A COMPARISON OF DISSECTED FOLLICLE NUMBERS AND FOLLICLE COUNTS ON THEOVARIAN SURFACE FOR THE EVALUATION OF OVARIAN FOLLICULAR POPULATIONS IN BOS-INDICUS COWS

Ovaries (n = 140) from 70 mixed-age multiparous, lactating Brahman cro ss (3/4-7/8 Bos indicus) cows were used to examine the hypothesis that counts of follicles visible on the surface of the ovaries of Bos indi cus cows and their classification into diameter size classes, are clos ely correlated with numbers of follicles in those size classes found b y complete dissection of the ovary. immediately after ovariectomy, mea n diameters (long and short axes averaged) of all follicles greater th an or equal to 2 mm visible on the surface of each ovary were measured . All follicles greater than or equal to 2 mm were dissected from the ovaries, excess stroma removed and follicle diameters measured under a stereomicroscope using an ocular graticule. For each ovary, follicles were classified in either small (<4 mm), medium (4-8 mm) or large (>8 mm) categories based on either diameters of surface or dissected foll icles. Data for numbers of surface and dissected follicles (mean +/- S E) in small, medium, large categories and total follicle numbers, resp ectively, were 24.4 +/- 1.6 vs. 28.0 +/- 1.9, 1.6 +/- + 0.2 vs. 11.6 /- 1.0, 0.5 +/- 0.1 vs. 0.7 +/- 0.1 and 26.4 +/- 1.6 vs. 40.4 +/- 2.5. Correlation coefficients (r) for counts of surface and dissected foll icles in small, medium, large and total follicle numbers were 0.76, 0. 40, 0.69 and 0.79, respectively. Medium size follicles presented only a small translucent area on the surface of the ovary, leading to an un derestimate of numbers when categorised by surface evaluation. Counts of follicles visible on the surface of the ovaries of Bos indicus cows and their classification into size classes based on estimated diamete r, are closely correlated with numbers of follicles in those size clas ses found at dissection of the ovary for small (<4 mm), large (>8 mm) and total follicles but not for medium sized (4-8 mm) follicles. (C) 1 997 Elsevier Science B.V.