Effects of inclustion and exposition times of sugar cane to calcium oxide on the physiologic and digestive parameters of Nellore heifers

It was aimed to evaluate the effect of inclusion and times of sugar cane exposition to whitewash on intake and total and partial digestibility of nutrients and ruminal parameters and to compare titanium dioxide and chromium oxide as markers to estimate fecal dry matter excretion and dry matter abomasal flow. It was used six rumen and abomasum cannulated Nellore females, with average body weight of 250 +/- 19 kg, distributed in an incomplete 6 x 6 latin square design. The experiment was set in a 3 x 2 factorial scheme with three levels of whitewash (0; 0.5 or 1.0% natural matter) and two times of sugar cane storage (0 and 3 days). There was no effect of storage times neither interaction among levels of whitewash and storage times on the intake of nutrients. However, levels of whitewash linearly increased consumption of dry matter (DM), organic matter (OM) and non-fibrous carbohidrates (NFC). Storage times reduced total apparent digestibility of dry matter, organic matter and neutral detergent fiber corrected for ash and protein (NDFap), but they did influence ruminal apparent digestibility of the nutrients. The inclusion of whitewash increased the consumption of total digestible nutrients (TDN), but it did not affect total digestibility and ruminal digestibility of the nutrients. The markers produced similar results for the estimates of total and ruminal apparent digestibility of all the evaluated nutrients. Interactions for ruminal pH were observed. However, values of amonical nitrogen were only influenced by sampling times. Addition of whitewash does not affect preservation of sugarcane, but it positively influences consumption of DM, OM, and TDN of the animals. The markers produced similar estimative to total tract and ruminal apparent digestibility of all nutrients. Titanium dioxide and chromium oxide markers produce similar estimates of digestibility.