West Nile virus and greater sage-grouse: estimating infection rate in a wild bird population

Understanding impacts of disease on wild bird populations requires knowing not only mortality rate following infection, but also the proportion of the population that is infected. Greater sage-grouse (Centrocercus urophasianus) in western North America are known to have a high mortality rate following infection with West Nile virus (WNv), but actual infection rates in wild populations remain unknown. We used rates of WNv-related mortality and seroprevalence from radiomarked females to estimate infection rates in a wild greater sage-grouse population in the Powder River basin (PRB) of Montana and Wyoming from 2003 to 2005. Minimum WNv-related mortality rates ranged from 2.4% to 13.3% among years and maximum possible rates ranged from 8.2% to 28.9%. All live-captured birds in 2003 and 2004 tested seronegative. In spring 2005 and spring 2006, 10.3% and 1.8% respectively, of newly captured females tested seropositive for neutralizing antibodies to WNv. These are the first documented cases of sage-grouse surviving infection with WNv. Low to moderate WNv-related mortality in summer followed by low seroprevalence the following spring in all years indicates that annual infection rates were between 4% and 29%. This suggests that most sage-grouse in the PRB have not yet been exposed and remain susceptible. Impacts of WNv in the PRB in the near future will likely depend more on annual variation in temperature and changes in vector distribution than on the spread of resistance. Until the epizootiology of WNv in sagebrush-steppe ecosystems is better understood, we suggest that management to reduce impacts of WNv focus on eliminating man-made water sources that support breeding mosquitoes known to vector the virus. Our findings also underscore problems with using seroprevalence as a surrogate for infection rate and for identifying competent hosts in highly susceptible species.     

Effects of breed, sex, and age on the variation and ability of fecal near-infrared reflectance spectra to predict the composition of goat diets

The effects of breed, sex, and age of goats on fecal near-infrared reflectance spectroscopy-predicted percentage juniper in the diet were investigated, as were spectral differences in feces from goats differing in estimated genetic merit for juniper consumption. Eleven goats from each breed, sex, and age combination, representing 2 breeds (Angora and meat-type), 3 sex classifications (female, intact male, and castrated male), and 2 age categories [adult and kid (less than 12 mo of age)] were fed complete, pelleted rations containing 0 or 14% juniper. After 7 d on the same diet, fecal samples were collected for 3 d, and the spectra from the 3 replicate samples were averaged. Fecal samples were assigned to calibration or validation data sets. In a second experiment, Angora and meat goats with high or low estimated genetic merit for juniper consumption were fed the same diet to determine the effect of consumer group on fecal spectra. Feces were scanned in the 1,100- to 2,500-nm range with a scanning reflectance monochromator. Fecal spectra were analyzed for the difference in spectral characteristics and for differences in predicted juniper in the diet using internal and independent calibration equations. Internal calibration had a high precision (R(2) = 0.94), but the precision of independent validations (r(2) = 0.56) was low. Spectral differences were affected by diet, sex, breed, and age (P < 0.04). However, diet was the largest source of variation in spectral differences. Predicted percentage of juniper in the diet also showed that diet was the largest source of variation, accounting for 95% of the variation in predictions from internal calibrations and 51% of the variation in independent validations. Predictions from independent calibrations readily detected differences (P < 0.001) in the percentage of juniper in the 2 diets, and the predicted differences were similar to the actual differences. Predicted juniper in the diet was also affected by sex. Feces from goats from different juniper consumer groups fed a common diet were spectrally different, and the difference may have resulted from a greater intake by high- compared with low-juniper-consuming goats. Fecal near-infrared reflectance spectroscopy predictions of botanical composition of diets should be considered an interval scale of measurement.     

Thermotolerance of L3 Ostertagia (Teladorsagia) circumcincta and some of its enzymes

Parasitic nematodes of ruminants can be expected to experience temperatures in excess of 40 degrees C in faeces on pasture and, perhaps, in the host. L3 Ostertagia (Teladorsagia) circumcincta survived for at least 90 min at 45 degrees C in vitro in water, but the larvae were inactivated rapidly by only slightly higher temperatures. The glycolytic enzymes hexokinase and pyruvate kinase were inactivated in a similar temperature range, whereas malate dehydrogenase maintained its activity at temperatures in excess of 50 degrees C. These data imply that the loss of glycolytic activity might explain the loss of larval motility at temperatures between 45 degrees C and 50 degrees C.     

