Influence of insulin on circulating hormones, ovarian function, liver enzymes and embryo production in Holstein cows

• Grant number: 14/03580-0
• Support type: Regular Research Grants
• Duration: April 01, 2015 - September 30, 2017
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal researcher: Roberto Sartori Filho
• Grantee: Roberto Sartori Filho
• Home Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Assoc. researchers: Alexandre Vaz Pires

Abstract

The energy source can influence rumen fermentation, yielding different profiles of volatile fatty acids, and consequently changes in circulating insulin concentrations, however, little is known about their influence on ovarian function and embryo yield. The purpose of experiment 1 is to access the role of insulin in modulating follicular and luteal function. This experiment will use 16 non-lactating and non-pregnant confined Holstein cows, distributed according to age, body weight and BCS in a latin square type arrangement to the following experimental groups: Group CC = water pre and post follicle deviation (n = 16); group CI = propylene glycol and water pre and post follicle deviation, respectively (n = 16) group CI = propylene glycol and water pre and post follicle deviation, respectively (n = 16) and Group II = propylene glycol pre and post follicle deviation (n = 16). Propylene glycol or water will be supplied orally four times daily for 3 days pre deviation and for more 3 days after follicular deviation. The animals will be evaluated daily by ultrasound to check follicular and luteal dynamics. Blood samples will be taken every day and circulating progesterone, 17²-estradiol and insulin as well as glucose will be measured. The objective of experiment 2 is to evaluate the influence of an Insulinogenic diet on embryo production, the expression of liver enzymes (cytochrome P450 2C, 3A, and aldo-keto reductase 1C and 1D) and in circulating concentrations of progesterone in 24 non-lactating and non-pregnant Holstein cows. After 15 days of diet adaptation, the cows will be assigned to two experimental groups: 1) more insulinogenic diet and 2) less insulinogenic diet. Each experimental group will receive treatment diets for 70 days. The cows will be superovulated and embryos will be harvested after 35 and 70 days on diets, to then hold up the crossover. Embryos will be classified according to the degree of morphological development and quality. Furthermore, ovarian ultrasonographic examinations will be conducted to evaluate superstimulatory and superovulatory responses. Liver biopsies will be made 2 days after embryo collection, approximately 4 hours after the diet intake. Hepatic fragments will be conditioned for subsequent quantification in real-time PCR. Blood samples for determination of circulating progesterone, fructosamine and insulin will be taken at the beginning of the experimental period, the beginning of the superovulation protocol, on the day of embryo collection and on the day of liver biopsy, all at two times (immediately before feeding and 4 hours later). (AU)