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Blood Flow And Nutrient Uptake Of The Bovine Uterus And Fetus, Calvin L. Ferrell, Ronald L. Prior, Ronald K. Christenson, Stephen P. Ford

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

Basic knowledge of the nutritional and hormonal requirements for normal development of the fetus and other gravid uterine tissues is essential to establish bases from which to study factors that my contribute to abnormal fetal development. Despite recognition of this necessity, few data are available that describe blood flow to the gravid uterus of cows. Data obtained by Ferrell and Ford (1980) indicated blood flow to the gravid uterus was 75, 155, 154, 105, and 60 ml/min/kg at 80, 140, 180, 210, and 240 days of gestation. Silver and Comline (1975) reported blood flow to be 312±20 ml/min/kg gravid uterus …

Blood Flow To The Uterus, Sherrill E. Echternkamp, Stephen P. Ford

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

Pattern of blood flow to the bovine uterus was determined by using electromagnetic blood flow probes during the estrous cycle and early pregnancy to evaluate the effect of the early bovine conceptus on uterine blood supply. Pattern of blood flow through the middle uterine artery of pregnant and nonpregnant cows was similar until day 14 after mating or estrus. Between days 14 and 18 of pregnancy, blood flow to the uterine horn containing the conceptus increased two-to-threefold, whereas blood flow to the other uterine horn in these cows remained constant. By day 19 of pregnancy, blood to the pregnant horn …

Conception And Embryonic Development In The Beef Female, Ralph R. Maurer, Sherrill E. Echternkamp, William F. Pope

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

Reproduction is an important economic trait in beef cattle production. The average percent calf crop for the United States has been estimated between 80 to 85%. Approximately 60% of the reduction in calf crop can be attributed to fertilization failure and embryonic death. We conducted several studies to determine at what stage of the reproductive cycle losses were incurred in normal reproducing cows and heifers and in cows and heifers that failed to reproduce. In addition, we measured hormone levels in normal range cows and heifers and used techniques like embryo transfer and culture to study the development of the …

Cooperative Project On The Weak Calf Syndrome, William G. Kvasnicka

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

The "Weak Calf Syndrome" has been gaining wide recognition throughout the north~est and Rocky Mountain regions. The specific syndrome was first noted as possibly being caused 'by a new entity by Dr. Jack Ward in the Bitterroot Valley of Montana after Dr. Ward was unable to relate the observations of necropsied specimens with that of any known published reports. The actual origin of the disease responsible for the specific syndrome noted in the area is not known and may have had its origin elsewhere. However, interest in the problem is increasing in view of the apparent recognition of the disease …

Decreasing The Postcalving Anestrous Period In Suckled Beef Heifers, Sherrill E. Echternkamp

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

The interval from calving to first ovulation was reduced to less than 45 days in 2-year-old suckled heifers by feeding a high energy diet (ADG, 1.4-2.5 lb/day) during the postcalving period or by a single injection of exogenous gonadotropin (2,250 IU PMSG) on day 42 postcalving. A comparison of reproductive parameters for heifers on the high and low energy (maintenance) diets during the postcalving period indicated that a higher percentage of heifers on the high energy diet had ovulated by 46 days postcalving (100 vs 0 %) and that both basal plasma luteinizing hormone (LH) concentration and estrogen-mediated LH release …

Genetic Variation Among And Within Herds Of Angus And Hereford Cattle, Larry V. Cundiff, Keith A. Gregory

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

Historically, beef cattle record of performance programs have by necessity expressed variation as deviations or ratios from herd means because differences between herds are believed to be large primarily because of environment. To the extent differences between herds are genetic, this procedure underestimates or overestimates breeding values of individuals relative to breed average depending on whether they are produced in herds of above or below average genetic merit for a breed. We conducted this study in cooperation with the American Angus Association and the American Polled Hereford Association, and designed it to separate and evaluate the relative importance of between-herd …

Lipid Synthesis In The Beef Animal, Ronald L. Prior, Stephen B. Smith

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

Rates of in vitro fat synthesis from acetate and lactate were compared to the activities of enzymes thought to be involved in the process of lipid synthesis from lactate. Results of these studies indicate that lactate can be incorporated into fats by a pathway heretofore thought to be nonfunctional in ruminants, the citrate cleavage:malic enzyme pathway. Studies of the effects of age and diet on the enzymes of the citrate cleavage:malic enzyme pathway support the concept of a physiological role for this pathway in lipid synthesis in beef cattle.

