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ARS Home » Plains Area » Clay Center, Nebraska » U.S. Meat Animal Research Center » Livestock Bio-Systems » Research » Publications at this Location » Publication #373088

Research Project: Improving Livestock Production by Developing Reproductive and Precision Management Technologies

Location: Livestock Bio-Systems

Title: Effect of stair-step nutritional programming on ovarian development in replacement beef heifers

item ROSASCO, SHELBY - New Mexico State University
item MELCHIOR, EMILY - New Mexico State University
item COX, SHAD - New Mexico State University
item DUNLAP, RICHARD - New Mexico State University
item HERNANDEZ GIFFORD, JENNIFER - New Mexico State University
item SCHOLLJEGERDES, ERIC - New Mexico State University
item Cushman, Robert - Bob
item SUMMERS, ADAM - New Mexico State University

Submitted to: Translational Animal Science
Publication Type: Proceedings
Publication Acceptance Date: 6/22/2020
Publication Date: 12/22/2020
Citation: Rosasco, S.L., Melchior, E.A., Cox, S.H., Dunlap, R.L., Hernandez Gifford, J.A., Scholljegerdes, E.J., Cushman, R.A., Summers, A.F. 2020. Effect of stair-step nutritional programming on ovarian development in replacement beef heifers. Translational Animal Science. 4(Supplement 1):S32-S36.

Interpretive Summary:

Technical Abstract: Recent research has indicated it may be possible through nutritional management to influence the number of primordial follicles in the ovaries in the first year of life. Spring-born Angus crossbred heifers (n = 40) were utilized to determine the effect of a stair-step development system on growth and reproductive parameters. Heifers (11 mo) were assigned to 1 of 4 treatments: 1) constant gain drylot (CG-d), 2) stair-step drylot (SS-d), 3) constant gain native range (CG-r), and 4) stair-step native range (SS-r). Heifers were fed individually with a constant gain target of 0.5 kg/d ADG, while stair-step heifers were targeted to gain 0.25 kg/d the first 45 d (period 1) and 0.75 kg/d over the last 45 d (period 2). All heifers were ovariectomized on d 90. Heifer BW was similar on d 0 and d 45, however, native range heifers had an increased BW at d 90 (P < 0.01) compared to drylot developed heifers. Period 1 and overall ADG was greater in native range heifers (P < 0.01) compared to drylot heifers. During period 2 CG-r and SS-r heifers had an increased ADG compared to CG-d and SS-d heifers, with SS-d also having an increased ADG (P = 0.03) compared to CG-d heifers. Reproductive tract score was similar (P = 0.19) between treatments. Ovarian weight and preovulatory follicle diameter were decreased (P < 0.02) in drylot compared to native range developed heifers. Primary follicles per section was increased (P = 0.05) in stair-step developed heifers compared to constant gain heifers. Primordial follicles/section was increased (P = 0.04) in SS-r and SS-d heifers compared to CG-d heifers, with CG-r similar to all other treatments. Differences in diets between drylot and native range positively influences mechanisms controlling primordial follicle activation. Developing heifers on a stair-step nutritional program resulted in a larger ovarian reserve, potentially resulting in an increase in reproductive longevity.