Low oxygen tension during in vitro embryo production improves the yield, quality, and cryotolerance of bovine blastocysts.

Mammalian oocytes undergo maturation and fertilization in the low-oxygen (O) environment of the oviduct. To evaluate the effect of O tension during in vitro maturation and fertilization on embryo yield, quality, cryotolerance, and gene expression, we matured and fertilized bovine cumulus-oocyte complexes under low (5%) or high (20%) O tension. Presumptive zygotes from both groups were cultured at 5% O for 8 days.

Effect of creep feeding with rice bran and temporary weaning on cow-calf performance.

This study was conducted to investigate if calves supplemented with rice bran in a creep feeding (CF) system associated with temporary weaning (TW) affects the performance of the cow-calf pair grazing natural grasslands during summer. Two experiments were performed using 275 cow-calf pairs of British breeds and their crosses of different parities (primiparous [n = 188] in Experiment 1 and multiparous [n = 87] in Experiment 2). In both experiments, the factors evaluated were: (1) supplementation of calves with rice bran using CF: yes (+CF) or no (-CF); (2) TW for 14 days using nose plates: yes (+TW) or no (-TW).

Effect of season on germinal vesicle stage, quality, and subsequent in vitro developmental competence in bovine cumulus-oocyte complexes.

Although the reproductive performance of grazing cattle is lower in summer compared to winter, the effect of season on oocyte developmental competence has not been thoroughly examined. We measured the effect of season on oocyte chromatin compaction, cumulus cell quality, and embryonic development after in vitro fertilization. Cumulus oocytes-complexes (COCs) were collected from abattoir cows' ovaries during the winter and summer months.

Effect of Ethanol on Parthenogenetic Activation and α-Tocopherol Supplementation during Maturation on Developmental Competence of Summer-Collected Bovine Oocytes.

The use of α-tocopherol during maturation (IVM) is an alternative to minimize the adverse effects of heat stress on oocyte competence. However, α-tocopherol is diluted in ethanol, which can induce oocyte parthenogenetic activation (PA). This study aimed to evaluate the role of ethanol concentration on PA and the effect of α-tocopherol supplementation during IVM on the developmental competence and the expression of key genes in blastocysts derived from summer-collected oocytes.

Heat tolerance in cows of British breeds and their crosses with bonsmara under grazing conditions.

The objective of this study was to evaluate the influence of the increasing temperature-humidity index (THI) on the body temperature of cows from different breed groups. Vaginal temperature was monitored in cows from two breed groups: a) British breeds (Hereford, Angus and their crosses, n=4); and b) their crosses with Bonsmara (BO, n=6). Vaginal temperature in cows of British breeds was always higher (P < 0.

Time-dependent effects of heat shock on the zona pellucida ultrastructure and in vitro developmental competence of bovine oocytes.

The aim of this study was to determine the effects of different exposure lenght to heat shock (HS) during in vitro maturation (IVM) on zona pellucida (ZP) ultrastructure and developmental competence of bovine oocytes. Cumulus-oocyte complexes (COCs) were matured in vitro (IVM) at 38.5 °C for 24 h (control group, CG), or incubated at 41 °C (HS) for 6 h (HS-6h), 12 h (HS-12h), 18 h (HS-18h), and 22h (HS-22h) followed by incubation at 38.

The use of prostaglandins in controlling estrous cycle of the ewe: a review.

This review considers the use of prostaglandin F(2α) and its synthetic analogues (PG) for controlling the estrous cycle of the ewe. Aspects such as phase of the estrus cycle, PG analogues, PG doses, ovarian follicle development pattern, CL formation, progesterone synthesis, ovulation rate, sperm transport, embryo quality, and fertility rates after PG administration are reviewed. Furthermore, protocols for estrus synchronization and their success in timed AI programs are discussed.

INSL3 in the ruminant: a powerful indicator of gender- and genetic-specific feto-maternal dialogue.

The hormone Insulin-like peptide 3 (INSL3) is a major secretory product of the Leydig cells from both fetal and adult testes. Consequently, it is a major gender-specific circulating hormone in the male fetus, where it is responsible for the first phase of testicular descent, and in the adult male. In most female mammals, circulating levels are very low, corresponding to only a small production of INSL3 by the mature ovaries.