Development of insulin resistance in dairy cows by 150 days of lactation does not alter oocyte quality in smaller follicles

Author(s)

Oliveira, L. H. ; Nascimento, A. B. ; Monteiro, Jr., P. L. J. ; Guardieiro, M. M. ; Wiltbank, M. C. ; Sartori, R.

• Document type: Journal article
• Source: JOURNAL OF DAIRY SCIENCE; v. 99, n. 11, p. 9174-9183, NOV 2016.
• Web of Science Citations: 8

Abstract

The objective of this study was to test the hypothesis that high-producing dairy cows become increasingly resistant to insulin throughout lactation and that, consequently, oocyte quality is compromised. We used Holstein cows at 50 (51.5 perpendicular to 3.7; n = 30), 100 (102.3 perpendicular to 9.4; n = 30), and 150 (154.5 perpendicular to 18.9; n = 30) days in milk (DIM). We measured circulating insulin and glucose and performed a glucose tolerance test (GTT) after 5 h of fasting. To evaluate oocyte quality, we performed ovum pickup on the day before the GTT (581 oocytes). We performed statistical analyses using the MIXED procedure of SAS. The model included the fixed effects of DIM, period, time, parity, and an interaction between DIM and time. We observed no difference in the GTT between groups for any variable related to circulating glucose (for example, glucose peak = 203.3 perpendicular to 7.2, 208.8 perpendicular to 6.3, and 194.3 perpendicular to 5.9 mg/dL). However, various measures of circulating insulin were different in cows at 150 DIM compared with 50 or 100 DIM: higher basal insulin (8.8 perpendicular to 0.9, 8.8 perpendicular to 0.8, and 11.9 perpendicular to 0.8 mu IU/mL), peak insulin (61.9 perpendicular to 6.2, 69.1 perpendicular to 5.7, and 89.0 perpendicular to 6.1 mu IU/mL), delta maximum insulin (51.1 perpendicular to 5.5, 59.4 perpendicular to 5.0, and 73.5 perpendicular to 5.4 mu IU/mL), and area under the curve 5-60 (1,874.8 perpendicular to 171.0, 2,189.5 perpendicular to 157.8, and 2,610.5 perpendicular to 174.0 mu IU/mL x min). Nevertheless, we observed no difference among groups in the number of viable oocytes (3.2 perpendicular to 0.7, 3.9 perpendicular to 0.7, and 3.6 perpendicular to 0.7 per cow per ovum pickup) or percentage of viable oocytes (49.3, 52.2, and 51.8%). Increased circulating insulin before and throughout the GTT in cows at 150 DIM indicates that cows develop increasing insulin resistance with increasing DIM; however, increased insulin resistance was not associated with a detectable alteration in the quality of oocytes aspirated from small and medium-sized follicles. (AU)

• FAPESP's process: 12/50752-6 - Insulin resistance and oocyte quality in high producing dairy cows at different stages of lactation
• Grantee: Roberto Sartori Filho
• Support Opportunities: Regular Research Grants
• FAPESP's process: 11/07243-0 - Studies of physiology and reproductive management to better understand the causes of low fertility and increase reproductive parameters of high producing dairy cows
• Grantee: Anibal Ballarotti Do Nascimento
• Support Opportunities: Scholarships in Brazil - Post-Doctoral