Coprodutos do cacau e do maracujá e indicadores de consumo e digestibilidade aparente em dietas para novilhas leiteiras

Abstract

We aimed to evaluate the increasing levels of cocoa and passion fruit by-products substituting Tifton 85 hay, fecal output markers and apparent digestibility of dairy heifers. In the first experiment was evaluated in situ degradability parameters of the forage offered to the dairy heifers. In the second and fourth experiments were evaluated the increasing levels of inclusion of cocoa by-product (zero, 8, 16, 24% DM) and passion fruit (zero, 12, 24, 36% MS) substituting the Tifton 85 hay in diets offered to dairy heifers over the intake, apparent digestibility of nutrients, protein balance, energy balance and animal feeding behavior. In the third and fifth experiments effectiveness of external markers like chromium oxide (Cr2O3), titanium dioxide (TiO2), LIPE®, NANOLIPE®, and internal markers like indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and neutral detergent fiber (iADF) as estimator of fecal production and nutrient digestibility of diets was assessed. Sixteen Holstein x Zebu crossbred heifers were used, with average body weight (363.00 ± 27.70Kg), distributed in a completely randomized design with four treatments and four replications. In the first experiment, the effective and potential degradability and "c" rate of degradation of dry matter and crude protein of the passion fruit by-product was higher than Tifton 85 hay. The cocoa by-product presented potential degradation of nutrients lower than the forage evaluated, resulting in limited use in diets of dairy heifers of this by-product. In the second experiment, the intake was not altered by the inclusion of cocoa by-product in the experimental diets. There was a decrease in the apparent digestibility of dry matter, crude protein, neutral detergent fiber, acid detergent fiber, protein and energy balances with the inclusion of 24% of the cocoa by-product. The idle time increased with increasing inclusion of cocoa by-product in the experimental diets. The upper limit of inclusion of cocoa by-product was 16% in substitution of Tifton 85 hay in diets for dairy heifers. In the third experiment there was interaction between the evaluated indicators and the level of inclusion of cocoa by-product to the experimental diets. Nutrient digestibility and fecal output were estimated properly with external markers, chromium oxide, LIPE®, NANOLIPE® and internal, iNDF, at all levels of inclusion of cocoa by-product. In the fourth experiment, the intake of crude protein and ether extract increased with the inclusion of the passion fruit by-product to the experimental diets. The intake of nitrogen, absorbed and excreted nitrogen in the urine of the animals increased with increasing levels of passion fruit by-product the diets. The energy balance and ingestive behavior were no altered by treatments. The apparent digestibility of ether extract increased linearly with higher levels of increasing inclusion of passion fruit by-product in the diet and can be included in the upper limit of 36% in substitution of Tifton 85 hay in diets for dairy heifers. In the fifth experiment fecal production and digestibility were adequately estimated by external markers, chromium oxide, LIPE®, NANOLIPE® and internal, iNDF, with no interaction of the markers with the increasing inclusion of passion fruit by-product in the diets.