Effects of sampling position on blood hormone concentration in dairy cattle

Abstract Text: To evaluate the effects of sampling position on blood hormone concentration in dairy cattle, ten dairy cows (Milk yield= 28.2±2.1 kg/d, DIM=121±15 d) were selected. Blood samples from mammary vein, external pudic artery, coccygeal artery and vein were collected. Eight kinds of hormones were determined by radioimmunoassay method including insulin, growth hormone (GH), insulin-like growth factor-1 (IGF-1), leptin, adrenocorticotropic hormone (ACTH), estrogen, prolactin and progestin. Statistical analysis was performed using the PROC MIXED procedure of SAS 9.0. The results showed that no differences were observed in these hormones. Concentrations of hormones in mammary vein, external pudic artery, coccygeal artery and vein were averaged as followed: insulin (5.56 vs 6.39 vs 5.35 vs 5.38 μIU/ml, P > 0.05), GH (2.29 vs 2.34 vs 2.34 vs 2.40 ng/ml, P > 0.05), IGF-1 (290.57 vs 260.63 vs 283.64 vs 266.99 ng/ml, P > 0.05), Leptin (3.04 vs 3.10 vs 3.17 vs 2.97 ng/ml, P > 0.05), ACTH (11.35 vs 11.43 vs 11.50 vs 12.15 pg/ml, P > 0.05), Estrogen(12.67 vs 12.70 vs 14.45 vs 11.47 pg/ml, P > 0.05), Prolactin (315.88 vs 312.47 vs 290.28 vs 302.24 μIU/ml, P > 0.05), Progestin(0.21 vs 0.24 vs 0.23 vs 0.33 ng/ml, P > 0.05). It was implied that either of the four sampling positions could be representative for hormones measurement when estimating mammary gland metabolism.

Keywords: blood, hormone, mammary gland