Life Sciences Commons^™

Animal And Forage Response To Short-Duration Rotational Grazing, Hans-Joachim G. Jung, Richard W. Rice, Ling-Jung Koong

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

It has recently been suggested that the use of a short-duration rotational grazing (SDG) system can significantly increase total beef production on rangelands. The periodic intense grazing pressure of the SDG system is assumed to retard maturation of the forage and stimulate forage growth. This combination of immature, high quality forage and greater total forage production should allow higher stocking rates and/or improved animal performance. Such a system may be of greater utility with improved pastures planted to forages possessing a greater genetic potential for growth. This study was designed to determine the animal and forage responses to SDG on …

Causes And Influences Of Repeat Breeding In Beef Cattle, Ralph R. Maurer, Sherrill E. Echternkamp

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

Repeat-breeding females were classified as those females nonpregnant after two consecutive breeding seasons of 45 to 60 days' duration. Females were either naturally mated or artificially inseminated and exposed to clean-up bulls. Each year, approximately 7,000 beef females (6,803 to 7,374) at the Research Center were bred by either artificial insemination (approximately 2,000 females) and/or exposure to single or multiple sires in two breeding periods of 45 to 60 days' duration. Breeding periods were either May 15 to July 15 or November 1 to December 31 during 1979 through 1982. During the four years, 165 heifers and 241 cows (clinically …

Effects Of Heterosis On Longevity In Beef Cattle, Rafael Nunez-Dominquez, Larry V. Cundiff, Gordon E. Dickerson, Keith E. Gregory, Robert M. Koch

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

Longevity can be important to the economic efficiency of beef production. The longer cows remain productive in a herd, the fewer the number of replacement heifers needed and the greater the calf output per cow maintained. In this way, more heifers can be sold for feeding and slaughter, and the cost of growing out replacement females to a productive age is reduced. Less culling of infertile cows also increases output per cow exposed. This study was conducted to determine effects of heterosis on longevity and associated factors in crosses of the Hereford, Angus, and Shorthorn breeds.

Effects Of Sex Condition And Diet On Growth And Carcass Characteristics, John D. Crouse, Calvin L. Ferrell, Larry V. Cundiff

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

Studies quantifying the differences between bulls and steers have generally shown that bulls gain more rapidly and more efficiently than steers and produce leaner carcasses. The average of these studies gave bulls a 17 percent advantage in average daily gain and a 13 percent advantage in converting feed to liveweight gain. Feed efficiencies reported in these studies were determined on animals fed to similar ages or weights. The effects of sex condition on feed efficiency of animals fed to a similar fat composition or marbling endpoint needs to be examined.

Effects Of Sex Condition, Diet, And Electrical Stimulation On The Collagen And Palatability Of Two Muscles, John D. Crouse, H. Russell Cross, Steven C. Seideman

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

Meat obtained from intact males has been observed to be less tender than meat obtained from castrated males. Studies have shown that meat from intact males was one sensory panel score less tender than comparable meat from castrated males when animals were fed to about the same age. Reported studies comparing palatability characteristics of meat from bulls and steers have been made on animals fed to similar ages or weights; consequently, compared sex conditions have been confounded with carcass compositional differences.

The objectives of the present study were to determine the effects of sex condition and dietary energy density on …

Embryo Transfer In Beef Cattle Research, Ralph R. Maurer, Acacia A. Alcivar

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

Embryo transfer techniques have been utilized to increase the number of desirable animals (e.g., exotic breeds) or to study factors influencing embryonic development. Embryo transfer is predominantly used at the Research Center as a research tool to answer questions about embryonic development and maternal influence on subsequent growth of the newbom calf.

