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Animal breeding reports in the Journal of Animal Science (JAS) and in its predecessor, Proceedings of the American Society of Animal Production, were counted and categorized. In 22 volumes of the Proceedings of the American Society of Animal Production, 155 articles had animal breeding content, of which 54% were research reports, 17% extension communications, and 28% syntheses or reviews. Several of the latter featured advice from the livestock industry to the scientific community. Thirty-one percent of articles concerned swine, whereas beef cattle, dairy cattle, and sheep each accounted for an additional 20%. In the 67 yr of JAS publication, 3,045 research papers were identified with animal breeding content, nearly half of them published since 1990. Growth in publication output was modest during the 1950s, robust in the 1960s through 1980s, moderate in the 1990s, and static in the 2000s. Important topics included genetic resource evaluation (a subject in 55% of all manuscripts), genetic parameter estimation, selection programs, and nonrandom mating systems. Maternal effects and genotype × environment interactions were featured in 17 and 15% of all manuscripts, respectively, whereas 6% dealt with a simply inherited trait. Only 4% of manuscripts included economic analysis of a breeding program or intervention. Interest in molecular biology and biometry has surged in the 1990s and 2000s. Approximately 50% of all papers involved cattle, a fifth of which concerned dairy cattle or beef × dairy crossbreds. A quarter of papers concerned swine, 15% concerned sheep, and 3% considered laboratory rodents, with the proportional contribution of sheep research decreasing across time. Authors from the Midwestern and Southern sections of the American Society of Animal Science had greater proportional contributions than Western and Northeastern section authors, and contributions of university and state experiment station authors outnumbered those of USDA-ARS authors. The proportional contribution of international authors increased across time, reaching 45% for the 2000s, as that of university and experiment station authors decreased and that of USDA-ARS authors remained fairly constant. Subjective analysis suggested substantial levels of creativity, innovation, and cooperation in JAS animal breeding research, a strong international perspective, but also a marked degree of imitation and repetition in subject matter content. [ABSTRACT FROM AUTHOR]

Acute and subacute ruminal acidosis, bloat, liver abscesses, and polioencephalomalacia (PEM) were reviewed with respect to contributions published in the Journal of Animal Science (JAS) regarding these metabolic and digestive disorders in beef cattle. Increased grain feeding and expansion of the feedlot industry in the 1960s led to considerable research on acidosis, and. early publications defined ruminal changes with acute acidosis. The concept of subacute acidosis was developed in the 1970s. Significant research was published during the 1980s and 1990s on adaptation to high-grain diets, effects of ionophores, and the development of model systems to study ruminal and metabolic changes in acidosis. Since 2000, JAS publications on acidosis have largely focused on individual animal variability in response to acid loads and the role of management strategies in controlling acidosis. Increased grain feeding also was associated with an increase in the incidence of liver abscesses, which were quickly linked to insults to the ruminal epithelium associated with acidosis. The role of antibiotics, particularly tylosin, in decreasing the incidence and severity of liver abscesses was a significant contribution of JAS publications during the 1970s and 1980s. Papers on bloat were among the earliest published in JAS related to metabolic and digestive disorders in cattle. Noteworthy accomplishments in bloat research chronicled in JAS include the nature of ruminal contents in legume and feedlot bloat, the role of plant fractions and microbial populations in the development of bloat, and the efficacy of poloxalene, ionophores, and, more recently, condensed tannins in decreasing the incidence and severity of bloat. Although less research has been published on PEM in JAS, early publications highlighting the association between PEM and ruminal acidity and the role of thiaminase in certain forms of the disorder, as well as more recent publications related to the role of sulfur in the development of PEM, are noteworthy contributions. Since the 1940s, outstanding and often-cited review articles have made JAS a highly visible source of information on these disorders. Thus, JAS has played a significant role as a repository for information pertaining to metabolic and digestive disorders in cattle and other ruminants, and it will no doubt continue to be a premier resource for information on these conditions during the second century of the American Society of Animal Science. [ABSTRACT FROM AUTHOR]

Discoveries, understanding, and innovations in meat science during the last century have led to revolutionary changes in meat and poultry production, processing, marketing, and consumption. American Society of Animal Science members have made key contributions in most, if not all, categories of advancement. The first US university meat science program was begun in Minnesota in 1905. Use of mechanical refrigeration in the meatpacking industry, improved transportation and packaging, and home refrigeration provided more flexibility, variety, and consistency in meat and meat products in the early 1900s. Cooperative meat research was begun by 27 universities in 1925, with a focus on the observational characterization of carcass traits and composition, meat quality attributes, and causes of the wide variation in these variables. Scientific study of genetic, nutritional, and environmental influences on the growth, physiology, and postmortem biochemistry of muscle often used muscle-comparative investigations. Rigor mortis, cold shortening and thaw rigor, postmortem muscle metabolism, postmortem tenderization and tenderness variation, and postmortem myoglobin and lipid oxidation were studied vigorously in the 1960s and beyond, defining the biochemical bases for associated outcomes in fresh and processed products. Value-added benefits resulted from implementation of electrical stimulation, boxed beef and modified-atmosphere packaging, restructuring technologies, collagen recovery, and muscle profiling work. Isolation, purification, and definition of the primary structure and biophysical properties of the myofribillar and cytoskeletal proteins in muscle aided the understanding of contraction and postmortem changes. The role of Ca-dependent proteases in meat tenderness and muscle growth is being clarified. The chemistry of meat curing, meat emulsion formation, fermentation, and other processing methods led to new technologies, new meat products, and new benchmarks in product shelf life and quality. Meat safety assurance and our ability to manage the microbiological causes of food-borne illness and spoilage are imminently important now and in the future. [ABSTRACT FROM AUTHOR]

Development of nutritional energetics can be traced to the 1400s. Lavoisier established relationships among O2 use, CO2 production and heat production in the late 1700s, and the laws of thermodynamics and law of Hess were discovered during the 1840s. Those discoveries established the fundamental bases for nutritional energetics and enabled the fundamental entity ME = retained energy + heat energy to be established. Objectives became: 1) to establish relationships between gas exchange and heat energy, 2) to devise bases for evaluation of foods that could be related to energy expenditures, and 3) to establish causes of energy expenditures. From these endeavors, the basic concepts of energy partitioning by animals were developed, ultimately resulting in the development of feeding systems based on NE concepts. The California Net Energy System, developed for finishing beef cattle, was the first to be based on retained energy as determined by comparative slaughter and the first to use 2 NE values (NEm and NEg) to describe feed and animal requirements. The system has been broadened conceptually to encompass life cycle energy requirements of beef cattle and modified by the inclusion of numerous adjustments to address factors known to affect energy requirements and value of feed to meet those needs. The current NE system remains useful but is empirical and static in nature and thus fails to capture the dynamics of energy utilization by diverse animals as they respond to changing environmental conditions. Consequently, efforts were initiated to develop dynamic simulation models that captured the underlying biology and thus were sensitive to variable genetic and environmental conditions. Development of a series of models has been described to show examples of the conceptual evolution of dynamic, mechanistic models and their applications. Generally with each new system, advances in prediction accuracy came about by adding new terms to conceptually validated models. However, complexity of input requirements often limits general use of these larger models. Expert systems may be utilized to provide many of the additional inputs needed for application of the more complex models. Additional information available from these systems is expected to result in an ever-increasing range of application. These systems are expected to have increased generality and the capability to be integrated with other models to allow economic evaluation. This will eventually allow users to compute solutions that allow development of optimal production strategies. [ABSTRACT FROM AUTHOR]

The article presents abstracts on veterinary medicine topics which include reproductive performance in postpartum Rambouillet ewes and prepubertal ewe lambs treated with intravaginal progesterone, effect of bunk scoring on feedlot steer intake, and genetic parameter estimates for ultrasound indicators of carcass performance in Red Angus cattle.

