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The article presents abstracts of animal science research. They include "The effect of residual feed intake rank in beef cows on forage intake and pasture carrying capacity," "Evaluation of feed efficiency in Santa Gertrudis steers and relationships with temperament and feeding behavior traits," and "The effect of Bos Koolus fed during summer on the feedlot performance and carcass characteristics of steers."

The article presents abstracts on animal science which include the effects of waste products from plant materials on in vitro rumen fermentation, the value of feeds of barley varieties which can be determined using in vitro gas production technique, and the effects of yeast and type of starch on pH fluctuation, nutrient digestion and microbial fermentation in a dual flow continuous culture system.

The article presents abstracts on animal science which include the impacts of distiller grains finishing diet on fatty acid profiles of beef cattle, the influence of gender and slaughter weight on the quality of Duroc and Landrace crossbred pigs and the effect of clenbuterol exposure on the growth of mice.

The aim of this study was to investigate if a 2-step method of preventing suckling and cow-calf separation reduces the stress reaction in foster cows compared with a simultaneous separation method. Seven Swedish Holstein and 5 Swedish Red dairy cows were used as foster cows, each having a group of 4 calves. The foster cow-calf group was formed when calves were 1 wk old, and the calves were prevented from suckling at 10 wk of age. In 6 of the cow-calf groups, calves were prevented from suckling by simultaneous separation from the cow (control). In the other 6 groups, calves were fitted with a nose-flap, which prevented them from suckling while they were kept together with the cow for another 2 wk before they were separated (2-step). The behavior of the foster cows was observed at 4 observation periods, 0 to 2, 8.5 to 9.5, 24 to 26, and 72 to 74 h after the calves were prevented from suckling (2-step), after separation (2-step), and after calves were prevented from suckling by simultaneous separation (control). For both treatments, saliva cortisol was sampled once daily for 5 d at wk 10. This was repeated at wk 12 for the 2-step treatment. Heart rate was measured with the behavioral observations. Control foster cows vocalized more (P < 0.001) and walked more (P = 0.005) than the 2-step foster cows after prevention of suckling and after separation from the calves. When control cows were separated from their calves, they more frequently (P < 0.001) held their head out of the pen than was the case with 2-step cows when separated 2 wk after prevention of suckling. The variation in heart rate was larger in the control group compared with 2-step cows at 0 to 2 h after separation/prevention of suckling (P = 0.002). No effect of treatment was found on cortisol concentration. Our conclusion is that separating the 2 events "prevention of suckling" and "separation" reduces the stress experienced by the foster cow at weaning. [ABSTRACT FROM AUTHOR]

Two studies were conducted to determine the efficacy of an Escherichia coli-derived phytase (ECP) and its equivalency relative to inorganic phosphorus (iP) from monosodium phosphate (MSP). In Exp. 1, one thousand two hundred 1-d-old male broilers were used in a 42-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments were based on corn-soybean meal basal diets (BD) containing 239 and 221 g of CP, 8.2 and 6.6 g of Ca, and 2.4 and 1.5 g of nonphytate P (nPP) per kg for the starter and grower phases, respectively. Treatments consisted of the BD; the BD + 0.6, 1.2, or 1.8 g of iP from MSP per kg; and the BD + 250, 500, 750, or 1,000 phytase units (FTU) of ECP per kg. Increasing levels of MSP improved gain, gain:feed, and tibia ash (linear, P < 0.01). Increasing levels of ECP improved gain, gain:feed, tibia ash (linear, P < 0.01), apparent ileal digestibility of P, N, Arg, His, Phe, and Trp at d 21 (linear, P < 0.05), and apparent retention of P at d 21 (linear, P < 0.05). Increasing levels of ECP decreased apparent retention of energy (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.72, 0.78, and 1.19 g of iP from MSP per kg in broiler diets based on gain, feed intake, and bone ash, respectively. In Exp. 2, forty-eight 10-kg pigs were used in a 28-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments consisted of a positive control containing 6.1 and 3.5 g of Ca and nPP, respectively, per kg; a negative control (NC) containing 4.8 and 1.7 g of Ca and nPP, respectively, per kg; the NC diet plus 0.4, 0.8, or 1.2 g of iP from MSP per kg; and the NC diet plus 500, 750, or 1,000 FTU of ECP per kg. Daily gain improved (linear, P < 0.05) with ECP addition, as did apparent digestibility of Ca and P (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.49 and 1.00 g of iP from MSP per kg in starter pigs diets, based on ADG and bone ash, respectively. [ABSTRACT FROM AUTHOR]

