Submitted to: Biology of Reproduction Abstracts
Publication Type: Abstract only
Publication Acceptance Date: 4/23/1999
Publication Date: N/A
Citation: Echternkamp, S.E., Gregory, K.E., Lindsey, B.R., Mussard, M., Kinder, J.E. 1999. Comparison of FSH and LH response to follicle aspiration in cattle selected (twinner) and unselected (control) for twin births [abstract]. Biology of Reproduction Abstracts. 60 (Supplement 1):270. Interpretive Summary:
Technical Abstract: Genetic selection for dizygotic twins in cattle resulted in a larger pool of ovarian small antral follicles (1-5 mm), enhanced recruitment of growing follicles, and the subsequent selection of twin or multiple dominant/ovulatory follicles within a follicular wave. The endocrine role of FSH, LH and IGF-I in mediating the enhanced follicular development was evaluated using the follicle aspiration experimental model. All follicles >5 mm were aspirated transvaginally in 12 Twinner and 12 Control crossbred cows on d 7 or 8 (estrus=d 0). Jugular vein blood samples were collected at 12-h intervals for 48 h before aspiration and at 6-h intervals for 96 h after aspiration. FSH, LH and IGF-I were measured by RIA; IGF-I was acid-ethanol extracted. Follicular development was monitored daily by ultrasonography. Data were analyzed by repeated measures ANOVA for population and time. Plasma FSH concentration was elevated (p<0.01) within 6 h after aspiration, was maximal (84.2+/-3.5 ng/ml) at 24 h, and returned to baseline (32.4+/-3.5 ng/ml) by 66 h; LH was unaffected (p>0.1) by aspiration. Plasma FSH (46.0+/-2.3 vs 40.5+/-2.3 ng/ml) and LH (1.42+/-.12 vs 1.35+/-.12 ng/ml) concentrations did not differ (p>0.1) between Twinner vs Control cows, whereas IGF-I concentrations (74.5+/-8.0 vs 47.8+/-8.0 ng/ml; p<0.03) were greater in Twinners. Results suggest that enhanced follicular recruitment in Twinner cows after aspiration was not related to magnitude or timing of the endogenous FSH response but was associated with greater IGF-I concentrations.