The article presents abstracts on veterinary medicine topics which include dietary supplementation of colicin E1 to prevent post-weaning diarrhea in pigs caused by Escherichia coli, activation of caspase 3 enzyme in postmortem beef and lamb muscle, and factors affecting feed efficiency in feedlot steers.

Cattle health management in the feedlot sector continues to evolve and improve cattle welfare by promoting an understanding of illness and injury to minimize their effects. Many papers have focused on treating individual ill or injured cattle in cattle feeding facilities. However, care, treatment, and outcomes for chronically ill or injured cattle (“chronic cattle”) have received little attention in the literature. The purpose of this descriptive study was to present demographics, diagnoses, and outcomes of chronic cattle in 17 feedlots in the U.S. and Canada and discuss potential risk factors and welfare implications. Individual chronic cattle information and treatment records from 17 feedlots (U.S.: 8; Canada: 9) over 7 yr (2014 – 2020) were retrospectively retrieved from a large feedlot consulting and data-management service (Feedlot Health Management Services, a division of TELUS Agriculture Solutions Inc.). Chronic cattle were defined as those that had spent time in a feedlot’s designated chronic pen. Descriptive results are presented as means ± standard deviations. U.S. feedlots averaged 31,280 ± 23,231 cattle/yr, had an average chronicity rate of 2.24 ± 2.42 % (median 1.53%), and contributed 52,709 chronic cattle to the dataset. Canadian feedlots averaged 21,913 ± 10,497 cattle/yr, had an average chronicity rate of 1.41 ± 0.82% (median 1.10%), and contributed 15,940 chronic cattle to the dataset. U.S. chronic cattle were sourced across all seasons primarily from auctions and ranches, had an average arrival weight of 163 ± 59 kg, and an average days on feed (DOF) of 362 ± 172 d. Canadian chronic cattle were primarily auction-sourced in the fall, weighed 272 ± 95 kg at arrival, and averaged 246 ± 141 DOF. Chronic cattle were treated at least once for respiratory issues (U.S.: 46.3%; Canada: 26.9%), bullers (U.S.: 34.5%; Canada: 5.8%), musculoskeletal issues (U.S.: 2.2%; Canada: 1.4%), lameness (U.S.: 1.7%; Canada: 28.1%), metabolic issues (U.S.: 0.5%; Canada: 4.5%), or other diagnoses (U.S.: 2.2%; Canada: 6.3%), with many cattle treated for multiple issues (U.S.: 12.5%; Canada: 27.0%). Outcomes for chronic cattle were shipped (U.S.: 73.1%; Canada: 52.5%), railed (U.S.: 8.1%; Canada: 20.7%), euthanized (U.S.: 0.7%; Canada: 9.9%) died unassisted (U.S.: 18.1%; Canada: 16.2%), or transferred (U.S.: < 0.1%; Canada: 0.8%). These results are some of the first to describe chronic cattle populations and present interesting trends for further analysis. For example, differences in buller and lameness rates could reflect actual differences but may be artifices of the dataset and feedlot definitions. Additionally, high marketed cattle rates (shipped and railed) indicate positive outcomes for most cattle, but variable mortality rates merit further scrutiny [ABSTRACT FROM AUTHOR]

For genomic predictors to be of use in genetic evaluation, their predicted accuracy must be a reliable indicator of their utility, and thus unbiased. The objective of this paper was to evaluate the accuracy of prediction of genomic breeding values (GBV) using different clustering strategies and response variables. Red Angus genotypes (n = 9,763) were imputed to a reference 50K panel. The influence of clustering method [k-means, k-medoids, principal component (PC) analysis on the numerator relationship matrix (A) and the identical-by-state genomic relationship matrix (G) as both data and covariance matrices, and random] and response variables [deregressed estimated breeding values (DEBV) and adjusted phenotypes] were evaluated for cross-validation. The GBV were estimated using a Bayes C model for all traits. Traits for DEBV included birth weight (BWT), marbling (MARB), rib-eye area (REA), and yearling weight (YWT). Adjusted phenotypes included BWT, YWT, and ultrasonically measured intramuscular fat percentage and REA. Prediction accuracies were estimated using the genetic correlation between GBV and associated response variable using a bivariate animal model. A simulation mimicking a cattle population, replicated 5 times, was conducted to quantify differences between true and estimated accuracies. The simulation used the same clustering methods and response variables, with the addition of 2 genotyping strategies (random and top 25% of individuals), and forward validation. The prediction accuracies were estimated similarly, and true accuracies were estimated as the correlation between the residuals of a bivariate model including true breeding value (TBV) and GBV. Using the adjusted Rand index, random clusters were clearly different from relationship-based clustering methods. In both real and simulated data, random clustering consistently led to the largest estimates of accuracy, while no method was consistently associated with more or less bias than other methods. In simulation, random genotyping led to higher estimated accuracies than selection of the top 25% of individuals. Interestingly, random genotyping seemed to overpredict true accuracy while selective genotyping tended to underpredict accuracy. When forward in time validation was used, DEBV led to less biased estimates of GBV accuracy. Results suggest the highest, least biased GBV accuracies are associated with random genotyping and DEBV. [ABSTRACT FROM AUTHOR]

As input costs increase, producers need to be mindful of management practices to maintain profit margins and it is important to understand current management practices. Therefore, the objective of this study was to investigate current beef marketing strategies and beliefs of beef producers in the state of Mississippi in 2019. This survey was distributed to cattle producers in Mississippi in the June/July issue of "Cattle Business in Mississippi" magazine with return postage. There also was a link included in the "Monday Memo" email sent to members of the Mississippi Cattlemen's Association. The survey consisted of 22 questions that were divided into three sections: current practices, current cow-calf marketing practice, and general information. Responses from the survey were anonymous and confidential and were received via paper mail or electronic responses. Responses were stored and analyzed using Qualtrics. Data collected from this study were compared with 1999 data from a similar study conducted by Little et al. (2000). Out of 148 respondents, there was a 95% completion rate of surveys taken. Most respondents were 51 years and older with 54% of the respondents being part of the cattle industry for over 31 years. Ninety percent of respondents were members of the Mississippi Cattlemen's Association and almost 60% were certified in Beef Quality Assurance. The majority, 122 of 148 producers, stated their cattle operation was not the primary source of income for their household. The average number of cows, bulls, stockers/yearling, replacement heifers and cattle on-feed on an operation was greater in the 2019 data compared with 1999. On average, the number of cows per operation increased from 40 to 68 animals, bulls increased from 2 to 5 animals, and replacement heifers increased from 7 to 17 animals from 1999 to 2019. There was also an average increase from 30 to76 animals of stocker/yearling and an increase from 2 to 27 animals of on-feed cattle. Most producers vaccinate (81%) and deworm (85%) according to recommendations and indicated a lack of labor and time as reasons for not implementing some common management practices such as preconditioning. Respondents mainly purchased calves directly from a producer (61%) or from special sales (59%). In 1999, over one-half of respondents purchased from an auction. When it came to selling cattle, 58% of respondents sold at auction regularly in 2019. In 1999, 73% of respondents sold at auctions. In 2019, 72% of respondents stated they did not retain ownership while in 1999 only 58% of respondents did not retain ownership. In conclusion, our results suggest there have been key changes within the cattle industry regarding herd size increases and a shift in selling and purchasing habits since 1999. [ABSTRACT FROM AUTHOR]

Presents abstracts of studies on animal science submitted to the American Society of Animal Science in January 2001. `Subcellular Differences in Muscle Calcium and Phosphorus Due to Vitamin D[sub 3] Supplementation of Beef Cattle,' by J.L. Montgomery et al.; `Microbiological and Visual Characteristics of Whole Muscle Beef Steaks From the Round With 3 Different USDA Grade Groups as Affected by High Oxygen Case-Ready Packaging,' by W.B. Mikel et al.

