Avaliação de indicadores em estudos com ruminantes: digestibilidade

Abstract

RESUMO -Foram conduzidos dois experimentos com o objetivo de avaliar os indicadores internos fibra em detergente neutro indigestível (FDNi) e fibra em detergente ácido (FDAi), obtidos por incubação in situ durante seis dias, e os indicadores externos óxido crômico (Cr 2 O 3 ), dióxido de titânio (TiO 2 ) e lignina isolada, purificada e enriquecida (LIPE ® ) em dois esquemas de coleta total de fezes (3 ou 5 dias) para estimativa da digestibilidade em bovinos. O delineamento experimental foi o de blocos ao acaso com parcelas subdivididas. No primeiro experimento, foram utilizadas cinco novilhas mestiças alimentadas com cana-de-açúcar com 1% de ureia/sulfato de amônio e concentrado (1% do peso vivo). Não houve diferenças entre as metodologias de coleta para a digestibilidade da matéria seca. Quando estimada utilizando-se FDAi, a digestibilidade dos nutrientes foi subestimada, mas, quando estimada utilizando-se FDNi e os indicadores externos (óxido crômico, dióxido de titânio e LIPE ® ), não diferiu significativamente daquela determinada por coleta total de fezes. No segundo experimento, foram utilizadas oito vacas em lactação alimentadas com silagem de milho e 4 kg de concentrado. Não houve diferença na digestibilidade da matéria seca entre os períodos de coleta. A digestibilidade dos nutrientes, quando estimada utilizando-se FDNi, foi superestimada, mas, quando estimada utilizando-se FDAi e os indicadores externos (óxido crômico, dióxido de titânio e LIPE ® ), não diferiu significativamente daquela determinada por coleta total de fezes. Três dias de coleta são suficientes para estimativa da digestibilidade e os indicadores testados são eficientes na determinação da digestibilidade. Palavras-chave: coleta total, indicadores externos, indicadores internos Evaluation of markers in ruminant trials: digestibilityABSTRACT -Two studies were carried out to evaluate indigestible neutral detergent fiber (iNDF) and indigestible acid detergent fiber (iADF) as internal markers obtained by 144-h incubation in situ and chromium oxide (Cr 2 O 3 ), titanium dioxide (TiO 2 ) and isolated, purified and enriched lignin (LIPE ® ) as external markers, and two total fecal collection schemes (3 or 5 days) to estimate digestibility in bovines. The experimental procedure was a randomized block design in a split plot arrangement. In the first trial, five crossbreed heifers fed sugar cane plus 1% of urea/ammonium sulfate and concentrate (1% of body weight) were used. There was no difference for dry matter digestibility when the collection schemes were compared (5 days vs 3 days). The nutrient digestibility estimated by iADF was underestimated and those estimated by iNDF, chromium oxide, titanium dioxide and LIPE ® , did not differ from the digestibility calculated on total fecal collection. In the second trial, eight lactating cows fed corn silage and concentrate (4 kg/cow/day) were used. There was no difference for dry matter digestibility when the collection schemes were compared (5 days vs 3 days). The nutrient digestibility estimated by ...

Evaluation of fecal recovering and long term bias of internal and external markers in a digestion assay with cattle

“…Additionally, Marcondes et al (2008) and Ferreira et al (2009a) observed that titanium dioxide can be accurately used for estimating the individual intake of concentrate by group feeding cattle when it was associated with other markers. On the other hand, Titgemeyer et al (2001) verified in experiments with cattle that diet characteristics did not affect the fecal recovering of titanium dioxide.…”

“…The most evaluations are concerned non-tropical conditions (Titgemeyer et al, 2001;Myers et al, 2004;Glindemann et al, 2009) and studies on its use in the tropics are still incipient (Marcondes et al, 2006;Ferreira et al, 2009a;2009b).…”

Evaluation of internal markers as determinants of fecal dry matter output and digestibility in feedlot sheep

“…For instance, Cabral et al (2008) observed that iNDF was effective in determining the FDMO and DM digestibility in cattle fed corn silage, Tifton-85 grass hay and elephant-grass silage; iADF, in turn, was effective in determining the analyzed variables only when the animals consumed the corn or elephant-grass silages, but was ineffective when the hay was used. Ferreira et al (2009) observed different results in two experiments. In experiment 1, using crossbred heifers fed sugarcane + urea, iNDF was effective in determining the digestibility of DM, while iADF underestimated this variable.…”

Inclusion of copaiba oil (Copaifera sp.) as additive in supplements for cattle on pasture

“…The animals received titanium dioxide (TiO 2 ) for ten consecutive days, with adaptation to the external indicator for five days (1 st -5 th day) and five days of collection (6 th -10 th day). Titanium dioxide (10 g/day) was packed in paper cartridges and introduced directly into the rumen of the fistulated animals at 08 and 17h; as described by Ferreira et al (2009a). Fecal samples were collected for five days directly from the rectum of the animals once a day, at different times (6, 8, 10, 12 and 14h); in approximate amounts of 200 g, as described by Ferreira et al (2009b).…”