Board-invited review: Using behavior to predict and identify ill health in animals

We review recent research in one of the oldest and most important applications of ethology: evaluating animal health. Traditionally, such evaluations have been based on subjective assessments of debilitative signs; animals are judged ill when they appear depressed or off feed. Such assessments are prone to error but can be dramatically improved with training using well-defined clinical criteria. The availability of new technology to automatically record behaviors allows for increased use of objective measures; automated measures of feeding behavior and intake are increasingly available in commercial agriculture, and recent work has shown these to be valuable indicators of illness. Research has also identified behaviors indicative of risk of disease or injury. For example, the time spent standing on wet, concrete surfaces can be used to predict susceptibility to hoof injuries in dairy cattle, and time spent nuzzling the udder of the sow can predict the risk of crushing in piglets. One conceptual advance has been to view decreased exploration, feeding, social, sexual, and other behaviors as a coordinated response that helps afflicted individuals recover from illness. We argue that the sickness behaviors most likely to decline are those that provide longer-term fitness benefits (such as play), as animals divert resources to those functions of critical short-term value such as maintaining body temperature. We urge future research assessing the strength of motivation to express sickness behaviors, allowing for quantitative estimates of how sick an animal feels. Finally, we call for new theoretical and empirical work on behaviors that may act to signal health status, including behaviors that have evolved as honest (i.e., reliable) signals of condition for offspring-parent, inter- and intra-sexual, and predator-prey communication.     

Board-invited review: Applications of genomic information in livestock

The availability of whole genome sequences for individual species will change the landscape for livestock genomic research. Animal scientists will have access to whole-genome sequence-based technologies such as high-throughput SNP genotyping assays, gene expression profiling, methylation profiling, RNA interference, and genome resequencing that will revolutionize the scale upon which research will be conducted. These technologies will also alter the ways we think about addressing industry and scientific problems. In this review, we discuss the scientific bases for these emerging technologies and present recent highlights of their application in human, model species, and livestock as well as their potential for future applications in livestock. Additionally, we discuss strategies for their use in the genetic improvement and management of livestock. In particular, we present a strategy for the simultaneous identification of causal mutations underlying phenotypic traits in livestock and discuss issues that will arise in the application of whole genome selection for the prediction of genetic merit in livestock. We also point out that the statistical analysis that underlies the whole genome selection methodology is a sophisticated enhancement of single marker association mapping analysis to allow the entire genome to be simultaneously analyzed.     

Board-invited review: the ethical and behavioral bases for farm animal welfare legislation

Concerns about farm animal welfare vary among individuals and societies. As people increasingly consider the values underlying current farm animal production methods, farm animal welfare policy debates have escalated. Recent food animal protection policies enacted in the European Union have fueled highly contentious discussions about the need for similar legislative activity in the United States. Policymakers and scientists in the United States are apprehensive about the scientific assessment, validation, and monitoring of animal welfare, as well as the unforeseen consequences of moving too hastily toward legislating farm animal welfare. The potential impact of such legislation on producers, food prices, animals, and concerned citizens must also be considered. Balancing the interests of all stakeholders has therefore presented a considerable challenge that has stymied US policymaking. In this review, we examine the roles of ethics and science in policy decisions, discuss how scientific knowledge relative to animal behavior has been incorporated into animal welfare policy, and identify opportunities for additional refinement of animal welfare science that may facilitate ethical and policy decisions about animal care.     

Board-invited review: intrauterine growth retardation: implications for the animal sciences

Intrauterine growth retardation (IUGR), defined as impaired growth and development of the mammalian embryo/fetus or its organs during pregnancy, is a major concern in domestic animal production. Fetal growth restriction reduces neonatal survival, has a permanent stunting effect on postnatal growth and the efficiency of feed/forage utilization in offspring, negatively affects whole body composition and meat quality, and impairs long-term health and athletic performance. Knowledge of the underlying mechanisms has important implications for the prevention of IUGR and is crucial for enhancing the efficiency of livestock production and animal health. Fetal growth within the uterus is a complex biological event influenced by genetic, epigenetic, and environmental factors, as well as maternal maturity. These factors impact on the size and functional capacity of the placenta, uteroplacental blood flows, transfer of nutrients and oxygen from mother to fetus, conceptus nutrient availability, the endocrine milieu, and metabolic pathways. Alterations in fetal nutrition and endocrine status may result in developmental adaptations that permanently change the structure, physiology, metabolism, and postnatal growth of the offspring. Impaired placental syntheses of nitric oxide (a major vasodilator and angiogenic factor) and polyamines (key regulators of DNA and protein synthesis) may provide a unified explanation for the etiology of IUGR in response to maternal undernutrition and overnutrition. There is growing evidence that maternal nutritional status can alter the epigenetic state (stable alterations of gene expression through DNA methylation and histone modifications) of the fetal genome. This may provide a molecular mechanism for the role of maternal nutrition on fetal programming and genomic imprinting. Innovative interdisciplinary research in the areas of nutrition, reproductive physiology, and vascular biology will play an important role in designing the next generation of nutrient-balanced gestation diets and developing new tools for livestock management that will enhance the efficiency of animal production and improve animal well being.     