The article presents abstracts from papers related to animal nutrition that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Body Condition Score at Parturition and Effects of Postpartum Supplemental Fat on Metabolite and Hormone Concentrations of Beef Cows," by S. Laket, E. Scholljegerdes, V. Nayigihugu, R. Atkinson, E. Van Kirk, D. Rule, D. Hallford, G. Moss, and B. Hess, determined the effects of body condition score at parturition and postpartum lipid supplementation on blood metabolite and hormone concentrations. The paper "In-Vitro and In-Vivo Rumen Fermentation and Gas Production: Influence of Corn and Mineral Oils and Their Bloat Potential," B. Min and W. Pinchak, investigated the influence of mineral and corn oil on ruminal fermentation, gas production, and bloat potential in a series of in vitro and in vivo grazing studies. The paper "Fatty Acid Composition of Plasma, Medial Basal Hypothalamus, and Uterine Tissue in Primiparous Beef Cows Fed High-Linoleate Safflower Seeds," was presented by E. Scholljegerdes, D. Rule, U. Moss, and B. Hess.

The article presents abstracts from papers related to animal breeding and genetics that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Cultural Energy Analysis of Pasturing Systems for Cattle Finishing Programs," by H. Koknaroglu, K. Ekincil, M.P. Hoffman and P. Tsengeg, assessed cultural energy analysis of cattle production systems. Cultural energy includes labor manufacture of machinery, transportation, production of fertilizers and herbicides, processing material and finally marketing the product. The paper "The Effectiveness of Synergistic Blends of Organic Acids in the Stabilization of Wet Distillers Grains," was presented by S. Moore, J. Smith and V. Sewalt. The paper "Marker-Assisted Selection on Multiple QTL in a Crossbred Population," by N. Piyasatian, L.R. Totir, R.L. Fernando and J.C.M. Dekkers, evaluated the efficiency of marker-assisted selection on multiple QTL for a trail, with heritability 0.1 in a line-crossing program on the basis of frequencies of favorable QTL alleles and genetic gain over ten generations of selection, starting in the F2.

The article presents abstracts from papers related to animal nutrition that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Estimation of Undegradable Intake Protein Digestibility in Forages Using a Mobile Nylon Bag Technique," by J. Benton, J. MacDonald and M. Lamothe, used two ruminally and duodenally cannulated steers to estimate digestibility of undegradable intake protein of two forage types using a mobile bag technique. The paper "Combinations of Distiller's Grains, Gluten Feed, and Soy Hulls for Growing Cattle," by J. Sewell and L. Berger, evaluated co-products combinations compared to a program-fed corn based growing diet for feedlot cattle. The paper "Potential of Alimet Supplementation to Improve Growth and Reproduction of Beef Heifers Fed a Forage Diet," by E. Venable, M. Kerley and B. Miller, studied the importance of adequate growth rates by beef heifers. Supplementing rumen undegradable protein has been shown to enhance reproductive tract development in heifers.

The article presents abstracts from papers related to animal breeding and genetics that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Growth and Carcass Traits in Crossbred Cattle From Hereford, Angus, Norwegian Red, Swedish Red and White, Friesian, and Wagyu Maternal Grandsires," by E. Casas and L.V. Cundiff, studied post-weaning growth and carcass traits on 434 steers and 373 heifers obtained by mating F1 cows to Charolais sires. The paper "Selection for an Index of Placental Efficiency and Litter Size in Swine," by H. Mesa, T.J. Safranski, K.M. Cammack, and W.R. Lamberson, estimated genetic trends and parameters for individual and litter traits using data from four generations of replicated divergent selection on an index of reproductive traits. The paper "Reproduction and Maternal Performance of F1 Cross Females Sired by Hereford, Angus, Norwegian Red-Swedish Red and White, Friesian and Wagyu Sires," by L.V. Cundiff, characterized reproduction and maternal traits of F1 cross females calving at 3 through 7 years of age in cycle VI of the Germplasm Evaluation Program at the U.S. Meat Animal Research Center.

The article presents abstracts from papers related to tropically adapted animal breeds that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Florida Crossbreeding Research," by D.G. Riley, G.R. Hansen, J.F. Crockett, T.A. Olson and C.C. Chase, Jr., highlights the accomplishments of three University of Florida beef cattle research locations from the 1940s through the late 1980s. The paper "Birth to Harvest Attributes of Brahman and Brahman-Influenced Steers," by C.R. Long, J.I. Cele and R.D. Randel. The paper "Cow-Calf Performance of Brahman-British and Brahman-Continental Beef Females," by S.M. DeRouen, W.E. Wyatt, P.E. Humes, D.E. Franke and D.C. Blouin, evaluated Brahman-British and Brahman-Continental breeds and breed crosses for cow-calf performance. The paper "Evaluation of F1 Crosses of Five Boa Indicus Breeds With Hereford for Birth, Growth, Carcass, Cow Productivity and Longevity Traits," by J. Sanders, O. Riley, J. Paschal and D. Luntt, evaluated birth, growth, carcass and cow productivity traits in cattle out of Hereford cows arid.

This article presents abstracts of various papers related to beef cattle and its pastures and forage plants, that were presented during the symposium held on July 26, 2005, Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science and the Canadian Society of Animal Science. One of the papers presented is "Fatty Acid Composition in Subcutaneous and Intramuscular Fat of Steers Grazing Pasture Supplemented With Corn Oil," by E. Pavan and S. Duckett. To evaluate the effect of increasing corn oil supplementation of grazing steers on fatty acid composition, subcutaneous and intramuscular samples were taken from the left side of the carcass of 18 steers. Another paper discussed is "Coastal, Russell, and Tifton 85 Bermudagrass Hay and Supplement Intake and Digestion by Steers," by G.M. Hill, G.J. Andrae, B.C. Hand and B.G. Mullinix. Coastal , Tifton 85 and Russell bermudagrass hays harvested at 5-wk maturity were fed without or with a supplement to steers to determine DM1 and digestibility.

The article presents abstracts of various research papers related to nutrition of beef cattle that were presented during the symposium held on July 24-28, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. In one of the papers titled "Effect of Clinoptilolite Zeolite on Cattle Performance and Manure Nitrogen," a summer feedlot trial was conducted from May to September using 96 crossbred yearling steers to evaluate effects of adding clinoptilolite zeolite at 1.2% of the diet on steer performance and N removed in manure. Steers were stratified by weight and assigned randomly to 12 pens and one of two treatments. Treatments were control diet with 0% zeolite clay or treatment diet with 1.2% clinoptilolite zeolite clay. Diets consisted of 62.5% dry rolled corn, 25% wet corn gluten feed, 7.5% alfalfa hay and 5% supplement. Nitrogen intake was calculated using analyzed dietary N concentration for each feedstuff and total DMI.

