Serological evidence for Babesia canis infection of horses and an endemic focus of B. caballi in Hungary

In order to evaluate the seroconversion of horses to Babesia caballi and B. canis in Hungary, blood samples were collected from 371 animals on 23 different locations of the country. The presence of antibodies to B. caballi was screened with a competitive ELISA. All 29 positive samples came from one region (the Hortobágy). The prevalence of infection did not show correlation with sexes, and reached 100% in the age group of 2-5 years. Babesia canis-specific antibodies were demonstrated by IFAT in 6.74% of animals kept in 7 regions. The titres were low or medium level (1:40 to 1:160), indicating that the horses had previously been exposed to this piroplasm, but their infection must have been limited. The highest seropositivity rate was observed in the age group of 3-4 years, and males (stallions and geldings) were significantly more frequently infected than females. However, neither B. caballi nor B. canis could be identified in the peripheral blood samples of infected horses by PCR. Since most of the B. caballi-positive horses remained negative in the B. canis IFAT, whereas seroconversion solely to B. canis was detected in several regions of the country, serological cross-reaction between the two species can be discounted. This is the first serological evidence of horses being naturally infected with B. canis, supporting the view that piroplasms are less host specific than previously thought.     

Molecular tracing confirms that infection with infectious pancreatic necrosis virus follows the smolt from hatchery to grow‐out farm

Infectious pancreatic necrosis (IPN) is an important restraint to production of salmonids in aquaculture globally. In order to implement efficacious mitigation strategies for control of this disease, it is important to understand infection routes under current production systems. IPN virus has been shown to be transmitted vertically in Rainbow trout, from broodstock to fingerlings in hatcheries, and there is circumstantial evidence suggesting that vertical transmission can also occur in Atlantic salmon, in addition to horizontal transmission between grow‐out fish in farms. In this study, we show that the smolt carries infection with IPN from hatchery to the marine farm. We do this by comparing sequences from fish groups taken both in hatcheries and on corresponding marine grow‐out farms. We use statistical analysis to prove that sequences obtained from the same fish group in both hatchery and marine farm are more similar than sequences obtained from random fish groups on hatcheries and marine farms.     

UV‐light and dietary vitamin D and their effects on ionized calcium and 25‐OH‐D plasma concentrations in captive gentoo penguins (Pygoscelis papua)

In this study, the effect of ultraviolet (UV) light and dietary vitamin D on calcium metabolism in permanently indoor‐housed gentoo penguins (Pygoscelis papua ) was investigated. The study consisted of three periods, each completed with blood samples to analyse plasma concentrations of 25‐OH‐D, 1,25‐(OH)₂‐D, ionized (iCa) and total calcium (tCa). During the first study period (D), animals were housed under routine conditions without UV‐light and fed a diet of different fish species, supplemented with 1,000 IU vitamin D per animal and day. The following study period (Baseline) of 28‐day duration consisted of the same diet without any vitamin D supplementation and without UV‐light. During the study period (UVB) artificial UV‐light was added for 3 weeks. The vitamin D content of fish was measured by high‐performance liquid chromatography. It varied between fish species and between facilities, ranging from no measurable content in capelin (Mallotus villosus ) to 7,340 IU vitamin D/kg original matter (OM) in herring (Clupea spp). The average dietary vitamin D content was 311 IU/kg OM at facility 1 and 6,325 IU/kg OM at facility 2, resulting in a vitamin D intake per animal and day without supplementation of 130 IU (25.5 IU/kg body weight BW) and 2,454 IU (438.2 IU/kg BW) respectively. The supplementation of vitamin D elevated significantly the plasma concentrations of 25‐OH‐D by an intraindividual difference of 15 (range ?2 to 59) nmol/L and tCa by 0.1 (0.0–0.3) mmol/L only at facility 2. The exposure to UV‐light raised the blood concentrations of tCa at facility 2 by 0.15 (0.1–0.2) mmol/L, and of iCa and tCa for females at facility 1 by 0.23 (0.13–0.41) mmol/L and 1.8 (1.1–2.5) mmol/L respectively. No significant influence of the study periods (D) and (UVB) was found for the concentrations of 1,25‐(OH)₂‐D at both facilities.     

C and N dynamics of a range of biogas slurries as a function of application rate and soil texture: a laboratory experiment

Digestates vary in composition and studies regarding their impact on C and N dynamics in soils are scarce. The objective was to analyse the C and N dynamics of digestates originating from various substrates applied to a sandy Cambisol and a silty Anthrosol. In three laboratory experiments (4–6 weeks), the effects of digestate properties, N rate and water content were tested. Averaged over both soils, 21% of the C supplied was emitted as CO₂. Potential NH₃ emissions during the first week ranged between 6% and 12% of NH₄⁺ present in the digestates. The emission factors in the sandy Cambisol were on average 1.2 and 2 times higher for CO₂ and potential NH₃, respectively, compared to the silty Anthrosol. Similarly, net nitrogen mineralization in the sandy Cambisol was approximately twice the N mineralized in the silty Anthrosol. Net nitrification was not influenced by soil texture or different digestates, but increased with increasing application rates and had highest values at 75% of water holding capacity. Our results indicate that the type of substrate input for anaerobic digestion influences the properties of the digestate and therefore the dynamics of C and N. However, soil texture can affect these dynamics markedly.     

Economics of milkfish (Chanos chanos) production in Hawaii*

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.     

Fasciola hepatica - monitoring the milky way? The use of tank milk for liver fluke monitoring in dairy herds as base for treatment strategies

In this study 595 lactating cows originating from 31 carinthian farms were investigated in accordance of liver fluke infection using individual and tank milk as well as individual blood and faecal samples. Two commercial ELISAs were used to test the milk and blood serum, and the results were compared with coproscopy and a commercial copro-antigen ELISA. Receiver operating characteristics (ROC) and two-graph operating characteristics (TG ROC) of tank milk results were conducted based on the individual milk to determine the minimum reliable in-herd antibody prevalence for the predominant condition in the investigation area. In 17.8% of the examined individuals located in 64.5% of the farms eggs were detected by coproscopy. The copro-antigen ELISA delivered 13.4% positive individuals from 54.8% of the farms. The milk ELISAs showed 42.7% (Euroclone) and 44.2% (Pourquier) positive cows on 90.3% of the farms. The blood samples were positive in 43% (Euroclone) and 45.2% (Pourquier) of the individuals from 90.3% to 96.8% of the herds, respectively. Based on the milk and the blood an average in-herd prevalence of 30-45% can be assumed. The serum and milk samples delivered correlating results with kappa values between 0.94 and 0.97, whereas the coproscopy and copro-antigen ELISA did not correlate well with the ELISA results. The two different ELISA tests highly correlated on individual and on herd level. Both showed a reliable minimum in-herd prevalence of ～20%, meaning that one fifth of the individuals in a herd have to be positive to obtain a positive bulk tank milk result. In the investigated area a higher in-herd prevalence is expected, therefore the tank milk is useful as a monitoring tool and can be used as a basis for intervention strategies.