Primary bovine viral diarrhoea virus infection in calves following direct contact with a persistently viraemic calf.

Six calves, aged 24 to 58 days and not previously exposed to bovine viral diarrhoea virus (BVDV), were infected with this agent by nose-to-nose contact with a persistently BVDV viraemic calf. The study was conducted in two trials, using 3 calves in each. All 6 calves showed a peak interferon level in serum at 4 days post infection (dpi), and they seroconverted to BVDV at 16-21 dpi. The calves in trial 1 had diarrhoea for 2 or 3 days between 2 and 6 dpi and one calf again from 9 to 11 dpi. During the periods of fever, the calves were slightly depressed. Those in trial 2 were more depressed and their oral and nasal mucous membranes were reddened but they never had diarrhoea. In both trials, fever (up to 41.3 degrees C) was a prominent symptom at 8 to 9 dpi and 2 calves showed a diphasic fever course. Respiratory affection was mild and no medical treatment was required. Haematological assessment demonstrated a transient but significant leukopenia and lymphopenia at 4 dpi (P less than 0.01 and P less than 0.05 respectively) and 11 dpi (P less than 0.05 and P less than 0.01 respectively). A significant decrease in thrombocyte count was seen at 4 dpi (P less than 0.05, n = 3). This study has demonstrated that nose-to-nose contact is an effective way of transmitting BVDV from persistently infected to susceptible cattle.     

The helminth fauna from the common seal (Phoca vitulina vitulina, Linné, 1758) of the Wadden Sea in Lower Saxony. Part 2: Nematodes.

During the seal epidemic in 1988 and the beginning of 1989, 115 common seals found dead on the shores of the Wadden Sea of Lower Saxony were investigated for the presence of nematodes. The lungworm Otostrongylus circumlitus Railliet 1899 was found in 26.1% of the seals, the lungworm Parafilaroides gymnurus Railliet 1899 in 26.9% and the heartworm Dipetalonema spirocauda Leidy 1858 in 32.2% of the seals. In the digestive tract, two anisakid species were found, Pseudoterranova decipiens Mozgovoi 1951 in 87.8% and Contracaecum osculatum Rudolphi 1802 in 10.4% of the seals. Statistical analysis revealed a negative correlation between age of the seals and prevalence and intensity of infestation with the two lungworm species and the heartworms. Adult seals were found not to be infected with Dipetalonema spirocauda and Parafilaroides gymnurus, whereas the prevalence of the two anisakid species increased with increasing age of the seals. Pseudoterranova decipiens was found more often in autumn and winter than in summer. This parasite was more prevalent and had higher worm counts in the eastern part of the Wadden Sea than in the western part. Parafilaroides gymnurus and Dipetalonema spirocauda were found more often in seals with smaller blubber thickness than in well fed seals.     

Biochemical and serological properties of Streptococcus uberis.

The Strep-Zym identification system, a combination of 23 enzymatic tests, allowed a rapid biochemical characterization of Streptococcus uberis. The biochemical profiles of the S. uberis cultures clearly differed from those of S. agalactiae and S. dysgalactiae. Serological grouping of S. uberis revealed polysaccharide antigens of groups E, G, P and U. Some cultures of S. uberis demonstrated CAMP-like synergistic hemolytic activities on sheep blood agar and reacted specifically with the lectins of Helix pomatia and Dolichos biflorus. The occurrence of group polysaccharides, CAMP-like reactivities, and the lectin agglutination reactions were obviously not related to each other or to any of the biochemical properties. These reactions, possibly of importance as virulence factors, might serve as epidemiological markers.     

Pathogenesis of experimental combined infections with Isospora suis and rotavirus in conventional and gnotobiotic piglets

51 gnotobiotic and 63 conventional, one-, or two-days-old piglets were divided into five groups and infected orally either with Isospora suis or rotavirus alone, or with both agents simultaneously or successively with alternative sequences and various intervals. 15 gnotobiotic and 10 conventional piglets served as controls. The development of small intestinal lesions after infection with I. suis was biphasic. The dominant alteration resulting from rotavirus infection was villus atrophy, considerably more pronounced and extensive in gnotobiotic than in conventional piglets. Synergistic action of I. suis and rotavirus was manifested both clinically, and morphologically. This action culminated at the time of the actual, or presumed development of merogony of I. suis, i.e. on DPI 3 to 5. The action develops only if the intestinal epithelium is damaged functionally and morphologically by a preceding rotavirus infection. It is concluded that the synergistic action is based on a competition of rotavirus and I. suis for mature, enzymatically active absorptive cells.     