The genetic upper limit to daily whole-body protein deposition (Pdmax) is an important constraint on pig growth. The Pdmax was determined for a specified pig genotype using N balance and serial slaughter techniques. A traditional N-balance study, involving 36 and 90 kg of BW Large White x (Landrace × Large White) entire male pigs, was first conducted to demonstrate that a highly digestible, nutrient-dense diet (1.54% Lys; 18 MJ of DE/kg, air-dried basis) was able to support the attainment of Pdmax within the constraints of pig appetite. Animals were allocated to set levels of feed intake [set proportions of ad libitum DE intake (DEi), 50 to 100%]. Nitrogen retention increased linearly with DEi up to 25.3 and 35.2 MJ of DE/d for the 36 and 90 kg of BW pigs, respectively, then showed a departure (P < 0.05) from linearity. For DEi of the experimental diet above the latter intakes, which were approximately 80% of a determined ad libitum DEi, the pigs deposited protein at a rate approaching Pdmax. When a linear plateau response model (accepted a priori) was fitted, Pdmax values of 189.9 g/d at a DEi breakpoint of 28.3 MJ of DE/d at 36 kg of BW and 186.4 g/d at a DEi breakpoint of 37.3 MJ of DE/d at 90 kg of BW were found. In the serial slaughter study, 18 female and 18 entire male pigs were allocated to 5 slaughter BW (25, 45, 65, 85, and 110 kg) such that there were 5, 3, 3, 3, and 4 animals of each sex at each slaughter weight, respectively. Animals were fed the experimental diet ad libitum, and whole-body protein was determined at slaughter. Growth data were analyzed by differentiating and combining continuous mathematical functions for BW and body composition. The ad libitum DEi were 27.4 and 50.7 MJ/d at 36 and 90 kg of BW for the entire males and were assumed, based on the N-balance results, sufficiently high to allow expression of Pdmax. There was an effect (P < 0.05) of sex on Pdmax vs. time (days on trial). Over the BW range of 25 to 85 kg, Pdmax was constant for the entire male and female pigs at 170 and 147 g/d, respectively. Above 85 kg of BW, Pdmax was no longer constant for either sex. [ABSTRACT FROM AUTHOR]

The impact of using 2 p-adrenergic agonists in feedlot cattle fed finishing diets was evaluated using 54 steers (45 crossbred Charolais and 9 Brangus) initially weighing 424 + 26.6 kg in a randomized complete block design with 3 treatments and 6 blocks (i.e., 18 pens with 3 steers per pen). Response variables were feedlot performance, carcass characteristics, and meat quality. Treatments were 1) control (no supplement added); 2) zilpaterol hydrochloride (ZH; 60 mg·steer-1·d-1); and 3) ractopamine hydrochloride (RH; 300 mg·steer-1·d-1). The β-agonists were added to the diets during the final 33 d of the experiment. The groups of steers fed ZH or RH improved (P < 0.01) ADG by 26 or 24%, respectively, compared with control steers. Steers supplemented with RH consumed less (P = 0.03) DM (8.37 kg) than control steers (8.51 kg), whereas intake was similar (P = 0.37) for ZH and control steers. Addition of either p-agonist to the diet considerably improved (P < 0.01) the G:F (ZH, 0.253 and RH, 0.248 vs. control, 0.185). Hot carcass weight and carcass yield were enhanced (P < 0.05) with both β-agonists. The LM area was increased (P = 0.026) by ZH (75.2 cm²), but that of RH (72.2 cm²) was similar (P = 0.132) to the control steers (66.8 cm²). Meat from the ZH- (P = 0.0007) and RH- (P = 0.0267) supplemented steers had greater shear force values than control steers (ZH = 5.11; RH = 4.83; control = 4.39 kg/cm²). Variables related to meat color indicated that both p-agonists led to a similar redness of the LM area related to the control group. In general, feedlot performance was greatly enhanced by p-adrenergic agonists, and meat tenderness from treated animals was classified as intermediate. Furthermore, meat color was not altered by β-agonist supplementation. [ABSTRACT FROM AUTHOR]

