muscle color, lower USDA quality grades, and, often, less tender meat. The superior production performance of bulls has not been utilized by the meat and livestock industries partly because of these disadvantages.

Postmortem muscle color is associated with energy content of the diet, antemortem muscle glycogen content, postmortem muscle pH decline, and ultimate pH, all of which are …

Factors Associated With Tenderness Of Three Beef Muscles, Mohammad Koohmaraie, Steven C. Seideman, John D. Crouse

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Tenderness is the prominent quality determinant and probably the most important sensory characteristic of beef steak and roast meat. Currently postmortem aging (storage of carcass at refrigerated temperatures for 8 to 14 days) appears to be the best method for producing tender meat. Although the improvement in meat tenderness as a result of postmortem aging is measurable both subjectively and objectively, the exact mechanism responsible for this improvement in tenderness is unknown.

It is well known that different muscles within the same carcass react differently to postmortem storage; for example, tenderloin is tender to begin with and does not improve …

Fetal Development In Cows With Multiple Fetuses, Sherrill E. Echternkamp

Roman L. Hruska U.S. Meat Animal Research Center: Reports

About 60% of the nutrient requirements for beef production in the U.S. are for maintenance of the breeding herd. In addition, the bovine female only produces about .7 of her body wt per yr in progeny wt. Thus, increasing the reproductive rate in beef cattle would have a major economic benefit. Although most bovine females are capable of gestating two calves, the natural frequency of twin births is low, ranging from less than .5% to 4% of the calvings, depending upon the breed of cattle. Several studies have indicated that the frequency of multiple births in cattle can be increased …

Growth And Carcass Traits Of Heifers As Affected By Hormonal Treatment, John D. Crouse, Bruce D. Schanbacher, H. Russell Cross, Steven C. Seideman, Stephen B. Smith

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The beef industry traditionally has discriminated against young heifers in the marketplace when compared with steers. Price discrimination was probably the result of sex effects on fat partitioning and distribution. Also, steers have been observed to be more efficient than heifers in the conversion of feed to carcass weight.

Both testes and ovaries secrete steroids that influence performance traits of cattle. Testosterone appears to stimulate rate of gain and efficiency of feed conversion in the male. Efficiencies of conversion of feed to live animal weight gains have been less in spayed feedlot heifers than in intact heifers.

It has been …

Germ Plasm Evaluation In Cattle, Larry D. Cundiff, Robert M. Koch, Keith E. Gregory

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Breed differences in performance characteristics are an important genetic resource for improving efficiency of beef production. Diverse breeds are required to exploit heterosis and complementarity through crossbreeding and to match genetic potential with diverse market requirements and climatic zone-feed resource situations.. Genetic variation among breeds can be used to provide an array of beef products that differ widely in fat and caloric content. Diverse feed resources will continue to be used for cow herds among and within different geographical regions of the U.S. Thus, it is important to characterize breeds of cattle representing different biological types for a wide spectrum …

Germ Plasm Utilization In Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Heterosis achieved through well-organized crossbreeding systems can be used to increase weight of calf weaned per cow exposed to breeding by about 20%. Comprehensive programs of breed characterization have revealed large differences among breeds for most biological traits of economic importance.

Ahigh percentage of beef cattle in the U.S.and globally are in herds too small to use well organized crossbreeding systems on a self-contained basis. Further, there is wide fluctuation in breed composition between generations in rotational crossbreeding systems. Thus, there is need for experimental evaluation of the potential of composite populations as an alternative, or, as a supplement to …

Investigation Of The Major Histocompatibility Complex In Cattle And Its Association With Economically Important Traits, Noelle E. Muggli, Michael J. Stear, Roger T. Stone

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Efficiency of animal production could be increased by reducing losses due to diseases. Therefore, disease resistance is an obvious trait to include in a selection program. However, how to incorporate this trait into the program is a difficult question. While it has been experimentally shown that selection for resistance against specific diseases is effective, it would be impossible to select for resistance to all potential diseases. Also, selection studies in mice show that increasing resistance to one disease can result in increased susceptibility to other diseases. This may be because antagonistic relationships exist among the mechanisms of the immune system. …

Serum Concentrations Of Luteinizing Hormone, Testosterone, And Thyroid Hormones In Low And High Serving Capacity Beef Bulls, Garth W. Boyd, Donald D. Lunstra, Bruce D. Schanbacher, Larry R. Corah

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Adequate sex drive in bulls is essential for natural mating to be successful. Expression of male sexual behavior and mating ability during sexual maturation is dependent upon attaining adequate testicular development and blood levels of luteinizing hormone (LH) and testosterone (T). Several researchers have investigated the relationship between levels of sexual behavior in postpubertal bulls and blood concentrations of LH and T. Some of these researchers reported a positive relationship between T and serving capacity (SC), and others found that individual differences in sexual performance could not be predicted based on circulating levels of T or LH. In those studies, …

Relationship Of Growth Hormone, Prolactin, And Thyrotropin Secretion To Individual And Progeny Performance Of Hereford Bulls, Danny L. Ohlson, Robert M. Koch, John Klindt, Steven L. Davis

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Evidence from several studies has supported a predictive relationship between measures of somatotropic hormones and genetically determined growth potential in domestic ruminants. In these studies, blood concentrations of hormones associated with growth were generally higher in lines or breeds with greater growth potential. However, no significant positive correlations between measures of hormone secretion and measures of growth in individual animals were observed.

