Processing and ensiling of hydrated corn grain in diets of dairy cows

Abstract

The hypothesis of this study is that the increase in degradability of corn grain caused by rehydration and ensiling process of corn is affected by time of ensiling as well as the degree of processing, content Vitreousity Endosperm type of inoculation and temperature of drying grain at harvest. Further hypothesized that the increasing the degradability of the starch of corn silage caused by hydration and enhances production performance improves protein metabolism and decreases the excretion of nitrogen in the milk, and excreta of dairy cows when the protein content is reduced and the degradability of the protein is increased. To test the hypotheses 5 experiments will be conducted: 1) Experiment 1 will be carried out over 480 days in which three lots of corn grain (low, medium and high vitreousness) are rehydrated (35% moisture) and ensiled in experimental silos. 2) The second experiment will be conducted for 480 days and will feature the grain at 3 Vitreousity levels (low, medium, high) and four levels of processing by grinding (whole, 1, 3 and 8 mm), rehydrated (35% moisture ) and ensiled in experimental silos. 3) The third experiment will be conducted for 240 days in three lots of corn grain Vitreousity with three levels (low, medium and high), three drying temperatures of grain after harvest (40, 70 and 95 ° C) and rehydration with water containing 1% concentration of lactic acid, water in a concentration of 1% acetic acid and biological inoculant. The two units every 30 days (n = 2) will have their experimental fermentation stopped to perform analysis of the concentration of MS, MM, starch, pH, PB, zein, acetic acid, propionic acid, butyric acid, lactic acid and alcohol. Further sub-samples of all experimental units will be subjected to a test in vitro for 7 hours to model the effect of the variables on the degradability of DM, CP and starch MRE. 4:05 The experiments will be performed in vivo to evaluate the variation of the content (experiment 4) and degradability (experiment 5) of dietary protein in relation to the use of rehydrated and ensiled maize (MRE). In the experiments 4 and 5 15 dairy cows with average production of 30 liters / day will be used for evaluation of production and milk composition, ruminal fermentation parameters and nutrient digestibility, protein metabolism. In Experiment 4 three levels of CP (130, 160 and 180 g / kg DM) will be compared to diets using MRE in isoenergetic and iso RDP: RUP. In experiment 5 are tested three levels of degradability (90, 110 and 150 g RDP / kg DM) in isoenergetic and isonitrogenous diets. (AU)