In order to identify genes or markers responsible for economically important traits in the horse, the development of high resolution gene maps of individual equine chromosomes is essential. We herein report the construction of high resolution physically ordered radiation hybrid (RH) and comparative maps for horse chromosomes 14 and 21 (ECA14 and ECA21). These chromosomes predominantly share correspondence with human chromosome 5 (HSA5), though a small region on the proximal part of ECA21 corresponds to a ~5Mb region from the short arm of HSA19. The map for ECA14 consists of 128 markers (83 Type I and 45 Type II) and spans a total of 1828cR.Compared to this, the map of ECA21 is made up of 90 markers (64 Type I and 26 Type II), that segregate into two linkage groups spanning 278 and 760cR each. A total of 218 markers provide on average one marker every 0.9Mb along the length of the two equine chromosomes. This represents a 5-fold improvement over the previous maps. Of greater significance is the ~8-fold increase in the density of Type I loci that provide a comprehensive and finely aligned map for the two chromosomes in relation to homologues in a range of evolutionarily distantly related species, viz., human, chimpanzee, mouse, rat, dog, cattle, pig, cat and chicken. The orientation and alignment of the linkage groups was strengthened by 28 new FISH localizations, of which 27 are gene-specific (22 from HSA5 and 5 from HSA19). Comparative analysis between the horse and human reveals that the order of genes on HSA5 is remarkably well conserved in the horse, with an evolutionary break/fusion point that could be correlated to a ~2Mb region between 68.5 – 70.9Mb positions on HSA5. Among the species analyzed to date, the HSA5 and 19p neighboring segment combination is unique to Perissodactyls and Cetartiodactyls, but, in the Perissodactyls, the portion of HSA5 that corresponds to this combination is HSA5p – q13, while in the Cetartiodactyls, it is HSA5q13 – qter. This leads us to postulate that this neighboring segment combination arose as separate events during the divergence of Perissodactyls and Cetartiodactyls from a common ancestor.

Activity of group-transported horses was evaluated during onboard rest stops to determine if horses derive meaningful rest. A single-deck semi-trailer separated into three compartments was used for all shipments. In Experiment One, twelve video cameras were used to record behavior of horses during five, 16 to 20 h shipments, with a high (397.44kg/m2), medium (348.48 kg/m2) and low (220.91 kg/m2) density group in each shipment. One-hour rest stops occurred after 8 h of transport and prior to unloading, during which two groups were provided water. Movement of each horse visible on video was quantified by counting the number of times the head crossed the vertical and/or horizontal axes of the body at the withers. Mean number of movements per 5-min interval in each group (n=13) was used to compare effects of density, access to water, and order of stops. The high and low-density watered groups had increased activity during the first 10 min of both rest stops potentially due to maneuvering for access to water. The medium-density watered groups had increased activity during the first 10 min of only the second rest stop. Activity slightly increased in the medium and low-density groups after 55 min possibly indicating adequate rest, but a similar increase did not occur in highdensity groups. In Experiment Two, two shipments, lasting 23 h and 24 h respectively, consisted of three groups of horses loaded at high density (397.32 kg/m2). Ninety-minute rest stops occurred after every 6 h of transport and prior to unloading for a total of three rest stops. Percentage of visible horses "active" was averaged across each 5-min interval of the stop. Activity was highly variable within and between shipments. Activity was high at the beginning of stops one and three of Shipment One. A similar but less dramatic settling occurred at the start of all three rest stops in Shipment Two. Twenty three of thirty-four noted increases in alertness were due to aggression or noises outside the trailer. In both experiments horses remained active during all stops indicating fatigue had not become a major factor in these studies.

Six Quarter Horse yearling fillies were used in a duplicated 3 x 3 Latin square designed experiment to evaluate the technique of nitrogen retention as a response criterion for amino acid studies in the horse. The yearlings were paired by age and randomly assigned to one of three concentrates fed with a medium quality Coastal Bermudagrass hay throughout the study. Diets were fed at approximately 1.9% of horse body weight per day, divided into twice daily feedings with a 60:40 concentrate: hay ratio. With the exception of lysine and threonine, proposed amino acid requirements for yearling horses were calculated using nutrient to calorie ratios of gilts weighing 80-120 kg and gaining 325 g/d. Diet A was amino acid sufficient, as provided by a soybean meal-based concentrate. Diet B was amino acid deficient, with a cottonseed hull-based concentrate. Diet A and Diet B were isonitrogenous, containing approximately 12% crude protein. Diet C used the identical concentrate as Diet B, with synthetic essential amino acids and cysteine orally dosed to match the amino acid levels in Diet A. Nitrogen retention was not different between Diet A and Diet B. Diet C resulted in differences from Diets A and B in nitrogen retention; however, differences were a consequence of nitrogen intake. Nitrogen retained as a percent of nitrogen absorbed was lower (P < 0.05) for Diet B than for Diet A, for data not accounting for endogenous fecal and urinary losses. There were no differences in nitrogen retained as a percent of nitrogen absorbed for horses fed Diet C, when compared to either Diet A or Diet B, for data not accounting for endogenous losses. It was concluded that differences in nitrogen retained as a percent of nitrogen absorbed were observed between amino acid sufficient diets and amino acid deficient diets. However, horses fed amino acid deficient diets and orally dosed with synthetic amino acids, likely require some modified dosage level to achieve the same or higher values in nitrogen retained as a percent of nitrogen absorbed as those values for amino acid sufficient diets.

