The significance of the structural characteristics of the agent for the problems of immunization against blue tongue]

Bluetongue virus (BTV), an arthropod-borne virus, is transmitted primarily by biting midges of the genus Culicoides. Some insect species, which might serve as a potential vector, are prevalent in Central Europe. In sheep, bluetongue is acute and mortality is high, whereas in cattle, goats and most wild ruminants the infection is usually clinically inapparent. Viremia is of short duration in sheep, but cattle experience a prolonged viremia and provide a reservoir for the dissemination of BTV. At least 24 different BTV serotypes have been identified. Antigenic variations occur in the polypeptides of the outer viral capsid and the segmented nature of the viral genome provides the potential for evolution of the virus by a mechanism of reassortment. This renders the use of polyvalent vaccines inefficient and emphasizes the significance of import/export restrictions on ruminants from BTV endemic areas.     

Purification and characterization of hepatic triacylglycerol lipase isolated from rainbow trout,Oncorhynchus mykiss

Trialcylglycerol (TG) lipase was isolated and partially purified from rainbow trout liver. Triacylglycerol lipase activity was assayed by measuring¹⁴C-oleic acid release from¹⁴C-triolein.¹⁴C-oleic acid release was linear for up to two hours. Optimal activity occurred at pH 7.0 and 15°C. Most of the lipase activity was recovered in the cytosolic fraction. A 27,000-fold purification was achieved after Sepharose (Bio-gel A 0.5 M, 200–400 mesh) chromatography of a resuspended 20% ammonium sulfate fraction. The molecular weight of the trout hepatic lipase as determined by size-exclusion chromatography and by SDS-polyacrylamide gel electrophoresis was 40–43 kD. Lipase-mediated hydrolysis of TG resulted in the production of diacylglycerols, monoacylglycerols, and fatty acids. Kinetic analysis indicated that V_max=0.016 nmol/h/mg protein and that K_m=0.28 mM triolein. Lipolytic activity was enhanced in the presence of cAMP/ATP-Mg²⁺. These results suggest that the liver of trout possesses a neutral TG lipase that is responsible for mobilizing stored TG and is catalytically activated by phosphorylation.A part of this work was presented at the Annual Meeting of the American Society of Zoologists, December 26–30, 1990, San Antonio, TX.     

Teratogenicity testing of BI 58 EC (38% dimethoate) in chicken embryos with special respect to degradation of the active ingredient.

The insecticide formulation BI 58 EC was tested for teratogenicity in chicken embryos, with particular reference to degradation of the active ingredient (dimethoate) after the treatment of embryonated eggs. The pesticide was diluted in water to a concentration level of 0.8%, and the emulsion was injected into the air space in a volume of 0.1 ml/egg, or hen's eggs were treated by the immersion technique. Residues of dimethoate were measured in the samples on days, 13, 15 and 19 of the incubation of chicken embryos, and morphological examinations were performed simultaneously. Analytical chemistry data indicated a slower degradation of dimethoate in embryos after the immersion of eggs, and cyllosis was remarkable in this group among the sporadic developmental anomalies. The liver tissues of both treated groups exhibited severe fatty infiltration.     

Monthly model for genetic evaluation of laying hens 1. Fixed regression.

1. This paper addresses the possibility of using a monthly model for the genetic evaluation of laying hens, based on the definition of a test day model with fixed regression as used in dairy cattle, in which monthly records were treated as repeated measurements of the same trait. 2. Production records of 6450 hens, daughters of 180 sires and 1335 dams were analysed using an animal model with restricted maximum likelihood (REML). The traits considered were individual monthly egg production and cumulative egg production in 11 months. Four different models were fitted to various combinations of monthly and cumulative records. The covariates were derived from the regression of Ali and Schaeffer (1987). 3. Spearman rank correlations were computed to compare breeding values from different models. Two types of correlations were computed: between individual breeding values and between sire breeding values based on subsets of full-sib records. 4. The results indicated that a monthly model with nested covariates produced higher heritability and permanent environmental variance than the models with non-nested or without covariates. The estimates of heritability obtained from monthly model were lower than the estimates from the cumulative model. The monthly model resulted in higher correlations of sire breeding values between two subsets of full-sib records than those from cumulative models. 5. In conclusion, the monthly model with nested covariates appears to be better than the model with non-nested covariates or without covariate. Although the heritability estimates obtained from the monthly model were lower, the monthly model with nested covariates could be better than the cumulative model for genetic evaluation of laying hens in the 1st cycle of laying period when using either full or part records. The use of information from odd months of production could be of interest for the evaluation of full records.     

