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• Vitrification of mouse embryos by vitroloop technique

  81-83

  Nóra Vass

  Philip Klambauer

  András Jávor

  Zsuzsa Keresztes

  Sándor Ceh

  Views:

  86

  The objective of the study was to vitrify mouse embryos with the cryoloop technology using a new combination of vitrification mediums. Embryos were exposed to a 2- step loading of CPA, ethylene glycol and propylene glycol, before being placed on the surface of a thin filmy layer formed from the vitrification solution in a small nylon loop. After warming, the CPA was diluted out from the embryos by a 3-step procedure. Our data show that a high percentage of embryos survived (92.7%) vitrification in the mixture of EG and PG combined with cryoloop carrier and developing normally (89.1%) in vitro after thawing. 

• Examination of Reproductive Performance of Roe Deer (Capreolus capreolus) in Hungary

  33-38

  István Majzinger

  Views:

  93

  The objective of the research partly is to compare the reproduction performance of the populations living in different regions with regard to some special characteristics (age, condition).
  When estimating the age through tooth wear and cementum-layer-counting there was a difference of 0.87 years in favour of the first one (r=0,840; p<0,001). I found cementum layers at 42% of the does in the study after examining the MI teeth.
  There was lose connection between the weight (eviscerated, with head and legs) and the KFI (r=0,296; p<0,01), and for further analysis, I used only the KFI as the index for condition.
  The regional average KFI varied from 0.24-0.37 in fawns, 0.82-1.73 in does, with individual extremes of 0-4.05. Within the examined regions the highest index belonged to the prime-aged does, while the 1-year-olds had a lower rate, and it was the lowest in the does older than 8 years.
  The rate of fertility was between 83,3(ns)-100% as we can see from the presence of the CL. All the examined does were fertile, except in one region, while among the female fawns in two regions I only found three with active ovaries. The average number of CL was 1.5-2.13, and this varied by regions; all in all it was the highest in the 2-7-year-old group (1.96) and in the ones over 8 years (2.00!), while it was lower in the does younger than 1 year (1.90). The high fertility of the does over 8 years is remarkable.
  I could examine the number of embryos in two regions during the post-implantation period, and beside 100% fertility I found significant differences among the does, which can be associated with the condition. The ratio of CL carriers and the pregnant does was 100% and 73% in the two regions, the average number of CL were 1.92 and 1.72, while the average embryo number were 1.83 and 1.36 per doe. The difference between the CL and the embryo numbers on the two regions were 5% and 21%. The difference (prenatal loss) is in connection with the age (age class) of the doe. It is possible, however, that in some cases oestrus was not followed by gestation. But in roe deer, owing to the commonly known lack of luteolysis-mechanism (Flint et al., 1994), the regression of the CL of the does that did not get pregnant takes place in December and January, so the CL found in January cannot prove a previous pregnancy, which might have been followed by an abortion.
  Although it has to be proven, it seems that the number of the CL (potential progeny) can be associated with the age (r=0,418; p<0,01) and the weight (r=0,312; p<0,01) of the doe, while the embryo number (realised progeny) is influenced by the age of the doe and probably by external factors.
  It is essential to continue and extend the research to increase the reliability of the results and their correlation.

• Heat stress of cattle from embryonic phase until culling

  11-22

  Wissem Baccouri

  Edit Mikó

  István Komlósi

  Views:

  246

  Heat stress becomes a serious problem in the livestock sector as it affects cows' performance negatively. The objective of this paper review is to investigate the effects of heat stress during the different phases of the life cycle of cows; embryos, calves, heifers, and cows. Heat stress during early maternal gestation affects the ability of embryos to develop increasing the risk of abortion and early embryonic death. Heat stress during late maternal gestation affects the performance of calves and heifers later in their life, as it reduces growth performance, conducts physiological changes, impaired immunity, changes the behavior, and reduces the length and intensity of the estrus in heifers with decreasing in milk production in the first lactation. On the level of cows, milk quality and production, meat quality, and the final body weight decrease under hot temperatures. Heat stress decreases the conception rate, alters follicle growth, and estrous symptoms. Hormones secretion and physiological changes because of the heat stress conduct to impair the immunity system, and in oxidative stress and death in some cases. Same as for calves and heifers a change in the behavior of cows was detected in order to decrease their temperature.