The article presents abstracts of various papers related to growth and development of dairy animals that were presented during the symposium held on July 24-28, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. One of the papers titled "Improved Prediction of Retained Energy in a Dynamic Beef Cattle Growth and Composition Model Accounting for Variable Maintenance," states that animal growth and composition models base their predictions on estimated retained energy. Therefore, variation in maintenance requirements related to previous nutrition and animal state should be accounted for. In a study, the Davis Growth Model was re-parameterized using data from an independent experiment. The dataset contains measurements of diet energy concentration, dry matter intake, and initial and final body composition for 110 animals. Steers were fed one of two diets. Results of the study indicated that accounting for variable maintenance can significantly improve predictions in dynamic models of beef cattle growth and body composition.

Macro- and microminerals are required for all physiological processes in beef cattle. When mineral deficiencies occur in pasture-based production systems, a multitude of deficiency symptoms may occur, and most often, these deficiencies result in hidden losses to include reduced production potential, reduced immunity, and reproductive failure. More severe deficiencies will result in specific deficiency symptoms, depending on the specific mineral deficiency. In pasture-based beef operations, specific deficiency symptoms are seldom observed. Forage mineral supply is highly variable and dependent on the forage type, stage of forage growth, and soil fertility. Grazing cattle mineral requirements change throughout the production cycle. With the variability of forage mineral supply and the changing mineral requirements, care must be taken when developing mineral supplementation programs for grazing cattle. The macrominerals function in nerve transmission, bone development, and metabolism and as electrolytes. These are Ca, P, Mg, Na, K, Cl, and S. The microminerals function in various areas of metabolism, immune responsiveness, reproductive efficiency, and many other functions. These minerals are Zn, Cu, Fe, I, Mn, Se, Mo, and Co. Of these macro- and microminerals, those that are important for supplementation to pasture-based cattle include Ca, P, Mg, Na, Cl, Zn, Cu, I, Mn, Se, and Co. However, the amounts to be supplemented will depend on the specific mineral requirements and the forage supply of the minerals. Consequently, the development of free-choice mineral supplementation programs is a moving target. Generally, this entangled mess is sorted by taking one mineral at a time into consideration. However, in doing so, one has to be cognizant of the many interactions that occur when changing intake of just 1 mineral in the supplement with respect to the amount supplied in the base forage. Often times, mineral nutrition problems of one or more minerals are created when trying to correct a deficiency of another mineral. This paper will address specific factors that are important to consider when developing and delivering mineral supplementation programs in pasture-based production systems in the Southeastern United States. [ABSTRACT FROM AUTHOR]

The objective of this paper was to estimate the genetic parameters of certain internal diseases (multifocal necrosis in the liver [MNL], bovine abdominal fat necrosis [BFN], and inflammation of the large intestine [ILI]) and to investigate relationships between the internal diseases and carcass traits (carcass weight [CW], rib eye area [REA], rib thickness [RT], subcutaneous fat thickness, and beef marbling score [BMS]). Records of the internal diseases and the carcass traits of 5,788 Japanese Black cattle were used for this study. The data for all the diseases were recorded as binary data as to whether the disease was observed (1) or not (0). Genetic parameters were estimated using linear and threshold animal models. The prevalence rates of MNL, BFN, and ILI were 16.1, 23.0, and 6.8%, respectively, and heritability estimates ± posterior SD were 0.18 ± 0.06, 0.28 ± 0.06, and 0.18 ± 0.06, respectively. The genetic correlations of MNL with BFN and ILI were -0.23 (P = 0.19) and -0.49 (P < 0.05), respectively. In contrast, the correlation between BFN and ILI was positive and high (0.96; P < 0.05). The phenotypic correlations of the internal diseases with the carcass traits were weak and not different from 0 except for those of BFN and ILI with CW, REA, and RT, which were all negative (P < 0.05) and ranged from -0.21 (ILI and CW) to -0.05 (BFN and RT). The genetic correlations of MNL with the carcass traits were all weak and not significant. In contrast, the genetic correlations of BFN and ILI with CW, REA, and RT were all negative and significant (P < 0.05) between BFN and CW (-0.36) and between BFN and RT (-0.33). However, the genetic correlations for BFN and ILI with BMS were all positive at 0.21 (P = 0.16) and 0.39 (P < 0.05), respectively. The estimated heritability of the internal diseases suggests that they can be genetically improved. Genetic relationships of BFN and ILI with meat quantity traits were favorable for beef cattle breeding, because lower disease liabilities were associated with improved CW, REA, and RT for BFN and ILI. However, rather strong and unfavorable genetic relationships were found between BFN or ILI and BMS, which is related to meat quality. This suggests that selection for animals with superior BMS would increasingly lead to animals with higher liability to the internal diseases. [ABSTRACT FROM AUTHOR]

This study evaluated 8 empirical models for their ability to accurately predict mean ruminal pH in beef cattle fed a wide range of diets. Models tested that use physically effective fiber (peNDF) as a dependent variable were Pitt et al. (1996, PIT), Mertens (1997, MER), Fox et al. (2004, FOX), Zebeli et al. (2006, ZB6), and Zebeli et al. (2008, ZB8), and those that use rumen VFA were Tamminga and Van Vuuren (1988, TAM), Lescoat and Sauvant (1995, LES), and Allen (1997, ALL). A data set of 65 published papers (231 treatment means) for beef cattle was assembled that included information on animal characteristics, diet composition, and ruminal fermentation and mean pH. Model evaluations were based on mean square prediction error (MSPE), concordance correlation coefficient (CCC), and regression analysis. The prediction potential of the models varied with low root MSPE (RMSPE) values of 4.94% and 5.37% for PIT and FOX, RMSPE values of 9.66% and 12.55% for ZB6 and MER, and intermediate RMSPE values of 5.66% to 6.26% for the other models. For PIT and FOX, with the lowest RMSPE, approximately 96% of MSPE was due to random error, whereas for ZB6 and MER, with the highest RMSPE, 15.85% and 23.42% of MSPE, respectively, was due to linear bias, and 37.19% and 60.12% of the error, respectively, was due to deviation of the regression slope from unity. The CCC was greatest for PIT (0.67) and FOX (0.62), followed by 0.60 for LES and TAM, 0.52 for ZB8, 0.39 for MER, 0.34 for ALL, and 0.22 for ZB6. Residuals plotted against model-predicted values showed linear bias (P < 0.001) for all models except PIT (P = 0.976) and FOX (P = 0.054) and mean bias (P < 0.001) except for FOX (P = 0.293), LES (P = 0.215), and TAM (P = 0.119). The study showed that the empirical models PIT and FOX, based on peNDF, and LES and TAM, based on VFA, are preferred over the others for prediction of mean ruminal pH in beef cattle fed a wide range of diets. Several animal (BW and intake), diet (forage and OM contents), and ruminal (ammonia and acetate concentrations) factors were (P < 0.001) related to the residuals for each model. We conclude that the accuracy of prediction of mean ruminal pH was relatively low for all extant models. Consideration of factors in addition to peNDF and total VFA, as well as the use of data from studies with continuous measurement of ruminal pH over 24 h or more, would be useful in the development of improved models for predicting ruminal pH in beef cattle. [ABSTRACT FROM AUTHOR]