Embryo transfer utilizes the techniques of 1)superovulation; 2)surgical or nonsurgical embryo collection and transfer; and 3)handling the embryo between collection and transfer. Therefore follicular development as well as fertilization rates play important roles in the production of viable embryos. A large variation in response to the superovulatory procedure …

Feed Requirements For Maintenance And Lactation Of F1 Cows Representing Diverse Biological Types, Larry D. Cundiff, Calvin L. Ferrell, Thomas G. Jenkins

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

There are significant differences in weaning weight per cow exposed to breeding among F₁ cow breed groups. (See "Characterization of Breeds Representing Diverse Biological Types: Reproduction and Maternal Performance of F₁ Cows" elsewhere in this report.) These differences are associated with variation among breeds in reproduction, milk production, and growth rate of progeny. Also, there are significant differences among F₁ cows in mature weight. Heavier mature weight is associated with more rapid growth rate of progeny, and heavier weights increase output per cow from the production system when cows are sold. However, it also increases the nutrient …

Increasing Pregnancy Rate In Beef Cattle By Clitoral Massage During Artificial Insemination, Donald D. Lunstra, W. Gordon Hays, Robert A. Bellows, Dan B. Laster

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

Clitoral massage (stimulation) at the time of artificial insemination (AI) has been reported to increase pregnancy rate in lactating beef cows, but not to increase pregnancy rate in heifers. These reports have been limited to studies conducted at one location in the U.S. (Miles City, Montana), and the efficacy of clitoral massage on AI pregnancy rates of beef cattle at other geographic locations has not been reported. To our knowledge, there are no reports in the literature indicating a negative effect of clitoral stimulation on pregnancy rate of cows.

The following experiment was conducted to test the effects of clitoral …

Mineral Accretion During Prenatal Growth Of Cattle, Calvin L. Ferrell, Dan B. Laster, Ronald L. Prior

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

Published data on prenatal (fetal) growth in cattle have been limited primarily to birth weights or weights and linear measurements of fetuses at different stages of gestation. Others have provided data describing fetal growth in terms of weight, nitrogen, and energy. These and other data have provided insight into the rates of protein and energy accumulation by the fetus during development and serve as bases for the estimation of protein and energy requirements for fetal development. Objectives of the present study were to describe the patterns of calcium (Ca), phosphorous (P), sodium (Na), potassium (K), magnesium (Mg), iron (Fe), and …

Muscle Fiber Studies Comparing Bos Indicus And Bos Taurus Cattle, Steven C. Seideman

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

Beef cattle can be classified as either Bos taurus or Bos indicus. Bos taurus breeds of cattle are those originating from Europe,whereas Bos indicus are those breeds originating from India and southeast Asia to include such breeds as Brahman, Sahiwal, Baran, etc. Because of the heat and disease resistance of Bos indicus breeds of cattle, they have been used intensively in the southern U.S. However, some studies have shown Bos indicus breeds of cattle to produce carcasses with less marbling and less tender meat than Bos taurus breeds. Since carcass and meat characteristics are a reflection of the muscle …

Target Tissue Effects Of Active Immunization Of Heifers Against Steroids, Thomas H. Wise, Calvin L. Ferrell, Bruce D. Schanbacher

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

Gonadal steroids mediate many responses throughout the body, many of which may have economic considerations. Antibodies made against steroids by active immunization have provided unique tools to begin to identify steroid target tissues and understand some of the body responses to gonadal steroids. Immunization of farm animals against steroids may potentiate their effects upon target tissues resulting in increased ovulation rate (androgens) and increased feed efficiency and rate of gain (estrogens).

A major secretion function of the ovary involves the release of sex steroids which have' multiple effects upon the body. Follicles release estrogen, which prepares the animal for breeding. …

Weather And Climate Impacts On Beef Cattle, G. Leroy Hahn

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

The pervasive nature of weather and climate and the difficulties in adequately predicting their impact on beef cattle often lead to inadequate management strategies and tactics, resulting in a situation of coping as the need arises. This can lead to "management by crises" rather than rational decisions. The objective of this report is to summarize some of the known responses of cattle to their thermal environment and to address ways by which adverse impacts can be reduced. The discussion is based on results from U.S. Meat Animal Research Center and other research stations.

