Effects of recombinant bovine interleukin-8 (rbIL-8) treatment on health, metabolism, and lactation performance in Holstein cattle IV: Insulin resistance, dry matter intake, and blood parameters

• Published in: Journal of dairy science 2019-11, Vol.102 (11), p.10340-10359
• Main Authors: Zinicola, M., Batista, C. P, Bringhenti, L., Meira, E.B.S., Lima, F. S, McDonough, S.P., Bicalho, R.C.
• Format: Article
• Language: English
• Subjects: 3-Hydroxybutyric Acid - blood; Animals; Apoptosis - drug effects; Cattle - physiology; Cell Proliferation - drug effects; Diet - veterinary; dry matter intake; Eating - drug effects; Fatty Acids - metabolism; Female; Glucose - metabolism; Growth Hormone - drug effects; Growth Hormone - metabolism; Insulin - blood; Insulin Resistance; Insulin-Like Growth Factor I - drug effects; Insulin-Like Growth Factor I - metabolism; interleukin-8; Interleukin-8 - administration & dosage; Interleukin-8 - metabolism; Interleukin-8 - pharmacology; Ketosis - veterinary; Lactation - drug effects; Lactation - physiology; Liver - cytology; Liver - drug effects; metabolism; Milk - metabolism; milk production; Parturition; Postpartum Period - blood; Pregnancy; Recombinant Proteins - administration & dosage; Recombinant Proteins - metabolism; Recombinant Proteins - pharmacology
• ISSN: 0022-0302; 1525-3198
• DOI: 10.3168/jds.2019-16337

We have shown in 2 independent studies that cows who received recombinant bovine interleukin-8 (rbIL-8) administered intrauterinely shortly after parturition have a significant and long-lasting increase in milk yield. In the present study, we hypothesized that the increased milk production associated with rbIL-8 treatment is a consequence of increased postpartum dry matter intake (DMI) and orchestrated homeorhetic changes that prioritize milk production. Cows were enrolled into 1 of 3 treatment groups: those assigned to the control group (CTR; n = 70) received an intrauterine (IU) administration of 500 mL of Dulbecco's phosphate-buffered saline (DPBS) solution and 1 mL of DPBS solution intravenously (IV; jugular vein), those assigned to the rbIL-8 IV group (rbIL8-IV, n = 70) received an IV injection of 167 μg of rbIL-8 and 500 mL of DPBS solution IU, and cows assigned to the rbIL-8 IU group (rbIL8-IU, n = 70) received an IU administration with 1,195 μg of rbIL-8 diluted in 499.5 mL of DPBS solution and 1 mL of DPBS solution IV. Animals were housed in a tiestall from calving to 30 d in milk (DIM) to measure DMI. Blood samples were collected daily from calving to 7 DIM and weekly until 28 DIM. Insulin resistance was evaluated using an intravenous glucose tolerance test and intravenous insulin challenge test (IVICT) in a subgroup of cows (n = 20/treatment) at 10 and 11 DIM, respectively. Additionally, liver biopsy samples were taken at 14 DIM from the same subgroup of cows to measure triglyceride levels and cell proliferation and apoptosis. Cows treated with rbIL8-IU produced more milk (CTR = 36.9 ± 1.5; rbIL8-IU = 38.5 ± 1.5; rbIL8-IV = 36.6 ± 1.5 kg/d), energy-corrected milk (CTR = 42.9 ± 0.9; rbIL8-IU = 46.1 ± 0.8; rbIL8-IV = 43.7 ± 0.9 kg/d), and fat-corrected milk (CTR = 44.3 ± 0.9; rbIL8-IU = 47.8 ± 0.9; rbIL8-IV = 45.2 ± 0.9 kg/d) yields when compared with CTR cows, and no differences were observed between rbIL8-IV and CTR cows. The administration of rbIL8-IU significantly increased DMI compared with CTR (CTR = 18.8 ± 0.3; rbIL8-IU = 19.9 ± 0.3; rbIL8-IV = 19.3 ± 0.3 kg/d). Recombinant bIL-8 treatment did not affect glucose, insulin, or fatty acids (i.e., IVICT only) concentrations or their area under the curve in response to an intravenous glucose tolerance test and IVICT when compared with CTR. Moreover, rbIL-8 treatment administered IU or IV increased liver triglyceride levels. Additionally, cows treated with rbIL8-IU tended to have lower odds of de