Board-invited review: Estrogen and progesterone signaling: genomic and nongenomic actions in domestic ruminants

Progesterone and estrogens play key roles in regulating various physiological phenomena related to normal growth, development, and reproduction of domestic animals. This review focuses on the mechanisms by which progesterone and estrogens regulate the reproductive processes in these animals. The majority of research on the actions of progesterone and estrogens on the reproductive systems of cattle, sheep, and pigs has been genomic in nature and represents attempts to better understand how these steroids regulate gene expression. Results of recent research suggest that progesterone and estrogens can alter target cell responses nongenomically via membrane receptors. The characteristics of membrane receptors for progesterone and estrogen in various cell types are described and the intracellular signal pathways defined. Estrogens acting via membrane receptors can suppress LH secretion by gonadotropes and stimulate rapid increases in uterine blood flow. Progesterone acting via a membrane receptor has been shown to inhibit binding of oxytocin to oxytocin receptors in isolated endometrial plasma membranes and stimulate capacitation of spermatozoa. Results of research suggest that progesterone and estrogens can act nongenomically to alter target cell responses in domestic animals. The biological implications of this mode of action in these animals are discussed.     

Board-invited review: Peptide absorption and utilization: Implications for animal nutrition and health

Over the last 50 yr, the study of intestinal peptide transport has rapidly evolved into a field with exciting nutritional and biomedical applications. In this review, we describe from a historical and current perspective intestinal peptide transport, the importance of peptides to whole-body nutrition, and the cloning and characterization of the intestinal peptide transporter, PepT1. We focus on the nutritional significance of peptide transport and relate these findings to livestock and poultry. Amino acids are transported into the enterocyte as free AA by a variety of AA transporters that vary in substrate specificity or as di- and tripeptides by the peptide transporter, PepT1. Expression of PepT1 is largely restricted to the small intestine in most species; however, in ruminants, peptide transport and activity is observed in the rumen and omasum. The extent to which peptides are absorbed and utilized is still unclear. In ruminants, peptides make a contribution to the portal-drained visceral flux of total AA and are detected in circulating plasma. Peptides can be utilized by the mammary gland for milk protein synthesis and by a variety of other tissues. We discuss the factors known to regulate expression of PepT1 including development, diet, hormones, diurnal rhythm, and disease. Expression of PepT1 is detected during embryological stages in both birds and mammals and increases with age, a strategic event that allows for the immediate uptake of nutrients after hatch or birth. Both increasing levels of protein in the diet and dietary protein deficiencies are found to upregulate the peptide transporter. We also include in this review a discussion of the use of dietary peptides and potential alternate routes of nutrient delivery to the cell. Our goal is to impart to the reader the nutritional implications of peptide transport and dietary peptides and share discoveries that shed light on various biological processes, including rapid establishment of intestinal function in early neonates and maintenance of intestinal function during fasting, starvation, and disease states.     

Board-invited review: Recent advances in biohydrogenation of unsaturated fatty acids within the rumen microbial ecosystem

Recent advances in chromatographic identification of CLA isomers, combined with interest in their possible properties in promoting human health (e.g., cancer prevention, decreased atherosclerosis, improved immune response) and animal performance (e.g., body composition, regulation of milk fat synthesis, milk production), has renewed interest in biohydrogenation and its regulation in the rumen. Conventional pathways of biohydrogenation traditionally ignored minor fatty acid intermediates, which led to the persistence of oversimplified pathways over the decades. Recent work is now being directed toward accounting for all possible trans-18:1 and CLA products formed, including the discovery of novel bioactive intermediates. Modern microbial genetics and molecular phylogenetic techniques for identifying and classifying microorganisms by their small-subunit rRNA gene sequences have advanced knowledge of the role and contribution of specific microbial species in the process of biohydrogenation. With new insights into the pathways of biohydrogenation now available, several attempts have been made at modeling the pathway to predict ruminal flows of unsaturated fatty acids and biohydrogenation intermediates across a range of ruminal conditions. After a brief historical account of major past accomplishments documenting biohydrogenation, this review summarizes recent advances in 4 major areas of biohydrogenation: the microorganisms involved, identification of intermediates, the biochemistry of key enzymes, and the development and testing of mathematical models to predict biohydrogenation outcomes.     

