Abstract
Simple SummaryThe high embryo production cost in buffalo, compared to cattle, is currently the major factor limiting the commercial application of ovum pick-up and in vitro embryo production technologies. This is mainly due to the lower number of follicles that develop during each estrous cycle and consequently oocytes recovered per session. In this work, we tested two different hormonal treatments based on commercial follicle-stimulating hormone (FSH) and progesterone (P4) to enhance the number of follicles and competent oocytes. Furthermore, in the second experiment, we tested three different coasting times, i.e., periods between the last FSH administration and ovarian aspiration, which is known be the key period for the final oocyte maturation and competence acquisition. The results, in terms of number of aspirated follicles, oocyte quality, blastocyst yield, and superior quality blastocyst yield, allow us to suggest the use of high doses of FSH (40 mg given six times every 12 h) combined with the shorter coasting time (28–32 h) as the ideal protocol for ovarian superstimulation in buffalo.The aim of this work was to evaluate the efficiency of different FSH doses and FSH coasting times before ovum pick-up (OPU) on follicular growth and oocyte competence in buffalo. Experiment 1 involved two different FSH treatments: 40 mg FSH given three (FSH3) or six (FSH6) times, 2 days after dominant follicle removal were tested, with OPU carried out after 40–44 h of coasting. In experiment 2, OPU was carried out after FSH6 protocol followed by 28–32 h (C1), 40–44 h (C2), or 64–68 h (C3) of coasting time. Cumulus oocyte complexes (COCs) were classified, in vitro matured, fertilized, and cultured. The results demonstrated that FSH6 increased the total number of follicles, the number and percentages of medium and large follicles, the number and the proportion of good quality oocytes, and the number of grade 1,2 and fast-developing blastocysts compared to the control. C3 decreased the percentage of good quality oocyte and blastocyst rates compared to C1 and C2. A higher percentage of fast blastocysts and average number of grade 1,2 blastocysts was observed in C1 compared to C3, with intermediate values found in C2. The improved efficiency in terms of blastocyst yields suggests the use of FSH6 + C1 protocol for ovarian superstimulation in buffalo.
Highlights
Buffalo is the livestock species that has undergone the greatest increase in number of heads, milk production, and economical importance in the last decades [1,2]
This study investigated the effect of different follicle-stimulating hormone (FSH) doses and coasting times on follicular population and oocyte competence in highly productive Italian Mediterranean buffaloes in an attempt to improve the embryo yields per donor, which is currently still the major limiting factor the diffusion of in vitro embryo production (IVEP)
In addition to an increase of the number of total follicles and Cumulus oocyte complexes (COCs), this treatment significantly enhanced both the number and the percentages of medium and large follicles compared to the control, which was reflected in higher proportions of good quality oocytes
Summary
Buffalo is the livestock species that has undergone the greatest increase in number of heads, milk production, and economical importance in the last decades [1,2]. MOET is not commercially feasible in water buffalo because of the low number of embryos recovered per session, likely due to a defect in the capture of the oocyte by the fimbria and its transport through the oviduct [3,4,5]. Despite a low number of blastocysts produced per session, OPU-IVEP allows higher embryo yields on a long-term basis, as it can be repeated for long periods without interfering with the reproductive activity of the donors [7,8]. The low oocyte recovery, resulting in high embryo production costs, is certainly the major factor limiting the commercial application of OPU in buffalo. It is known that the size of the follicle is positively associated with oocyte competence in cattle, with the greatest embryo production obtained aspirating oocytes from 6 to 10 mm diameter follicles [20,21,22,23,24]
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