Influence of diet and ambient temperature on bovine serum insulin-like growth factor-I and thyroxine: relationships with non-esterified fatty acids, glucose, insulin, luteinizing hormone and progesterone

• Published in: Animal reproduction science Vol. 37; no. 3; pp. 267 - 279
• Main Authors: Richards, M.W., Spicer, L.J., Wettemann, R.P.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.1995
• Subjects: ACIDE GRAS; ACIDOS GRASOS; Cattle - endocrinology; COWS; DIET; DIETA; FACTEUR DE CROISSANCE IGF; FACTOR DE CRECIMIENTO IGF; FATTY ACIDS; GLUCOSA; GLUCOSE; Growth factors; INSULIN; INSULIN-LIKE GROWTH FACTOR; INSULINA; INSULINE; Luteinizing hormone; Nutrition; PROGESTERONA; PROGESTERONE; REGIME ALIMENTAIRE; TEMPERATURA; TEMPERATURE; THYROXINE; TIROXINA; VACA; VACHE; Cattle - endocrinology; Luteinizing hormone; Progesterone; Nutrition; Growth factors; Thyroxine
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/0378-4320(94)01338-M

Multiparous, nonlactating, Hereford cows were fed maintenance (M; n = 11) or restricted (R; n = 11) diets for 41 weeks to evaluate changes in insulin-like growth factor-I (IGF-I) and thyroxine during the onset of nutritionally induced anoestrus and during realimentation. Cows had a moderate body condition score (BCS = 5.5 ± 0.1; 1 indicating emaciated and 9 indicating obese) at the start of treatment. Cows on M diets maintained body weight (BW) and BCS, and R cows lost 1% of their initial BW weekly until they were anoestrus. When R cows were anoestrus their diets were increased to allow BW gain and resumption of ovarian activity. Relationships among concentrations of IGF-I, thyroxine, non-esterified fatty acids (NEFA), glucose, insulin, luteinizing hormone (LH), and progesterone in blood samples were determined. Anoestrus occurred when restricted cows had lost 24 ± 0.9% of their BW, had a BCS of 3.5 ± 0.1, and had nadir concentrations of IGF-I and thyroxine. Serum concentrations of IGF-I and thyroxine were reduced ( P < 0.01) in R compared with M cows, except during realimentation when R cows had greater concentrations of thyroxine. Concentrations of IGF-I in M cows were positively correlated with concentrations of insulin ( r = 0.31), glucose ( r = 0.21) and progesterone ( r = 0.24). In R cows, concentrations of IGF-I were positively correlated with insulin ( r = 0.39), glucose ( r = 0.23) and LH ( r = 0.37). Mean weekly ambient temperatures were negatively correlated with IGF-I ( r = −0.16), glucose ( r = −0.37) and thyroxine ( r = −0.40) in M cows. Our data indicate that ambient temperature and nutrient intake may both work to regulate concentrations of hormones and reproductive function in cattle.