IGF-1, leptin, insulin and GH levels in Nellore cattle and relation with reproduction efficiency

• Grant number: 14/03209-0
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: June 01, 2014
• End date: August 31, 2016
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: José Luiz Moraes Vasconcelos
• Grantee: Rogério Fonseca Guimarães Peres
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The metabolic status is among the factors that most affect the reproductive performance of female bovine (WEBB et al., 2004) and nutrition is a key item to alter the levels of metabolic hormones. With the objective to know the concentrations of IGF-1, leptin, growth hormone and insulin in Nellore cattle in different moments during the breeding season and evaluate nutritional strategies that allow to alter the levels of these hormones, four experiments were designed: Experiment 1 - 1000 multiparous Nellore cows will be synchronized with fixed-time artificial insemination protocol: insertion of an intravaginal device (CIDR®) and administration of 2 ml of estradiol benzoate (Gonadiol®) at D0. At D9, it will be performed CIDR withdrawal and the administration of 0.3 ml of estradiol cypionate, 2.5 ml of dinoprost tromethamine (Lutalyse®) and 300 UI of equine chorionic gonadotropin (Folligon®). At D11, 48 h after the withdrawal of progesterone intravaginal device, fixed time-IA will be performed. In Experiment 2, 226 heifers (12-15 months) will be submitted to a protocol of puberty induction and time-fixed IA according to experiment 1. Animals will be weighed and evaluated by US at D -24, D -12, D0 to identify the presence of corpus luteum. In experiment 3, 720 primiparous cows will be enrolled in fixed time-IA protocol described in experiment 1 and will be divided in two groups: GCC (Group Corn) - Supply of 1.0 kg/cow/day from D0 to D11 and 2.2 kg/cow/day from D11 to D41 and GC (Group Control) - without supply of corn. In Experiment 4, 2160 multiparous cows will be enrolled in time fixed-IA described in experiment 1 and will be divided in two groups: GV (Group Virginiamycin) - Supply of approximately 45 ppm/100 kg of live weight starting between 15 and 25 days after birth until weaning and GC (Group Control) - supply of supplement without virginiamycin. In experiments 1, 2, 3 and 4 blood sample collection will be performed at D0, D11 and D41. In experiment 2, it will be also sample collection at D-24 and D-12. Pregnancy diagnosis at 1a fixed time-IA and at the end of breeding season will be performed at D 41 and D131 and will be evaluated the presence of corpus luteum in non-pregnant cows. Blood samples will be stored at 4oC for 24 hours and posteriorly centrifuged at 1500 g for 15 minutes. Serum will be frozen at - 20 oC and stored until the moment of GH, leptin, IGF-1 and insulin analysis by radioimmunoassay. Binomial variables (pregnancy rate at 1ª TAI, percentage of cyclic cows after 1ª TAI, pregnancy rate at the end of breeding season) will be analyzed by PROC GLIMMIX and continuous variables (concentration of GH, leptin, IGF-1 and insulin) will be analyzed by PROC MIXED. (AU)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

PERES, Rogério Fonseca Guimarães. IGF-1, leptin and GH concentrations and its effects on reproduction in Nellore cattle.. 2016. Doctoral Thesis - Universidade Estadual Paulista (Unesp). Faculdade de Medicina Veterinária e Zootecnia. Botucatu Botucatu.