General observations: Domestic cattle fall into …

Breeding Cattle For Genetic Resistance To Disease, Roger T. Stone, Larry V. Cundiff

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

For many hundreds of years cattle with the greatest resistance to disease have probably survived to leave more offspring in succeeding generations than those less resistant to disease. Resistance to disease also may have increased indirectly through a favorable association with other characteristics, such as growth rate or milk yield, which have received major emphasis in genetic improvement programs in cattle. However, except for some selection against mastitis in dairy cattle, genetic resistance to disease has not received direct emphasis in genetic improvement programs. Greater understanding of biological mechanisms involved in disease resistance could lead to more effective selection of …

Characterization Of Breeds Representing Diverse Biological Types: Reproduction And Maternal Performance Of F1 Cows, Larry V. Cundiff, Keith E. Gregory, Robert M. Koch

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

It is estimated that today about 70 percent of the calves narketed from beef cattle herds in the U.S. are crossbred and hat between 50 and 60 percent of the cows are crossbred. This represents a major shift to crossbreeding from the straight-breeding programs which prevailed in the 1950's and early 1960's. This trend has been influenced by research demonstrating the favorable effects of heterosis and other advantages of crossbreeding. Also, increased use of feed grains in growing-finishing diets caused fatter carcasses contributing to increased consumer demand for leaner beef, which stimulated interest in breeds with greater potential for lean …

Contributions Of Acetate, Lactate, And Glucose To The Accumulation Of Fat In Intramuscular And Subcutaneous Tissues Of Beef Cattle, Stephen B. Smith, John D. Crouse

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

The U. S. meat industry faces a dual challenge: it must reduce the fat content of meat carcasses in order to provide a nutritious product with a minimum of waste, while not affecting meat palatability. The positive effects of marbling (fat deposited within muscle) on tenderness and palatability, as well as a meat grading system that penalizes carcasses with little marbling, make it desirable that animals be produced with minimal amounts of fat stored in depots, such as the subcutaneous and perirenal depots, without markedly decreasing intramuscular adipose tissue. This can be accomplished only if the factors regulating lipid deposition …

Effect Of Single-Sire And Multiple-Sire Natural Mating On Pregnancy Rate Of Beef Cattle, Donald D. Lunstra

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

Although artificial insemination (AI) is widely used in dairy cattle, AI has found only limited application in beef cattle. Use of bulls in natural mating programs accounts for more than 95 percent of the pregnancies achieved each year in the U.S. beef cattle industry. Success of such natural mating programs depends on the reproductive capacity and fertility of the individual herd sires used, but very little research on the natural mating fertility of beef bulls has been conducted. Because of the general lack of information on effective techniques for identifying sires with superior fertility, procedures currently used for selecting herd …

The Effects Of Carcass Electrical Stimulation And Cooler Temperature On The Quality And Palatability Of Bull And Steer Beef, John D. Crouse, Steven C. Sideman, H. Russell Cross

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

The advantages of producing bulls as opposed to steers in production efficiency, performance, and carcass leanness have been well documented. However, it also has been observed that bulls have darker colored lean and lower carcass quality grades than steers. In all studies summarized in a literature review, meat obtained from bulls was less tender when compared with meat from steers. Consequently, the superiority of bulls over steers in performance and carcass cutability have been largely countered by the inferior carcass quality of bulls. Production of beef by bulls, therefore, has not been widely undertaken in the United States.

Recent technological …

Effects Of Dietary Stress On Dark-Cutting Beef, John D. Crouse, Stephen B. Smith

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

The advantages of bulls compared with steers in production efficiency, performance, and carcass leanness have been well documented. However, it has also been well documented that meat obtained from bulls is darker in color and less tender than meat produced by steers. It may be concluded that the superiority in production performance of bulls over steers has not been exploited largely due to meat characteristics that differ from those of steers.

