title: Daily treatment of horses with equine somatotropin from 4 to 16 months of age.
abstract: Fourteen foals between 4 and 4.5 mo of age were used to determine the effects of 12 mo of daily treatment with equine somatotropin (eST) on growth, metabolic, and hormonal characteristics. The foals were paired by sex, type, and lineage, and one of each pair was administered eST daily at 20 microg/kg of BW. Body weights, body measurements, and assessments of glucose tolerance and feedback effects on endogenous somatotropin (ST) secretion were made routinely. Treatment with eST did not alter (P > 0.10) BW, height at withers, length of body, widths of chest and rump, heart girth, length of head, front or rear cannon lengths, front or rear cannon circumferences, gaskin circumference, or skin thickness, even though plasma IGF-I concentrations were doubled (P = 0.012). Glucose concentrations were higher (P = 0.03) in treated horses before glucose infusion; there was no difference (P > 0.10) in the glucose response to infusion. The insulin response to glucose infusion in the treated horses was generally higher (P = 0.0069) than in controls. Endogenous ST secretion in response to a ST secretagogue was reduced (P = 0.0001) in foals treated with eST in all months. The prolactin and thyroid-stimulating hormone responses to thyrotropin-releasing hormone on June 1 were not affected (P > 0.10) by treatment. In conclusion, daily treatment of growing horses with eST for 12 mo at the recommended dose altered the hormonal and metabolic characteristics known to be affected by ST but did not alter the growth characteristics of the animals.
authors.affiliation: Department of Animal Science, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge 70803, USA.
authors.forename: E L
authors.initials: EL
authors.lastname: Capshaw
authors.forename: D L
authors.initials: DL
authors.lastname: Thompson
authors.forename: K M
authors.initials: KM
authors.lastname: Kulinski
authors.forename: C A
authors.initials: CA
authors.lastname: Johnson
authors.forename: D D
authors.initials: DD
authors.lastname: French
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001786:Blood Glucose / Q000032:analysis*; D001827:Body Height / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage* / Q000378:metabolism; D006736:Horses / Q000254:growth & development* / Q000378:metabolism; D007328:Insulin / Q000097:blood*; D007334:Insulin-Like Growth Factor I / Q000187:drug effects; D008137:Longitudinal Studies; D008297:Male; D009842:Oligopeptides / Q000494:pharmacology; D011388:Prolactin / Q000097:blood; D013972:Thyrotropin / Q000097:blood; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology; D016896:Treatment Outcome
chemical_list: D001786:Blood Glucose; C437972:EP 51389; D007328:Insulin; D009842:Oligopeptides; D013973:Thyrotropin-Releasing Hormone; D007334:Insulin-Like Growth Factor I; D011388:Prolactin; D013972:Thyrotropin; D013006:Growth Hormone