Passage kinetics of digesta in horses fed with coastcross hay ground to different degrees

Abstract

This study was conducted to evaluate the kinetics, physicochemical characteristics and particle size of digesta in the right ventral colon (RVC) of horses fed coastcross hay ground to different degrees. Four horses fitted with cannulae in the RVC were used and were fed the following forms of hay: long, chopped, ground to 5 mm and ground to 3 mm. A Latin Square 4x4 study design was used. Each experimental period included 10 days for diet adaptation, four days for feces collection and one day for digesta collection. The kinetics of the particulate and solute phases of digesta were evaluated based on the mean retention time (MRT), passage rate (k) and transit time (TT) using two external markers: Cr-NDF and Co-EDTA. The TT of solid phase digesta was 3 hours longer (P<0.05) for ground hay than with the other physical forms of hay. There was no difference (P>0.05) in k or MRT in either the liquid or solid phase of digesta as a function of the different degrees of hay grinding. However, the liquid phase of digesta presented a higher k than the solid phase, with values of 3.28 and 2.73 h -1 being obtained, respectively. The smallest particle size and the lowest neutral detergent fiber contents in colon digesta were observed when hay ground to 3 mm was offered, leading to values of 0.51 mm and 53.46%, respectively. Grinding the hay increased the transit time of the liquid phase in the digestive tract of the horses, whereas no change in the kinetics of the solid phase digesta was observed. The grinding of hay reduced the NDF and the average particle size in the right ventral colon.Index terms: Chromium, digestion, particle size, passage rate. RESUMOEste trabalho teve como objetivos avaliar a cinética de passagem da digesta, as características físico-químicas e o tamanho da partícula da digesta do cólon ventral direito (CVD) de equinos alimentados com feno de coastcross com diferentes tamanhos de partículas. Utilizaram-se quatro equinos fistulados CVD alimentados exclusivamente com feno de coastcross: inteiro; feno picado, moído (5 mm) e moído (3 mm). Utilizou-se o delineamento em quadrado latino 4x4. Cada período experimental teve 10 dias de adaptação às dietas, quatro dias de coleta de fezes e um dia de coleta do conteúdo do cólon. A cinética de passagem da fase sólida e líquida da digesta no trato digestório foi estimada através do tempo médio de retenção (TMR), da taxa de passagem (k) e do tempo de trânsito (TT) utilizando os indicadores: Cr-FDN e Co-EDTA. O TT da fase sólida da digesta foi maior em 3 horas (P<0,05) nos equinos alimentados com o feno moído, em relação às outras formas do feno. Não houve diferença (P>0,05) no TMR e k tanto da fase líquida quanto na sólida da digesta em função das diferentes formas físicas do feno. No entanto, houve maior velocidade de passagem da fase líquida de 3,28 h -1 , comparada à fase sólida, de 2,73 h -1 , em todas as dietas. Quando se forneceu feno moído a 3 mm foram observados o menor tamanho de partícula e o menor teor da fibra em detergente neutro na digesta do cólon...

No size‐dependent net particle retention in the hindgut of horses

“…The finding of no discrimination by particle size also matches observations that in the equid hindgut, there is no difference in the particle retention time for hay fed whole and a barley-based pelleted concentrate fed simultaneously (Austbø & Volden, 2006), even though it cannot be excluded that ingestive mastication reduced all material to the same particle size. Note that this similar retention of hay and concentrate does not contradict findings that if the same feed is fed at the same intake level at different particle sizes, horses have different overall retention times between these treatments (Drogoul et al, 2000), even though this effect is also often limited or absent (Miyaji et al, 2011;Moore-Colyer et al, 2003;Silva et al, 2014). This difference in overall retention time observed by Drogoul et al (2000) does not imply a discrimination by particle size in the digestive tract, but different effects of the same diet at different particle size on overall gut motility.…”

Equine fecal inoculum optimization in in vitro fermentation assays of dehydrated roughage

“…Several studies with equine species were performed using in vivo or in situ methodologies to better understand the digestion process, which invariably involves kinetics of passage and nutrient degradation. Therefore, we have used the kinetic of passage (Van Weyenberg et al, 2006;Silva et al, 2014) and nutrient degradation information (Hyslop, 2006;Silva et al, 2010) to support the interpretations of the present study. Additionally, due to limitation to obtain fistulated animals for in vitro fermentation studies, a limiting factor nowadays, we had to use the information currently existing in the literature.…”

“…Additionally, due to limitation to obtain fistulated animals for in vitro fermentation studies, a limiting factor nowadays, we had to use the information currently existing in the literature. Therefore, Van Weyenberg et al (2006) described values of mean retention time (MRT) in horses fed different feedstuffs no longer than 48 h. Verifying the in situ degradation of nutrients of fibrous feed, Hyslop (2006) used the incubation up to 48 h as the maximum time for cecal incubation, and recently, Silva et al (2014) fed fistulated horses coastcross hay with different particle size and observed values of 36.7 h of MRT. Consequently, the incubation time in in vitro fermentation essays with equine fecal inoculum should not exceed 48 h.…”

Effect of Wheat Dietary Fiber Particle Size during Digestion In Vitro on Bile Acid, Faecal Bacteria and Short-Chain Fatty Acid Content

“…The second group consists of samples with WF 500 dietary fibre, characterized by a high content of hemicellulose and ash. The research conducted by Silva et al [ 26 ] demonstrated a reduction in the level of NDF in ground hay together with the reduction of particle size, therefore, the hemicellulose fraction content was higher in ground hay of larger particle size. Because vectors depicting such variables as hemicellulose and ash point in the opposite directions to those representing NDF, SDF and cellulose, it can be concluded that these variables are inversely correlated.…”