Avaliação de indicadores para estimar consumo total, produção fecal, digestibilidade aparente e consumo diferenciado de volumoso, concentrado e suplemento mineral por bovinos leiteiros

The objective of this study was to evaluate the external markers NANOLIPE, Titanium dioxide (TiO2), and internal markers indigestible dry matter (iDM), indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) to estimate fecal output, dry matter intake (DMI) and apparent digestibility of dry matter (ADDM); and using the technique of double markers to estimate intake of concentrate using TiO2 (while fecal output was estimated by NANOLIPE), the intake of forage using iNDF and iADF (having the fecal output also estimated by the NANOLIPE), and the intake of mineral salt using NANOLIPE (with fecal output being estimated by TiO2). Eight crossbred cows were fed corn silage or Tifton 85 hay, concentrate and mineral mix, using a 4x4 double and simultaneous latin square as statistical design. The Titanium was evaluated using two different collection periods (3 and 5 days), as well as the NANOLIPE, with different amount of adaptation days (1 and 2 days). The NANOLIPE was supplied to the animals for two days in a dosage of 500 mg/day. For a period of 11 days (7 for adaptation and 4 for sampling) 10g of Titanium dioxide was supplied to each animal daily. The residues of the internal markers were determined with an in situ incubation of 246 hours. The markers NANOLIPE and iNDF correctly estimated the PF, the CMS and the DAMS; the same was not possible with the use of TiO2. The ADFi was efficient to determine the same parameters in diets with Tifton 85 hay, but not when used corn silage, as with the MSi occurred otherwise. There was statistical difference between the concentrate and mineral salt intake when they were estimated, respectively, by TiO2 and NANOLIPE. The iNDF was efficient in estimating the forage intake, however the use of iADF must be carried with caution, since the type of forage seems to influence results.