Aflatoxicosis in farm animals

Under conditions presently prevailing in the UK aflatoxicosis in farm animals, as defined in this paper, is largely confined to cattle but acute and chronic clinical liver disease is seldom if ever encountered. There is circumstantial evidence for sub-clinical and non-specific aflatoxicosis but dose-effect relationships have yet to be established, particularly at lower levels of dietary aflatoxin contamination.     

Genomic selection for maternal traits in pigs

The aim of this study was to compare alternative designs for implementation of genomic selection to improve maternal traits in pigs, with a conventional breeding scheme and a progeny testing scheme. The comparison was done through stochastic simulation of a pig population. It was assumed that selection was performed based on a trait that could be measured on females after the first litter, with a heritability of 0.1. Genomic selection increased genetic gain and reduced the rate of inbreeding, compared with conventional selection without progeny testing. Progeny testing could also increase genetic gain and decrease the rate of inbreeding, but because of the increased generation interval, the increase in annual genetic gain was only 7%. When genomic selection was applied, genetic gain was increased by 23 to 91%, depending on which and how many animals were genotyped. Genotyping dams in addition to the male selection candidates gave increased accuracy of the genomic breeding values, increased genetic gain, and decreased rate of inbreeding. To genotype 2 or 3 males from each litter, in order to perform within-litter selection, increased genetic gain 8 to 12%, compared with schemes with the same number of genotyped females but only 1 male candidate per litter. Comparing schemes with the same total number of genotyped animals revealed that genotyping more females caused a greater increase in genetic gain than genotyping more males because greater accuracy of selection was more advantageous than increasing the number of male selection candidates. When more than 1 male per litter was genotyped, and thereby included as selection candidates, rate of inbreeding increased because of coselection of full sibs. The conclusion is that genomic selection can increase genetic gain for traits that are measured on females, which includes several traits with economic importance in maternal pig breeds. Genotyping females is essential to obtain a high accuracy of selection.     

MALT structure and function in farm animals

Mucosa-associated lymphoid tissue (MALT) is defined as an organized lymphoid tissue in the mucosa that samples antigens. The morphological characteristics that distinguish MALT from lymphoid infiltrates are discussed. MALT has been extensively investigated in laboratory animals, while knowledge in cattle, sheep, goats, pigs and horses that are summarized under the term farm animals in this review is fragmentary. Literature data about the distribution, morphology, function and involvement in infectious diseases of MALT in farm animals are described. The understanding of specific features of MALT in other species than laboratory animals is important for comparative research, in order to understand pathological and immunological processes in the respective species and as a potential route of vaccination of mucosal surfaces.     

Prostaglandins and reproduction in female farm animals

Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, pyometra, and chronic endometritis. Improved therapeutic uses for prostaglandins will be developed when we understand better their involvement in implantation, maintenance of luteal function, and establishment and maintenance of pregnancy.     

Pain management in horses and farm animals

Objective: This review discusses the different analgesic drugs and routes of administration used in large animals for acute pain management. General guidelines and doses are given to assist in choosing techniques that provide effective analgesia. Etiology: Noxious stimuli are perceived, recognized, and localized by specialized sensory systems located at spinal and supraspinal levels. Diagnosis: Localizing the source of the noxious stimulus as well as understanding the behavioral aspects and physiological changes that result from such insult is important to adequately diagnose and treat pain. Pain assessment is far from being definite and objective; not only are there species differences, but also individual variation. In addition, the behavioral and physiological manifestations vary with the acute or chronic nature of pain. Therapy: Pain management should include (1) selecting drugs that better control the type of pain elicited by the insult; (2) selecting techniques of analgesic drug administration that act on pathways or anatomical locations where the nociceptive information is being processed or originating from; (3) combining analgesic drugs that act on different pain pathways; and (4) provide the best possible comfort for the animal. Prognosis: Providing pain relief improves the animal's well being and outcome; however, interpreting and diagnosing pain remains difficult. Continuing research in pain management will contribute to the evaluation of the pathophysiology of pain, pain assessment, and newer analgesic drugs and techniques.     