Genetic parameters for LM fatty acid composition were estimated in Scottish Blackface sheep, previously divergently selected for carcass lean content (LEAN and FAT lines). Furthermore, QTL were identified for the same fatty acids. Fatty acid phenotypic measurements were made on 350 male lambs, at approximately 8 mo of age, and 300 of these lambs were genotyped across candidate regions on chromosomes 1, 2, 3, 5, 14, 18, 20, and 21. Fatty acid composition measurements included in total 17 fatty acids of 3 categories: saturated, monounsaturated, and polyunsaturated. Total i.m. fat content was estimated as the sum of the fatty acids. The FAT line had a greater i.m. fat content and more oleic acid, but less linoleic acid (18:2 n-6) and docosapentaenoic acid (22:5 n-3) than did the LEAN line. Saturated fatty acids were moderately heritable, ranging from 0.19 to 0.29., and total SFA were highly heritable (0.90). Monounsaturated fatty acids were moderately to highly heritable, with cis-vaccenic acid (18:1 n-7) being the most heritable (0.67), and total MUFA were highly heritable (0:73). Polyunsaturated fatty acids were also moderately to highly heritable arachidonic acid (20:4 n-6) and CLA were the most heritable, with values of 0.60 and 0.48, respectively. The total PUFA were moderately heritable (0.40). The QTL analyses were performed using regression interval mapping techniques. In total, 21 chromosome-wide QTL were detected in 6 out of 8 chromosomal regions. The chromosome-wide, significant QTL affected 3 SFA, 5 MUFA, and 13 PUFA. The most significant result was a QTL affecting linolenic acid (18:3 n-3) on chromosome 2. This QTL segregated in 2 of the 9 families and explained 37.6% of the phenotypic variance. Also, 10 significant QTL were identified on chromosome 21, where 8 out of 10 QTL were segregating in the same families and detected at the same position. The results of this study demonstrate that altering carcass fatness will simultaneously change i.m. fat content and oleic, linoleic, and docosapentaenoic acid content. The heritabilities of the fatty acids indicate opportunities for genetically altering most fatty acids. Moreover, this is the first, report of detection of QTL directly affecting fatty acid composition in sheep. [ABSTRACT FROM AUTHOR]

Economic benefits from the use of expected progeny of a sample of beef bulls with genetic evaluations were calculated over an integrated supply chain for combinations of price discounts for intramuscular fat and LM area. Fixed backfat finish and marketing at the point of optimized gross margins were considered. An economic model was used to calculate average expected gross margins for a sample of bulls. Across-breed, age-constant genetic evaluations were used to predict carcass characteristics of progeny including weight, retail yield, intramuscular fat, and LM area, as well as input requirements including feed and housing as a function of time on feed. Proportion of retail cuts affected by price discounts was included in the calculations. Optimizing endpoints did not affect rankings to any extent relative to a fixed end point in this sample of bulls, as a result of fixed endpoints being similar to optimized endpoints for the economic situation considered. However, rank correlations were only 0.63 and 0.71 between rankings for no discount being applied and rankings with discounts for intramuscular fat and LM area, for fixed and optimized endpoints, respectively. We conclude that market prices are necessary considerations in choices of bulls to use in commercial beef production. [ABSTRACT FROM AUTHOR]

