title: Effect of concentrate source and amount in diets on plasma hormone concentrations of prepubertal heifers.
abstract: Effects of concentrate source (corn or soybean hulls) and amount (40 or 80% of DMI) on plasma hormone concentrations were evaluated for 32 prepubertal Holstein heifers in a 2 x 2 factorial design. Blood samples were collected every other day from d -4 through d 28 of the experiment and were analyzed for growth hormone, prolactin, IGF-1, and glucose. Ruminal samples were collected by esophageal tube on d 0, 7, 14, 21, and 28 and were analyzed for VFA content. Serial blood samples were collected on either d 25 or 26 at 20-min intervals for 8 h and were used for profile analysis of growth hormone and prolactin. Heifers fed 80% concentrate had higher IGF-1 concentrations in serum (158.1 vs. 131.9 ng/ml) than did heifers fed 40% concentrate, and heifers fed corn tended to have higher IGF-1 concentrations than heifers fed soybean hulls. Prolactin concentrations in samples that were collected every other day were higher for heifers fed the 80% soybean hull diet than for those fed 40% concentrate diets or the 80% corn diet. Effects of source and amount of concentrate on plasma prolactin concentrations were not evident in serial samples. Concentrate source or amount had no effect on plasma growth hormone or glucose. At high concentrate intakes, the source (soybean hulls vs. corn) affected intake parameters, ruminal VFA content, and prolactin concentrations.
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul 55108, USA.
authors.forename: B B
authors.initials: BB
authors.lastname: Nosbush
authors.forename: J G
authors.initials: JG
authors.lastname: Linn
authors.forename: W A
authors.initials: WA
authors.lastname: Eisenbeisz
authors.forename: J E
authors.initials: JE
authors.lastname: Wheaton
authors.forename: M E
authors.initials: ME
authors.lastname: White
mesh_terms: D000085:Acetates / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D002087:Butyrates / Q000378:metabolism; D020148:Butyric Acid; D002417:Cattle / Q000097:blood*; D004032:Diet; D005260:Female; D013006:Growth Hormone / Q000097:blood; D006728:Hormones / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D000455:Medicago sativa; D011374:Progesterone / Q000097:blood; D011388:Prolactin / Q000097:blood; D011422:Propionates / Q000378:metabolism; D012417:Rumen / Q000378:metabolism; D013025:Glycine max; D003313:Zea mays
chemical_list: D000085:Acetates; D001786:Blood Glucose; D002087:Butyrates; D006728:Hormones; D011422:Propionates; D020148:Butyric Acid; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013006:Growth Hormone; C029658:propionic acid