Differential mRNA Abundance of Amino Acid Transporters B 0,+ , CAT-1, LAT-2, and LAT-3 in Five Segments of the Equine Intestine

Woodward, Adrienne; Holcombe, Susan J.; Staniar, Burt; Liesman, J.S.; Trottier, N. L.

doi:10.1016/j.jevs.2009.04.056

Cited by 1 publication

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“…Passive diffusion of AA across the wall of the large intestine might occur to explain the slight appearance of isotopes N 15 or C 14 in the blood, but Bochrö der et al (1994) pointed out the impermeability of colon mucosa to AA using in vivo experiments. However, in a recent study, Woodward et al (2009 and2010) refer to the presence of AA transporters in the cecum and colon of horses, indicating that the large intestine might contribute to both cationic and neutral AA uptake and absorption. The topic of peptide and AA absorption in the equine hindgut remains controversial; either it is microbial protein AA or dietary originated AA.…”

Section: Nitrogen Metabolism In the Hindgutmentioning

confidence: 99%

Understanding the equine cecum-colon ecosystem: current knowledge and future perspectives

Santos¹,

Rodrigues²,

Bessa³

et al. 2011

Animal

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Having evolved as a grazing animal, a horse's digestive physiology is characterized by rapid gastric transit, a rapid but intense enzymatic digestion along the small intestine, and a long and intense microbial fermentation in the large intestine. The process of understanding and describing feed degradation mechanisms in the equine digestive system in general, and in the hindgut ecosystem in particular, is essential. Regardless of its importance for the nutritional status of the host, the significance of the cecum-colon ecosystem has not yet been fully understood, and few reports have focused deeply on the contribution of the hindgut microbial population to the nitrogen and energy requirements of the horse. Compared to ruminal activity, very little is known about hindgut ecosystem activity in the horse. Information concerning the metabolism of this microbial population and its requirements is lacking. The use of internal bacterial markers for quantifying microbial outflow in ruminants is widely reported. These techniques can be applied to cecum-colon microbial quantification, contributing to a better characterization of this ecosystem. It is likely wrong to believe that the optimization strategy in the hindgut is similar to what happens in the rumen -that is, to maximize microbial growth and, therefore, fermentation. If we consider the type of substrate that, in normal conditions, arrives in the hindgut, we can expect it to be nitrogen limiting, providing limited nitrogen-based substrates for microbial fermentation. In this review paper, we intend to gather existing information on the equine ecosystem and to provide future perspectives of research.Keywords: horse, cecum, colon, digestive strategy ImplicationsThe process of understanding and describing degradation mechanisms in the equine digestive ecosystem in general, and in the hindgut in particular, is essential to provide information for proper feeding practices to be implemented. Regardless of its importance for the nutritional status of the host, the significance of hindgut fermentation has not yet been fully understood, and few reports have focused deeply on the contribution of the hindgut microbial population to the nitrogen and energy requirements of the horse. In this review paper, we intend to gather existing information on the equine ecosystem and to provide future perspectives of research. IntroductionHorses are free-ranging herbivores of grassland environments adapted to eat large quantities of high fiber feeds (Janis, 1976;Bennett, 1980). Nowadays, with the increase of their use in sports and leisure, many horses are housed during long periods of time and fed daily on two or three meals of forages plus concentrate. The forage component of the diet is sometimes characterized by having low-tomedium energy concentration and variable levels of fiber and protein (Micol and Martin-Rosset, 1995). This pattern of feed supply is not as expected by the horse's phylogenetic adaptation to grassland environments (Janis, 1976). These management procedures have i...

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Section: Nitrogen Metabolism In the Hindgutmentioning

confidence: 99%