Cana de açúcar associada à ureia e cal virgem na alimentação de bovinos leiteiros

Abstract

The aim of this study was to evaluate the effect on dairy cattle of sugarcane associated with urea as a source of non-protein nitrogen and calcium oxide as a hydrolytic agent, through performance, degradability, digestibility and blood and urinary parameters. Thus two experiments were conducted in 4 x 4 Latin square using four Jersey steers, ruminally cannulated with average body weight of 370 ± 44.4 kg and average age of 24 months and 4 multiparous cows Girolando breed (3/4 Holstein x 1/4 Gyr), 21 days after delivery, mean weight 493.0 ± 43.0 kg and mean age of 48 months, respectively. The animals were kept in confinement and fed with sugarcane (Saccharum officinarum) with a ratio of forage: concentrate in dry matter of 70:30 respectively. The urea and calcium oxide were added at 1% as fed sugar cane. The treatments were: Sugarcane in natura (Ca); Sugarcane in natura with Urea (CaUr); Sugarcane hydrolyzed with Calcium oxide (CaCal) and Sugarcane hydrolyzed with Calcium oxide more Urea (CaUrCal). Data were processed by analysis of variance and Tukey test (p <0,05). In the first trial, using ruminally cannulated steers, with a duration of 72 days divided into four periods of 18 days, yielded concentrations of Short Chain Fatty Acids (SCFA), ammoniacal nitrogen (NH3-N), pH and kinetics of ruminal liquid phase similar between treatments. Diets CaUr and CaUrCal had higher ruminal disappearance of crude protein and diet CaUr provided disappearance values of ruminal dry matter inferior to the other treatments. The combination of urea and calcium oxide additives promoted greater ruminal disappearance of fibrous fractions of sugarcane. In the second trial, using lactating cows of the breed Girolando, lasting 84 days divided into four periods of 21 days, we obtained production and milk composition similar between treatments. In both trials the food intake, the digestibility of the feed, serum glucose and urea, as well as the loss of nitrogen and urinary urea were similar between treatments.