The recruitment of ovarian follicles is enhanced by increased dietary intake in heifers

• Published in: Journal of animal science Vol. 75; no. 7; p. 1876
• Main Authors: Gutierrez, C.G. (Roslin Institute, Midlothian, Scotland, UK.), Oldham, J, Bramley, T.A, Gong, J.G, Campbell, B.K, Webb, R
• Format: Journal Article
• Language: English
• Published: United States 01.07.1997
• Subjects: 3-HYDROXYBUTYRIC ACID; ACIDE GRAS; ACIDOS GRASOS; Animal Nutritional Physiological Phenomena; Animals; AZUCAR EN SANGRE; Blood Glucose - metabolism; BLOOD PLASMA; BLOOD SUGAR; Body Weight - physiology; BREEDS (ANIMALS); Cattle - blood; Cattle - physiology; CICLO ESTRAL; CYCLE OESTRAL; DAIRY COWS; Diet - veterinary; Eating - physiology; ENSILADO; ENSILAGE (PRODUIT); Estrus - physiology; FACTEUR DE CROISSANCE IGF; FACTOR DE CRECIMIENTO IGF; FATTY ACIDS; FEED GRASSES; FEEDING LEVEL; Female; FOLICULOS OVARICOS; Follicle Stimulating Hormone - blood; Follicle Stimulating Hormone - physiology; FOLLICULE OVARIEN; FSH; GENISSE; GRAMINEAS FORRAJERAS; GRAMINEE FOURRAGERE; Growth Hormone - blood; Growth Hormone - physiology; HEIFERS; HFS; HOLSTEIN-FRIESIAN; Hydroxybutyrates - blood; INSULIN; Insulin - blood; Insulin - physiology; INSULIN-LIKE GROWTH FACTOR; Insulin-Like Growth Factor I - analysis; Insulin-Like Growth Factor I - physiology; INSULINA; INSULINE; NIVEAU D'ALIMENTATION; NIVEL ALIMENTICIO; NOVILLA; OESTROUS CYCLE; OESTRUS SYNCHRONIZATION; Ovarian Follicle - diagnostic imaging; Ovarian Follicle - growth & development; Ovarian Follicle - physiology; OVARIAN FOLLICLES; PAILLE; PAJA; PLANE OF NUTRITION; PLASMA SANGUIN; PLASMA SANGUINEO; PROGESTERONA; PROGESTERONE; RACE (ANIMAL); RAZAS (ANIMALES); Regression Analysis; SILAGE; SINCRONIZACION DEL CELO; SOMATOTROPIN; SOMATOTROPINA; SOMATOTROPINE; STRAW; SUCRE DU SANG; SYNCHRONISATION DE L'OESTRUS; Time Factors; Ultrasonography - methods; Ultrasonography - veterinary; UREA; Urea - blood; UREE; VACAS LECHERAS; VACHE LAITIERE
• ISSN: 0021-8812; 1525-3163
• DOI: 10.2527/1997.7571876x

The objective of this study was to determine whether dietary-induced changes in growth hormone (GH), insulin, and IGF-I alter the pattern of ovarian follicular development in heifers. Twenty-eight 2- to 3-yr-old Hereford-Friesian heifers were equally allocated (n = 7 ) to one of four dietary treatments: Control (C) fed a maintenance diet as two meals per day; twice maintenance (2M2) given as two meals per day; twice maintenance (2M6) given as six meals per day; feed-deprived (F) fed maintenance requirements as for C, changed to straw ad libitum for 3 d from a synchronized estrus. On d 4 (estrus = d 0) heifers were transferred to grass silage (ad libitum access) until the end of the experiment. Blood samples were collected hourly for 10 h on d 1 and 3 and daily for an additional 14 d. Follicular development was monitored daily by ultrasonography until d 14. The number of small follicles ( 4 mm) was increased (P .05) by 37% on d 1 and 2 in 2M2 and 2M6 heifers, with no carryover effect of nutrition to the second follicular wave. Number of medium-sized (4 to 8 mm) and large ( 8mm) follicles did not vary ( P . 05) among treatments. The FSH concentrations were not different (P .05) among treatments. Insulin concentrations were higher (P .05) in 2M2 and 2M6 heifers than in C or F heifers, with no carryover after the diet was changed. Increase in number of small follicles was independent of changes in FSH and IGF-I, negatively associated with GH, but positively associated with circulating insulin. These results indicate that a short-term increase in nutritional plane can affect follicular recruitment in cycling heifers