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It aimed to estimate the forage intake by lambs managed in different leaf allowances on Brachiaria-grass using internal and external markers. Forty-eight Texel lambs with 17.52 ± 3.48 kg were evaluated which were 12 testers and 36 regulators. The lambs were kept in twelve paddocks, subdivided into four treatments based on green leaf allowance (60, 75, 90, and 105 g/kg of BW). The experimental design was completely randomised. To estimate dry matter intake (DMI), the following markers were used: indigestible dry matter (iDM); indigestible neutral detergent fibre (iNDF); indigestible acid detergent fibre (iADF); lignin in indigestible acid detergent (iADL) and titanium dioxide (TiO2). Comparisons between intake markers were made using Chromic Oxide (Cr2O3) as a control marker. The leaves allowance tested did not alter the voluntary intake by lambs kept in Brachiaria-grass pasture. Comparison between the control intake marker (Cr2O3) and the other markers by Dunnett's test showed that, regardless of green leaf allowance, the Cr2O3, TiO2 and iADL markers provided similar estimates of DMI, but with lower values than the other markers. External marker TiO2 and the internal iADL were demonstrated to be more suitable for estimating the dry matter intake in grazing lambs regardless of the leaf allowance. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the indirect methods of obtaining digestibility with the direct method of total fecal collection to estimate the apparent digestibility of nutrients in sheep and goats supplemented with non-protein nitrogen. Five goats and five sheep with no defined racial pattern were used, distributed in two 5 × 5 Latin squares, with split plots, considering the diets as plots and the apparent digestibility determination methodologies as subplots. The diets were composed of buffelgrass hay and the addition, via ruminal infusion, of increasing amounts of nitrogen supplementation in order to gradually raise the CP level of the basal diet in intervals of 2% points, that is, + 2, +4, + 6 and + 8%. Samples of the feeds offered, and the leftovers were collected daily during the five days of collection to determine the nutrient intake, as well as the total collection of feces to determine the apparent digestibility of the nutrients. The amount of fecal dry matter excreted was estimated by the concentration of Indigestible Acid Detergent Fiber (ADFi), Indigestible Neutral Detergent Fiber (NDFi), Indigestible Dry Matter at 244 h (DMi 244 h) and Indigestible Dry Matter at 264 h (DMi 264 h). Among the evaluated markers, DMi 264 h had the lowest accuracy in estimating fecal excretion and nutrient digestibility. For the goat species, the markers ADFi and DMi 244 h proved to be able to adequately predict fecal excretion and digestibility indices, while NDFi stood out for both species. Among the evaluated markers, NDFi is the one that most accurately estimates the nutrient digestibility of the diet for goats and sheep. [ABSTRACT FROM AUTHOR]

A data set of individual observations was compiled from 17 digestibility trials with sheep with the aim of evaluating the impact of the method of analysis and, within each method, the effect of dietary fibre content and trial on the faecal recovery rate (RR) of indigestible dry matter (iDM) and indigestible neutral detergent fibre (iNDF). Markers concentration in samples of diet and faeces were determined either in polyester filter bags of 40 μm of porosity incubated in situ for 144 h (method A; n = 257) or in bags of 16 μm of porosity incubated in situ for 288 h (method B; n = 321). Regardless of the incubation method, the intake of either iDM or iNDF was linearly (P < 0.05) related to the amount excreted in faeces and, for all linear relationships, the slopes were lower than 1 (i.e. between 0.53 and 0.71). Within both methods, the RR of both markers linearly decreased at increased NDF content in diet (P < 0.05). The root mean square error of the linear relationships varied from 0.147 to 0.189 which represented from 19% to 24% of the respective average RR of markers. In conclusion, regardless of the incubation method, the RR of both markers showed high individual variability and, thus, the use of average RR values obtained in controlled digestibility trials as an index to correct the individual digestibility values obtained with either marker in field trials has the potential to improve the accuracy but not the precision of the digestibility estimates. [ABSTRACT FROM AUTHOR]