Desempenho de novilhas girolando alimentadas com dietas à base de palma forrageira, cana-de-açúcar mais ureia e concentrado

Abstract

The objective of this study was to evaluate the effect of a diet based on Orelha de Elefante Mexicana spineless cactus (Opuntia stricta [Haw] Haw), sugar cane (Saccharum ssp) and urea + ammonium sulfate (SA) allied to concentrate levels on dry matter intake and digestion and its compenents, performance and nitrogen balance in crossbreed holsten (Girolando) heifers (5/8 Holstein x Gir). Therefore, twenty confined heifers with an average age of 14 months were used and distributed in a completely randomized design, considering initial body weight (160 ± 8,39 kg) as covariable. The base diet for all animals was composed of spineless cactus (56.5%), sugar cane (38.1%), mineral mix (1.1%), common salt (0.5%) and urea + SA (3.8%), differing only in treatments: 0.0; 0.4; 0.8 and 1.2 kg/day of concentrate in the natural matter. The diets influenced (P <0.05) the intake of dry matter, organic matter, crude protein, non fibrous carbohydrates and metabolizable energy (Mcal / day). There was no influence of the experimental diets on the dry matter digestibility and its components. When the animals growth was evaluated by means of the morphometric measurements, no significant changes were observed, but the average daily weight gain increased linearly (P <0.05), from 0.51 to 0.85 kg / day, with addition of the concentrate. Nitrogen balance increased linearly (P <0.05), where as plasma and urinary urea concentrations were not influenced by diets (P> 0.05). By the findings, it is clear the potential of the forage palm Orelha de Elefante Mexicana, sugar cane and urea assossiation with low amounts of concentrate on the performance of Girolando Heifers. It is recommended to provide the diet with 400 g/day of concentrate for growing dairy females, as it promotes satisfactory weight gain, anticipating the age at first calving and reducing the costs of rearing animals.