MicroRNAs in farm animals

MicroRNAs (miRNAs) are a class of ∼22 nucleotide-long small noncoding RNAs that target mRNAs for translational repression or degradation. miRNAs target mRNAs by base-pairing with the 3′-untranslated regions (3′-UTRs) of mRNAs. miRNAs are present in various species, from animals to plants. In this review, we summarize the identification, expression, and function of miRNAs in four important farm animal species: cattle, chicken, pig and sheep. In each of these species, hundreds of miRNAs have been identified through homology search, small RNA cloning and next generation sequencing. Real-time RT-PCR and microarray experiments reveal that many miRNAs are expressed in a tissue-specific or spatiotemporal-specific manner in farm animals. Limited functional studies suggest that miRNAs have important roles in muscle development and hypertrophy, adipose tissue growth, oocyte maturation and early embryonic development in farm animals. Increasing evidence suggests that single-nucleotide polymorphisms in miRNA target sites or miRNA gene promoters may contribute to variation in production or health traits in farm animals.     

Giardia infection in farm animals

Giardia infection is prevalent in farm animals from an early age. Despite the wide occurrence of the infection and recent understanding of its epidemiology, many aspects of giardiasis of farm animals remain unclear. In this article, Lihua Xiao discusses the prevalence, patterns, sources and clinical importance of Giardia infection in a variety of farm animals.     

Lice of farm animals in Libya

Abstract. This first report on the lice of farm animals in Libya lists a total of fifteen species, as follows: Haematopinus quadripertusus and Linognathus vituli from cattle, Bovicola ovis, Linognathus pedalis, L.afrlcanus and L.ovillus from sheep, L.stenopsis, L.africanus and Bovicola caprae from goats. Poultry harboured Lipeurus caponis, L.heterographus, Menacanthus stramineus, Menopon gallinae, Goniocotes gallinae, Goniodes gigas and G.dissimilis.     

Comparative mapping in farm animals.

This paper summarises the current status of comparative mapping in farm animals. For most of the major farm animal species, a wide range of genomic tools are now available to create high-resolution genetic and physical maps of the genome. For many farm animals, the use of radiation hybrid panels and sequence data from expressed sequence tag (EST) projects has accelerated the development of high-resolution comparative maps, with human--the model species for farm animals. These tools and comparative maps are being used to map and identify the genes at the loci for simple and complex traits. The development of detailed physical maps in farm animals based on radiation hybrid panels and bacterial artificial chromosome (BAC) contigs provides a direct link between the 'information-poor' maps of farm animals and the 'information-rich' genomes of human and other model organisms.     

Survey of aflatoxicosis in farm animals.

Over a 22-month period, 278 submissions of farm animals were made to the North Carolina Diagnostic Laboratory for suspected aflatoxicosis, and 94 cases were confirmed on the basis of finding aflatoxin in the feed and the occurrence of bile ductule proliferation. There was an annual variation in the incidence of aflatoxicosis, as well as a seasonal variation: the peak incidence occurred in the winter, and the minimum incidence occurred during the summer. The annual increase coincided with the corn harvest. All confirmed cases occurred on farms that raised and stored their own corn, and 88% were in swine. The cases were geographically localized in the eastern section of North Carolina (94% of the total cases) where 82% of the swine and 79% of the corn are produced. Mean concentration of aflatoxin in feed samples from the confirmed cases was 3,890 mug/kg, and the mean value for corn used in making the feed was 5,180 mug/kg. Only aflatoxin B1 was found in the samples. These data were interpreted to mean that the incidence and severity of aflatoxicosis is greater than previously suspected, that poor on-farm storage of corn is a primary contributing factor, that aflatoxin formation continues during and after the milling process, and that mycotoxicoses other than aflatoxicosis may cause equal or greater problems.     

Clostridium difficile in young farm animals and slaughter animals in Belgium

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in Europe. The main objective of this study was to determine the presence of C. difficile in pigs and cattle at the slaughterhouse. C. difficile was isolated in 6.9% of the cattle at the slaughterhouse. None of the pig slaughter samples were positive for C. difficile after an enrichment time of 72 h. For complementary data, a short study was conducted in piglets and calves at farms. C. difficile was more prevalent in piglets (78.3%) than in calves (22.2%) on the farms. Regarding the piglet samples, 27.8% of the positive samples were detected without enrichment of stools. The PCR ribotype 078 was predominant in farm animals. Samples isolated from slaughter cattle presented the widest range in PCR-ribotype variety, and the most prevalent PCR ribotype was 118a UCL. The results of this study confirm that C. difficile is present in slaughter animals in Belgium with a large percentage of toxigenic strains also commonly found in humans.     