A novel algorithm, OCSELECT, is presented for the calculation of optimal genetic contributions with a restricted rate of inbreeding when the number of selection candidates is very large. The calculation of optimal genetic contributions requires the relationship matrix between the candidates and its inverse. The relationship matrix was written as: A = ZApZ′ + D, where Ap is the relationship matrix of the parents, D is a diagonal matrix of Mendelian sampling variances, and Z contains genetic contributions from parents to offspring. Therefore, A-1 = d-1 - d-1Z(Z′d-1Z + Ap-1)-1 Z′d-1, requires only inversion of matrices of the size of the number of parents instead of the number of offspring. The new algorithm was compared with the software package GENCONT on a salmon data set containing 39,214 selection candidates and 45,846 pedigreed fish in total. Because GENCONT could not handle such a large data set, this data set was split into 19 smaller data sets. Both algorithms gave the same solution with respect to the genetic gain and very similar solutions with respect to the number of selected animals. The OCSELECT algorithm was able to calculate the optimal contributions for the complete data set of 39,214, and therefore no preselection of the 39,214 fish was necessary before entering the fish into the new optimal contribution selection procedure. [ABSTRACT FROM AUTHOR]

The article presents information about the business meeting of the American Society of Animal Science (ASAS). President James Males called the meeting. New members of the ASAS Board were introduced and included Maynard Hogberg, President-Elect; Larry Reynolds, Editor-in-Chief; Jack Britt, ASAS Foundation Chair; Steve Lonergan, Midwest Section Director. President Males provided some written comments on his year as ASAS President and thanked ASAS for its efforts. The ASAS continues to provide its members with access to the highest ranked scientific journal in general animal science in the world and the opportunity to participate in outstanding scientific meetings. Although there are a couple of journals that have higher impact factors in the category in which "Journal of Animal Science" is ranked, they are journals that publish more specialized research. The "Journal of Animal Science," continues to grow in number of submissions and number of manuscripts published. To combat the decline in membership, the ASAS Board of Directors approved a change in the membership dues for undergraduate students. Beginning in 2006, the dues for undergraduates will be waived.

In-home consumer steak evaluations, followed by centralized laboratory-setting auctions, were used to determine consumer (n = 74 consumers) acceptability and willingness to pay for various beef chuck muscles. The infraspinatus (IF), serratus ventralis (SV), supraspinatus (SS), and triceps brachii (TB) from the beef chuck were evaluated against LM steaks from the rib to determine price and trait differentials. Muscles from USDA Choice, boneless, boxed-beef sub- primals were aged 14 d, frozen, and cut into 2.5-cm- thick steaks. Consumers received two steaks from each muscle for in-home evaluations of uncooked steak appearance and cooked steak palatability. After in-home evaluation of steaks, consumers participated in a random nth price auction session to determine willingness to pay for those steaks. Muscles differed (P < 0.05) for overall like of appearance, like of size, like of shape, and like of leanness; LM generally rated the highest. Steaks from the LM rated highest (P < 0.05) for overall like, and steaks from the SS and SV were lowest (P < 0.05) for overall like. Juiciness and beef flavor intensity scores were highest (P < 0.05) for steaks from the LM and IF, whereas SS steaks received the lowest (P < 0.05) juiciness scores, and SS and SV steaks were rated lowest (P < 0.05) for beef flavor intensity. Average auction price differentials differed (P < 0.05) from the LM, and were $-0.71, $-0.79, $-L75, and $-2.4410.45 kg for the TB, IF, SS, and SV, respectively. Average appearance trait differentials and average palatability trait differentials were correlated significantly with average price differentials. Results indicate the IF and TB were acceptable to consumers as steaks but only at prices lower than the LM. [ABSTRACT FROM AUTHOR]

