Despalha da cana-de-açúcar e desempenho de novilhas e vacas leiteiras

Abstract

Two experiments evaluated the responses in weight gain of heifers and milk yield of cows to the removal of the apical and lateral leaves of sugarcane. In both the animals were individually fed in total confinement. In Experiment 1, 32 Holstein x Gir heifers (295±45kg of body weight) were paired, blocked and allocated to a treatment for 42 days, following a 14-day standardization period. Treatments were whole or deleafed sugarcane. Body weight and intake were measured over time. The content of ingredients and nutrients in diets dry matter (DM) were 77.1% sugarcane, 19.2% soybean meal, 1% urea, 14.1% crude protein (CP), and 38.8% neutral detergent fiber (NDF) for deleafed sugarcane, and 78.6%, 17.9%, 0.9%, 13.7%, and 45.3% for whole sugarcane, respectively. Daily weight gain was 1.395kg for deleafed and 1.125kg for whole sugarcane (P=0.05). There was no treatment effect on DM intake (P=0.78). Leaf removal increased the rate of feed intake (P=0.04) and the daily intake of digestible non-NDF organic matter (P=0.03). In Experiment 2, 14 Holsteins (256±124 days of lactation) were paired blocked and allocated to a sequence of two treatments in a cross-over design, with 21-day periods, and measurement of the response on the third week. The deleafed sugarcane diet had 18.4% sugarcane in DM, 37.6% corn silage, 44% corn, citrus pulp, soybean meal based concentrate, 17.3% CP, and 32.9% NDF, while the whole sugarcane diet had 18.2%, 37.7%, 44.1%, 16.6%, and 34.7%, respectively. Deleafing tended to increase DM digestibility (P=0.06) and the daily intake of digestible organic matter (P=0.10), without affecting milk yield (18.4kg, P=0.65). Deleafing sugarcane increased the weight gain of heifers consuming a high proportion of sugarcane in the diet, but this practice did not induce a positive performance response in late lactating cows consuming 18% sugarcane in the diet.