The effect of high crude protein diet during energy restriction and compensatory growth in cattle

• Grant number: 17/02704-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: August 28, 2017
• End date: August 27, 2018
• Field of knowledge: Agronomical Sciences - Animal Husbandry - Animal Nutrition and Feeding
• Principal Investigator: Gustavo Rezende Siqueira
• Grantee: Verônica Aparecida Costa Mota
• Supervisor: Dennis Paul Poppi
• Host Institution: Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). São Paulo , SP, Brazil
• Institution abroad: University of Queensland, Gatton (UQ), Australia
• Associated to the scholarship: 16/05131-4 - Strategies for increasing nitrogen use efficiency in cattle growth phase pastures in Nellore, BP.DR

Abstract

The objective is to collaborate the project that has as main proposal to determine the effect on the performance of cattle fed a diet with a high crude protein (CP) during of metabolizable energy (ME) restriction and what the compensatory growth response (in body and skeletal weight) When these animals come to have access ad libitum to the diet with high CP and ME. Two genotype, fifteen Bos indicus steers (Brahman cruzado - BX) and fifteen Bos taurus steers (Holstein-Friesian - HF), with a mean body weight (BW) of 230 ± 34 and 178 ± 6 kg, respectively, will be used. Each genotype will be blocked according to BW and distributed in individual stalls and the treatments will be assigned randomly within each block referring to the genotype and each animal will be the experimental unit. The treatments consist of: HCP-HME, high CP and high ME; HCP-LME, high CP and low ME; LCP-LME, low CP and low ME. The experiment will be divided into two phases, the first phase (93 days) the animals of the HCP-HME and LCP-LME treatments will receive a source of ad libitum and the animals of the HCP-LME treatment will receive a restricted source of the equivalent ME intake to the animals receiving the LCP-LME treatment. In the second phase (103 days) all animals will receive bulky ad libitum. The parameters evaluated will be: weekly body weight throughout the periods of the experiment; body size; chemical composition of diets, fecal, urinary and ruminal parameters; blood variables and endocrine and bone histomorphometric bone parameters. The data after verifying normality and homoscedasticity will be analyzed using the linear mixed model procedure of the package "nlme" from software R (R Core Team, 2013). Daily body weight gain and body size will be calculated from the regression of these variables over time. Treatments and genetype will be included in the model as fixed effects and animals within block considered random effect. The statistical difference will be declared as P <0.05 and the differences between the averages will be compared by the Tukey test. It is hoped in the end to explore the knowledge about the consequences of the specific nutritional restriction and its effect the compensation in gain, by understanding how the ME restriction and diets with high CP affect the performance of cattle, endochondral ossification, bone remodeling and compensatory growth. In addition to the experiment in question the aim of the stage is to follow experiments in in progress at the University of Queensland, Australia in the field of beef cattle. (AU)