Efficacy of avermectin B1 given orally against equine intestinal strongyles and Onchocera microfilaria

Three groups of horses and ponies (N = 13, 13 and 12) were treated with ivermectin paste (0.2 mg/kg p.o.), avermectin B1 solution (0.2 mg/kg p.o.), or fenbendazole suspension (10 mg/kg via nasogastric tube). The avermectin B1 was a 1% solution in a propylene glycolglycerol formal base. Faecal strongyle egg counts were performed before, and 14, 28, 42, 56 and 70 d, after treatment. Full-thickness skin biopsies from the neck, pectoral and umbilical regions were examined for Onchocera microfilaria before treatment, and again 14 and 70 d later. Ivermectin therapy produced a significant (P less than 0.01) decrease in mean strongyle egg counts 14, 28, 42 and 56 d after treatment. Avermectin B1 therapy resulted in significant (P less than 0.01) decreases in mean strongyle egg counts 14, 28 and 42 d after treatment. All horses given ivermectin or avermectin B1 had zero strongyle egg counts 14 and 28 d after treatment. Fenbendazole failed to significantly decrease strongyle egg counts. Both ivermectin and avermectin B1 resulted in zero microfilaria counts in all horses 14 d after treatment. On day 70 the percentage decrease in microfilaria counts were 100% and 99.6% respectively. Fenbendazole failed to significantly decrease microfilaria counts. The oral administration of this formulation of avermectin B1 appeared to be highly efficacious against intestinal strongyles and Onchocera microfilaria. The duration of anti-strongyle activity was, however, significantly (P less than 0.01) shorter than that of ivermectin paste.     

Acute Mortality,Bacterial Load,and Pathology of Select Lines of Adult Rainbow Trout Challenged with Weissella sp. NC36

Abstract

A challenge for improving disease resistance in fish through genetics is to understand specificity of resistance and whether selection for one pathogen alters the response to unrelated pathogenic microorganisms. Adult Rainbow Trout Oncorhynchus mykiss that had been bred for differential susceptibility to Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD) and designated ARS-Fp-R (resistant), ARS-Fp-S (susceptible), and ARS-Fp-C (control line), as well as a pool of commercial-stock Rainbow Trout, were intraperitoneally challenged with Weissella sp. NC36. Clinical signs, survival, and innate mechanisms affecting disease resistance were monitored over 9 d. Acute disease signs included exophthalmia associated with retrobulbar inflammation and hemorrhage, cerebral hemorrhage, and mild to moderate granulomatous pericarditis. The ARS-Fp-R line did not demonstrate significant survival differences over a 9-d period compared with the ARS-Fp-C and ARS-Fp-S lines (P ≥ 0.09) indicating that during the acute phase of disease, the resistance factors that limit BCWD do not confer cross protection against Weissella sp. NC36. The linear effect of body weight at challenge was statistically significant, as each 10-g increase in body weight increased the hazard of death by 1% (P = 0.02). Bacterial loads on day 3, assessed by splenic and cerebral CFU counts, did not differ between ARS-Fp-R and ARS-Fp-S trout and there was no correlation between CFU counts and body weight. These findings help elucidate the specificity of disease resistance in selectively bred lines and contribute to our understanding of disease caused by Weissella sp., a recently described pathogen found in cultured Rainbow Trout.

Received June 19, 2013; accepted June 23, 2013     

B-mode, real-time ultrasound for estimating carcass measures in live sheep: accuracy of ultrasound measures and their relationships with carcass yield and value

