Calculation of fecal kinetics in horses fed hay or hay and concentrate.

Abstract

Marker methods are needed for estimating fecal output by grazing animals in studies of nutrition and environmental impact. In addition, estimates of prefecal mass and turnover time are relevant to exercise performance and certain digestive disorders. As a first step in developing marker methods for field use, a chromic oxide model of fecal kinetics was developed and tested in the context of a digestion balance experiment with stall-fed horses. The model consists of removal of feces at a constant rate from a single compartment, the prefecal mass. Four horses were fed hay, and another four were fed hay and concentrate. Balance-marker experiments were conducted for 10 d, following 7 d of adaptation. A dose of chromic oxide mixed in chopped hay and molasses was administered from a nose bag at 0700 daily for 10 d. Dry matter and Cr were measured in feeds and feces. Fecal Cr concentration (C, mg/kg DM) varied during the day, so data from total daily collections were used for model development. These fecal Cr data (Ct) at time t (days) were fitted to a single exponential, with one rate constant (k), rising to an asymptote (Ca): Ct = Ca - Ca x e(-kt). Superior fits were obtained when a delay (d) was introduced between the pulse oral dose and the entry of marker into the prefecal pool: Ct = Ca - Ca x e(-k(t-d)). Using pooled data, delays of 2.7 and 2.0 h gave best fits (highest estimates of R2) for pooled data from horses fed hay or hay plus concentrate, respectively. The model generated estimates of 3.4 and 3.8 kg/d of DM for fecal outputs (dose/Ca) of horses fed hay or hay and concentrate, respectively. The rate constants yielded turnover times (1/k) of 33 and 18 h, and prefecal masses [(dose/Ca)/k] of 4.6 and 2.9 kg of DM for hay or hay and concentrate groups, respectively. Using data from individual horses, mean estimates for each diet were similar to corresponding values for the pooled data. In balance experiments, feces collected were 3.7 and 4.4 kg/d, and Cr recoveries were 108 and 115% dose for the hay and hay plus concentrate diets, respectively. Marker estimates (M) were correlated with total collection estimates (T) of fecal output [M = T(.890 +/- .045); r = .70, P = .041]. Adjusting for recovery improved the regression coefficient to 1.009 +/- .028 (r = .87, P = .002). The findings suggest that if Cr doses are more frequent than daily and if Cr inputs other than dose can be eliminated this method should give accurate and precise estimates of fecal output.

Valor nutritivo e estudo cinético do trato digestivo de dietas contendo grãos secos ou ensilados de sorgo de baixo e alto tanino para eqüinos

“…Para eqüinos, o TT com valor médio de 28,42 h expressa o tempo gasto para a partícula percorrer o intestino delgado, o qual se assemelha ao valor registrado por Oliveira et al (2003), de 25,5 h, em eqüinos consumindo ração com 60% de volumoso e 40% de concentrado, e supera o obtido por Holland et al (1998), de 18,1h, para a mesma espécie animal alimentando-se de dieta mista. Adicionalmente, este parâmetro superou os resultados de 12,26 a 23,0h encontrados nos estudos com ruminantes consumindo concentrado e volumoso.…”

“…Os primeiros seis dias corresponderam à fase de adaptação dos animais às instalações, dietas e condições de manejo, de acordo com as metodologias descritas por Gibbs et al (1996) e Oliveira et al (2003), para os ensaios de digestibilidade, e Holland et al (1998), para avaliação da cinética digestiva. A fase seguinte foi destinada à coleta parcial de fezes, com duração de seis dias, na qual se determinaram os coeficientes de digestibilidade e as estimativas do trânsito gastrintestinal das dietas experimentais.…”

Trânsito gastrintestinal e digestibilidade aparente de nutrientes em eqüinos alimentados com dietas contendo grãos secos ou silagem de grãos úmidos de triticale

“…O concentrado O experimento teve duração total de 60 dias, subdivididos em cinco períodos de 12 dias cada um. Os primeiros seis dias corresponderam à fase de adaptação dos animais às instalações, dietas e condições de manejo, de acordo com as metodologias descritas por Gibbs et al (1996) e Oliveira et al (2003a), para os ensaios de digestibilidade, e Holland et al (1998), para avaliação da cinética digestiva. A fase seguinte foi destinada à coleta parcial de fezes, com duração de seis dias, determinando-se, assim, os coeficientes de digestibilidade e as estimativas do trân-sito gastrintestinal das dietas experimentais.…”

“…Controle 50-TS 50-TE 100-TS 100-TE concentrado, e supera o TT de 18,1h para a mesma espécie animal alimentando-se com dieta mista (Holland et al, 1998). Este parâmetro foi superior ao obtido com ruminantes, cujas médias variaram de 12 a 23h para bovinos recebendo uma mistura de concentrado e volumoso (Krysl et al, 1998).…”

Risk factors associated with colic in horses

“…* Forages: a high percentage of fibre has been suggested to favour the impaction of the small intestine by stimulating intestinal motility, resulting in an important absorption of water [13]. In a study conducted on 18 horses involved in sporting events in Georgia and fed with a forage composed of Cynodon spp., a graminae very rich in crude cellulose, 7 horses developed impaction [23].…”