A review of the diagnostic possibilities of illegal drug administration in slaughtered animals and meat inspection

A review of possible residues of selected antibacterial substances, hormones, beta-agonists, thyreostatics and tranquillizers in meat is given in this paper. Showing their application mode and the few clinical effects and pathological findings, the collection of samples becomes very important. For each group of substances tissues or body-fluids are proposed as samples. With modern analytical detection methods residues in food of animal origin can be demonstrated at levels of micrograms/kg. The detection of the above mentioned substances could be supported by a well-aimed sampling and the illegal use can be diminished.     

Board-invited review: St. Anthony's Fire in livestock: causes, mechanisms, and potential solutions

After a brief history of ergot alkaloids and ergotism, this review focuses on the metabolism and mechanisms of action of the ergot alkaloids. The authors provide models of how these alkaloids afflict grazing livestock under complex animal-plant/endophyte-environmental interactions. Alkaloid chemistry is presented to orient the reader to the structure-function relationships that are known to exist. Where appropriate, the medical literature is used to aid interpretation of livestock research and to provide insight into potential modes of action and alkaloid metabolism where these are not known for livestock. In closing the paper, we discuss management of ergot alkaloid intoxication in livestock and future research needs for this field of study.     

Board-invited review: recent advances in management of highly stressed, newly received feedlot cattle

Morbidity and mortality from bovine respiratory disease (BRD) and associated losses in performance and carcass merit continue to plague the beef cattle industry. Several viral/bacterial agents are responsible for BRD, and interactions occur among the agents. Viral agents often predispose animals to bacterial infections, and Mannheimia haemolytica is the most frequently isolated organism in cattle with BRD. Laboratory tests are available to characterize organisms causing BRD using easily obtained nasal swab samples. Testing for persistent infection with bovine viral diarrhea virus can be done by a 2-stage technique using PCR and immunohistochemistry. Preconditioning programs that include preweaning viral vaccination programs along with castration could have a significant influence on decreasing BRD in the cattle feeding industry. Metaphylactic antibiotic programs continue to be effective; however, antibiotic resistance is a public concern, and additional management options (e.g., direct-fed microbials or other compounds with antimicrobial properties) deserve attention. Diets with an increased energy concentration achieved by decreasing the dietary roughage concentration may slightly increase the rate of BRD morbidity; however, these diets also increase ADG, DMI, and G:F compared with lower-energy, greater-roughage diets. The extent to which performance and BRD morbidity are affected by dietary protein concentration needs further study, but low and high protein concentrations should probably be avoided. Several trace minerals (e.g., Cu, Se, and Zn) affect immune function, but the effects of supplementation on performance and immune function in model challenge systems and in field studies are equivocal. Adding vitamin E to receiving diets at pharmacological levels (e.g., >1,000 IU x animal(-1) x day(-1)) seems beneficial for decreasing BRD morbidity, but it has little effect on performance. Given the limited ability to consistently modify immune function and BRD morbidity through dietary manipulations, we recommend that the diets for newly received cattle be formulated to adjust nutrient concentrations for low feed intake and to provide optimal performance during the receiving period.     

Board-invited review: Sensitivity and responses of functional groups to feed processing methods on a molecular basis

In complex feed structures, there exist main chemical functional groups which are associated with nutrient utilization and availability and functionality. Each functional group has unique molecular structure therefore produce unique molecular vibration spectral profile. Feed processing has been used to improve nutrient utilization for many years. However, to date, there was little study on processing-induced changes of feed intrinsic structure and functional groups on a molecular basis within intact tissue. This is because limited research technique is available to study inherent structure on a molecular basis. Recently bioanalytical techniques: such as Synchrotron Infrared Microspectroscopy as well as Diffuse Reflectance Infrared Fourier Transform molecular spectroscopy have been developed. These techniques enable to detect molecular structure change within intact tissues. These techniques can prevent destruction or alteration of the intrinsic protein structures during processing for analysis. However, these techniques have not been used in animal feed and nutrition research. The objective of this review was show that with the advanced technique, sensitivity and responses of functional groups to feed processing on a molecular basis could be detected in my research team. These functional groups are highly associated with nutrient utilization in animals.     

Coprophagy in animals: a review

Coprophagy is performed by rodents and lagomorphs and to a lesser degree by piglets, foals, dogs and nonhuman primates. Due to the construction of the digestive system of rodents and rabbits, coprophagy is necessary to supply many essential nutrients. Bacterial synthesis of nutrients occurs in the lower gastrointestinal tract in these animals where little absorption is realized. The eating of their feces provides a method for obtaining these nutrients.     

