Simple media were developed to study the metabolic requirements of bovine embryos up to Day 7 (Day 0 = day of oocyte aspiration) in vitro. Embryos were derived from oocytes matured and fertilized in vitro. At 45 +/- 2 h post insemination, embryos (> or = 2 cells) were randomly allotted to treatments. Examined in experiments 1 and 3 was the effect of pyruvate concentration in the presence of lactate. In the presence of lactate, pyruvate (0.2-5.0 mM) had no effect (p > 0.05) on the percentage of morulae or blastocysts. However, increasing the concentration of hemicalcium L-lactate from 5 mM to 10 mM decreased (p < 0.001) the percentage of embryos reaching the morula or blastocyst stage (experiment 3). Neither magnesium sulfate (0.5 mM) nor EDTA (10 mM) improved embryo development when added to the medium CR1 (experiment 2). Increasing the calcium level to 5 mM or the lactate level to 10 mM had no effect (p > 0.05) on embryo development (experiment 4). However, the interaction of adding calcium and lactate resulted in a decreased (p < 0.05) percentage of morulae. Determined in experiment 6 were the independent effects of pyruvate, lactate, and glucose on embryo development in vitro. As pyruvate or lactate level was increased from 1 to 10 mM, the percentage of blastocysts was decreased (p < 0.05). These experiments indicate that adding pyruvate to a medium containing lactate is not necessary for development of bovine embryos in vitro.

After a brief history of ergot alkaloids and ergotism, this review focuses on the metabolism and mechanisms of action of the ergot alkaloids. The authors provide models of how these alkaloids afflict grazing livestock under complex animal-plant/endophyte-environmental interactions. Alkaloid chemistry is presented to orient the reader to the structure-function relationships that are known to exist. Where appropriate, the medical literature is used to aid interpretation of livestock research and to provide insight into potential modes of action and alkaloid metabolism where these are not known for livestock. In closing the paper, we discuss management of ergot alkaloid intoxication in livestock and future research needs for this field of study.

Due to the complicated media used for culturing bovine embryos, most of the nutrient requirements are unknown. Recently, we developed a simple, serum-free medium (CR1) that allows bovine embryos to develop in vitro. Therefore, our objective was to determine whether development of bovine embryos would be improved by the addition of free amino acids and vitamins to CR1. Oocytes were recovered from slaughterhouse ovaries and matured 22 +/- 2 h, following which the oocytes were randomly allotted to treatment. The experiment was a randomized block design with a 2 x 5 factorial treatment structure. The oocytes were fertilized with or without cumulus cells intact. The five fertilization media were 1) Control (CR1 +/- 10 micrograms/mL of phenol red); 2) control + basal medium Eagle (BME) essential amino acids (EAA) + minimum essential medium (MEM) nonessential amino acids (NEA) + MEM vitamins (VIT); 3) control + EAA + NEA; 4) control + EAA + VIT; and 5) control + NEA + VIT. Cleavage rate was greater (P < .001) when cumulus cells remained on the oocytes during fertilization (51.7 vs 73.2% without and with cumulus cells, respectively). The frequency of blastocysts was increased (P < .001) when EAA or NEA were added to CR1; however, adding VIT had no effect or tended (P = .12) to decrease the frequency of embryos attaining the blastocyst stage. This experiment demonstrates that development of bovine embryos in vitro can be improved by the addition of free amino acids to a simple medium. Contrary to work in rodents, the mixture of vitamins in MEM was not beneficial for bovine embryos.

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