Postmortem (after slaughter) muscle color is directly associated with antemortem (pre-slaughter) muscle glycogen content, postmortem muscle pH decline, and ultimate muscle pH, which, in tum, is affected by live …

Effects Of Managing Heifers To Calve First At Two Vs Three Years Of Age On Longevity And Lifetime Production Of Beef Cows, Rafael Nunez-Dominquez, Larry V. Cundiff, Gordon E. Dickerson, Keith E. Gregory, Robert M. Koch

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

Resources used by cow herds for beef production vary greatly. To optimize reproduction and other production characteristics in the cow herd, breeding and management should be matched with the feed resources available for production. One management decision is whether to develop replacement females to calve first as 2-year-olds or as 3-year-olds. When feed resources are limited or expensive relative to other costs and value of output, it may be economical to delay the first calving until 3 years of age. When feed resources are adequate to support rapid growth and development of heifers and thus to reduce age at puberty …

Energy Requirements For Maintenance Of Beef Cattle Differing In Genetic Potential For Mature Size And Milk Production, Thomas G. Jenkins, Calvin L. Ferrell

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

Relative differences in expected performance for breed crosses of cattle are provided elsewhere in this report; see "Characterization of Breeds Representing Diverse Biological Types." This information may be utilized by beef cattle producers to identify breed types for possible use in their beef cattle enterprises. In conjunction with information descriptive of production characteristics, variation in energy requirements among the breed types needs to be considered. Using general relationships between production potential and energy requirements, producers may identify the beef cattle breeds that would perform optimally in their respective production environments.

Energy (either harvested by the animal or provided via supplementation) …

Energy Utilization By Hereford And Simmental Males And Females, Calvin L. Ferrell, Thomas G. Jenkins

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

Observed growth of cattle during the postweaning period reflects the genetic potential for growth as modified by the environment. Various breeds or breed crosses of cattle have been characterized for postweaning liveweight gain under ad libitum feeding conditions. Previous results showed calves by Simmental males had greater rates of postweaning gain than those sired by Hereford males. Simmental-sired steers were more efficient during a weight-constant interval, of equal efficiency during a time-constant interval and less efficient to a fat-constant end point than Hereford-sired steers. Differences among breeds in efficiencies of energy utilization for maintenance and gain have been reported. Similarly, …

Genetic Relationships Among Carcass Traits And Their Implications In Selection Programs, Robert M. Koch, Keith E. Gregory, Larry V. Cundiff

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

Two alternatives for breeders to match cattle resources with other production resources and market requirements are (1) identify a breed that is a good fit for the production requirements or (2) use systematic crossing of breeds that will complement each other most effectively to provide for the most profitable combination of characteristics. In either alternative, selection within breeds can be used to change the genetic values of specific traits to increase adaptability to the production system. The study reported here evaluates the genetic relationships among growth and carcass traits and assesses responses expected from selection.

Effects Of Chronic Environmental Heat Stress On Blood Flow And Nutrient Uptake By The Uterus And Fetus Of The Pregnant Cow, Lawrence P. Reynolds, Calvin L. Ferrell, John A. Nienaber, Stephen P. Ford

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

Chronic exposure of pregnant cows to elevated environmental temperatures results in decreased birth weights of calves. This phenomenon is economically important since reduced birth weights are associated with decreased calf survival and growth. The adverse effects of environmental heat stress on fetal development have been greater than can be explained by a reduction in maternal feed intake or length of gestation.

The rate of uterine blood flow seems to be a primary determinant of nutrient uptake by the gravid (pregnant) uterus, and acute heat stress on days 120 to 130 of gestation has been shown to decrease uterine blood flow …

Germ Plasm Utilization In Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch, Donald D. Lunstra, W. Gordon Hays

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 more than 20 percent. Comprehensive programs of breed characterization have revealed large differences among breeds for most biological traits of economic importance. Because of the high percentage of beef cattle in the U.S. and globally that are in herds too small to use well organized crossbreeding systems on a self-contained basis, and because of the wide fluctuation in breed composition between generations in rotational crossbreeding systems, there is need for experimental evaluation of the potential of composite populations as …

Cattle Management At U.S. Meat Animal Research Center, Margaret S. Mcalhany, W. Gordon Hays, William G. Kvasnicka

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

The Cattle Operations Unit is designed to function as a support area to the research scientists. The operations personnel maintain 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.

