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|Title:||Manipulation of Endogenous Growth Hormone in Growing or Lactating Dairy Cattle: Effects on Production|
|Author(s):||Vicini, John Lewis|
|Department / Program:||Animal Science|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Subject(s):||Agriculture, Animal Culture and Nutrition|
|Abstract:||Growth hormone (GH) is one of the major hormones associated with animal production. Exogenous administration of GH increases milk production and growth of lactating and growing ruminants. Two nutritional components (sodium bicarbonate and arginine) and immunization against somatostatin were investigated as potential means of altering endogenous GH concentrations and animal production.
In Experiment 1, eight Holstein cows were used in a 2 x 2 factorial treatment design. One-half of the cows were fed ad libitum and the other half were fed 80% of their required dry matter intake. All cows were fed diets with or without 1% sodium bicarbonate in a switchback design for three 21 d periods. Restricting feed intake decreased milk and solids-not-fat production, increased plasma concentrations of GH, and decreased concentrations of insulin, tri-iodothyronine, thyroxine, glucagon, and prolactin. Supplementing the diet with sodium bicarbonate increased dry matter intake and fat-corrected milk production for cows fed ad libitum. Sodium bicarbonate did not alter hormone concentrations in plasma.
For Experiment 2, three Holstein cows in mid-lactation were used in a 3 x 3 Latin square design with 5 d periods. Treatments were: control; arginine infused into jugular vein twice daily; and continuous infusion of arginine into the abomasum. Intravenously infused arginine resulted in acute increases in concentrations of GH and insulin. Arginine infusion into the abomasum did not alter significantly the concentrations of either hormone. Treatments did not affect milk production.
In the third experiment, Holstein calves were used in two trials to determine effects of active immunization against somatostatin on plasma concentrations of GH and growth. In one trial, four immunized calves grew faster and had lower concentrations of plasma urea-nitrogen than five control calves, but concentrations of GH were not different. Differences in plasma GH, weight, and body size of five immunized and five control calves were not detected in the second trial.
Endogenous changes in GH and a concomitant increase in production were not obtained in any of the experiments. These data suggest that it may be difficult to increase endogenous concentrations of a specific hormone to the extent that is required to improve production, possibly because of the complex regulation of secretion of key metabolic hormones.
Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987.
|Date Available in IDEALS:||2014-12-16|