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Effect of multiple pregnancies on cow milk production and reproduction indices. The aim of the studies was to determine the effect of multiple pregnancies on milk performance and the reproduction indicators of cows. The studies covered 6755 animals in which at least one'multiple birth occurred during 6 years. The data concerning cow milk performance during previous, parallel lactation and that one, occurring directly after multiple pregnancy and gestation period and cow reproduction parameters - inter-calving and inter-pregnancy periods during, before and after multiple pregnancy. It was found that the multiple pregnancies did not lower milk performance. After multiple pregnancy, the examined reproduction indices were abbreviated as compared to their length before the multiple pregnancy.
Multiple pregnancies in cattle and the frequency of their occurrence. The aim of the studies was to determine the effect of the sequence of lactation and season of calving on occurrence of multiple births. The studies included 6755 cows which had at least one multiple pregnancy during 6 years. The percentage of multiple pregnancies was increasing from year to year but it did not exceed 2% of all parturitions. It was found that the greatest number of multiple births occurred in cows in the second (26.63%) and the third (21.01%) lactation. A significant influence is exerted by season of calving; the greatest number of multiple births occurs in winter-spring season, that is, in months: December-May (53% of all multiple births); it comes from spring-summer fertilization (effective insemination) of the cows (March-August).
The aim of the research was to determine the influence of multiple pregnancy on delivery complications and calf mortality. The experiment was conducted on 6755 cows in which at least one multiple calving took place. Data came from the documentation of the Polish Federation of Cattle Breeders & Milk Producers and concerned calving type, sex structure of the newborn calves, as well as their perinatal mortality. The results of the investigation showed that twin pregnancies constituted over 99% of all multi pregnancies. In the fetal sex structure of twin pregnancies the share of heterosexual fetuses was the greatest (36.4%), whereas unisexual male the smallest (29.7%). Almost 75% of cows with multiple pregnancies needed some human assistance during the delivery. Difficult calvings occurred most often in the case of heterosexual pregnancy, and seldom in unisexual male fetation. The percentage of stillborn calves and the ones dead in the perinatal period amounted to 8.58% and was higher by 1.19% in bull calves than in heifer calves. The obtained results together with the large percentage of stillborn calves as well as those that died during the perinatal period indicate the decreasing profits from an increased amount of calves from multiple and twin pregnancies.
Six bacterial strains isolated from the surface water of the southern Baltic Sea were described on the basis of their morphological, physiological and biochemical features, and were classified on the basis of 16S rDNA sequence analysis. Comparative analyses of the 16S rDNA sequences of five of the six bacterial strains examined displayed a ≥98% similarity to the sequences available in the NCBI GenBank. The 16S rDNA sequence of strain 2 shared only a 96% similarity with other published sequences, which suggests that this is a new, hitherto unknown species. The isolated heterotrophic bacteria belong to the families Bacillaceae (strain 1), Flexibacteriaceae (strain 2), Sphingomonadaceae (strains 3, 5), Micrococcaceae (strain 4) and Aurantimonadaceae (strain 6). This is the first study in which the polyphasic approach has been applied to the identification of heterotrophic bacteria from the brackish waters of the Gulf of Gdańsk and Gdańsk Deep.
An experiment was carried out concerning the effect of the initial stocking density per area unit on the growth and survival of the common barbel, Barbus barbus, larvae under controlled conditions. During the 21 days of rearing, the effect of fish stocking density between 2500 and 6250 individuals m⁻² was determined. Water temperature was 25oC throughout the experimental period. Fish were fed on live Artemia sp. nauplii. During the experiment, the mean total length (TL) of larvae as well as their weight (W) and survival were measured. On the basis of the obtained data, specific growth rate (SGR), Fulton condition coefficient (K) and fish biomass per area unit were calculated. The developmental stage of larvae was also determined. This study proved that initial stocking density of larvae does not affect survival, developmental stage or growth parameters. In all experimental treatments survival rate exceeded 98%. On the last day of rearing, all fish reached juvenile stage and TL of 28.5–30.2 mm. SGR ranged from 14.2 to 15% day⁻¹. The analysis of variance did not reveal statistical differences between the groups (P>0.05) for each measured parameter. The results obtained in this study indicate the possibility of a significant increase in the production intensity of fry-stocking material of the common barbel under controlled conditions, which should positively affect the economic effectiveness of rearing.
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