Prediction of microbial CP (MCP) synthesis in the rumen is an integral part of the MP system. For the NRC beef model, MCP is calculated as 0.13 multiplied by TDN intake (TDNI), with adjustment for physically effective NDF (peNDF) concentrations less than 20%. Despite its application for nearly 2 decades, MCP predictions using this approach have not been extensively evaluated. We assembled a database of 285 treatment means from 66 published papers using beef cattle and dairy or dairy x beef crossbred steers, fed diets with a wide range of TDN, CP, and ether extract (EE) concentrations, in which MCP synthesis was measured. Fat-free TDN (FFTDN) concentration was calculated by subtracting 2.25 x percent EE from the TDN concentration. Based on initial model selection procedures indicating that DMI and concentrations of TDN, FFTDN, and CP were significantly (P < 0.04) related to MCP synthesis, linear and quadratic effects of TDNI and FFTDN intake (FFTDNI) and CP intake (CPI) were considered as potential independent variables. Mixed model regression methods were used to fit 1-, 2-, and 3-independent variable models based on either TDNI or FFTDNI (e.g., TDNI only, TDNI and CPI, and TDNI, CPI, and the quadratic effect of TDNI; or FFTDNI only, FFTDNI and CPI, and FFTDNI, CPI, and the quadratic effect of FFTDNI). Tme ruminal OM digested (TROMD; g/d) was highly related (r² = 0.84 using citation-adjusted data) to MCP synthesis. Similarly, both TDNI and FFTDNI were highly related to citation-adjusted TROMD (r² > 0.96) and MCP synthesis (r² > 0.89). Models with FFTDNI were slightly more precise with slightly smaller prediction errors than those with TDNI. Randomly dividing the citations into Development (60%) and Evaluation (40%) data sets indicated that models such as those derived from the overall database accounted for 46 to 56% of the variation in MCP synthesis, with neither mean nor linear bias (P ≥ 0.26). In contrast, calculating MCP as 0.13 x TDNI, with or without adjustment for peNDF concentration, resulted in overprediction of MCP (P < 0.001 for both mean and linear bias). Cross-validation using 5,000 randomly drawn training and testing data sets yielded results similar to the Development/Evaluation approach. Recommended equations are provided, but the errors of prediction associated with these empirical regression equations were on the order of 25 to 30% of the mean MCP. [ABSTRACT FROM AUTHOR]

Improving the traits that underlie meat quality is a major challenge in the beef industry. The objective of this paper was to detect QTL linked to sensory meat quality traits in 3 French beef cattle breeds. We genotyped 1,059,1,219, and 947 young bulls and their sires belonging to the Charolais, Limousin, and Blonde d'Aquitaine breeds, respectively, using the Illumina BovineSNP50 BeadChip (Illumina Inc., San Diego, CA). After estimating relevant genetic parameters using VCE software, we performed a linkage disequilibrium and linkage analysis on 4 meat traits: intramuscular fat content, muscle lightness, shear force, and tenderness score. Heritability coefficients largely ranged between 0.10 and 0.24; however, they reached a maximum of 0.44 and 0.50 for intramuscular fat content and tenderness score, respectively, in the Charolais breed. The 2 meat texture traits, shear force and tenderness score, were strongly genetically correlated (-0.91 in the Charolais and Limousin breed and -0.86 in the Blonde d'Aquitaine breed), indicating that they are 2 different measures of approximately the same trait. The genetic correlation between tenderness and intramuscular fat content differed across breeds. Using a significance threshold of 5 x 10 for QTL detection, we found more than 200 significant positions across the 29 autosomal chromosomes for the 4 traits in the Charolais and Blonde d'Aquitaine breeds; in contrast, there were only 78 significant positions in the Limousin breed. Few QTL were common across breeds. We detected QTL for intramuscular fat content located near the myostatin gene in the Charolais and Blonde d'Aquitaine breeds. No mutation in this gene has been reported for the Blonde d'Aquitaine breed; therefore, it suggests that an unknown mutation could be segregating in this breed. We confirmed that, in certain breeds, markers in the calpastatin and calpain 1 gene regions affect tenderness. We also found new QTL as several QTL on chromosome 3 that are significantly associated with meat tenderness in the Blonde d'Aquitaine breed. Overall, these results greatly contribute to the goal of building a panel of markers that can be used to select animals of high meat quality. [ABSTRACT FROM AUTHOR]

Interannual variation of forage quantity and quality driven by precipitation events influence beef livestock production systems within the Southern and Northern Plains and Pacific West, which combined represent 60% (approximately 17.5 million) of the total beef cows in the United States. The beef cattle requirements published by the NRC are an important tool and excellent resource for both professionals and producers to use when implementing feeding practices and nutritional programs within the various production systems. The objectives of this paper include evaluation of the 1996 Beef NRC model in terms of effectiveness in predicting extensive range beef cow performance within arid and semiarid environments using available data sets, identifying model inefficiencies that could be refined to improve the precision of predicting protein supply and demand for range beef cows, and last, providing recommendations for future areas of research. An important addition to the current Beef NRC model would be to allow users to provide region-specific forage characteristics and the ability to describe supplement composition, amount, and delivery frequency. Beef NRC models would then need to be modified to account for the N recycling that occurs throughout a supplementation interval and the impact that this would have on microbial efficiency and microbial protein supply. The Beef NRC should also consider the role of ruminai and postruminal supply and demand of specific limiting AA. Additional considerations should include the partitioning effects of nitrogenous compounds under different physiological production stages (e.g., lactation, pregnancy, and periods of BW loss). The intent of information provided is to aid revision of the Beef NRC by providing supporting material for changes and identifying gaps in existing scientific literature where future research is needed to enhance the predictive precision and application of the Beef NRC models. [ABSTRACT FROM AUTHOR]

The article presents abstracts from papers related to animal physiology that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Effects of Flunixin Meglumine on Pregnancy Establishment in Beef Cattle," by R. Ansotegui, A. Roberts, R. Waterman, M. MacNeil, E. Grings, B. Thompson and R. Lipsey, determined effects of a single injection of the prostaglandin inhibitor Flunixin Meglumine approximately 13 d after A1 on pregnancy establishment. The paper "Intraluteal Treatment of Bovine CL With Indomethacin," by R.D. Speckmann, K.K. Kane, L.M. Dixon, J.S. Nelson, J.E. Bruemmer, O.D. Niswender and D.E. Hawkins, determined if inhibition of cyclooxygenase with intraluteal indomethacin prevented or delayed luteolysis in beef cows. The paper "Artificial Insemination Pregnancy Rates Using a Modified Co-Synch Protocol for Primiparous Suckled Cows Exposed to the Biostimulatory Effect of Bulls," by J. Berardinelli, R. Joshi and S. Tauck, evaluated whether exposing primiparous suckled beef cows to the biostimulatory effect of bulls alters breeding performance associated with an estrous synchronization protocol that included GnRH, PGF2a and fixed-time A1.

The article presents abstracts from papers related to animal behavior that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Estimates of the Effectiveness of Current Beef Cattle Tracking Systems," by K. Ringwall, studied the current state of the beef industry regarding the ability to track cattle. The paper "The Northwest Pilot Project: Finding Real World Solutions to Animal Identification," was presented by J.A. Morrison, R.R. Stott, J.B. Glaze, Jr. and J.K. Ahola. The Northwest Pilot Project (NWPP) is a producer-driven coalition in California, Hawaii, Idaho, Nevada, Oregon, Utah, and Washington formed to develop solutions for the implementation of the National Animal Identification System in the region. The NWPP is using applied production systems to test multiple identification methods to track livestock across state and national borders and from the herd of origin through harvest. The NWPP is working with the U.S. to help build uniformity in premises definitions and registration processes, while providing actual production scenarios to assist in the development of state identification programs and databases.

