Avaliação do uso de frações indigestíveis do alimento como indicadores internos de digestibilidade em ovinos

Abstract

RESUMO -Avaliou-se o uso de matéria seca indigestível (MSi) e de fibra detergente neutro indigestível (FDNi) como indicadores internos de digestibilidade em ovinos. Utilizaram-se dados e amostras provenientes de seis ensaios independentes de digestibilidade com ovinos mantidos em gaiolas de metabolismo recebendo à vontade diversos tipos de volumoso e/ou concentrado. Os resíduos indigestíveis (MSi e FDNi) foram determinados após 144 horas de incubação in situ de amostras de alimentos e fezes. O grau de recuperação da MSi variou de 64,8 a 108,5% e o da FDNi, de 49,5 a 67,9%. Quando a relação entre a concentração dos indicadores nas fezes e nos alimentos não foi corrigida para a recuperação fecal, a maior parte das estimativas médias de digestibilidade da matéria orgânica dos experimentos foi inferior às médias obtidas in vivo. Quando a relação foi corrigida para a recuperação fecal, as estimativas médias de digestibilidade da matéria orgânica usando os dois indicadores foram similares às obtidas in vivo em todos os experimentos. Quando as estimativas individuais, corrigidas para recuperação fecal do indicador, foram relacionadas às observações in vivo por análise de regressão, o coeficiente de regressão linear foi similar a 1 usando a MSi, mas foi menor que 1 usando a FDNi. Os valores individuais de digestibilidade da matéria orgânica estimados com os dois indicadores, contudo, foram pobremente relacionados às observações in vivo (r 2 variou de 0,60 a 0,63). Corrigindo-se para a recuperação fecal, a matéria seca residual após 144 horas de incubação in situ pode ser utilizada como indicador interno para estimar a digestibilidade média da dieta consumida por um grupo de animais, mas não é precisa para detectar pequenas diferenças na digestibilidade de alimentos impostas pelos tratamentos em um experimento.Palavras-chave: consumo, digestibilidade, fibra em detergente neutro indigestível, matéria seca indigestível, recuperação fecal Evaluation of indigestible feed fractions as internal markers for predicting digestibility in lambsABSTRACT -The use of indigestible dry matter (iDM) and indigestible neutral detergent fiber (iNDF) as internal markers to estimate digestibility in lambs was evaluated. Data and samples were obtained from six independent digestion trials with lambs housed in metabolism cages given ad libitum different forage and concentrate feedstuffs. Indigestible residues were determined after 144 hours of in situ incubation of feed and faeces samples. Recovery rate varied from 64.8 to 108.5% for iDM, and from 49.5 to 67.9% for iNDF. As the marker ratio between marker concentration in the faeces and the feed was not corrected for fecal recovery, the large part of the estimated apparent organic matter digestibility (AOMD) of the experimental means were lower than the in vivo that obtained. As the marker ratio was corrected for fecal recovery of the marker, the AOMD means estimated using both markers were similar to the in vivo data in all experiments. As individual estimates, corrected for fecal recovery of ...

Effects of dietary brown propolis on nutrient intake and digestibility in feedlot lambs

“…However, in another study on lambs, Kozloski et al (2009) observed that fecal recovery of internal indigestible DM and iNDF markers was not complete and varied considerably among assays. These authors suggest that digestion and/or partial absorption of the markers is a probable cause for this variation, along with physicochemical modifications throughout the digestive tract and deficiencies in analytical procedures.…”

Digestibility markers of sheep diets containing hydrolyzed sugarcane-top hay

“…The fecal recovery of the external markers was below 100% is attributed to the partial absorption of the marker in the digestive tract or to its transformation into other compounds, which may cause an underestimate of the total fecal DM production. The fecal recovery of iDM was the one that was closest to 100%, which was obtained with total feces collection and was higher than that obtained by Kozloski et al (2009). The use of iDM as a marker can provide exact results and high correlations with the total collection, never the less, the presence of contaminants may compromise the obtained results, since no detergent solutions are used to obtain the iDM content, which prevents the removal of residues from the cell wall and bacterial contamination.…”

“…Detmann et al (2007) evaluated internal markers iDM, iNDF, and iADF in grazing cattle and found better estimates with iDM and iNDF for indirect evaluation of digestibility, whereas the values obtained by iADF showed variable effects with errors stemming from the analytical process, which affected its accuracy as a marker. Kozloski et al (2009) observed a fecal recovery of iDM of 108.5%, and no differences between the digestibility of organic matter estimated by that marker (77.0%) and by total collection (76.00%); however, these authors stress the little precision and variation in the estimate when changes are caused by experimental treatments. Regarding the external markers, the fecal recovery of Cr 2 O 3 (92.5±6.6%) was higher, near 100%, result similar to the 86.1 obtained by Rodrigues et al (2010) in sheep also fed highconcentrate diets.…”

Nutritive value of sheep diets made up of hay from Tifton 85 grass and leucaena

“…The apparent digestibility (AD) of the DM, CP, NDF, ADF and energy, were calculated from the difference between ingested nutrients and nutrients excreted in the faeces, as a function of nutrient intake (KOZLOSKI et al, 2009): AD (% ) = [ (nutrient intakenutrient excreted in the faeces) / nutrient intake ] x 100. The metabolisable energy (ME) was obtained by subtracting the energy losses through the urine and methane, from the digestible energy.…”