The present study further assesses the association between growth potential, growth rate, and secretion of growth hormone (GH), prolactin (PRL), and thyrotropin (TSH) using bulls of two Hereford lines that differ in growth rate as a result of …

Twinning And Efficiency Of Beef Production, Gordon E. Dickerson, Pedro Guerra-Martinez, Gary Anderson, Ronnie D. Green

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Twinning is relatively rare in most breeds of beef cattle - less than 1 to 2% of calvings and less frequent for immature females. Twin calving has generally been considered undesirable because of the smaller calf size, higher calf mortality, infertility of females born twin with a male, more retained placentas, and possible delayed rebreeding experienced with twin calvings when observed under feeding and management that is geared to single calving. However, costs for just maintaining the breeding herd account for over one-half of the total costs of beef production. Thus genetic twinning may offer a means of increasing total …

Roman L. Hruska U.S. Meat Animal Research Center: Overview, Robert R. Oltjen

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The U.S. Meat Animal Research Center (U.S. Meat Animal Research Center) was authorized by Congress on June 16, 1964, thereby creating a single facility that provides an unusual opportunity for making major contributions to the solution of problems facing the U.S. livestock industry. Development of the 35,000-acre facility started in the spring of 1966and is continuing at the present time. Phase I construction, consisting of an office-laboratory building for intensive investigations, was completed in January 1971.These facilities provide a physical plant for 42 scientists and about 200 support personnel. Phase II construction, consisting of the Meats Research Laboratory and the …

A Voice-Input And Knowledge-Based Expert System For Grading Carcass Beef, Yud-Ren Chen

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Assessing meat yield and quality in carcasses is important for exporting meat and for the domestic consumer. The U.S. livestock and meat industries depend heavily on USDA to provide the rating of their meat for marketing. There is also a trend in the U.S. meat industry to process meat closer to the site of slaughter because of increasing transportation and energy costs. Only the edible portion of the carcass will leave the slaughter plant. These trends will increase the volume and demand for more consistent, equitable, and timely methods for grading meat.

Since the USDA meat grading system was first …

Anabolic Steroids And Implants In Feedlot Steers, Bruce B. Schanbacher, John Brethour

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Profit from livestock production is affected by daily liveweight gain, cost of gain, and feed conversion efficiency. Young beef calves are recognized as suitable converters of forages and grains into wholesome red meat, but constraints to maximum production efficiency are recognized. While their growth and development are often discussed in light of genetic potential, nutritional requirements, and environmental constraints, administration of anabolic agents to maximize their gains is a common practice. Several implants are available to the cattle industry as growth promotants; some of these contain steroids of gonadal origin while others are nonsteroidal.

Steroids secreted by the testes are …

Beef Facilities And Management At U.S. Meat Animal Research Center, Margaret S. Mcalhany, W. Gordon Hays, Gary S. Ross

Roman L. Hruska U.S. Meat Animal Research Center: Reports

The Cattle Operations Unit functions as a support service to the research scientists and maintains the animal populations necessary for our livestock research. Indirectly, this also involves responsible land management and herd health procedures. All the facilities and procedures employed in maintaining the extensive cattle herd are determined by research needs. Consequently, while providing a function sometimes indirectly related to research, the operations unit is necessary to provide adequate feedstuffs and healthy animals for research studies.

Breed And Heterosis Utilization In Rotational And Composite Crosses, Gary L. Bennett, Michael D. Macneil

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Rotational crossbreeding systems breed heifers sired by one breed to bulls from another breed. Heifer offspring are then bred to the next breed in the rotation, etc. Composite systems result in a "new" breed consisting of fixed proportions of "old" breeds. Both systems produce their own replacement heifers rather than requiring the purchase of F₁ heifers or special matings. Both systems have potential advantages for producers of slaughter beef because a high level of heterosis (hybrid vigor) is present in cows and calves. High levels of heterosis increase efficiency and reduce the cost of producing beef.

The level of …

Current Concepts For Understanding Ovarian Follicular Growth And Function In Cattle, Leon J. Spicer, Sherrill E. Echternkamp

Roman L. Hruska U.S. Meat Animal Research Center: Reports

Ovarian follicular development in cattle during either the estrous cycle or postpartum anestrus is not presently well understood. Although several investigators have suggested that follicular development is continuous, the notion that follicular growth occurs in waves still persists. A better understanding of bovine folliculogenesis is required to solve beef production problems such as prolonged postpartum infertility and variable responses to superovulation and estrous synchronization treatments. Therefore, research was conducted at U.S. Meat Animal Research Centerand results compared with earlier studies to explain follicular growth and function in cattle during postpartum anestrus.