Disruption of Bovine Oocytes and Preimplantation Embryos by Urea and Acidic pH1

Department of Animal Sciences, University of Florida, Gainesville, 32611-0910
Journal of Dairy Science - J DAIRY SCI 01/2003; 86(4):1194-1200. DOI: 10.3168/jds.S0022-0302(03)73703-5

ABSTRACT Feeding cattle diets high in degradable crude pro- tein(CP)orinexcessofrequirementscanreducefertil- ityandloweruterine pH.Objectivesweretodetermine direct effects of urea and acidic pH during oocyte mat- uration and embryonic development. For experiment 1, oocytes were matured in medium containing 0, 5, 7.5,or10mMurea(0,14,21,or28mg/dlureanitrogen, respectively). Cleavage rate was not reduced by any concentration of urea. However, the proportion of oo- cytes developing to the blastocyst stage at d 8 after insemination was reduced by 7.5 mM urea. In addi- tion, the proportion of cleaved oocytes becoming blas- tocysts was decreased by 5 and 7.5 mM urea. For ex- periment 2, putative zygotes were collected ∼ 9ha fter inseminationandculturedinmodifiedPotassiumSim- plex Optimized Medium (KSOM). Urea did not reduce the proportion of oocytes developing to the blastocyst stage, although 10 mM urea reduced cleavage rate slightly. For experiment 3, dimethadione (DMD), a weak nonmetabolizableacid, was used todecrease cul- ture medium pH. Putative zygotes were cultured in modified KSOM containing 0, 10, 15, or 20 mM DMD for 8 d. DMD reduced cleavage rate at 15 and 20 mM and development to the blastocyst stage at all concen- trations. Results support the idea that feeding diets rich in highly degradable CP compromises fertility through direct actions of urea on the oocyte and

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    Asian Journal of Animal and Veterinary Advances. 01/2011; 1:1-18.
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    ABSTRACT: Aim: This study was conducted to examine the effect of blood metabolites on embryo quality in post-partum suckling Japanese Black cattle.Methods: Blood samples were taken from 23 cows 30 days before, at and 30 days after parturition. Cows were synchronized 40 or 41 days after calving (day 0) and divided into three groups: control (n = 6), gonadotropin-releasing hormone ([GnRH]n = 10) and estradiol benzoate ([EB]n = 7). All groups received a controlled internal drug release (CIDR) device intravaginally together with 2 mg EB i.m. on day 0 and superovulation was induced in all groups from days 5–7 with a gradually decreasing dose of follicle-stimulating hormone (FSH). Two milligrams of EB was given on day 8 and GnRH (0.1 mg) was given on day 9 of insertion of the CIDR in the EB and GnRH groups. Cows were inseminated twice after the onset of estrus and embryos were recovered 7–8 days after artificial insemination.Results: The number of corpus luteum detected by ultrasonography in the EB group was significantly higher (P < 0.05) than that in the GnRH group. The number and rate of transferable and freezable embryos did not differ significantly among the groups. Regardless of the treatments, the total cholesterol level from parturition until 30 days after parturition was significantly higher (P < 0.01) in the good category than in the poor category of cows.Conclusions: The number of transferable embryos produced by post-partum superovulated suckling Japanese Black cattle was affected by the level of total cholesterol from parturition until 30 days after parturition. Moreover, administration of EB in CIDR-treated cows increased the numbers of corpus luteum and yielded better rates of transferable and freezable embryos. (Reprod Med Biol 2008; 7: 55–62)
    Reproductive Medicine and Biology 04/2008; 7(2):55 - 62.
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    ABSTRACT: Unsatisfactory reproductive performance in dairy cows, such as reduced conception rates, in addition to an increased incidence of early embryonic mortality, is reported worldwide and has been associated with a period of negative energy balance (NEB) early post partum. Typically, NEB is associated with biochemical changes such as high non-esterified fatty acid (NEFA), high β-hydroxybutyrate (β-OHB) and low glucose concentrations. The concentrations of these and other metabolites in the follicular fluid (FF) of high-yielding dairy cows during NEB were determined and extensively analyzed, and then were replicated in in vitro maturation models to investigate their effect on oocyte quality. The results showed that typical metabolic changes during NEB are well reflected in the FF of the dominant follicle. However, the oocyte seems to be relatively isolated from extremely elevated NEFA or very low glucose concentrations in the blood. Nevertheless, the in vitro maturation models revealed that NEB-associated high NEFA and low glucose levels in the FF are indeed toxic to the oocyte, resulting in deficient oocyte maturation and developmental competence. Induced apoptosis and necrosis in the cumulus cells was particularly obvious. Furthermore, maturation in saturated free fatty acid-rich media had a carry-over effect on embryo quality, leading to reduced cryotolerance of day 7 embryos. Only β-OHB showed an additive toxic effect in moderately hypoglycemic maturation conditions. These in vitro maturation models, based on in vivo observations, suggest that a period of NEB may hamper the fertility of high-yielding dairy cows through increased NEFA and decreased glucose concentrations in the FF directly affecting oocyte quality. In addition to oocyte quality, these results also demonstrate that embryo quality is reduced following an NEB episode. This important observation may be linked to the typical diet provided to stimulate milk yield, or to physiological adaptations sustaining the high milk production. Research into this phenomenon is ongoing.
    animal 08/2008; 2(8):1120-7. · 1.65 Impact Factor


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