Performance Characteristics Of Feedlot Bulls And Steers Implanted With Estradiol-17Β, Bruce D. Schanbacher, Ronald L. Prior

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

Bulls were shown to grow more rapidly (+18%) and convert feed to live weight gain more efficiently (22% less feed) when compared to steers. Whereas bulls had larger loin eye areas and yielded a higher percentage of major retail cuts, marbling scores and quality grades were similar for bulls and steers. Implants containing estradiol-17β dipropionate had no major effects on performance characteristics of steers but reduced the performance of bulls to approximately that of steers. Our research shows that estradiol can suppress performance of feedlot bulls by inhibiting testosterone secretion from the testes.

Relationship Of Selected Beef Carcass Traits With Meat Palatability, John D. Crouse

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

Relationships among selected carcass traits and cooked meat palatability were studied on 240 carcasses obtained from steers of different biological types produced under a wide range of feeding regimens. Breed type of steer or feeding regimen had little or no effect on correlations among taste panel (TP) scores for tenderness, juiciness, flavor, and general acceptability. Treatments also had little effect on correlations of conformation, lean color, lean texture, and final maturity with TP observations. Late maturing breeds of steers and steers fed on low energy regimens were rated more youthful than early maturing breeds of steers and steers fed on …

Sexual Aggressiveness In Beef Bulls, Donald D. Lunstra

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

Large differences in conception rate during pasture-mating can exist among beef bulls having semen of acceptable quality. Based on data from artificial insemination, we know also that conception rate increases as the number of inseminations increases, and it is probable that conception rate to natural mating increases as number of matings per cow increases. Sexual aggressiveness (libido) is a behavioral factor that can influence the number of matings a bull can achieve and, thus, may influence the conception rate obtained during natural mating. Accurate evaluation of sexual aggressiveness and its relationship to fertility may provide useful information for selecting young …

Beef Research Program Progress Report No. 1 (1982): Table Of Contents

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

ROMAN L. HRUSKA U.S. MEAT ANIMAL RESEARCH CENTER, Robert R. Oltjen........iii

BREEDING AND GENETICS

Sixteen years of selection for weaning weight, final weight, and muscling score in Hereford cattle: Robert M. Koch, Larry V. Cundiff, and Keith E. Gregory. . . . . . . . . . . .. 1

Effects of heterosis in Hereford, Angus, and Shorthorn rotational crosses: Larry V. Cundiff, Keith E. Gregory, and Robert M. Koch. . . . . . . . .. . . . . . .. 3

Heterosis and breed maternal and transmitted effects in beef cattle: Keith E. Gregory, Larry …

Characterization Of Breeds Representing Diverse Biological Types: Carcass And Meat Traits Of Steers, Robert M. Koch, Larry V. Cundiff, Keith E. Gregory, M. E. Dikeman

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

Carcass characteristics, including composition and palatability of meat from different breeds or breed crosses, are important in determining the potential value of alternative germ plasm resources.

Chemical Composition Of Carcasses From Hereford, Limousin, And Simmental Crossbred Battle As Related To Growth And Meat Palatability, John D. Crouse, Michael E. Dikeman

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

Nine Hereford x Angus (HxA), nine Simmental x Angus (SxA), and nine Limousin x Angus (LxA) crossbred steers were slaughtered in three equal groups (three from each breed) after 200, 242, and 284 days on feed to evaluate carcass chemical composition differences and their relation to growth and meat palatability.

LxA carcasses were higher in protein and retail product percentages and significantly lower in chemical fat and fat trim percentages than either SxA or HxA carcasses. SxA carcasses were superior to HxA carcasses only in having a lower percentage of fat trim.

SxA steers gained slightly faster in the feedlot …

Effect Of Pregnancy On Disease Resistance, Rita C. Manak

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

During pregnancy, the immune response of cattle has an altered potential to overcome infection than during an open period. Several mechanisms seem to control this immune response, and they are being currently researched.

