R.J. Coleman

AIR EXCHANGE RATE IN A HORSE TRAILER DURING ROAD TRANSPORT

Horses traveling by road commonly experience heat stress conditions and poor air quality, which may be caused by insufficient ventilation; however, there are few estimates of air exchange in a horse trailer during transport. Air exchange rate was measured at ten locations within a four-horse trailer (internal volume 18.5 m3) using tracer gas decay measurement to assess the adequacy of ventilation. Three vehicle speeds (13, 48, and 97 km h-1) and three window configurations (all windows and roof vents closed, all windows open, all windows open and roof vents open forward) were tested with and without animals present in the trailer. External air temperature ranged from 22.3°C to 28.3°C with an average of 25.3°C, and internal air temperature ranged from 29.9°C to 34.8°C with an average of 31.3°C with animals present. Air exchange rate increased with vehicle speed and open window and vent area. The average air exchange rate over all vehicle speeds and ventilation configurations was 0.52 min-1 with animals present and 0.76 min-1 without animals. Without animals present, the maximum mean exchange rate was 1.42 min-1 at 97 km h-1 at the rear left window with all windows and vents open; the lowest mean exchange rate was 0.12 min-1 at 13 km h-1 with all windows and vents closed at the lower position of the rearmost stall divider. With animals present, the maximum air exchange rate observed was 0.84 min-1 with all windows and vents open and traveling at 97 km h-1. Ventilation in the trailer was not adequate when compared to recommendations for stabled horses for any combination of vehicle speed or ventilation configuration. Increasing open vent area, either by increasing the number and size of roof vents or the size of windows in the sidewall, would be the most cost-effective means of increasing air exchange in a horse trailer.

Growth and condition at weaning of extensively managed creep-fed foals

Summary A study was conducted to evaluate the effects of creep feeding on the growth and value of extensively managed foals. One hundred four Quarter Horse type mares (551±45.9 kg) and their foals (140±21 kg) were assigned to one of three treatments. The treatments were no creep ration (NC), 13% protein creep ration (13%) and 17% protein creep ration (17%). The foals were offered creep ration daily at 0.45 kg per month of age in a suitable creep feeder for 53 days. Concentrate intakes for the 13% and the 17% creep-fed groups were 0.84 and 0.56 kg/head/day, respectively (P>0.05). Overall average daily gains for the NC, 13% and 17% groups were 1.06, 1.20, and 1.14 kg/day, respectively with the creep-fed foals having significantly (P 0.05) between the creep-fed groups. Following weaning the creep-fed foals had general assessment scores that were higher (P 0.05). Sale price was significantly (P

Ergovaline stability in tall fescue based on sample handling and storage methods

Ergovaline is an ergot alkaloid produced by the endophyte Neotyphodium coenophialum (Morgan-Jones and Gams) found in tall fescue [Schedonorus arundinacea (Schreb.) Dumort.] and blamed for a multitude of livestock disorders. Ergovaline is known to be unstable and affected by many variables. The objective of this study was to determine the effect of sample handling and storage on the stability of ergovaline in tall fescue samples. Fresh tall fescue was collected from a horse farm in central Kentucky at three harvest dates and transported on ice to the University of Kentucky Veterinary Diagnostic Laboratory. Plant material was frozen in liquid nitrogen, milled and mixed before being allocated into different sub-samples. Three sub-samples were assigned to each of 14 sample handling or storage treatments. Sample handling included increased heat and UV light to simulate transportation in a vehicle and on ice in a cooler per standard transportation recommendations. Storage conditions included storage at 22°C, 5°C, and −20°C for up to 28 days. Each sub-sample was then analyzed for ergovaline concentration using HPLC with fluorescence detection and this experiment was repeated for each harvest date. Sub-samples exposed to UV light and heat lost a significant fraction of ergovaline in 2 h, while sub-samples stored on ice in a cooler showed no change in ergovaline in 2 h. All sub-samples stored at 22°C, 5°C, and −20°C lost a significant fraction of ergovaline in the first 24 h of storage. There was little change in ergovaline in the freezer (−20°C) after the first 24 h up to 28 days of storage but intermittent losses were observed at 22°C and 5°C. To obtain results that most closely represent levels in the field, all samples should be transported on ice to the laboratory immediately after harvest for same day analysis. If immediate testing is not possible, samples should be stored at −20°C until analysis.

Coat Color Genotypes and Risk and Severity of Melanoma in Gray Quarter Horses

BACKGROUND Both graying and melanoma formation in horses have recently been linked to a duplication in the STX17 gene. This duplication, as well as a mutation in the ASIP gene that increases MC1R pathway signaling, affects melanoma risk and severity in gray horses. OBJECTIVE To determine if melanoma susceptibility in gray Quarter Horses (QH) is lower than gray horses from other breeds because of decreased MC1R signaling resulting from a high incidence of the MC1R chestnut coat color allele in the QH population. ANIMALS A total of 335 gray QH with and without dermal melanomas. METHODS Blood or hair root samples were collected from all horses for DNA extraction and genotyping for STX17, ASIP, and MC1R genotypes. Age, sex, and external melanoma presence and grade were recorded. The effect of age and genotype on melanoma presence and severity was evaluated by candidate gene association. RESULTS Melanoma prevalence (16%) and grade (0.35) in this QH cohort was lower than that reported in other breeds. Age was significantly associated with melanoma prevalence (P = 5.28 × 10(-11)) and severity (P = 2.2 × 10(-13)). No significant effect of MC1R genotype on melanoma prevalence or severity was identified. An effect of ASIP genotype on melanoma risk was not detected. Low STX17 homozygosity precluded evaluation of the gray allele effect. CONCLUSION AND CLINICAL IMPORTANCE Melanoma prevalence and severity is lower in this population of gray QH than what is reported in other breeds. This could be because of the infrequent STX17 homozygosity, a mitigating effect of the MC1R mutation on ASIP potentiation of melanoma, other genes in the MC1R signaling pathway, or differences in breed genetic background.

Methods for Assessing Horse Well Being During Transport

Horse transport has been associated with numerous ailments such as injuries and respiratory infections. Previous studies have reported physiological responses to transport, including changes in body temperature, heart rate, behavior, and blood chemistry, some of which might be useful as indicators of well being. This research focuses on evaluating a telemetry-based system for continuous monitoring of core body temperature (CBT). The monitoring system consists of an ingestible temperature sensor and an external recording device that receives the transmitted signals. This system can be used simultaneously with external electrodes to measure and record heart rate. To assess the utility of this new temperature monitoring method, the system was applied concurrent with traditional equine body temperature monitoring methods. Eight mature geldings were instrumented with three monitoring devices (blood temperature BT, rectal temperature RT, and telemetry-based temperature TBT), for simultaneous sampling every 10 s for 6 h. On average, TBT was 0.5°C higher than RT (P<0.001) and 1.0°C higher than BT (P<0.001), reflecting temperature variation among these three sites within the horse’s body. Though CBT values for each method were different, TBT reflected changes in temperature over time similarly to RT. BT had greater variability than TBT and RT. Beyond validation, the usefulness of this system has been assessed for monitoring during transport.