Genetic regulation of meat production by embryonic muscle formation - a review

SUMMARY: The biological basis for meat production in livestock animals is localized in the muscles, where lean meat production is under the genetic control of tissue-specific and more ubiquitously operating genes. The muscle tissue-specific MyoD gene family is at the centre of the genetic regulation of myoblast proliferation and differentiation into myofibres. The regulation of embryonic muscle tissue formation (development) by the MyoD genes is duscussed in the context of livestock animals used in meat production. The possibility that the MyoD genes could be useful candidate genes for breeding is discussed. It is concluded that marker assisted selection (MAS) using markers in functional genes is advantageous over MAS using associated markers. ZUSAMMENFASSUNG: Genetische Regulierung der Fleischproduktion bei der embryonalen Muskelbildung - Ein Literaturüberblick Die biologische Grundlage für Fleischproduktion, lokalisiert in den Muskeln, steht unter genetischer Kontrolle durch gewebsspezifische una mehr ubiquit?r arbeitende Gene. Die gewebsspezifische MyoD Genfamilie in den Muskeln befindet sich im Zentrum der genetischen Regulierung des Prozesses der Myoblastteilung und Differenzierung zu Myofasern. Die Ubersicht betrifft Regulierung der Bildung des embryonalen Muskelgewebes (Entwicklung) mit Hilfe der MyoD Gene. Die M?glichkeit, da? MyoD Gene erfolgreiche Kandidatengene für Tierzüchtung sein k?nnen, wird besprochen. 'Marker-assisted selection' (MAS) mit Hilfe von Markern funktioneller Gene sollte vorteilhafter sein als MAS mit gekoppelten DNA-Sequenzen. RéSUMé: Régulation génétique de la production de viande par la formation embryologique des muscles - un résumé La base biologique de la production de viande dans les animaux d'élevage se situe dans les muscles, là où la production de viande maigre est sous contr?le génétique de gènes générals et tissu-spécifiques. La famille des gènes muscle-spécifiques MyoD forme le centre de la régulation des procès de prolifération des myoblastes et de différenciation vers les myofibres. Le but de cet article rétrospectif est de situer la discussion sur la régulation de la formation embryologique des muscles par les gènes MyoD dans le cadre de l'élevage. La possibilité que les gènes MyoD soient des gènes candidats utiles pour l'élevage sera discutée. La conclusion faite est que 'marker assisted selection' (MAS) en employant des marquers situés dans des gènes fonctionnels a plus d'avantages que MAS avec des marquers associés.     

Board-invited review: Sensitivity and responses of functional groups to feed processing methods on a molecular basis

In complex feed structures, there exist main chemical functional groups which are associated with nutrient utilization and availability and functionality. Each functional group has unique molecular structure therefore produce unique molecular vibration spectral profile. Feed processing has been used to improve nutrient utilization for many years. However, to date, there was little study on processing-induced changes of feed intrinsic structure and functional groups on a molecular basis within intact tissue. This is because limited research technique is available to study inherent structure on a molecular basis. Recently bioanalytical techniques: such as Synchrotron Infrared Microspectroscopy as well as Diffuse Reflectance Infrared Fourier Transform molecular spectroscopy have been developed. These techniques enable to detect molecular structure change within intact tissues. These techniques can prevent destruction or alteration of the intrinsic protein structures during processing for analysis. However, these techniques have not been used in animal feed and nutrition research. The objective of this review was show that with the advanced technique, sensitivity and responses of functional groups to feed processing on a molecular basis could be detected in my research team. These functional groups are highly associated with nutrient utilization in animals.     

Epidermolysis bullosa in animals: a review

Epidermolysis bullosa (EB) is a hereditary mechanobullous disease of animals and humans, characterized by an extreme fragility of the skin and mucous membranes. The main feature of EB in humans and animals is the formation of blisters and erosions in response to minor mechanical trauma. Epidermolysis bullosa is caused by mutations in the genes that code for structural proteins of the cytoskeleton of the basal keratinocytes or of the basement membrane zone. Based on the ultrastructural levels of tissue separation, EB is divided into the following three broad categories: epidermolysis bullosa simplex, junctional epidermolysis bullosa and dystrophic epidermolysis bullosa. Human types of EB are divided into several subtypes based on their ultrastructural changes and the mode of inheritance; subtypes are not fully established in animals. In humans, it is estimated that EB affects one in 17,000 live births; the frequency of EB in different animals species is not known. In all animal species, except in buffalo with epidermolysis bullosa simplex, multifocal ulcers are observed on the gums, hard and soft palates, mucosa of the lips, cheek mucosa and dorsum of the tongue. Dystrophic or absent nails, a frequent sign seen in human patients with EB, corresponds to the deformities and sloughing of the hooves in ungulates and to dystrophy or atrophy of the claws in dogs and cats. This review covers aspects of the molecular biology, diagnosis, classification, clinical signs and pathology of EB reported in animals.