Effect Of Breed And Postweaning Rate Of Gain On Onset Of Puberty And Productive Performance Of Heifers, Calvin L. Ferrell

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

Age at puberty is an important production trait in beef cattle where heifers are bred to calve at 2 years of age, especially when a restricted breeding season is used. It is not only important that heifers breed and conceive, but, for maximum efficiency, they should breed and conceive early in the breeding season. Thus, age at puberty may be an important selection trait for identifying breeds most suited for efficient utilization of feed resources. Several researchers have demonstrated large differences among breed or breed cross in age at puberty of heifers. Other researchers have demonstrated that undernutrition may result …

Elfazepam And Synovex-S Influences On Growth And Carcass Characteristics Of Steers Fed Two Dietary Energy Levels, Ronald L. Prior, John D. Crouse, Virden L. Harrison

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

Synovex-S improves the average daily gain and carcass traits of steers and reduces losses under high feed price levels when compared to nonimplanted steers. High energy diets also influence average daily gain (ADG) favorably, but they increase the amount of fat and decrease the protein in carcass soft tissue in comparison to low energy diets.

Energy Utilization By Mature Cows, Calvin L. Ferrell, Thomas G. Jenkins

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

Although considerable effort has been directed toward describing nutrient requirements for maintenance and gain in growing-finishing beef cattle, relatively little effort has been made to establish nutrient requirements for these functions in mature beef cows. A high proportion (about 60%) of the feed resources required for beef production can be attributed to maintenance of the cow herd, thus more information is needed on the utilization of nutrients for maintenance and gain and how these parameters are affected by size and type of cow.

Estimation Of Retail Product Of Carcass Beef, John D. Crouse

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

Carcasses from 1,121 steers (progeny of Hereford or Angus cows mated to Hereford, Angus, Charolais, Simmental, Limousin, South Devon, or Jersey sires by artificial insemination) were examined to develop equations to estimate percentage of retail product. The independent variables chosen and resultant accuracy of the equations developed, reflect different kinds of measurements that could be used to predict cutability over a wide range of data collection conditions.

Of 18 traits readily obtained in the cooler, adjusted fat thickness, rib eye area, estimated kidney and pelvic fat, hot carcass weight, and marbling score were the most important in predicting percentage of …

Heterosis And Breed Maternal And Transmitted Effects In Beef Cattle, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

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

Heterosis has been shown to have important effects on most economic traits of beef cattle. This is a report of the results from the first phase of an experiment designed to evaluate heterosis and breed maternal and transmitted effects on economic traits of beef cattle and involves some combinations of breeds not previously included in crossbreeding experiments. Results are reported on preweaning traits, growth rate and puberty in females, growth traits in steers, and carcass traits of steers produced in an experimental design that included the straightbreds and all possible crosses of the Red Poll, Brown Swiss (European and domestic), …

Characterization Of Breeds Representing Diverse Biological Types: Postweaning Growth And Feed Efficiency, Larry V. Cundiff, Robert M. Koch, Keith E. Gregory

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

On a life-cycle basis, about 30% of the energy requirements for beef production are consumed by steers and heifers during the period from weaning to slaughter. About 45 to 55% of the total feed costs are incurred in the postweaning period, depending on the cost of feed resources for the cow herd relative to those for the feedlot. We find it is important, therefore, to characterize breeds of cattle for rate and efficiency of postweaning gain.

Effects Of Heterosis In Hereford, Angus, And Shorthorn Rotational Crosses, Larry V. Cundiff, Keith E. Gregory, Robert M. Koch

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

Seedstock breeders of poultry and of many plants; such as corn, may use static systems of mating that produce sufficient hybrids for complete use of heterosis in commerical production. Use of heterosis in these species can be maximized because only a small proportion of the total population is required for seedstock production. Complete use of heterosis is more difficult in cattle because of their relatively low reproductive rate and long generation interval, which overlaps from one year to the next. However, this difficulty does not preclude the use of a high level of heterosis in commercial beef production. Systems of …

Preliminary Observations On The Immune Status Of Newborn Normal And Weak Calf Syndrome Calves, Rita C. Manak, William G. Kvasnicka

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

Thymus-derived lymphocytes from weather-stressed calves decline in response t6 Concanavalin A (Con A) and Pokeweed Mitogen (PWM) as the age of calf increases. Maximal response is from 24-hr old normal calves; very little response is from Weak Calf Syndrome (WCS) calves. This depressed response reflects the observed thymus degeneration in WCS calves and contributes to the animals' impaired immune system development.

