28 Relationships between Antral Follicle Numbers and Postpartum Interval in Multiparous Brahman Cows

• Published in: Journal of animal science 2018-03, Vol.96 (suppl_1), p.15-15
• Main Authors: Quail, L K, Mund, M E, Neuendorff, D A, d’Orey Branco, R A, Banta, J P, Welsh, T H, Randel, R D
• Format: Article
• Language: English
• ISSN: 0021-8812; 1525-3163
• DOI: 10.1093/jas/sky027.029

Abstract Ovarian antral follicle count (AFC) has been associated with reproductive efficiency as the more fertile cattle have more growing follicles than do less fertile cattle. The purpose of this study was to correlate AFC at d 28 post-calving and at d 8 post-estrus with postpartum interval (PPI) in Brahman cows. Ultrasonography (3D; GE Voluson I: Sono AVC) was performed on cows (n=46) at d 28 post-calving and at d 8 post-estrus. Follicles were counted and measured to determine the number of total follicles, small follicles (≤17 mm3), medium follicles (17 mm3 to 67 mm3), and large follicles (≥67 mm3) on each ovary. Estrus was detected using sterile bulls fitted with chin-ball markers for AI and tail paint for natural service. The time from calving to estrus was used to calculate PPI. Classes of AFC were determined using the µ and SD. Cows with AFC ≥ ½ SD above the µ were classified as high, those within ½ SD of the µ were classified as intermediate, and those ≤ ½ SD below the µ were classified as low. Classes of AFC for total follicles included low (L≤82), intermediate (83≤I≤121), and high (H≥122). Classes of AFC for small follicles included low (L≤60), intermediate (61≤I≤94), and high (H≥95). Classes of AFC for medium follicles included low (L≤15), intermediate (16≤I≤25), and high (H≥26). Classes of AFC for large follicles included low (L≤2), intermediate (I=3,4), and high (H≥5). The PROC MIXED procedure of SAS was used to analyze classes of AFC and PPI. The PPI differed among classes of total (P=0.03; L=62.5 ± 5.2, I=46.4 ± 4.7, H=42.8 ± 5.6), and small AFC (P=0.04; L=60.8 ± 5.1, I=48.6 ± 5.2, H=41.7 ± 5.2). The PPI did not differ among classes of medium (P=0.32), and large AFC (P=0.88). Data were analyzed by PROC CORR of SAS. The PPI was negatively correlated with small (r = -0.32, P=0.03), and total AFC (r = -0.27, P=0.07). The PPI was not correlated with medium (r = -0.15, P=0.33), or large AFC (r = 0.04, P=0.77). Total AFC at d 28 post-calving and total AFC at d 8 post-estrus were positively correlated (r = 0.83, P