The article presents abstracts from papers related to environment and livestock management that were published in the February 2005 issue of the "Journal of Animal Science." The paper "Timing of Puberty, Anoestrus, and Return to Cyclicity in Female Offspring of Ewes Treated With Propylthiouracil and Melatonin During Pregnancy," by R. Knight, C. Gifford, and D. Hailford, used twenty four Rambouillet ewe lambs to examine seasonal cyclic responses after maternal thyroid suppression and melatonin treatment during gestation. The paper "The Effect of Bloat on Ingestive Behavior Patterns of Steers Grazing Wheat Forage," by W. Pinchak and B. Min, examined the effect of bloat status and time of day on grazing behavior of 4 bloated and 4 non-bloated rumen cannulated steers on continuously stocked wheat forage swards maintained at 8 to 9 cm sward surface height. Grazing behavior dynamics over 24 hours periods were measured automatically using jaw movement sensors to quantify temporal patterns of grazing, ruminating and idling behavior.

The article presents abstracts from papers related to meat science that were published in the February 2005 issue of the "Journal of Animal Science." In the paper "Relationship Between Ultrasound and Carcass Measures of Charolais-Cross Harvest Cattle Using an Automated Computer Tracing Software," by T. Perkins, C. Fercherio, and J. Worthington, yearling beef steers representing typical Charolais-cross commercial cattle, were evaluated for body composition measures of muscle and fat deposition utilizing real-time ultrasound measurements. The paper "Effects of Sodium Chloride, Phosphate Type and Concentration and Pump Rate on Beef Biceps Femoris Quality and Sensory Characteristics," by R.T. Baublits, F.W. Pohiman, A.H. Brown, Jr. and Z.B. Johnson, studied the effects of enhancing beef biceps lemons muscles with solutions comprising 2.0 % sodium chloride and either sodium hexametaphosphate, sodium tripolyphosphate, or tetra-sodium pyrophosphate at either 0.2 % or 0.4 % of product weight on quality and sensory characteristics. The paper "Meat Quality and Sensory Characteristics of Beef Biceps Femoris Steaks Treated With Sodium Chloride and Differing Phosphate Types, Concentrations and Pump Rates, Compared With Untreated Steaks or Steaks Treated With Only Sodium Chloride," was presented by R.T. Baublits, F.W. Pohiman, A.H. Brown, Jr. and Z.B. Johnson.

The article presents abstracts of various research papers related to ruminant nutrition, that were presented during the symposium held on July 25, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. In one of the papers titled "Feedlot Performance of a New Distillers Byproduct for Finishing Cattle," three hundred crossbred yearling steers were utilized in a randomized complete block design to evaluate the effect of level of Dakota Bran (DB) on feedlot performance and carcass characteristics. Dakota Bran is a new distillers byproduct feed produced as primarily corn bran plus distillers solubles containing 14.9% CP. Dietary treatments consisted of 0, 15, 30, and 45 % DB and 30% dried distillers grains plus solubles, replacing corn. Basal ingredients consisted of high-moisture corn and dry-rolled corn, fed at a constant 1:1 ratio, plus ground alfalfa hay and dry supplement each fed at 5% of diet. Steers were blocked by weight, stratified by weight within block, and assigned randomly to pen.

The hypothesis tested in this paper is that double-muscled (DBM) and conventional cattle, considerably differing in body composition, have similar NE requirements when: a) NEm is scaled as a function of current (Pi) and adult (Pm) protein mass; and b) ME for gain (MEK) is estimated from protein (Pr) and lipid (Lr) retention and their partial ME use efficiencies, the kp and k, values, respectively. First, 2 databases were examined: 1 was developed combining well known literature information from comparative slaughter trials conducted on British beef steers; the other was based on a trial conducted using extremely lean DBM Piemontese bulls. From the first database, NEm was calculated to be 1.625 x pi &divde Pm x Pm0.73 (MJ/kg0.73). From the second database, the daily MEy was determined as 22.8 MJ x pr &divide kp + 38.74 MJ x Lr kj, assuming (from prior reports) that k = 0.20 and k1 = 0.75. Thereafter, MEm was defined as ME intake minus ME and, hence, NEm was predicted as 1.625 x Pj - Pm x Pm0-73 (where 1.625 was the value obtained from the first dataset). The resulting km (NEm/MEm) averaged 0.67. This km value did not differ from that (0.65; P = 0.12) predicted by Garrett's equation, which uses dietary ME content as the only predictive variable. Second, the procedure was tested for the ability to detect effects on km caused by increasing BW and dietary factors not estimable from the dietary ME content only. Data were gathered from a trial involving 48 DBM Piemontese bulls divided into 4 groups fed 1 of 4 diets differing in CP content (145 or 108 g/kg DM), with or without addition of 80 g/d of rumen-protected CLA (rpCLA). Bulls were examined at 3 consecutive periods of growth, corresponding to 365, 512 and 631 kg of average BW. All energy balance items were influenced by increasing BW, except (P = 0.61), in agreement with the expectation that NEm requirement depends on the degree of maturity (Pi/Pm) and the Pm0.73 of an animal, whereas km reflects characteristics of the feed provided. The km value was also influenced by the CP x rpCLA interaction (P = 0.013). We conclude that DBM and British beef steers have similar NE requirements when these are scaled as a function of Pi and Pm, and gain composition, considering Pr, kp, Lr and k,. The proposed procedure will be useful to predict the energy requirements and feed use in cattle of different types that vary in BW, provided that body and gain compositions are known or accurately predicted. [ABSTRACT FROM AUTHOR]

A total of 3,050 German Angus (Aberdeen Angus x German dual–purpose breeds), Charolais, Hereford, Limousin, and German Simmental calves were used to examine temperament traits of beef cattle using 2 different test procedures. The chute test and the flight–speed test have been validated in terms of routine on–farm applicability. Behavior tests were performed in 2006 and 2007 on 24 commercial beef cattle farms located in the northern and eastern part of Germany. A single, trained observer assigned subjective scores to characterize the behavior of each animal during restraint in the head gate (calm, restless shifting, squirming, vigorous movement, violent struggling) and when leaving the chute (walk, trot, run, jumping out of the chute). Breed was a significant source of variation in chute scores and flight–speed scores (P < 0.001). Charolais and Limousin cattle had the greatest scores in both traits, whereas Herefords had the least (P < 0.001) chute scores. German Angus and Hereford calves had the least (P < 0.001) flight–speeds, indicating that these breeds have a more favorable temperament. Ternperament scores differed significantly between male and female calves (P < 0.01), with females scoring better for both traits. Average daily BW gains of the calves were significantly influenced by effects of breed (P < 0.001) and sex (P < 0.001) of the calves. Heritabilities were estimated for chuteand flight–speed scores of beef cattle. They were least for chute score and flight–speed score of Limousin cattle with values of 0.11. In contrast, greatest heritabilities were 0.33 for chute score and 0.36 for flight–speed score of Hereford cattle. Genetic correlations were estimated among both temperament traits, with values between 0.57 and 0.98. Chute scores and visual flight–speed scores were negatively correlated with daily BW gain of the calves in most breeds. The results presented in this paper indicate that on–farm evaluation of beef cattle temperament is possible, either using the chute test or the flight–speed test. Genetic selection seems to be promising to improve temperament traits of beef cattle without decreasing production traits like ADG of the calves. [ABSTRACT FROM AUTHOR]

