The Evolutionary Strategy of the Equidae and the Origins of Rumen and Cecal Digestion

Janis, Christine M.

doi:10.1111/j.1558-5646.1976.tb00957.x

Cited by 382 publications

(172 citation statements)

References 31 publications

(43 reference statements)

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“…The abomasum and intestine are closely related, as are the stomach and intestine in nonruminants, and the rumen is closely related to the abomasum and intestine as well as the reticulum and omasum. These results, plus previous reviews that suggest that foregut evolution is evolutionarily easy [12], indicate an early foregut evolutionary event stemming from the intestine and later development of compartments stemming from a subsequently evolved rumen.…”

Section: Discussionsupporting

confidence: 74%

Elucidating the Evolutionary Relationships among Bos taurus Digestive Organs Using Unigene Expression Data

Beck

Jiang

Zhang

2009

International Journal of Evolutionary Biology

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Although the nature of ruminant evolution is still disputed, current theory based on physiology and genetic analysis suggests that the abomasum is the evolutionarily oldest stomach compartment, the rumen evolved some time after the abomasum, and the omasum is the evolutionarily youngest stomach compartment. In addition, there is some evidence of relaxed selective constraint in the stomach-like organ and the foregut shortly after the foregut formation event. Along with the assumption of a mean, stochastic rate of evolution, analysis of differences in genetic profiles among digestive body organs can give clues to the relationships among these organs. The presence of large numbers of uniquely expressed entries in the abomasum and rumen indicates either a period of relaxed selective constraint or greater evolutionary age. Additionally, differences in expression profiles indicate that the abomasum, rumen, and intestine are more closely related to each other, while the reticulum and omasum are more closely related to the rumen. Functional analysis using Gene Ontology (GO) categories also supports the proposed evolutionary relationships by identifying shared functions, such as muscle activity and development, lipid transport, and urea metabolism, between all sections of the digestive tract investigated.

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Section: Discussionsupporting

confidence: 74%

Elucidating the Evolutionary Relationships among Bos taurus Digestive Organs Using Unigene Expression Data

Beck

Jiang

Zhang

2009

International Journal of Evolutionary Biology

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“…Horses are hindgut fermenters, adapted to grazing continually on marginal forages that change seasonally, thus slowly [1]. The hindgut (caecum and colon) comprises roughly two thirds of the volume of the equine digestive tract [2].…”

Section: Introductionmentioning

confidence: 99%

An In Vitro Model of the Horse Gut Microbiome Enables Identification of Lactate-Utilizing Bacteria That Differentially Respond to Starch Induction

2013

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Laminitis is a chronic, crippling disease triggered by the sudden influx of dietary starch. Starch reaches the hindgut resulting in enrichment of lactic acid bacteria, lactate accumulation, and acidification of the gut contents. Bacterial products enter the bloodstream and precipitate systemic inflammation. Hindgut lactate levels are normally low because specific bacterial groups convert lactate to short chain fatty acids. Why this mechanism fails when lactate levels rapidly rise, and why some hindgut communities can recover is unknown. Fecal samples from three adult horses eating identical diets provided bacterial communities for this in vitro study. Triplicate microcosms of fecal slurries were enriched with lactate and/or starch. Metabolic products (short chain fatty acids, headspace gases, and hydrogen sulfide) were measured and microbial community compositions determined using Illumina 16S rRNA sequencing over 12-hour intervals. We report that patterns of change in short chain fatty acid levels and pH in our in vitro system are similar to those seen in in vivo laminitis induction models. Community differences between microcosms with disparate abilities to clear excess lactate suggest profiles conferring resistance of starch-induction conditions. Where lactate levels recover following starch induction conditions, propionate and acetate levels rise correspondingly and taxa related to Megasphaera elsdenii reach levels exceeding 70% relative abundance. In lactate and control cultures, taxa related to Veillonella montpellierensis are enriched as lactate levels fall. Understanding these community differences and factors promoting the growth of specific lactate utilizing taxa may be useful to prevent acidosis under starch-induction conditions.

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“…From allometric trends in metabolic rates, smaller ruminants are expected to have higher dietary requirements, and hence higher faecal nutrient thresholds for tissue maintenance, than larger‐bodied species. Nonruminants have higher rates of digestive passage than ruminants of similar body size, and hence are able to tolerate higher indigestible fibre and correspondingly lower nutrient concentrations in the food they ingest than ruminants (Janis, ; Duncan et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Faecal nutritional indicators in relation to the comparative population performance of sable antelope and other grazers

Macandza

Owen‐Smith

2013

Afr. J. Ecol.

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In the Kruger National Park, sable antelope underwent a substantial decline in abundance after 1987. Our study investigated whether forage quality as reflected by faecal nutrient contents could be restricting population recovery. Faecal samples were collected from sable, zebra and buffalo in one study area and from sable only in a second study area with higher mean rainfall, during the dry seasons of two successive years. Faecal samples were analysed for nitrogen, phosphorus, sodium and crude fibre. Faecal nitrogen and phosphorus levels were similar for sable and buffalo and remained around or slightly above putative maintenance levels, but were higher than shown by nonruminant zebra. Faecal sodium levels were substantially lower for sable than for the other two grazers. In the wetter study area, faecal nitrogen levels for sable herds fell below the minimum maintenance level throughout the dry season in the drier year. Although faecal nutrient levels for sable appeared only marginally limiting under the conditions that prevailed during the study, malnutrition could have contributed to the population decline by sable during a persistently low-rainfall period.

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The Evolutionary Strategy of the Equidae and the Origins of Rumen and Cecal Digestion

Cited by 382 publications

References 31 publications

Elucidating the Evolutionary Relationships among Bos taurus Digestive Organs Using Unigene Expression Data

Elucidating the Evolutionary Relationships among Bos taurus Digestive Organs Using Unigene Expression Data

An In Vitro Model of the Horse Gut Microbiome Enables Identification of Lactate-Utilizing Bacteria That Differentially Respond to Starch Induction

Faecal nutritional indicators in relation to the comparative population performance of sable antelope and other grazers

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