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Medycyna Weterynaryjna
|
2010
|
tom 66
|
nr 08
s.559-561,tab.,bibliogr.
The aim of the study was the evaluation of the epizootic situation of contagious equine metritis (CEM) in selected horse breeding centers in Poland. In the years 2007-2009, 765 samples collected from 212 horses (83 mares and 129 stallions) were examined. Animals came from the National Stud, stallion’s depot and stud farms, in which procreation was based on natural service or artificial insemination. Swabs for examination were taken from predilection sites of the urinary-genital tract of stallions and mares harbored by Taylorella equigenitalis. Two stallions (0.9% of the examined population) coming from two different breeding centers were identified as CEM carriers. Isolated strains of Taylorella equigenitalis were susceptible to streptomycin, novobiocin, oleandomycin, cefoperazone, neomycin and oxytetracycline. The stallion-carriers were treated, with three sets of samples were taken from each stallion after treatment. Samples were collected every other day, not earlier than 7 days post therapy. The control examinations gave a negative result. The animals were admitted as cured and no longer as carriers of Taylorella equigenitalis.
The aim of the study was to determine the influence of chosen factors: subsequent lactations in which pregnancy was diagnosed, the month in which successful insemination was performed, the length of the calving-conception period, the number of inseminations, and the culling rate on the pregnancy loss index, and to evaluate the relationship between culling and risk of abortion. The analysis involved 1,056 pregnancies diagnosed in 378 cows during nine years of observations. An increase in the number of cows being in the third and following lactations in successive years was connected with an increasing pregnancy loss ratio up to 90 d after insemination (P=0.034) and decreasing pregnancy loss observed later (P=0.045). The pregnancy loss rate during the first trimester was the lowest in primiparous cows (4.73%). Simultaneously, in primiparous cows and in cows in the second lactation, the highest pregnancy loss rate between 91-260 d after insemination was noted (8.19% and 8.68%, respectively). It was demonstrated that pregnancy loss up to 90 d of its development was observed most frequently after inseminations made in April (P=0.027) and most seldom after inseminations made in August. Pregnaney losses in the second and third trimesters were the most frequently observed after inseminations performed in July (P=0.040) and October (P=0.031), and the most seldom when the inseminations were performed in April. Culling of primiparous cows decreased the risk of pregnancy loss after inseminations in the second lactation in the other cows.
The aim of this paper was the presentation of some problems connected with pregnancies located in the uterine horn contralaterally to the corpus luteum (CL) in cows. Contralateral pregnancies occur very rarely (0.2%) and have a lower chance for development than ipsilateral pregnancy. However, owing to the application of the available biotechnic methods it is possible to introduce the embryo in the uterine horn, contralaterally to the CL and to favor their growth to the time of parturition. Such an action was accomplished even in cows with aplasia of one uterine horn. No statistical differences were found in pregnancy rates after the transfer of a second embryo ipsilaterally or contralaterally to the CL to already inseminated cows. However, better conditions for the development of the pregnancy were on the side of the functional CL even when two fetuses were growing, and the ipsilateral transfer of the second embryo to an already mated cows was a more efficient twin induction technique than a contralateral transfer. The maintenance of an early pregnancy in cows is possible using the exogenous progesterone (P), even in cases of the absence of functional CL on ovary. In cows supplemented with P a spontaneous ovulation can take place along with the establishment of a new CL that is able to maintain the pregnancy. At such a time the formation of CL can be induced pharmacologically. Cows with the newly created CL maintained the pregnancy up to mature parturition, even in cases when the fetus was placed contralaterally to such a corpus. Beneficially for maintaining the pregnancy was the presence on the ovary of accessory CL, independently of the supplementation with P. Their presence limited the occurrence of cases of embryo morality and the abortions of fetuses. Pregnancy losses were not observed in females in which the injection of hCG or GnRH induced the establishment of two new luteal structures. The increase of embryonic survival after bilateral nonsurgical embryo transfer is enabled by the stimulation of recipients with low doses of FSH. This treatment causes the presence of few CL on the ovaries at the day of embryo transfer and enables attaining a high percentage of pregnant females. A considerable portion of them carry twins.
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