STUDIES REGARDING THE CRIOPROTECTIVE PROPRIETIES OF THE VITRIFICATION MEDIA, WITH ETHYLENE GLYCOL, SUCROSE, FICOLL 70 AND GALACTOSE USED IN MAMMALIAN EMBRYO CRYOPRESERVATION

Crioprotectors are the main component of any vitrification media. The penetrant crioprotectors areessential for cell dehydration and for the decrease of the freezing point of the solution, allowing a longertime for dehydration to set in. The aim of our paper was to make a series of experiments in order todetermine the concentration at which four cryoprotectants (ethylene glycol, sucrose, Ficoll 70 andgalactose) singly and in pairs would vitrify on plunging into liquid nitrogen and remain vitreous whenthawed in water bath. A total of 156 solutions were tested. During freezing, vitrification was evidenced bythe formation of transparent glass when the unsealed straws were plunged into liquid nitrogen, at -196°C. Crystallization (ice formation) resulted in a milky appearance. Solutions that vitrify on freezingwere tested if they remain vitreous on thawing. For thawing we tested three temperatures 20°C, 25°C and37°C. During thawing, solutions that did not devitrified were transformed from solid clear state to theliquid state without evidence of a milky appearance. From the combinations of two cryoprotectors weretested a number of 51 solutions vitrify on freezing (19 solutions with ethylene glycol and galactose; 19solutions with ethylene glycol and sucrose; 13 solutions with ethylene glycol and Ficoll). The ethyleneglycol and galacose pair give the best results on thawing (3 combinations remained vitreous on thawing)at 37°C

ASSESSMENT OF MOUSE EMBRYO VIABILITY BY ESTERASIC ACTIVITY DETECTION

In order to evaluate the esterasic activity within the viable embryos we used the Fluorescein diacetate(FDA) staining test. For staining was used a 0.5 mg/ml FDA stock solution. The embryos were recoveredat 48 hours post coitus from superovulated Swiss mouse females. Before staining the embryos weremicroscopically evaluated by morphological criteria and classified in 4 quality codes. The two methodsused for quality and viability assessment were correlated applying Pearson coefficient. The calculatedvalue of the Pearson coefficient (r=1) showed a strong correlation between the two methods used andindicate FDA staining test and esterasic activity as a fast, easy and reliable method for embryo viabilityassessment

Bio-economic impact of energy and protein level in feed for laying hens raised in organic system

The economic results of organic egg production are largely dependent on the cost of the feed and productive performance. The paper aims to establish the productive performance of laying hens raised under specific conditions specific for the ecological system, and also performing a feeding costs estimation based on mathematical models starting from experimental data required. The hens in the experiment were fed a mixture of concentrated (MC) with 2728 kcal metabolizable energy (ME), 15.85% crude protein (CP), 0.67% lysine, 0.52% methionine + cystine, containing in its structure only fodder types organically certified. Throughout the entire experimental period, chickens have recorded a total MC consumption of 13.240 kg with an average daily consumption between 0.110 and 0.130 kg, when they produced a daily average of 31.55 g mass-egg. The amount of mass-egg produced (y) under this experiment can be predicted based on metabolizable energy intake (x1) and crude protein (x2) using the following mathematical model y=a+b*x1+c*x12+d*x13+e*x14+f*x15+g*x2 (R2=0.99%). Between the values obtained after the experiment and the predicted values obtained using the mathematical relationship, the differences are very small 2.17% at the end of experimental period. The costs incurred by feeding the laying hens (y) organically raised can be predicted using the following mathematical model y=exp(a*x1+b*x2+c*x3+d) (R2=0,96), with a rate of error of less than 2.2%, depending on the amount of mass-egg produced (x1), metabolizable energy intake (x1) and crude protein intake (x2)