The aim of this paper was to estimate the genetic relationships among calving ease (CE), calf survival (CS), and gestation length (GL) to assess the possibility of including this information in beef cattle breeding programs. A total of 35,395 field records were available for CE, 30,684 for GL, and 36,132 for CS from the Asturiana de los Valles beef cattle breed. The 3 traits were analyzed as traits of the calf fitting a multivariate linear mixed model. Estimates of heritability (±SE) for the direct genetic effects (CEd, GLd, and CSd) were 0.325 ± 0.022, 0.331 ± 0.026, and 0.226 ± 0.018, respectively, whereas the estimates for maternal genetic effects (CErn, GLm, and CSm) were 0.066 ± 0.018, 0.066 ± 0.017, and 0.034 ± 0.011. The estimates for the ratio of permanent environmental variance to phenotypic variance were CEc 0.090 ± 0.011, GLc 0.066 ± 0.011, and CSc 0.024 ± 0.007. Genetic correlations between direct, maternal genetic, or permanent environmental effects involving CE and CL were, in general, positive and moderate, whereas those involving CE and CS were high. All were significant except for the pair CEm-GLm (0.277 ± 0.172). Correlations between GL and CS were nonsignificant. Genetic correlations for CEd-CEm, GLd-GLm, and CSd-CSm were negative and high, ranging from -0.461 ± 0.120 for GLd-GLm to -0.821 ± 0.145 for CSd-CSm. The genetic correlations for CEd-CSm and for CSd-CEm were negative, significant, and high, whereas that for GLd-CEm was moderate (-0.323 ± 0.124) and that for GLd-CSm was nonsignificant. The genetic correlations for GLm with the direct effects of the other traits were non-significant. Strong selection for CE will result in a significant correlated response in CS. Therefore, CE can be considered an early indicator of CS performance. The benefit of using CL as a correlated trait in a genetic evaluation with CE and CS seems limited. [ABSTRACT FROM AUTHOR]

Adjustment factors to allow comparison of EPD from several breed associations for birth, weaning, and yearling weights have been available for more than 10 yr. This paper describes steps to calculate adjustment factors for EPD for 4 carcass traits: marbling score, fat thickness, ribeye area, and retail product percentage. The required information is the same as for the weight traits: 1) breed of sire solutions based on measurements on progeny at the US Meat Animal Research Center (USJVIARC) that have sires with breed association EPD, 2) mean EPD of sires weighted by number of progeny at USMARC (USMARC progeny not included in breed association EPD), and 3) mean EPD of nonparents from breed associations (defined as animals born 2 yr prior to calculation of EPD). Records at USMARC are adjusted to 100% heterozygosity because the purpose of the adjustment factors is to allow prediction of performance of progeny of sires mated to other breeds of dam. A critical step is to adjust breed of sire solutions, which are based on an earlier sample of sires, to the equivalent of a sample from a more recent nonparent group using the difference between mean EPD from information sources 2) and 3). The difference is multiplied by the coefficient of regression of USMARC progeny on EPD of their sires. With weight traits, these coefficients are not greatly different from unity. With the carcass traits, 2 sets of coefficients can be used depending on whether the EPD are based on carcass or ultrasound measurements. The regression coefficients also reflect differences in conditions for USMARC progeny (all steers) and factors associated with breed association EPD. Only for marbling score and ribeye area were any estimates of the regression coefficients near unity. For other traits, the coefficients ranged from 1.65 to 2.82. The solutions for breed of sire, differences in mean EPD, and regression coefficients are then used to calculate adjustment factors for EPD of 11 breeds including the arbitrary base breed, Angus. [ABSTRACT FROM AUTHOR]

The article presents abstracts of various research papers related to animal science, that were presented during the symposium held on July 25, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. One of the article "Dose Titration of Optaflexx Evaluating the Effects on Standard Carcass Characteristics in Feedlot Steers," informs that Optaflexx ractopamine HCl, was recently approved by the U.S. Food and Drug Administration CVM for feeding to cattle during the last 28 to 42 of the finishing period. The effects of feeding Optaflexx on standard carcass characteristics in beef steers assigned to one of four treatments was evaluated at five different geographical sites. A randomized complete block design was used at each site. This resulted in a total of 25 experimental units per Optaflexx concentration. Harvest was conducted in commercial beef packing plants.

Growth curve analysis is an important issue for many agricultural and laboratory species, for both phenotypic and genetic studies. The aim of this paper is to present the use of a novel statistical approach, namely the structured antedependence (SAD) models, to deal with this issue. The basic idea of these models is that an observation at time t can be explained by the previous observations. These models are especially appropriate to deal with cumulative traits such as growth, as BW at age t clearly depends on BW measures at ages (t - 1), (t - 2), etc. These models were applied on an INRA experimental Charolais herd data set. The data comprised BW records for 560 cows born over an 11-yr period (from 1988 to 1998) from 60 sires and 369 dams. The proposed SAD models were compared with the well-known random regression (RR) models that are already widely used in various areas of longitudinal data analysis. It was found that the SAD models fit the growth process better with far fewer parameters than the RR models (9 instead of 16 covariance parameters for the phenotypic analysis, and 14 instead of 21 for the genetic analysis). Despite this smaller number of covariance parameters, the likelihood value was found to be much higher with the SAD vs. the RR models, with a difference of 262.9 for the phenotypic analysis with a quartic polynomial for the RR and 751.5 for the genetic analysis with a cubic polynomial for both the genetic and environmental parts of the RR model. The SAD models also proved to be better able to interpolate missing values. Heritability, genetic, and environmental correlation coefficients were estimated for weights from birth to adulthood. The structured antedependence models proved, in this study, to be very appropriate to model growth data in a parsimonious and flexible way. [ABSTRACT FROM AUTHOR]

Designing a sound cow-calf nutritional program requires knowledge of nutrient requirements, diet quality, and intake. Effectively using the NRC (1996) beef cattle requirements model (1996NRC) also requires knowledge of dietary degradable intake protein (DIP) and microbial efficiency. Objectives of this paper are to 1) describe a framework in which 1996NRC-applicable data can be generated, 2) describe seasonal changes in nutrients on native range, 3) use the 1996NRC to predict nutrient balance for cattle grazing these forages, and 4) make recommendations for using the 1996NRC for forage-fed cattle. Extrusa samples were collected over 2 yr on native upland range and subirrigated meadow in the Nebraska Sandhills. Samples were analyzed for CP, in vitro OM digestibility (IVOMD), and DIP. Regression equations to predict nutrients were developed from these data. The 1996NRC was used to predict nutrient balances based on the dietary nutrient analyses. Recommendations for model users were also developed. On subirrigated meadow, CP and IVOMD increased rapidly during March and April. On native range, CP and IVOMD increased from April through June but decreased rapidly from August through September. Degradable intake protein (DM basis) followed trends similar to CP for both native range and subirrigated meadow. Predicted nutrient balances for spring- and summer-calving cows agreed with reported values in the literature, provided that IVOMD values were converted to DE before use in the model (1.07 × IVOMD − 8.13). When the IVOMD-to-DE conversion was not used, the model gave unrealistically high NEm balances. To effectively use the 1996NRC to estimate protein requirements, users should focus on three key estimates: DIP, microbial efficiency, and TDN intake. Consequently, efforts should be focused on adequately describing seasonal changes in forage nutrient content. In order to increase use of the 1996NRC, research is needed in the following areas: 1) cost-effective and accurate commercial laboratory procedures to estimate DIP, 2) reliable estimates or indicators of microbial efficiency for various forage types and qualities, 3) improved estimates of dietary TDN for forage-based diets, 4) validation work to improve estimates of DIP and MP requirements, and 5) incorporation of nitrogen recycling estimates. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the accuracy and repeatability of beef carcass longissimus muscle area (LMA) measurements obtained by three different methods. Longissimus muscle area for beef carcass sides (n = 100) randomly selected in a commercial packing plant was determined: 1) independently by three USDA grading supervisor "experts" using the grid method to obtain triplicate measurements of the same longissimus muscle (LM); 2) by three different Colorado State University personnel tracing the LMA on acetate paper and subsequently measuring the area via a polar planimeter three different times (total of 3 × 3 = 9 observations/LM); and 3) by use of two identical video image analysis (VIA) instruments making triplicate measurements for each LM using three different procedures. Video image analysis Procedure 1 required that LMA be measured by placing the camera head unit over the LM and collecting three sequential images without moving the camera head unit while carcasses were in a stationary position; Procedure 2 required measurement of LMA by placing the camera head unit over the LM and collecting three images, but removing and repositioning the camera head unit between collection of each image while carcasses were in a stationary position; and Procedure 3 required that LMA be measured by placing the camera head unit over the LM and obtaining an image while carcasses were in continuous motion (chain speed of 360 carcasses/ h) during three different circulations past the grading stand. Overall, VIA-derived LMA measurements were highly accurate for all three procedures compared with expert-gridded (R² = 0.92, 0.90, and 0.84 for Procedures 1, 2, and 3, respectively) and acetate/planimeter-traced (R² = 0.94, 0.93, and 0.86 for Procedures 1, 2, and 3, respectively) LMA measurements. Instrument LMA repeatability also was comparable to expert-gridded and acetate/planimeter-traced LMA repeatability, as the means of the absolute differences... [ABSTRACT FROM AUTHOR]