Effects Of Late Castration And Zeranol On Growth Rate, Feed Efficiency, And Carcass And Meat Traits Of Bovine Males, Keith E. Gregory, J. Joe Ford, Steven C. Seideman, W. Gordon Hays

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

It is generally recognized that intact bovine males gain weight faster and require less feed per unit of gain than castrate bovine males. Further, carcasses from intact bovine males have a higher percentage of retail or edible product, but meat from intact males is generally evaluated slightly lower on palatability characteristics, particularly tenderness, than carcasses from castrate bovine males. It has been suggested that much of the advantage of intact vs castrate for rate of gain, efficiency of gain, and composition of gain may be expressed by an age of about 1 year and the disadvantages, including aggressive male behavior, …

Heterosis Retention In Advanced Generation Angus-Hereford Crosses, Robert M. Koch, Gordon E. Dickerson, Larry V. Cundiff, Keith E. Gregory

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

Crossbreeding in beef cattle is a widely accepted production practice that influences about 70 percent of the cattle marketed in the United States. Systematic crossbreeding provides for use of heterosis and of differences among breeds to optimize average genetic merit of performance traits for adaptability to the various climatic and nutritive environments encountered in beef production. Because low reproduction rate restricts the use of specialized crossbreeding systems, it is generally assumed that rotational crossbreeding is an efficient method of using heterosis in beef cattle. In rotational crossbreeding, purebred populations are required only to produce replacement sires; whereas, mating of a …

Length Of Feeding Interval Influences Accuracy Of Selection For Growth, Robert M. Koch, Larry V. Cundiff, Keith E. Gregory

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

Rapid growth is an important trait for market beef production. Faster growth rate increases the proportion of feed intake that is used for building body tissues and reduces total input/unit of weight gain. This happens because over one-half of the feed energy and nearly two-thirds of the total cost for growing the beef animal goes to maintain normal life processes.

Selection for increased growth rate has been directed largely at postweaning gain because it is highly heritable. Performance tests to evaluate postweaning gain generally vary in length from 112 to 252 days with initial dates beginning at weaning or 30 …

Effects Of Heterosis On Lifetime Production In Beef Cows, Larry V. Cundiff, Rafael Nunez-Dominquez, Gordon E. Dickerson, Keith E. Gregory, Robert M. Koch

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

Results from a crossbreeding experiment conducted at the Fort Robinson Beef Cattle Research Station with Herefords, Angus, Shorthorns, and their reciprocal crosses demonstrated that weaning weight per cow exposed to breeding was increased 23 percent/year by favorable effects of heterosis on survival and growth of crossbred calves and by improved reproduction and maternal ability of crossbred cows. More recent results have shown that heterosis also increases longevity of beef cows. The present study was conducted to evaluate total effects of heterosis on longevity, calf crop percentage weaned, and weaning weights of progeny when combined into one trait (lifetime production of …

Genetic Correlations Of Reproductive And Maternal Traits With Growth And Carcass Traits In Beef Cattle, Michael D. Macneil, Larry V. Cundiff, C. A. Dinkel, Robert M. Koch

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

Some genes may affect more than one trait. Therefore, the traits can be genetically correlated. Knowledge of genetic correlations among traits is useful for efficient selection of replacement bulls and heifers if the breeder considers more than one trait. In designed selection programs, emphasis to be placed on the various traits can depend, in part, on the genetic correlations among them. In addition, genetic correlations can be used to predict what is expected to happen to traits other than those used in selection as a result of that selection. This effect on traits other than those used in selection is …