Bovine embryo development after IVF with spermatozoa having abnormal morphology.

The study was conducted to evaluate the effects of scrotal insulation on semen samples collected from bulls on embryonic development after IVF. Semen samples were obtained and cryopreserved from four Holstein bulls before and after a scrotal insulation period of 48 h (Day 0). Three types of samples were used for IVF: (1) semen from the test bulls collected 5 d prior to scrotal insulation (pre-insult); (2) semen from Day 13 (2-week post-insult; 2-week PI); and (3) semen from Day 20 (3-week PI). After 18 h of sperm-oocyte co-incubation, the zygotes were cultured for 8 d when a developmental score (0=degenerate, 1=2-cell embryo through 5=blastocyst) was assigned to each embryo. The post-thaw morphological evaluation of sperm samples revealed a decrease (P<0.01) in the percentages of normal spermatozoa in the 3-week PI samples in comparison with the pre-insult samples for Bulls I and III (74-22.3% and 67.7-0.5 %, respectively). The percentage of vacuolated spermatozoa increased significantly for Bull II. The cleavage and blastocyst formation rates and embryo development scores were affected (P<0.01) by the interaction of bull by sample collection time. For Bulls I and III (severe responders) the scrotal insulation effects persisted from the time of cleavage through blastocyst formation. In contrast, the cleavage and blastocyst formation rates for Bulls II and IV were unaffected, despite high percentages of vacuolated spermatozoa present in the post-insult samples for Bull II. In conclusion, the use of scrotal insulation to elevate scrotal temperature was an effective method to obtain semen samples with high percentages of abnormal spermatozoa. The decrease in embryonic development after IVF when using spermatozoa with morphological abnormalities seemed to be multifaceted and related to changes in head morphology.

Effects of energy balance of hormones, ovarian activity, and recovered oocytes in lactating Holstein cows using transvaginal follicular aspiration.

The effects of energy balance on hormonal secretion patterns and the structure of recovered oocytes were evaluated in 20 lactating Holstein cows during two trial periods. Cows were randomly assigned to one of two dietary treatments formulated so that dry matter consumption was 3.6% of body weight (high energy; 1.78 Mcal/kg) or 3.2% of body weight (low energy; 1.52 Mcal/kg). Ovum recovery procedures were conducted twice weekly between d 30 and 100 of lactation. Follicle size and number were recorded. Follicular fluid aspirated from the largest follicle and serum samples were collected for hormone assay. Milk yield averaged 41.6 +/- 0.3 kg/d (mean +/- SE) for high energy fed cows and 32.8 +/- 0.3 kg/d for low energy fed cows. Oocyte numbers increased linearly from d 30 to 100 postpartum. Cows fed high energy diets produced more good (+) oocytes than did cows fed low energy diets.