Određivanje optimalne veličine folikula za dobivanje najkvalitetnijih oocita za in vitro oplodnju

The aim of this study was to determinate optimal follicular size for collection of high quality oocytes, and the subsequent capacity of the oocyte to mature and be fertilized and to develop in vitro. The ovaries of dairy cows were cut out immediately after slaughter and transported within one hour. The follicles were separated and divided into three groups according to diameter, i.e. small (3-5 mm), medium-size (6-9 mm), large (10-20 mm). Quality grading (A, B, C, D) of the oocytes was performed on the basis of cumulus cell development and homogeneity of cytoplasm. A total of 284 COCs were aspirated from 123 ovaries. Among 143 COCs, 236 were grades A and B and 48 were grades C and D. The maturation rate of the oocytes from medium size follicles A and B grade was 56.01% better than C and D grade. Only A and B graded oocytes were fertilized in vitro with 1×106 sperm/mL using Fert-TL, with 0.3% BSA, 22 μg/mL sodium pyruvate, 10 μg/mL heparin. The cleavage rate in the small follicle oocytes was significantly lower (35.89%) than in the medium-size follicle oocytes (56.41%), and a similar trend was observed in the morula development rates, independent of the oocyte grade. Good quality oocytes received from medium size follicles, and oocytes with more than three complete layers of cumulus cells (Grades A and B) have better competence for in vitro maturation and cleavage.Cilj ovoga istraživanja bio je odrediti optimalnu veličinu folikula kako bi se prikupile oocite visoke kvalitete s obzirom na visoki kapacitete za sazrijevanje, oplodnju i razvoj in vitro. Jajnici krava mliječne pasmine izrezani su odmah nakon klanja i prevezeni unutar sat vremena. Folikuli su izdvojeni i podijeljeni u tri skupine s obzirom na njihov promjer: u skupinu malih folikula (3 - 5 mm), skupinu folikula srednje veličine (6 - 9 mm) i skupinu velikih folikula (10 - 20 mm). Stupnjevanje kvalitete oocita (A, B, C, D) učinjeno je na temelju razvoja kumulusnih stanica i homogenosti citoplazme. Aspirirane su ukupno 284 kumulusne oocite iz 123 jajnika. Od ukupno 284 kumulusne oocite njih 236 bilo je A i B-stupnja, a 48 ih je bilo C i D-stupnja. Sazrijevanje oocita iz skupine folikula srednje veličine A i B-stupnja bilo je 56,01 % bolje od onih stupnja C i D. Samo su oocite A i B-stupnja oplođene in vitro s 1×106 sperme po mililitru uz upotrebu Fert-TL-a, s 0,3 % Bovine Serum Albumin-a, 22 μg/mL natrijeva piruvata i 10 μg/mL heparina. Brazdanje oocita dobivenih iz folikula male veličine bilo je znakovito niže (35,89 %) nego u skupini folikula srednje veličine (56,41 %), a slično je uočeno i u razvoju morula, neovisno o kvaliteti oocita. Zaključeno je da oocite dobre kvalitete dobivene u skupini folikula srednje veličine, oocite s više od tri cjelovita sloja kumulusnih stanica (stupnjevi A i B) imaju veće šanse za sazrijevanje in vitro i brazdanje

The Effect of Supplementation of Rumen-Protected Choline on Reproductive and Productive Performances of Dairy Cows

We aimed to evaluate the effects of organic herbal preparations containing rumen-protected choline (RPC) in dairy cow milk’s BHB and progesterone (P4) concentration changes, reproduction, and production performances. Cows were divided into the following two groups: The CHOL (n = 60) cow diet was supplemented with 10 g/day RPC from 20 days pre-calving to 20 days post-calving, and CONT (n = 60) were fed a conventional diet. BHB and P4 concentrations were measured at 5–64 DIM and 21–64 DIM, respectively, with DelPro 4.2. BHB was lower in the CHOL group at 5–64 DIM than CONT p > 0.05. The first post-calving P4 peak, p < 0.001, was determined earlier in the CHOL group, and the P4 profile during 21–64 DIM was similar, p > 0.05. The insemination rate was lower, and the interval between calvings was shorter. The first insemination time was earlier in the CHOL group, p < 0.05. Milk yield was higher in the CHOL group at 21–64 DIM, p > 0.05. The CHOL group had more fat in their milk at 31–60 DIM, p < 0.05. There were no significant differences in protein and SCC between the groups, p > 0.05. Based on our results, we concluded that the supplementation of RPC pre- and post-calving had statistically significant effects on the first peak of P4, and benefited the reproduction performances, milk yield, and milk fat during the early postpartum period