Assessment of comfort and well-being in farm animals

The assessment of comfort and well-being in farm animals is discussed in terms of physical damage, physiological responses and behavior. Injuries may be due to the physical environment or contact, such as aggression, with other animals. Animals may reduce the frequency of injuries by modifying their behavior. Evaluation of injuries requires a methodical assessment of specific areas of the body and examination of the facilities and behavior of the animal to determine cause. The physiological response of an animal is dependent upon its psychological response. The adrenal medullary and cortical responses represent distinct strategies that may occur simultaneously or independently of each other. Stress frequently results in suppression of immune responses, although some aspects of the immune system are enhanced. Inadequate or excessive motivation results in behavioral problems and facilities must accommodate the behavior of the animals. Methods of preference-testing have been improved to evaluate factors in the environment and assess motivation for specific behaviors more reliably. All of the methods used to assess comfort and well-being must consider the animal's ability to adapt to different environments. Although it remains difficult to assess comfort and well-being across systems, improvement within a system can be demonstrated.     

Noroviruses and sapoviruses in man and farm animals

Noro- and Sapoviruses belong to the virus family Caliciviridae and are important causative agents of acute epidemic gastroenteritis in man. In many cases transmission of Noro- and Sapoviruses occurs via contaminated food or water and the respective diseases are therefore designated as food borne. Recently, the presence of Noro- and Sapoviruses in farm animals has attracted increasing attention. Clinical symptoms were observed after experimental infection of cattle and swine with members of the two virus groups. Thus far it is not known, whether virus transmission from animals to man does occur.     

Stress in farm animals: a need for reevaluation

In animal husbandry, stress has usually been conceived as a reflex reaction that occurs ineluctably when animals are exposed to adverse environmental conditions, and which is the cause of many unfavorable consequences, ranging from discomfort to death. The inadequacy of this view is apparent from the new concepts that have been developed from research aimed at understanding the relationships between hormonal and behavioral reactions to stressful situations. Psychological aspects of environmental stimuli are powerful activators of endocrine responses. The amount of psychological stress that an animal experiences determines how much the pituitary-adrenal axis responds. Indeed, removing the variable of emotional arousal reduces or eliminates responses to some other stressors such as heat and cold. This means that one of the most important characteristics of the stress response, its nonspecificity, lies in the afferent part of the response, not the efferent. Hormonal and behavioral responses are intimately related in stressful situations. In particular, the perception and ensuing behavior of the subject are critical to the nature and intensity of hormonal response. Evidence from experiments in farm animals is presented to support these concepts. Because adjustment abilities are limited by genetics and previous experience, the respective role of each of these factors needs to be delineated more accurately. In addition, most experimental studies have been concerned with acute stress, while chronic multiple stress, which is more likely to be encountered in intensive husbandry, has received little attention. The approach in this field is hampered by the lack of suitable physiological criteria to assess long-term adaptive changes. Opportunities for further research are delineated and the need for a more integrated view of stress reactions in farm animals is emphasized.     

Learning and the training of farm animals

The focus of learning studies shifted considerably about 30 years ago. Research moved away from using farm species as experimental animals (that is, as a tool) in which to study learning theory, to a genuine interest in the learning abilities and training processes of individual species. Growing use is being made of operant conditioning and other learning techniques to assess how animals learn from experience and their ability to control their environment to improve their well-being. The processes involved in extinguishing undesirable behaviors and establishing behaviors more compatible with farming operations, the use of handling during early sensitive periods, and the careful habituation of animals to intensive farming conditions and modern automated systems complement the on-going genetic selection of farm animals more suited to modern farms. Learning is an important way for animals to cope with and adapt to changing environments and, as such, is fundamental to their general well-being. Learning in farm animals is of vital concern to veterinarians, agricultural engineers, and those involved with animal husbandry and welfare.