The replication of equine infectious anemia virus (EIAV) in macrophages not only leads to cell death, but also to the induction of a variety of cytokines that may affect immune function. Cytokine production may be responsible for the fever, anorexia, hemorrhages, lethargy or thrombocytopenia seen in the acute and chronic phases of equine infectious anemia (EIA). The study of the equine immune system and inflammatory responses, by measuring cytokine expression, can provide important insight into disease pathogenesis in the horse. We have extended studies of virulent and avirulent EIAV clones by examining the effects of Env proteins on cytokine expression in equine monocyte-derived macrophages (EMDM) using EIAV17, EIAV19, EIAV17SU, and EIAV17TM viruses. In the current studies a set of quantitative real-time polymerase chain reaction (QPCR) assays for the equine cytokines IL-1a, IL-1b, IL-6, IL-8 and TNF-a were validated using QPCR primers and probes which were generated for the aforementioned equine genes.

Thesis (M.S.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains ix, 117 p. : ill. Includes abstract. Includes bibliographical references (p. 99-105).

Inaug.-diss.-Gottingen. / Issued also in this series. Lebenslauf. "Literaturangabe": p. [131].

Thesis (M.Sc.(Agric.))(Genetics)--University of Pretoria, 2000. / Summary in English and Afrikaans Includes bibliographical references.

Thesis (M. Phil.)--University of Hong Kong, 2002. / Includes bibliographical references (leaves.

Previous research has documented shifts in microbial hindgut populations resulting from dietary starch inclusion, and recent evidence indicates only 30% of equine cecal contents has been cultured successfully. Next generation sequencing (NGS) techniques allows detection of new species previously undetected. Therefore, the objective of this study was to determine community profiles equine cecal microbiota in response to abrupt dietary starch inclusion. Seven cecally cannulated Quarter horse geldings (497 to 580 kg) were utilized in a crossover design with two 28 d periods and a 28 d washout between each. Horses were randomly assigned to dietary treatments consisting of commercial concentrate offered individually at either 0.6% (LS) or 1.2% BW (HS; as fed) daily divided into 2 meals at 12 h intervals. Prior to start of each period horses were allowed ad libitum access to coastal bermudagrass (Cynodon dactylon) hay and concentrate was fed on d 1 with no adaptation. Samples of cecal fluid were collected on d 1 prior to 0 h and 3, 6, 9, and 12 h post morning meal and on d 1, 2, 3, and 7 at 6 h post morning meal. Cecal pH was determined immediately and a samples of cecal fluid were stored. Genomic DNA was extracted and the V4-V6 segment of 16s rRNA gene was PCR amplified using universal Eubacterial primers 530Fand 1100R and sequenced on the Roche 454 FLX platform. The reads were denoised, chimera checked, and Operational Taxonomic Units (OTUs) were identified using the reference Ribosomal Database Project 16S rRNA dataset. Data were analyzed using PROC MIXED procedure of SAS. Bacterial phyla were largely unaffected by dietary treatment for the first 12 h after the initial concentrate meal except for Verrucomicrobia which was greater in LS horses (P ≤ 0.04). Regardless of treatment, Bacteriodetes increased (P ≤ 0.02) over the first 12 h following initial addition of dietary starch. Adaptation to dietary treatments over 7 d resulted in decreased numbers of Tenericutes (P ≤ 0.07) in HS horses compared to LS. Cecal environment and microbial populations were altered after abrupt and long term exposure to dietary starch.

Nineteen yearling Quarter Horses were utilized in a randomized, complete block design to evaluate systemic cytokine gene expression and circulating leukocyte population in young horses following an intra-articular lipopolysaccharide (LPS) challenge. Horses were administered an injection of 0.25 ng (n = 7) or 0.50 ng (n = 6) of LPS or lactated Ringer?s solution (n = 6; control). Blood was collected via jugular catheter at pre-injection h 0 and at 2, 6, 12, and 24 h following aseptic injection of the left radiocarpal joint. Aseptic arthrocentesis was performed at the same times to sample synovial fluid for a companion study. Total RNA was isolated from leukocytes using a commercially available kit and real-time PCR was used to determine relative gene expression of the cytokines; interleukin (IL)-1beta (beta), IL-6, IL-8, IL-10, and tumor necrosis factor-alpha (TNF-alpha). Determination of total leukocyte subpopulations and differentials was performed by Texas Veterinary Medical Diagnostic Laboratory. Data were analyzed using the PROC MIX procedure of SAS. Gene expression of all cytokines analyzed was unaffected by treatment. However, changes over time were observed in some cytokines. Interleukin-1? was increased above baseline at 6, 12, and 24 h (P = 0.04), IL-6 was decreased slightly at 6 and 12 h and then increased at 24 h (P = 0.002), and TNF-alpha was increased at 6 and 12 h (P = 0.01). Only IL-8 exceeded a 2-fold change in expression (P = 0.01), peaking at 12 h and indicating greater responsiveness to arthrocentesis than was observed in the other cytokines. No treatment effects on the leukocyte population were observed; however, total circulating leukocytes increased over time (P = 0.04), peaking at 6 h post-injection. Similarly, an increase over time was observed in monocytes (P = 0.002) and in platelets (P = 0.01) at 24 h post-injection. The results indicate that regardless of treatment, a mild immune response was elicited, likely due to repeated arthrocentesis. Future experiments should consider the effects of arthrocentesis and potential systemic inflammatory response, even in control animals, when administering intra-articular LPS to young horses.