A cooperative research study involving 353 litters was conducted at three stations to determine the effects of graded levels of supplemental Cr from chromium tripicolinate (CrPic) on reproductive performance of sows and preweaning performance of their pigs. Primiparous and multiparous sows were fed fortifled corn—soybean meal diets with supplemental levels of 0, 200, 600, or 1,000 ppb Cr (as-fed basis). Each station used at least three of the supplemental Cr levels, with two of those levels being 0 and 200 ppb. Station effects were observed for sow gestation weight gain, lactation weight change, lactation feed intake, litter size at birth and weaning, and pig weight at birth and weaning (P = 0.001 to 0.087). Supplemental Cr increased the number of pigs born live per litter (9.49, 9.82, 10.94, and 10.07; quadratic, P = 0.05) and sow lactation weight change (−0.2, 0.8, −4.1, and −3.9 kg; linear, P = 0.01) but decreased individual birth weight of total pigs born (1.61, 1.57, 1.47, and 1.56 kg; quadratic, P = 0.10). Tissues were obtained from a subset of sows from one station after they had completed three parities on the study. The content of Cr in the adrenal gland (16.4, 20.0, 34.0, and 48.4 ppb), kidney (35.8, 56.4, 132.6, and 176.0 ppb), and liver (22.8, 37.4, 87.6, and 92.2 ppb) was increased linearly (P = 0.001 to 0.005) by increasing CrPic supplementation. The results suggest that the supplementation level that maximizes the biological response is above that currently allowed. Additionally, supplementation of Cr at 1,000 ppb (five times currently permitted supplementation levels) was not detrimental to sow performance, even when fed continuously for three parities. There may be merit to continued research to evaluate higher supplementation rates. [ABSTRACT FROM AUTHOR]

Fecal egg count (FEC) has been widely used as an indicator of host resistance to gastrointestinal parasites in sheep and has been shown to be a heritable trait. Two other possible indicators of parasites, dag score (DS; accumulated fecal material) and fecal consistency score (FCS), were investigated in this study, along with BW. All four traits were studied to see how heritability and genetic correlations varied with age from weaning (4 mo) to hogget age (approximately 400 d). More than 1,100 lambs, the offspring of 37 rams, were recorded eight times between weaning (3 to 5 mo of age) and hogget age (13 to 18 mo of age) on two farms. Sire models were fitted to the data from each trait at each recording and in a repeatability model involving the whole data set. Overall, the heritabilities were 0.28 ± 0.072 (FEC), 0.11 ± 0.036 (DS), 0.12 ± 0.036 (FCS), and 0.23 ± 0.070 (BW). By fitting random regression models to the time-series data, it was possible to see how these heritability values varied as the lambs aged, from weaning to hogget age. The heritability of FEC rose from 0.2 at weaning to 0.65 at 400 d. Dag score had a higher heritability (0.25) in the middle of the age range and a low value at weaning (<0.1) and hogget age (0.16). The heritability of FCS was low, with a value of 0.2 at weaning reducing to 0.05 as the animals aged. Body weight had zero heritability at weaning, which rose to greater than 0.6 at hogget age. Most traits had low genetic correlations between them, the only exception being that between FCS and DS (0.63). Most genetic correlations varied little over the age range with the exception of FEC and BW, which fell from 0 at weaning to −0.63 at hogget age. Whereas FCS and DS may be good indicators of scouring, they are very different from FEC as an indicator of host resistance to gastrointestinal parasites. [ABSTRACT FROM AUTHOR]

Breeding for host resistance to parasites has become an imperative in many sheep industries. Because of the widespread use of AI in sheep breeding schemes, it is important to understand how the performance of offspring from rams varies in different flock environments, both for resistance to parasites and key production traits. This study used both variance component and reaction norm models to investigate the level of genotype x environment interaction for fecal egg count (FEC) and important Merino production traits in a range of flock environments in Australia. These flocks were linked by the use of common rams in a sire-referencing scheme. Both linear and quadratic polynomial reaction norm models were used. The heritability of these traits and the genetic correlation between them and FEC also was investigated using the reaction norm model. A contemporary group (CG) was defined by a flock, year, age class, sex, and paddock combination. Each CG environment was characterized by the mean value of any given trait for that CG. The recorded data used in the study were analyzed in a standardized form. Standardization for each trait was achieved within a CG by subtracting the CG mean from each observation and dividing by the CG SD. The genotype x environment effect accounted for <0.05 of the phenotypic variance for all traits. In most traits the heritability varied little across environments. The exceptions were FEC, BW, and both greasy and clean fleece weights, which had a higher heritability at the lower end of the environmental range. Fecal egg count also had a higher heritability in high-FEC environments. Genetic correlations between FEC and several key production traits were similar in the flock environments studied. Quadratic polynomial models and models with a variable residual fitted the data better than linear models. The genotype x environment effect for FEC and the genetic correlations between FEC and production traits were effectively zero; thus, sheep breeding programs for increased parasite resistance can be run effectively by ignoring these factors. Some account should be taken of the high heritabilities of FEC and fleece and BW in different flock environments. [ABSTRACT FROM AUTHOR]