An Epidemiologic and Economic Study of Respiratory Diseases in Two Conventional Danish Swine Herds. I: Prevalence of Respiratory Lesions at Slaughter and Their Effects on Growth

A total of 578 slaughter pigs from 2 Danish conventional farrow-to-finish operations (Herds A and B) were followed from an age of 14 days to slaughter. Pigs were weighed at 3 weeks intervals and at slaughter and an extended post mortem examination of the plucks was done. Comparison of growth rates in pigs with and without specific types of lesions by the t-test and those with multiple lesions with regression models demonstrated that Mycoplasma-like pneumonia, complicated pneumonia, anterio-ventral pleuritis, fissures and atrophic rhinitis significantly reduced mean daily gain and increased the time required to reach slaughter weight. The total impact of the lesions in Herd A was an estimated reduction in mean daily gain of 27 grams and a 2 day increase in the interval from 14 days of age until slaughter (MDG14). Decreases in MDG14 in Herd B were more substantial, 98 grams and 16.7 days. Reductions in mean daily gains during the interval from the fourth weighing until slaughter were 31 grams in Herd A and 137 grams in Herd B. Chronic dorso-caudal and parietal pleuritis, without other lesions present, had no significant adverse effects on growth rates in either herd. Interactions between lesions did not significantly alter the estimates. The R² values obtained for the regression models showed that the presence, absence or extent of lesions at slaughter explained only 13-27% of the variations in growth rates in the 2 herds.     

Maximal lactate concentrations in horses after exercise of different duration and intensity

Lactate kinetics in whole blood of horses was investigated after exercise of differing velocities and duration. The following categories of exercise were used: A: <11 m/second and >180 seconds (n=35), B: >11 m/second and <180 seconds (n=17) and C: <11 m/second and <180 s (n=10). The mean peak lactate concentration determined in horses in category A was 4.49 ± 2.21 mmol/1, in B, 16.32 ± 4.81 mmoVl and in C, 4.58 ± 1.59 mmol/l. While the maximum lactate concentrations in categories A and C were always found immediately after the exercise, the peaks in category B were measured between the first and tenth minute after exercise. Mean lactate concentrations measured at 2-minute intervals after bouts of category-B exercise tended to stabilize 3 to 10 minutes after exercise; however, mean lactate concentrations measured during the intervals before and after the peak value differed significantly. The lactate concentration returned to pre-exercise levels within 20 minutes after exercise bouts of category C, but remained above pre-exercise levels up to 60 minutes after bouts of category-A and -B exercise. It was concluded that, for an evaluation of lactate data after intensive anaerobic exercise, sequential blood sampling at 2-minute intervals for a period of up to 12 minutes after exercise is necessary. Less frequent sampling may be a reason for the often described irreproducibility of lactate concentrations in horses. After aerobic or mild anaerobic exercise, one sample is sufficient, but it has to be taken as soon as possible after exercise.     

Microcirculation in the follicles and corpora lutea of the bovine ovary--a corrosion anatomical study

With the help of a new synthetic material follicles and corpora lutea from the ovaries of 80 cows in different stages of the sexual cycle were examined for modifications of their blood vessel architecture. In the theca externa the main artery which runs towards the follicle, separates into arterioles of which capillaries derive in the theca interna, building a basket-like network around the zona granulosa. After ovulation the follicle wall forms characteristic fields. Capillaries grow into the zona granulosa and thus the folds form the lobular structure of the corpus luteum. Capillaries which rise from the ruptured part of the follicle, spread centripetally and together with lutein cells they build up the not lobulated cupola of the corpus luteum. The regression of the corpus luteum starts around the 16th day of the cycle, beginning at the capillary network of the cupola. A contraction of the vessels and a quick decrease of the volume follow.