Effects of growth hormone on growth performance, haematology, metabolites and hormones in iron-deficient veal calves.
Effects of subcutaneous (s.c.) administration of 50 micrograms/kg body weight of recombinant bovine growth hormone (rbGH) or saline were studied for 11 weeks in 40 intact male veal calves supplied 50 mg or 10 mg of iron (Fe)/kg of milk replacer (MR). Feed intake, average daily gain and growth: feed ratio were reduced in Fe-deficient calves, but not significantly influenced by rbGH. Plasma Fe and haemoglobin concentration, red-cell number and packed cell volume were decreased in Fe-deficient calves (P < 0.05) and rbGH further reduced red-cell number in Fe-deficient calves (P < 0.05). The age-dependent increase of total Fe binding capacity was greater in Fe-deficient calves and enhanced by rbGH (P < 0.05). Plasma urea concentrations increased, whereas glucose (G) and triiodothyronine (T3) levels decreased in Fe-deficient calves. rbGH significantly increased G in calves fed MR containing 50 mg/kg (P < 0.05) and influenced urea concentrations (P < 0.05). Plasma insulin (I) and IGF-I concentrations were lower in Fe-deficient calves (P < 0.05). Plasma GH in the first hours after rbGH injections increased (P < 0.05) to higher levels in calves fed 10 than in those fed 50 mg Fe/kg MR, but incremental changes were comparable. In conclusion, low Fe intake caused haematologic, metabolic and endocrine changes. Plasma IGF-I, I and T3 concentrations after rbGH administration and effects of rbGH on IGF-I in Fe-deficient calves were reduced, even though plasma GH levels were increased.
Ceppi
A
A
Division of Nutrition Pathology, University, Berne, Switzerland.
Blum
J W
JW
D018798:Anemia, Iron-Deficiency / Q000188:drug therapy / Q000378:metabolism / Q000662:veterinary*; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000378:metabolism; D004906:Erythrocyte Count / Q000662:veterinary; D013006:Growth Hormone / Q000494:pharmacology / Q000627:therapeutic use*; D006400:Hematocrit / Q000662:veterinary; D006454:Hemoglobins / Q000032:analysis; D006728:Hormones / Q000097:blood*; D007501:Iron / Q000097:blood; D008297:Male; D011994:Recombinant Proteins / Q000494:pharmacology / Q000627:therapeutic use; D015430:Weight Gain / Q000187:drug effects*
D006454:Hemoglobins; D006728:Hormones; D011994:Recombinant Proteins; D013006:Growth Hormone; D007501:Iron