Cellular mechanisms of implantation in domestic farm animals

In order for pregnancy to be established, the conceptus of domestic animals must signal its presence upon arrival in the uterus, a process known as maternal recognition of pregnancy. The conceptus derived signal(s) prevent(s) the structural and functional demise of the corpus luteum to ensure the maintenance of a uterine environment that supports implantation and embryonic development. Implantation is a remarkable event that has been described as a biological paradox because an adhesive interaction is formed between two apical surfaces of epithelial cell types that are typically covered by non-adhesive glycoproteins. In domestic animals (such as pigs, horses, sheep, does and cows), the implantation process is not invasive as it is in most other mammalian species. This review describes the interaction between the conceptus (embryo and surrounding membranes) and the uterine epithelial surface in domestic farm animals and ability of the conceptus to control the lifespan of the corpus luteum to maintain pregnancy.     

Genetic dissection of phenotypic diversity in farm animals

Farm animal populations harbour rich collections of mutations with phenotypic effects that have been purposefully enriched by breeding. Most of these mutations do not have pathological phenotypic consequences, in contrast to the collections of deleterious mutations in model organisms or those causing inherited disorders in humans. Farm animals are of particular interest for identifying genes that control growth, energy metabolism, development, appetite, reproduction and behaviour, as well as other traits that have been manipulated by breeding. Genome research in farm animals will add to our basic understanding of the genetic control of these traits and the results will be applied in breeding programmes to reduce the incidence of disease and to improve product quality and production efficiency.     

Identification of coagulase-negative staphylococci from farm animals

The species identify of 661 strains of coagulase-negative staphylococci isolated from the skin and nares of cattle, pigs, poultry, goats and sheep was determined. They belonged either to the novobiocin-sensitive species Staphylococcus hyicus, Staph. simulans, Staph. epidermidis, Staph. haemolyticus and Staph. warneri or to the novobiocin-resistant species Staph. sciuri, Staph. lentus, Staph. xylosus, Staph. cohnii, Staph. saprophyticus and Staph. gallinarum; twenty-one strains remained unidentified. The staphylococcal flora of the farm animals studied differed markedly from that associated with man; several species which do not occur in man were isolated and novobiocin-resistant strains, which occur infrequently in man, were present in large numbers in animals. Two simplified schemes for the identification of staphylococci from farm animals and man are presented.     

Identification of coagulase-negative staphylococci from farm animals

The species identity of 661 strains of coagulase-negative staphylococci isolated from the skin and nares of cattle, pigs, poultry, goats and sheep was determined. They belonged either to the novobiocin-sensitive species Staphylococcus hyicus, Staph. simulans, Staph. epidermidis, Staph. haemolyticus and Staph. warneri or to the novobiocin-resistant species Staph. sciuri, Staph. lentus, Staph. xylosus, Staph. cohnii. Staph. saprophyticus and Staph. gallinarum ; twenty-one strains remained unidentified. The staphylococcal flora of the farm animals studied differed markedly from that associated with man; several species which do not occur in man were isolated and novobiocin-resistant strains, which occur infrequently in man, were present in large numbers in animals. Two simplified schemes for the identification of staphylococci from farm animals and man are presented.     

Efficient transgenesis in farm animals by lentiviral vectors

Microinjection of DNA is now the most widespread method for generating transgenic animals, but transgenesis rates achieved this way in higher mammals are extremely low. To address this longstanding problem, we used lentiviral vectors carrying a ubiquitously active promoter (phosphoglycerate kinase, LV-PGK) to deliver transgenes to porcine embryos. Of the 46 piglets born, 32 (70%) carried the transgene DNA and 30 (94%) of these pigs expressed the transgene (green fluorescent protein, GFP). Direct fluorescence imaging and immunohistochemistry showed that GFP was expressed in all tissues of LV-PGK transgenic pigs, including germ cells. Importantly, the transgene was transmitted through the germ-line. Tissue-specific transgene expression was achieved by infecting porcine embryos with lentiviral vectors containing the human keratin K14 promoter (LV-K14). LV-K14 transgenic animals expressed GFP specifically in basal keratinocytes of the skin. Finally, infection of bovine oocytes after and before in vitro fertilization with LV-PGK resulted in transgene expression in 45% and 92% of the infected embryos, respectively.