|ECHTERNKAMP, SHERRILL - Collaborator|
|Cushman, Robert - Bob|
Submitted to: Society for the Study of Reproduction Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 3/20/2015
Publication Date: 6/20/2015
Citation: Echternkamp, S.E., Cushman, R.A. 2015. Impact of maternal nutritional level on progeny ovarian development and fertility in cattle [abstract]. Society for the Study of Reproduction Annual Meeting. pp. 133.
Technical Abstract: Development of replacement beef heifers on dietary energy levels to achieve 55 vs. 65% of mature body weight at 14 mo of age did not affect their ovarian follicular development or subsequent fertility (Eborn et al., 2013, J. Anim. Sci. 91:4168). Because bovine ovarian gametogenesis and folliculogenesis begin early in fetal development, the objective was to determine the impact of maternal nutrition during gestation on ovarian development and fertility of their female progeny. In a 2x2 factorial, prepubertal beef heifers (8-mo-old) were fed either a high (HE) or low (LE) energy diet for 6 mo before breeding (prebreeding) plus the first 22 d of a 47-d breeding period to achieve 55 or 65% of mature body weight, respectively, at breeding. Pregnancy was diagnosed at about 75 d of gestation. The pregnant heifers were then housed and managed together on grass pasture until onset of the third trimester of gestation, at which time they were randomly and equally reassigned to two precalving (PC) dietary energy levels to achieve a gain of either 0.70 (PCHE) or 0.45 (PCLE) kg/d until parturition. After weaning, all female progeny (n = 114) were housed together and managed by a standard heifer protocol. Number of antral follicles (AFC) and ovarian size were measured for their ovaries by transrectal ultrasonography at 14 mo of age and just prior to a 29-d natural breeding period with multiple fertile bulls. Data were analyzed by analysis of variance with diet, year, and diet by year as fixed effects. Progeny birth weight (34.0 ± 0.4 kg) was not affected by prebreeding dietary level but calves of PCHE-treated dams were heavier (P = 0.02) at birth than PCLE calves (34.9 vs. 33.2 ± 0.6 kg, respectively). Ovaries of progeny born to HE-treated dams contained more (P = 0.02) small (2 to 5 mm) follicles (21.6 vs. 17.9 ± 0.9; HE vs. LE), and total AFC (23.7 vs. 19.8 ± 1.0; HE vs. LE), whereas total AFC did not differ between precalving treatments (21.8 vs. 21.9 ± 1.0; PCHE vs. PCLE). Ovarian length (28.9 ± 0.3 mm) and height (15.1 ± 0.2 mm) were not affected by prebreeding or precalving diets. Proportion of daughters pregnant to the 29-d breeding period did not differ between prebreeding diets (71.0 vs. 71.3 ± 0.5%; HE vs. LE) but was greater (P = 0.08) for progeny of PCHE- vs. PCLE-treated dams (79.7 vs. 66.0 ± 0.6%, respectively). Treatment differences in progeny ovarian AFC indicate that maternal dietary energy levels influenced ovarian gametogenesis and folliculogenesis during early gestation, whereas nutritional influence on fetal growth and fertility occurred later in gestation.