The asymmetric distribution of ovarian functional structures in cattle

The results of continually repeated transrectal palpations, performed in 168 post partum periods, 383 estrous cycles and 178 early pregnancies, were used to describe and to discuss the left-right distribution of ovarian functional structures. In cycling as well as in pregnant cattle, anovulatory interestral follicles and estrous follicles or corpora lutea in the mean were all distributed at 41% and 59% on the left and right ovaries respectively. No signs were found indicating that the position of functional structures would be influenced by local interactions between follicles and corpora lutea. At least for cyclic ovarian activity, and in early pregnancy, the interrelationship observed between the locations of these structures could be put down to the normally increased activity of the right ovary. After delivery, the first follicles preferentially became discernible on the ovary opposite to the previously pregnant uterine horn. But, as from the 4th follicle p.p. onward, the distribution of new ovarian structures again agreed with the one of the ensuing reproductive stages. After calving, probably the position of new follicles is temporally influenced by direct signals from the uterine horns affected differently by pregnancy. Several observations indicate that the factors causing asymmetrical ovarian activity could exert a selective effect on the recruitment of the dominant and solitary interestral follicles from the pool of their minor and less differentiated precursors.     

Lymphoid organs in sturgeons (Acipenseridae)

Lymphoid (lymphomyeloid) tissues in sturgeons (hybrid sturgeon, Huso huso X Acipenser ruthenus, and white Pacific sturgeon, A. transmontanus) were investigated by dissection, histology and transmission electron microscopy. The main lymphomyeloid tissues are the thymus, the spleen, the anterior part of the kidney, the meningeal myeloid tissue, the pericardial tissue and lymphoid masses of the intestine, especially in the spiral valve. The kidney is the main hemopoietic tissue. The meningeal tissue is bone marrow-like (myeloid), mainly granulopoietic, but it also contains lymphoid elements. The pericardial tissue is predominantly lymphoid. The pericardial tissue has a lymph node-like appearance. It seems to be the site of interaction between lymphocytes and vascular endothelium. The thymus contains cortex and medulla. The spleen, as in higher vertebrates, is differentiated into white and red pulp. The highly diversiform and well developed lymphoid tissues of sturgeons may serve as basis of efficient immune mechanisms.     

北大营示范场黑麦草引种与品比试验研究

利用1998年2－11月在云南省北大营示范场引种的10个黑麦草品种的观测资料，统计分析了在高、中、低3种施肥水平下黑麦草的累计产量、月平均产量及其生长速度的变化规律，研究了影响产量的主导因子及其监测模型。结果表明，在10个品种中，伯生（Bison Intermdiate）及安巴瑟（Embassy）具有良好的生产性能。黑麦草产量主要受气候、土壤肥力及品种等因素的影响，其中测草盘高度、降水量、蒸发量、日照时数和牧草生长天数等5个因子，可以较好地模拟、评估黑麦草产量的变化动态。     

Effects of boron supplementation of adequate and inadequate vitamin D3-containing diet on performance and serum biochemical characters of broiler chickens.

In this study, supplementation of two levels (5 and 25 parts per million; ppm) of boron into broiler diets including 125 IU kg(-1) (inadequate) and 2000 IU kg(-1) (adequate) vitamin D3 was investigated. The effects of supplementation on performance and biochemical characters (Ca, P, Mg, glucose and AP) of broilers from 1 to 45 days of age were evaluated. Boron provided significant increases in performances of chicks fed both adequate and inadequate vitamin D3-containing diets. The improvements in the inadequate vitamin D3-containing group were higher than that of adequate vitamin D3-containing group. The boron addition had a positive effect on Ca, P and alkaline phosphatase levels of chicks. Boron might be regarded as beneficial in inadequate vitamin D3-containing broiler feed.