Forages are the base source of nutrition for any cow-calf operation. Forage types vary based on soil type and climate. Tall fescue (Lolium arundinaceum) is the most commonly used cultivated grass for grazing beef cattle in the United States. This cool-season perennial is easily established; is resistant to drought, insects, and nematodes; and has the ability to withstand heavy grazing pressure. Most tall fescue varieties are infected with the endophyte fungus (Neotyphodium coenophialum) that is essential for the plant's survival but detrimental to cattle performance. Ergot alkaloids are the generally accepted toxic agents produced by the fescue endophyte. Cattle that consume forages infected with this endophyte can develop fescue foot, fat necrosis, or fescue toxicosis. It is estimated that the beef industry loses over US$500 million annually due to fescue toxicosis through heat stress, reduced weight gain, suppressed appetite, and decreased reproductive performance. Other symptoms include a retained or rough hair coat and increased body temperature, which can be detrimental when animals are located in hot and or humid environments. Different forages and forage systems, feed additives, and animal management strategies have been tested through the years allowing the use of tall fescue in beef production systems while minimizing the adverse effects. An animal genetics approach needs to identify and select animals less susceptible to the ergot alkaloids. Research in this area reports that different cattle within the same herd can respond differently when grazing tall fescue, and evidence exists that breed type may also play a role in genetic tolerance to the negative effects on performance. Some studies have looked at the potential of identifying genetic markers that may assist in the selection of more resistant animals. From these studies, there is evidence that genetic variation does exist for resistance to the ergot alkaloids present when grazing endophyte-infected tall fescue. Forage management coupled with animal genetic selection could allow for more efficient use of tall fescue as a significant forage source in beef cattle systems. These would allow producing more beef per hectare in the United States in response to an increasing population combined with decreasing resources. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at a symposium during the American Society of Animal Science Southern Section annual meeting, held on February 6, 2012, in Birmingham, Alabama, on beef cattle production, is presented. Topics include stocker cattle production models, physiology of newly received calves, and nutrition and management practices to enhance calf health. The symposium featured several experts on animal science including Curt Lacy, Darrell Rankins, and Clint Krehbiel.

To quantify the effects of the TDN and CP in the diet of pregnant beef cows on fetal weight and birth weight of calves, a systematic review and meta-analysis were performed. We searched on 2 electronic databases (Scopus and ISI Web of Knowledge) from 1945 to October 2016, and we checked references of relevant review papers. Data were extracted using predefined protocols. Inclusion criteria were complete studies using pregnant beef cows receiving different diets that analyzed fetal weight and/or birth weight of calves. Random effect meta-analyses were conducted for each indicator separately with the mean of the control and the treated group. The analysis was conducted with the TDN and CP levels in relation to cows' requirements (NRC, 1996). The results were presented with the pooled mean difference (MD) and I² (the percentage of total variation between studies that is due to heterogeneity rather than chance). For fetal weight at 4 mo (FW4), we included 4 studies reporting 6 trials involving 170 animals; for fetal weight at 8 mo (FW8), we included 4 studies, 4 trials, and 156 animals; and for birth weight of calves (BiW), we included 48 studies, 125 trials, and 9,053 animals. The heterogeneity between studies was high for FW4 (I² = 94.4%), FW8 (I² = 91.08%), and BiW (I² = 96.9%). When control cows received 20 to 40% less TDN than the treated group, the FW4 was reduced by 2.27 kg (P < 0.001; I² = 65.06), because both groups received 19 to 25% more TDN than their requirements. The cows from control group tended to show (P = 0.057) a lower MD (1.57 kg; I² = 91.08%) when consuming 30% of CP above their requirements. The fetuses from control group were 2.23 kg lighter (P < 0.001; I² = 0%) when their cows consumed 20% TDN above their requirements. The BiW was lower (MD = -0.761; I² = 96.4%; P < 0.001) only for cows in the third period of pregnancy. The calves from both groups were born 0.560 and 0.761 kg lighter when cows consumed CP (P = 0.0015; I² = 97.1%) and TDN (P < 0.001; I² = 96.4%) more than their requirements, respectively. Our study demonstrates that FW4, FW8, and BiW were reduced when CP was 19 to 25% and TDN was 30% above of cows' requirements as published by the NRC (1996). [ABSTRACT FROM AUTHOR]

The article presents abstracts of various research papers related to alpharma beef cattle nutrition that were presented during the symposium held on July 25, 2005 in Cincinnati, Ohio, which was organized by the American Dairy Science Association, the American Society of Animal Science, and the Canadian Society of Animal Science. One of the papers titled "Sites, Rates, and Limits of Starch Digestion and Glucose Metabolism in Growing Cattle," states that growing cattle in the U.S. consume up to 6 kg of starch daily, mainly from corn or sorghum grain. Total tract apparent digestibility of starch usually ranges from 90 to 100% of starch intake, Ruminal starch digestion ranges from 75 to 80% of starch intake, and is not greatly affected by intake over a range of 1 to 5 kg starch Id. Starch apparently digested in the small intestine ranges from 36 to 49% of starch entering the small intestine, and digestibility decreases as starch entry increases. Starch apparently digested in the large intestine ranges from 44 to 46% of starch entering the large intestine. Approximately 70% of starch digested in the small intestine appears as glucose in the bloodstream. However, glucose use by visceral tissues regularly exceeds glucose supply from intestinal starch digestion.

The demand for goods and services produced from grazinglands has continued to accelerate over the past twenty. Complex interactions of environment, nutrients, plants, and animals within regions containing grazingland reduce the probability of consistently producing enough high quality crops and forages to maintain a stable and productive livestock enterprise. Simulation modeling has been used to examine the effects of agricultural management practices on environmental quality and to develop improved management practices, which are environmentally sound and profitable to the producer. These models are designed to represent the complex interaction of many factors. Models have been developed for the entire management system and for individual components of the system. The purpose of this paper is to examine various applications of simulation models to beef cattle production, forage production, carbon sequestration and storage, and other problems associated with grazingland management. The objectives of each modeling effort will be presented along with any lessons learned and gaps in our existing knowledge and abilities. An overall evaluation of the current ability to use simulation models to address natural resource problems will be addressed. [ABSTRACT FROM AUTHOR]