Growth hormone related to insulin and sugar in nocturnal blood plasma of lactating cows.
Nocturnal blood plasma samples from about 190 indoor-fed cows at varying stages of the lactation cycle showed wide variations in the concentrations of sugar (43-88 mg/100 ml) and acetoacetate (0.12-8.7 mg/100 ml). Plasma immunoreactive insulin decreased and acetoacetate increased with decreasing sugar. Plasma growth hormone (GH) was significantly correlated to insulin (r=-0.24, P less than 0.001) and to sugar (r=-0.15, P less than 0.05), but not to acetoacetate (r=+0.13). Since the plasma level of GH in bovines is known to vary widely from hour to hour, individual cows are poorly represented by single determinations of the hormone. However, in accordance with the results from the correlation tests, different GH averages, about 11 and 9 ng/ml, were found for groups of animals with plasma sugar respectively below and above 70 mg/100 ml. By subgrouping according to insulin levels within sugar ranges, categories could be singled out with GH averages as different as 12.7 ng/ml (low sugar-low insulin) and 8.3 ng/ml (high sugar-high insulin). The findings are consistent with the view that GH is involved in the regulation of energy metabolism in bovines. But no support has been provided for the hypothesis of GH hypersecretion as a cause of ketosis in cows.
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D002417:Cattle / Q000097:blood* / Q000502:physiology; D005260:Female; D013006:Growth Hormone / Q000097:blood*; D007328:Insulin / Q000097:blood*; D007774:Lactation; D011247:Pregnancy; D013997:Time Factors
D001786:Blood Glucose; D007328:Insulin; D013006:Growth Hormone