Effect of energy density of the diet and chromium supplementation on serum concentrations of glucose and insulin on lactating dairy cows

• Grant number: 13/14372-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Effective date (Start): September 01, 2013
• Effective date (End): August 31, 2014
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Reproduction
• Principal Investigator: José Luiz Moraes Vasconcelos
• Grantee: Fabiana Nunes Corrá
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil

Abstract

The objective of this study is to evaluate the influence of the energy density of the diet and chromium supplementation on the serum concentrations of glucose and insulin-lactating cows. Eighteen of crossbred Holstein x Gir cows, allocated in two pastures and receiving free-choice of corn silage and water, will be blocked by parturition (primiparous x multiparous) and milk yield, and randomly assigned to one of three treatments on d0 of the experiment: 1) Control: diet formulated to reach 100% of requirements for maintenance and lactation, without chromium supplementation (n=6); 2) GPSC: diet formulated to reach 100% and 160% of the requirements for lactation and maintenance, respectively, without chromium supplementation (n=6); 3) GPCC: diet formulated to meet 100% and 160% of the requirements for lactation and maintenance requirements, respectively, with chromium supplementation (n=6; 2,5g of KemTRACETM Chromium Propionate 0,4% - Kemin Industries, Inc. - added in 97,5g of cornmeal/animal/day). Experimental diets will be fed twice daily. Treatments will be analyzed as a contrast to identify major contrast responses: Control versus GPSC to determine the effect of the energy density, and GPSC versus GPCC to determine the effect of chromium supplementation in high energy diets. A glucose Tolerance Test will be performed to determine the glucose clearance rate and insulin release. All variables will be analyzed using the MIXED procedure of SAS (Inst., Inc., Cary, NC) and cow as the experimental units.(AU)