Serum thyrotropin and thyroxine after thyrotropin releasing hormone in dairy cows fed varying amounts of iodine

Journal Article · Wed Jun 01 04:00:00 EDT 1977 · J. Dairy Sci.; (United States)

DOI:https://doi.org/10.3168/jds.S0022-0302(77)83972-6· OSTI ID:7212779

Convey, E M ^[1]; Chapin, L; Kesner, J S; Hillman, D; Curtis, A R

---

1. Michigan State Univ., East Lansing

The objective was to determine whether dairy cows fed relatively large amounts of iodine had altered thyroid status. In addition, polarographic analysis for determination of iodine and bromine in milk and urine is described. Five dairy herds fed an average of 16 mg iodine/head per day (range 11 to 25) and five fed 164 mg iodine/head per day (range 74 to 402) were identified. Iodine fed was estimated from minimal guaranteed iodine content of concentrates, iodized salt, minerals, liquid supplements, and silage topdressing. Iodine from other dietary sources was considered negligible. Each dairyman selected three cows each in early (less than 90 days), middle (90 to 120 days), and late (greater than 120 days) lactation. Blood was collected from each cow selected; then 150 ..mu..g thyrotropin releasing hormone were given. Iodine in milk (..mu..g/ml) and urine (..mu..g/mg creatinine) were 2.2 and 65 for cows in high iodine herds, more than that (.37 and 20) in low iodine herds. At resting (ng/ml) serum thyroxine was 33 and 32 and thyrotropin was 7.4 and 7.9. Serum thyroxine and thyrotropin concentrations were increased following releasing hormone; however, increase was not affected by quantity of dietary iodine. Thyroxine in serum at resting (ng/ml) was less for cows in early lactation (25.9) than for those in middle (36.1) or late (35.5) lactation.

• OSTI ID: 7212779
• Journal Information: J. Dairy Sci.; (United States), Journal Name: J. Dairy Sci.; (United States) Vol. 60:6; ISSN JDSCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400105 -- Separation Procedures
560305* -- Chemicals Metabolism & Toxicology-- Vertebrates-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
AMINO ACIDS
ANIMALS
BIOLOGICAL ACCUMULATION
BIOLOGICAL EFFECTS
BIOLOGICAL FUNCTIONS
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BODY
BODY FLUIDS
BROMINE
CARBOXYLIC ACIDS
CATTLE
CHEMICAL ANALYSIS
COWS
DOMESTIC ANIMALS
ELEMENTS
ENDOCRINE GLANDS
FOOD
GLANDS
HALOGENS
HORMONES
IODINE
MAMMALS
METABOLISM
MILK
NONMETALS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC IODINE COMPOUNDS
ORGANS
PEPTIDE HORMONES
QUANTITATIVE CHEMICAL ANALYSIS
RUMINANTS
THYROID
THYROID HORMONES
THYROXINE
TOXICITY
TRH
URINE
VERTEBRATES
WASTES