Evaluation Of Traits In The Usda Yield Grade Equation For Predicting Beef Carcass Cutability In Breed Groups Differing In Growth And Fattening Characteristics, John D. Crouse

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

Carcasses of 786 steers derived from crosses of Hereford or Angus cows bred to Hereford, Angus, Charolais, Limousin, Simmental, South Devon, and Jersey sires were fabricated into closely trimmed, semi-boneless retail cuts to study relationships among independent variables in the USDA yield grade equation in breed groups that differ in growth and fattening characteristics.

fattening characteristics. Simple correlations indicate carcass weight was a good predictor of cutability within a breed group but a poor indicator over all breed groups. Rib eye area had the lowest predictive value of the four variables studied. Rib eye area may be more useful in …

Sixteen Years Of Selection For Weaning Weight, Final Weight, And Muscling Score In Hereford Cattle, Robert M. Koch, Larry V. Cundiff, Keith E. Gregory

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

Selection is the primary force for changing average genetic composition of herds, breeds, or species. Individual changes from one generation to the next associated with selection are usually small. In time, however, the change can be dramatic.

Selection is deciding which bulls and cows get to become parents and how many offspring we allow them to have. Both the will of man and the will of nature are directive forces in selection. Rate of progress from selection is determined by (1) average selection differential of parents for all traits under selection, (2) heritability of traits, (3) genetic correlations between traits, …

Methane And Protein From Beef Cattle Manure, Andrew G. Hashimoto, Yud-Ren Chen, Vincent H. Varel, Ronald L. Prior

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

Dwindling supplies of conventional fossil fuels have prompted renewed interest in recovering energy through the bioconversion of waste organic materials. The large quantities of manure produced in confinement feedlots and the need to manage this manure effectively make feedlots a logical choice for assessing the feasibility of recovering methane and protein through anaerobic fermentation.

Research at U.S. Meat Animal Research Center is designed to determine the technical and economic feasibility of recovering methane and protein from beef cattle manure.

Specific Objectives are to:

1. Develop design criteria for optimum production of methane and protein through anaerobic fermentation of beef cattle …

Characterization Of Breeds Representing Diverse Biological Types: Postweaning Growth And Puberty Of Females, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

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

Puberty traits in beef cattle are important criteria for evaluating the use of breeds for different beef production systems. Age at puberty is an important trait in beef cattle where females are bred to calve at 2 years of age, especially when a restricted breeding season is used. It is not only important that heifers reach puberty and conceive, but that they conceive early in the breeding season. Heifers that fail to reach puberty or that reach puberty and conceive late in the breeding season cause reduced production efficiency. Thus, from a breed selection standpoint, puberty is an important trait …

Characterization Of Breeds Representing Diverse Biological Types: Preweaning Traits, Keith E. Gregory, Larry V. Cundiff, Robert M. Koch

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

The germ plasm base for beef cattle production in the United States has been broadened considerably during the last decade, primarily as a result of the development of appropriate quarantine facilities and procedures by the Canada Department of Agriculture that have provided for importing several new breeds of European origin. Also, the importation of new breeds, along with other factors, has stimulated interest in increased use for beef production of several breeds that have been available in North America for many years. The newly introduced breeds added to the breeds already available in the United States provide a wide range …

Testicular Development And Onset Of Puberty In Beef Bulls, Donald D. Lunstra

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

Selection and management of young beef bulls have been hampered by a lack of information on reproductive development, growth, and puberty. The use of an increasing number of sire breeds in the beef cattle industry has placed additional emphasis on the importance of defining differences in sexual maturation within and among breeds. We conducted the following studies as part of a program designed to characterize reproductive development and puberty in breeds of beef bulls.

Roman L. Hruska U.S. Mean Animal Research Center: Overview On Center

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) 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 1966 and 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 …