Confirmed and presumptive cervical vertebral compressive myelopathy in older horses: a retrospective study (1992-2004)

BACKGROUND: Cervical vertebral compressive myelopathy (CVCM) is a common cause of myelopathy in horses aged 6 months to 4 years. Little information is available regarding the types of lesions, treatment, and outcomes in horses with CVCM that are > or =4 years old. ANIMALS: Twenty-two affected horses (10 with a confirmed diagnosis of CVCM and 12 presumptive cases) and 210 contemporaneous control horses. METHODS: Horses > or =4 years old that were diagnosed with CVCM between January 1992 and January 2004 were identified from medical records at Texas A&M University and the University of Florida. Data analyzed included history, signalment, neurologic examination findings, lesion location, treatment, and outcome. Signalment was also recorded in a population of contemporaneous controls. RESULTS: Horses identified had a median age of 8.4 years, and there was a greater percentage of male horses among the cases than among the controls. The most common breeds represented were warmblood (n=6) and quarter horse (n=5) types; warmbloods were significantly (P < .05) overrepresented relative to control horses. The caudal cervical vertebral column was the most common site of CVCM lesions, and the C5-C6 (4/9) and C6-C7 (3/9) articulations were most often identified as abnormal via myelography. The most common lesions seen with radiography and myelography were articular process osteophytes. Of the 22 affected horses, 8 were euthanized and a diagnosis of CVCM was confirmed by necropsy for all; 5 of 8 of these horses had spinal cord compression caused, entirely or in part, by articular process osteophytes. Medical management was the therapy chosen in all horses, and administration of corticosteroids and nonsteroidal anti-inflammatory drugs resulted in improvement in the greatest number of horses. CONCLUSIONS AND CLINICAL IMPORTANCE: CVCM should be a differential diagnosis in older horses with cervical myelopathy. Articular process osteophytes are the most frequently identified cause of spinal cord compression in this group. Male horses and horses of warmblood or Tennessee Walking Horse breeds may be predisposed to this condition.     

How much do fish aggregating devices (FADs) modify the floating object environment in the ocean?

Natural floating objects (e.g., logs) have always been a component of the habitat of tropical tunas. However, the introduction of fish aggregating devices (FADs) modifies this environment. To assess the changes due to the deployment of FADs, we compared the spatial distribution of natural and artificial floating objects (FADs), using data from observers onboard tuna purse seine vessels in the Indian Ocean from December 2006 to December 2008. Although natural objects occur more commonly in waters south of 7°S and FADs are more common in waters north of 7°S, all types of floating objects can be found everywhere. Using different spatial scales (quadrats of size 1° × 1°, 2° × 2°, 5° × 5°, and 10° × 10°), we computed the proportion of FADs observed in quadrats without natural objects. The scale of 2° × 2° quadrats represented a threshold: distributions of the two types of objects were different at scales smaller than this threshold. The strongest change that has occurred since the introduction of FADs (besides the increased catches) has been the dramatic increase in the total number of floating objects. Since the introduction of FADs, the number of objects has at least doubled everywhere (except in the Mozambique Channel and Chagos) and in some areas (e.g., Somalia area) the multiplication factor has reached as high as 20 or 40. Our study sets the ranges of values of key parameters of the floating object environment, which are crucial in the design of future experimental studies aimed at investigating the impacts of FADs on the ecology of tunas.     

Proposal for a unified nomenclature for target‐site mutations associated with resistance to fungicides

Evolved resistance to fungicides is a major problem limiting our ability to control agricultural, medical and veterinary pathogens and is frequently associated with substitutions in the amino acid sequence of the target protein. The convention for describing amino acid substitutions is to cite the wild‐type amino acid, the codon number and the new amino acid, using the one‐letter amino acid code. It has frequently been observed that orthologous amino acid mutations have been selected in different species by fungicides from the same mode of action class, but the amino acids have different numbers. These differences in numbering arise from the different lengths of the proteins in each species. The purpose of the present paper is to propose a system for unifying the labelling of amino acids in fungicide target proteins. To do this we have produced alignments between fungicide target proteins of relevant species fitted to a well‐studied ‘archetype’ species. Orthologous amino acids in all species are then assigned numerical ‘labels’ based on the position of the amino acid in the archetype protein. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Genotypic diversity,a survival strategy for the apicomplexan parasite Theileria parva