Restricted BLUP (R-BLUP) is derived by imposing restrictions directly within a multiple-trait mixed model. As a result, the R-BLUP procedure requires the solution of high-order simultaneous equations. If restrictions are imposed on breeding values for only some animals in a population, calculations become more complex. A new procedure for computing the RBLUP of breeding values was derived when constraints were imposed on the additive genetic values of only some animals in a population. Rules for including records when proportional constraints are imposed were developed based on the traits that are recorded for an animal. The technique was better than the previous method in both memory requirement and central processing unit time. [ABSTRACT FROM AUTHOR]

The objective of this article, adapted from the book Building the Beef Industry, is to summarize the 100-yr history of the National Cattlemen's Beef Association. Because the activities of the Association through the years largely parallel major developments in the beef industry, this is essentially a history of beef production in the United States. Early cattle industry leaders recognized that many problems—and opportunities—could be better addressed by working in concert with other cattle producers. Yet free-spirited cattle producers, known for their individualism and independence, were difficult to organize. Two attempts at national associations failed before the National Live Stock Association, organized in 1898, sustained and after several name changes became the National Cattlemen's Beef Association. Some challenging areas that demanded cooperation by producers included roundups on the open range, disease control or eradication, development of export markets, restriction of competing imports, continued access to public lands, restrictions on packer monopoly and collusion, limited government help, resistance to government price controls and beef boycotts by consumers, expanded beef research, and self-help beef promotion. The oldest issue for western cattle producers has been the public domain. The "biggest cattle deal ever" was the government purchase-and-slaughter program in 1934, when 8.3 million cattle were slaughtered, reducing the cattle population by 11%. A "transportation revolution" occurred when the railroads put trail drivers out of business; when trucks put the railroads out of the business of transporting cattle; when local auction markets, made viable by trucks and trailers, put terminal markets out of business; and when packing plants moved from terminal markets to the proximity of new commercial feedyards. Among the great legislative victories for the Association were the Packers and Stockyards Act of 1921, the Counter-Cyclical Meat Import Act of 1979, and the Beef Promotion and Research Act of 1985, which authorized the $1/animal check-off and made nearly $80 million a year available for beef programs. [ABSTRACT FROM AUTHOR]

Livestock management on rangelands is challenging because rangelands are characterized by inherently low and variable precipitation, a complex native forage base that varies widely in nutritive value and toxicity, and topographic variation encompassed by large pastures. One approach to managing the consequent low and variable forage supply is to exploit the natural abilities of animals. Livestock adapted to low forage supply are those with low relative maintenance requirements. Livestock management systems can be designed to respond to distinct seasonal plant growth patterns by ensuring that peak nutrient demand coincides with the period of nutritious available forage. Herbivores vary substantially in their ability to harvest and digest range-land forages. Making efficient use of existing forage resources can therefore be accomplished by selecting the species and breed of animal that has the natural ability to eat the available forage. The differences between herbivores in landscape use patterns could also be exploited to create livestock enterprises that best meet the topographic character of a specific ranch. Livestock well adapted to rangeland conditions can be selectively culled and bred for desired characteristics and given opportunities to learn about the grazing resource. The flexible and opportunistic strategies necessary for successful management in variable ecosystems are rooted in a clear understanding of the challenges facing the grazing animal and its natural abilities to meet these challenges. The livestock manager's role is to facilitate and exploit these natural abilities to efficiently convert forage into saleable livestock products. [ABSTRACT FROM AUTHOR]

