Effect of pre and post-AI nutrition on ovarian dynamics, steroidogenesis, and estrus expression in beef heifers [Abstract]

Authors: EPPERSON, KAITLIN - South Dakota State University; RICH, JERICA - South Dakota State University; Zezeski, Abby; ZOCA, SAULO - South Dakota State University; WALKER, JULIE - South Dakota State University; Geary, Thomas; PERRY, GEORGE - South Dakota State University

Submitted to: International Congress on Animal Reproduction
Publication Type: Abstract Only
Publication Acceptance Date: 1/31/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Nutrition plays a pivotal role in modulating reproduction. The objective of this study was to evaluate the effect of plane of nutrition before and after artificial insemination (AI) on follicular dynamics, estrus expression, and steroidogenesis. Seventy-nine beef heifers were randomly assigned to one of two dietary treatments (High or Low, 155 or 86% of maintenance, respectively) 30d prior to AI. Estrus was synchronized (PG 6-d CIDR protocol) and heifers were AI (d0) 8 to 12h following detection of estrus. On d0, half of the heifers were randomly reassigned to generate four final Pre x Post-AI treatments; High-High (HH, n=20), High-Low (HL, n=20), Low-High (LH, n=19), and Low-Low (LL, n=20). Heifers remained in their new diet treatment for 7 to 8d after AI when embryo collection occurred (flush). Blood samples were collected on d-3 to d0, and d1, 3, 5, 7 and 8 to measure plasma concentrations of estradiol (E2) and progesterone (P4). Dominant follicle diameter was evaluated on d-3 and d0, and CL diameter was recorded at time of flush. Statistical analyses were completed in SAS using the MIXED (Body weight, E2, P4), GLIMMIX (estrus expression), and GLM (ovarian parameters, interval to estrus) procedures. There was a Pre-AI by time interaction on body weight (P<0.0001). LH and LL heifers lost 8.22kg and HL and HH heifers gained 9.34kg. There was a Post-AI by time interaction on body weight (P<0.0001), HL and LL lost 5.21kg and LH and HH gained 6.33kg. Estradiol concentrations increased (P<0.0001) from d-3 (2.18±0.15pg/mL) to d0 (6.05±0.04pg/mL). Increased estrus expression (80±6.3% vs. 59±7.9%; P=0.05), and larger dominant follicles (11.7±1.42mm vs. 10.68±1.33mm; P=0.0016) were observed for HL and HH heifers compared to LH and LL. Pre-AI treatment also impacted Post-AI P4 (P=0.015); HL and HH heifers had greater P4 compared to LH and LL (4.85±0.37ng/mL vs. 3.53±0.38ng/mL). Post-AI treatment did not influence concentrations of P4 (P=0.88). There was no effect of Pre, Post or Pre x Post-AI treatment on E2 concentrations, initial follicle size, growth rate of the dominant follicle, interval to estrus, and CL size at flush (P>0.10). In conclusion, nutrient restriction prior to and after AI negatively impacted ovarian function, steroidogenesis, and estrus expression.