Pregnancy rate after ultrasound-guided follicle aspiration in nonlactating cows from different breeds

Laparoscopic ovum collection in sheep: gross and microscopic evaluation of the ovary and influence on ooctye production

Gross and microscopic evaluations of the ovaries of sheep subjected to successive ovum collection were performed with the objective of identifying if there was interference in oocyte production and morphology of gonads. Gross evaluation of the internal genital tract was also performed. Eighteen ewes of the Santa Inês breed were randomly distributed into three experimental groups of six animals each; G0, G1 and G9 with no, one and nine repetitions, respectively. Estrous synchronization was achieved with a short protocol using MAP followed by single dose stimulation with 80mg of FSHp and 300 IU of eCG (IM). Laparoscopic ovum pick-up was performed 36h later, with 7-day intervals. The number of visualized follicles, aspirated follicles and oocytes recovery was recorded. After the last intervention, ovariectomy was performed for evaluation of gross and microscopical appearance and existence of lesions caused by follicular puncture, which were classified as absent (0), mild (1), moderate (2) and severe (3). The number of visualized follicles, aspirated follicles and oocytes recovery were 13.2±2.0, 11.3±3.0 and 5.8±2.3, respectively, with a recovery rate of 51.7%. No statistical difference was found between the nine sessions (P>0.05). Nine sessions of superovulation and ovum collection procedures did not cause ovarian lesions and did not interfere with the production of follicles in ewes of the Santa Inês breed.

Caracterização de seqüelas subseqüentes à punção folicular em bovinos

Objetivaram-se avaliar lesões no trato genital em animais utilizados como doadores de oócitos. Foram examinadas vacas da raça Gir (n=20) que participaram de diferentes experimentos envolvendo a técnica de punção folicular. Ao término de cada período experimental, os animais foram examinados por palpação retal, ultra-sonografia e vaginoscopia. Um grupo de vacas (n=8) foi selecionado para a caracterização histopatológica das lesões ovarianas. Os ovários foram retirados cirurgicamente, fixados e processados, e as lâminas obtidas coradas e analisadas. Foram avaliados animais submetidos a entre nove e 42 sessões de punção, e que produziram entre 10 e 719 oócitos. Observou-se uma baixa prevalência (5,26%) de processos inflamatórios na mucosa do fundo de saco vaginal. A ocorrência de aderências apresentou uma correlação positiva com o número de sessões de punção a que o animal foi submetido (r=0,31; P<0,05), mas não com o total de oócitos recuperados (r=0,03; P>0,05). Tendência oposta foi observada em relação à fibrose ovariana, que apresentou uma alta correlação com o número de oócitos recuperados (r=0,53; P<0,05). A avaliação histopatológica demonstrou a presença de tecido cicatricial, infiltrados de células inflamatórias e presença de tecido luteal disperso no estroma ovariano.

Utilization of the growth phase of the first follicular wave for bovine oocyte collection improves blastocyst production

Characteristics of the follicle population and oocyte developmental competence at selected stages of follicular development were studied in cows with the aim to increase embryo production derived from oocytes collected by transvaginal aspiration. In Experiment 1, the growth phase before dominant follicle selection and the low dominant phase during dominant follicle regression were compared. Twenty-four cyclic Holstein cows, 4 to 6 yr of age, were divided into 2 groups. Animals were synchronized using two injections of prostaglandin F2alpha at 11 d intervals, and onset of estrus was determined (Day 0). Using ultrasonography, all follicles were counted and classified. Oocytes were aspirated once on Days I through 3 (Group 1, n=5) or Days 15 and 16 (Group 2, n=3) of the estrus cycle. The experiment was carried out in 3 replicates. In Experiment 2, the growth phase of the first follicular wave before dominant follicle selection was characterized in detail. Twelve cows of the same breed and age were divided into 3 groups. Their first estrus was synchronized as in Experiment 1, and each following estrus was induced using one injection of prostaglandin F2alpha administered 4 to 6 d after each aspiration performed. The ovaries were examined, and oocytes were collected repeatedly (total of 5 times per cow) on Days 1 (Group 3, n=4), 2 (Group 4, n=4) or 3 (Group 5, n=4) after estrus at 10 d intervals during a 40 d period. Viable oocytes were matured, fertilized and cultured using the standard methods. In Experiment 1, the mean numbers (+/-SD) of all follicles and of recovered and viable oocytes per donor were higher in Group 1 than in Group 2, but only the mean numbers (+/-SD) of larger follicles and recovered oocytes were statistically significant (8.0 +/- 0.6 and 6.2 +/- 0.6.vs. 3.3 +/- 0.5 and 2.8 +/- 0.2; P< 0.05). In Experiment 2, the percentage of larger follicles out of all visible follicles and the mean numbers (+/-SD) of larger follicles per donor were significantly higher (P<0.05) in Groups 4 (75.7 and 9.1 +/- 2.7) and 5 (66.3 and 8.5 +/- 2.9) when compared to Group 3 (27.9 and 3.8 +/- 0.8). The development rate of fertilized oocytes was significantly higher (P<0.05) in Groups 4 (27.8) and 5 (27.5) than in Group 3 (12.8). It can be concluded that it is possible to improve the efficiency of transvaginal aspiration and in vitro embryo production by utilization of the growth phase of the first follicular wave before dominant follicle selection.