Effects of recombinant bovine somatotropin on puberty of Nellore heifers

• Grant number: 12/14368-7
• Support Opportunities: Scholarships in Brazil - Master
• Start date: September 01, 2013
• End date: December 31, 2014
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: Guilherme de Paula Nogueira
• Grantee: David Giraldo Arana
• Host Institution: Faculdade de Medicina Veterinária (FMVA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

From previous researches conducted in our laboratory a greater live weight at 12 months of age in precocious heifers (pregnancy at 16 mo), there was no difference in leptin concentrations before the first ovulation. O the other way higher IGF-I concentration was observed in precocious heifers suggesting that live weight and IGF-I concentration are more important for the first ovulation and sexual precocity than leptin concentration. This research will evaluate whether rbST administration in Nellore heifers will increase IGF-I, decrease leptin concentration and anticipates the age at first ovulation, quantification of IGF-I, leptin, insulin, glucose and progesterone, besides the evaluation of follicular and body development will be performed. Sixty Nellore heifers will be distributed according to age and weight into two groups with thirty animals each. All animals will be at pasture and receive mineral supplement and water ad libitum. The rbST group will be injected with 250 mg (s.c.) rbST and the control group will be injected with saline solution (2,5 ml s.c.) every 14 days from the 12 until the 19-month of age. The group will have a teaser with a chin ball, and every week the heifers will be inspected for ink marks. At rbST injection day venous blood sample will be collected for hormonal quantification, also follicular diameter will be evaluated. Every other month fat thickness at the 12th rib and body weight will be measured. The results will be analyzed by repeated measures ANOVA, PROC GLM in SAS.

Academic Publications

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

ARANA, David Giraldo. Efeitos da somatotrofina recombinante bovina na puberdade de novilhas nelore. 2015. Master's Dissertation - Universidade Estadual Paulista (Unesp). Faculdade de Medicina Veterinária. Araçatuba Araçatuba.