The tick-borne protozoan parasite Theileria parva causes East Coast fever (ECF), a severe lymphoproliferative disease of cattle that is a major constraint to the improvement of livestock in eastern, central and southern Africa. Studies in cattle experimentally infected with T. parva have shown that the protective cytotoxic T lymphocyte (CTL) response is tightly focused, with individual animals recognizing only one or two dominant antigens, the identity of which varies with MHC class I phenotype. It is well known that cross-protection between T. parva stocks is limited, but precise evaluation of genetic diversity in field populations of the parasite has been hampered by a lack of molecular markers spanning the genome. A recently described panel of satellite markers has provided evidence for substantial genotypic diversity and recombination but does not provide cover for large segments of the genome. To address this deficiency, we undertook to identify additional polymorphic markers covering these regions and we report herein 42 newly identified PCR-RFLP markers distributed across the 4 T. parva chromosomes, as well as 19 new satellite markers for chromosomes 1 and 2. This brings the total number of available polymorphic markers to 141 for the 8.5 Mb genome. We have used these markers to characterise existing parasite stabilates and have also shown that passage of the parasite through naïve cattle and ticks can lead to substantial changes of parasite populations in resulting stabilates. These markers have also been used to show that passage of mixed parasites through an immunised calf results in the removal of the immunising genotype from the parasite population produced by ticks fed on this animal.     

Effect of Ergovaline Ingestion on Recovery of Horses Subjected to an Anaerobic Standard Exercise Test

The objective of this study was to determine whether consumption of tall fescue seed which contained high levels of ergovaline would affect post-exercise recovery of horses subjected to an anaerobic exercise test. Ten Quarter horses were separated into two groups and fed alfalfa hay, commercial sweet feed, and either endophyte-infected (E+) or endophyte-free (E−) ground tall fescue seed. Diets contained 11.8% seed, which resulted in 459 ppb of ergovaline for the E+ diet. During the first 28 days, horses in group A received E+ and group B received E−. Diets were reversed during the next 28 days (crossover design). Horses were ridden for 5 days per week. On day 14, 28 (period 1), 42, and 56 (period 2), they were subjected to a standardized exercise test (SET) that consisted of 41 turns in 4 minutes and was designed to raise the horse’s heart rate (HR) beyond the anaerobic threshold (150 bpm). There was a horse effect (P < .05) on post-SET respiration rate, HR, and post-exercise whole blood lactate level, but not rectal temperature (RT). For these variables or period effects, there was no horse × treatment, period × treatment, or period × horse interactions (P < .05). Treatment had no effect on whole blood lactate level, RT, or HR at any time measured. Respiration rate did not vary by treatment at rest or 1 minute after SET but was higher for the E+ treatment at 5 and 10 minutes after SET (P < .005). Consumption of diets that averaged 450 ppb of ergovaline caused the horses expend more respiratory effort in an attempt to recover to resting RT.     

Expression analysis of key somatotropic axis and liporegulatory genes in ghrelin- and obestatin-infused dairy cows

Ghrelin, an orexigenic hormone, is the endogenous ligand for the growth hormone secretagogue receptor (GHSR). Obestatin is produced from the same precursor peptide as ghrelin, and although obestatin was initially thought to promote actions opposite to those of ghrelin, many studies have failed to confirm this hypothesis. In the current study, multiparous cows were continuously infused with ghrelin (n = 10) or obestatin (n = 10) for 8 wk and compared to an untreated group (n = 10) to examine the effects of these hormones on somatotropic and liporegulatory gene expression. The expression of key genes was measured by quantitative real-time polymerase chain reaction. Growth hormone secretagogue receptor mRNA expression was altered in ghrelin- and obestatin-infused cows in a similar manner, as expression was increased at 4 wk, however it had decreased by 8 wk. Obestatin-infused cows presented with a significant decrease in the expression of ATP-binding cassette A1 (ABCA1) in adipose tissue, suggesting changes in cholesterol transport. Liver insulin-like growth factor (IGF) binding protein-3 mRNA displayed a week-by-treatment interaction, as expression was increased in control and obestatin-infused cows; however, expression decreased in ghrelin-infused cows. Adipose expression of hormone sensitive lipase (LIPE) mRNA was not altered by treatment or time, suggesting hormone infusion is not initiating lipolysis. The expression of lipogenic genes in adipose tissue increased with time in all groups, consistent with the general lactational profile of lipogenesis in dairy cows. These data indicate that continuous infusion of ghrelin or obestatin does not alter the expression of key somatotropic or liporegulatory genes in the lactating dairy cow, although obestatin infusion may alter cholesterol transport.