Pale, soft, and exudative (PSE) pork is primarily caused by an accelerated rate of postmortem glycolysis resulting in low muscle pH while carcass temperature remains high, thus causing protein denaturation. Numerous factors influence the rate of postmortem metabolism and may be responsible for the rapid pH decline characteristic of PSE pork during the 1st h postmortem. Release of high levels of Ca2+ from the sarcoplasmic reticulum into the sarcoplasm triggers an accelerated rate of postmortem glycolysis and is responsible for the high incidence of PSE observed in halothane pigs. Because total muscle ATPase activity is closely associated with rate of glycolysis, differences in myosin ATPase activity may explain in part the accelerated glycolysis in PSE development. Although important in determining the overall rate of glycolysis, differences in glycolytic enzyme activities have failed to explain discrepancies in postmortem metabolism between PSE and normal muscle. Elevated muscle glycogen content and an extended duration of postmortem glycolysis can also result in PSE-like characteristics, as seen in RN− pigs. Shifts in muscle fiber type toward higher proportions of glycolytic fibers may help explain the incidence of PSE. Inherent differences in mATPase activity, Ca2+ regulation, glycolytic enzyme profiles, and glycogen content between muscle fiber types integrate various mechanisms responsible for the abnormal postmortem glycolysis in PSE muscle. In an effort to delineate potential mechanisms responsible for PSE, models to artificially induce PSE, such as retarding temperature decline and electrical stimulation, provide useful tools. The value and limitations of these models stem from their abilities to alter postmortem temperature and pH declines and to effectively simulate the protein denaturation typical of PSE pork. [ABSTRACT FROM AUTHOR]

The impact of method of calculating breeding values (best linear unbiased prediction, BLUP, vs individual performance, MASS), selection intensity, and population size on short- (Generation 5) and long-term (Generation 20) response to selection with dominant (heterotic) and additive (nonheterotic) gene action traits was examined using a gene-level simulation program that assumed a finite number of loci and a finite population size with either a completely additive or dominant type of gene action. Results showed that for additive gene action there was a short-term advantage but a long-term disadvantage of increasing selection intensity. In the short term, maximum response for both methods was achieved with a proportion selected of 5%, and selections based on BLUP were always superior to those based on MASS. In the long term, BLUP selections remained superior to MASS, but maximum response for both methods was achieved with a proportion selected of 10%. In contrast, with dominant allele effects, MASS was superior to BLUP in the short term for proportions selected of less than 10% and in the long term for proportions selected of less than 20%. With intense selection the increased accuracy of selection based on BLUP breeding values could not offset negative impacts of associated increased inbreeding. With less intense selection, the increased accuracy of BLUP selection could offset negative impacts of associated increased inbreeding. However, the differences between selection based on BLUP and on MASS breeding values were not as important as optimizing the proportion selected. With dominant gene action in the long term, with a proportion selected of 20%, the superiority of BLUP over MASS was less than 2%, both of which were at least 100% greater than that achieved with a higher selection intensity corresponding to a proportion selected of 5%. This result was due to cumulative inbreeding depression associated with the smaller effective population size with intense selection. In general, the breeding program with the greatest rate of response per unit of inbreeding will give the greatest response in the long term. Breeders should be more concerned with increasing effective population size than with the method of computing expected breeding values. [ABSTRACT FROM AUTHOR]

The article focuses on the appropriate role of ethics in animal science in teaching and addressing contemporary issues in a morally responsible manner. It explains the nature of policy issues and the nature, conflicts and complexity of values. It discusses the use of reconstruction and deconstruction of issues in ways that enhance understanding for moral perspectives and respect for diversity as well as the ability to distinguish between situations particularly when it subjects minority groups.

The article offers information on a study regarding construction of science for animal agriculture. It information on development of the theories of quantitative genetics led to the recognition of opportunities for applying animal breeding toward agricultural development. It informs that animal science must retain its purpose to fill a storehouse of basic principles and scientific tools.