title: Effect of dietary energy and protein on bovine follicular dynamics and embryo production in vitro: associations with the ovarian insulin-like growth factor system.
abstract: Heifers were assigned either low or high (HE) levels of energy intake and low or high concentrations of dietary crude protein. The effect of these diets on the plasma concentrations of insulin, insulin-like growth factor (IGF)-I, and urea on follicular growth and early embryo development is described. We propose that the observed dietary-induced changes in the ovarian IGF system increase bioavailability of intrafollicular IGF, thus increasing the sensitivity of follicles to FSH. These changes, in combination with increased peripheral concentrations of insulin and IGF-I in heifers offered the HE diet, contribute to the observed increase in growth rate of the dominant follicle. In contrast to follicular growth, increased nutrient supply decreased oocyte quality, due in part to increased plasma urea concentrations. Clearly a number of mechanisms are involved in mediating the effects of dietary energy and protein on ovarian function, and the formulation of diets designed to optimize cattle fertility must consider the divergent effects of nutrient supply on follicular growth and oocyte quality.
authors.affiliation: Division of Integrative Biology, Roslin Institute (Edinburgh), Roslin, Midlothian EH25 9PS, United Kingdom. david.armstrong@bbscr.ac.uk
authors.forename: D G
authors.initials: DG
authors.lastname: Armstrong
authors.forename: T G
authors.initials: TG
authors.lastname: McEvoy
authors.forename: G
authors.initials: G
authors.lastname: Baxter
authors.forename: J J
authors.initials: JJ
authors.lastname: Robinson
authors.forename: C O
authors.initials: CO
authors.lastname: Hogg
authors.forename: K J
authors.initials: KJ
authors.lastname: Woad
authors.forename: R
authors.initials: R
authors.lastname: Webb
authors.forename: K D
authors.initials: KD
authors.lastname: Sinclair
mesh_terms: D000818:Animals; D001755:Blastocyst / Q000502:physiology; D002417:Cattle / Q000196:embryology / Q000502:physiology*; D004044:Dietary Proteins / Q000494:pharmacology*; D005314:Embryonic and Fetal Development; D002149:Energy Intake; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000097:blood; D017403:In Situ Hybridization; D007328:Insulin / Q000097:blood; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000235:genetics; D018974:Insulin-Like Growth Factor Binding Protein 4 / Q000235:genetics; D007334:Insulin-Like Growth Factor I / Q000032:analysis / Q000235:genetics / Q000502:physiology; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D007700:Kinetics; D006080:Ovarian Follicle / Q000502:physiology*; D010053:Ovary / Q000378:metabolism*; D011374:Progesterone / Q000097:blood; D012333:RNA, Messenger / Q000032:analysis; D013002:Somatomedins / Q000502:physiology*; D014508:Urea / Q000097:blood
chemical_list: D004044:Dietary Proteins; D007328:Insulin; D018971:Insulin-Like Growth Factor Binding Protein 2; D018974:Insulin-Like Growth Factor Binding Protein 4; D012333:RNA, Messenger; D013002:Somatomedins; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D014508:Urea; D005640:Follicle Stimulating Hormone