Accuracy and repeatability of live-animal ultrasound measures, and the relationships of these measures with subprimal yields and carcass value, were investigated using data from 172 wethers. Wethers were F(1) progeny from the mating of 4 terminal sire breeds to Rambouillet ewes and were finished in a feedlot to a mean BW of 62.9 kg (SD = 9.5 kg). Before transport to slaughter, LM area, LM depth, and backfat thickness were measured from transverse ultrasound images taken between the 12th and 13th ribs. After slaughter, these measures were taken on each carcass. Carcasses were fabricated into subprimal cuts, and weights were recorded. Ultrasound accuracy and repeatability were assessed using bias, SE of prediction, SE of repeatability, and simple correlations. Relationships among ultrasound and carcass measures, and between these measures and carcass yield and value, were evaluated using residual correlations and linear prediction models. Ultrasound bias approached 0 for LM area, and backfat thickness was overestimated by only 0.69 mm. The SE of prediction and r were 1.55 cm(2) and 0.75 for LM area, and 1.4 mm and 0.81 for backfat thickness, respectively. The SE of repeatability was 1.31 cm(2) and 0.75 mm for LM area and backfat thickness, respectively. At a standardized BW and backfat thickness, wethers with larger LM area and LM depth yielded larger and more valuable carcasses, and these relationships were detectable with ultrasound. For each SD increase in carcass LM area, dressing percentage increased 1.57 percentage points, gross carcass value increased US$5.12, and boxed carcass value increased US$6.84 (P < 0.001). For each SD increase in ultrasound LM area, dressing percentage increased 0.95 percentage points, gross carcass value increased US$3.15, and boxed carcass value increased US$3.86 (P < 0.001). When LM area effects were adjusted for carcass weight, the response in boxed carcass value attributed to disproportionate increases in high-value subprimal cut weights was small. Associations of dressing percentage and carcass value with ultrasound and carcass LM depth were significant (P < 0.01) but smaller than corresponding associations with LM area. These data indicate biological and economical incentives for increasing LM area in wethers, and live-animal ultrasound can provide reliable estimates of carcass measures. These results are applicable to terminal sire breeders and producers who market sheep using carcass-merit pricing systems.     

Surgical resection of a dysgerminoma in a mare

A mare was referred for further evaluation of a mass found in the left caudal abdomen during a routine postpartum reproductive palpation. The mare was clinically normal with no history of health problems. Ultrasonographic examination of the mass confirmed its presence, but the origin of the mass could not be accurately determined. Routine haematology and serum biochemistry results were within normal limits. The mare was initially treated conservatively with antibiotics, but the mass continued to increase in size, so it was surgically excised. The mass involved the left ovary. The mare showed transient abdominal pain after surgery, but developed no other complications and was in foal 7 months later. On histology, the mass was diagnosed as a dysgerminoma, a rare ovarian tumour of germ cell origin.     

Assessing First-Order Emulator Inference for Physical Parameters in Nonlinear Mechanistic Models

We present an approach for estimating physical parameters in nonlinear models that relies on an approximation to the mechanistic model itself for computational efficiency. The proposed methodology is validated and applied in two different modeling scenarios: (a) Simulation and (b) lower trophic level ocean ecosystem model. The approach we develop relies on the ability to predict right singular vectors (resulting from a decomposition of computer model experimental output) based on the computer model input and an experimental set of parameters. Critically, we model the right singular vectors in terms of the model parameters via a nonlinear statistical model. Specifically, we focus our attention on first-order models of these right singular vectors rather than the second-order (covariance) structure.     

Supplementing rainbow trout (Oncorhynchus mykiss) broodstock diets with choline and methionine improves growth in offspring

Nutritional programming represents the mechanism through which broodstock feeding strategies have lifelong effects on the offspring generation. The objective of this study was to determine whether supplementing rainbow trout, Oncorhynchus mykiss broodstock diets with choline and methionine affects offspring growth performance. Experimental diets were produced by top-dressing a commercial broodstock diet with (a) 12,000 ppm methionine, (b) 7,400 ppm choline, (c) 12,000 ppm methionine and 7,400 ppm choline, or (d) water (control). Six rainbow trout families were fed experimental diets beginning 18 months post-hatch through spawning; the offspring consumed a commercial diet. The broodstock diet did not affect maternal body weight, body condition, egg size, or egg yield (p > .05). Eggs from choline-treated broodstock contained 10% more choline than control eggs (p < .05). Offspring from choline-treated broodstock were smaller than controls at 146 days post-hatch (dph) (p < .05). At the final harvest (439 dph), offspring from the control broodstock weighed 12–18% less than offspring from broodstock consuming the supplemented diets (p < .05). However, there was a significant diet-by-family interaction on offspring growth (p < .05); supplemented diets improved performance in three of the six broodstock families. These findings indicate that supplementing broodstock diets with methionine and choline causes a nutritional programming effect that benefits growth in offspring.