The effect of chewing by sheep in the release of nitrogen and soluble carbohydrates from plant cells

Mayne²,

et al. 2002

Anim. Res.

-The objective of the trial was to analyse the effects of the mechanical resistance of cell walls and chewing behaviour on the proportion of intracellular constituents (ICs) released during the ingestive mastication of fresh perennial ryegrass (Lolium perenne L.) by steers. The mechanical resistance of cell walls was varied by the stage of maturity (15 vs. 30 days of regrowth). Herbage was offered at two chop lengths (long and short) for each stage of maturity, to influence chewing behaviour. Four steers, each fitted with a large ruminal cannula, were fed indoors with the ryegrass in a 4 × 4 Latin square design. Ingested boli were collected at the cardia and their IC contents were compared with the IC contents of the grass. The average shear energy was lower with the young grass because of a lower proportion of stems and pseudostems. The eating time per unit of dry matter intake was unaffected by the stage of maturity, but was slightly lower with the short herbages. The nature of the ICs had a strong effect on their release with the larger molecules, or the molecules contained in the chloroplasts, being less rapidly released. The ICs released (as a proportion of intake) ranged from 0.166 for the chlorophyll to 0.612 for the nitrates. The treatments had no effect on the rate of release of the small vacuolar or cytoplasmic ICs. The intracellular nitrogenous fractions, partly in the chloroplast, were released faster in the mature grass, because the animals had to masticate more intensively to obtain a 'swallowable'bolus due to it having a higher shear energy. The release of ICs did not seem to be dependent on the duration of chewing but rather on other parameters of mastication like the force exerted by the jaws, the surface-area of the molars, or the quantity of grass eaten per bolus. Résumé -Effet du stade de maturité et de la longueur des brins sur la libération des contenus cellulaires du ray-grass anglais frais (Lolium perenne L.) au cours de la mastication d'ingestion sur des bouvillons nourris à l'auge. L'objectif de cet essai était d'analyser les effets spécifiques de la résistance mécanique des parois et du comportement masticatoire des animaux sur les proportions de constituants intracellulaires (ICs) libérées lors de la mastication d'ingestion chez des bouvillons nourris avec du ray-grass anglais frais (Lolium perenne L.). La résistance mécanique des parois a été modulée par le stade de maturité (15 vs. 30 jours de repousse). Pour chaque stade, le comportement masticatoire a été modulé en offrant l'herbe à deux longueurs de brins (long vs. court). Quatre bouvillons, munis d'une large canule ruminale ont été nourris à l'auge en carré latin 4 × 4. Des bols d'ingestion ont été collectés directement au cardia et leurs teneurs en ICs ont été comparées avec celles de l'herbe offerte. La résistance mécanique de l'offert a été mesurée comme la moyenne des quantités d'énergie nécessaires pour couper chaque type d'organe végétal, pondérée par les proportions pondé-rales de chacun des organes dans l'offert...

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Section: The Release Depends On the Mean Size Of The Considered Icsupporting

confidence: 60%

Section: The Release Depends On the Mean Size Of The Considered Icmentioning

confidence: 99%

Effects of stage of maturity and chop length on the release of cell contents of fresh ryegrass (Lolium perenne L.) during ingestive mastication in steers fed indoors

Mayne²,

et al. 2002

Anim. Res.

show abstract

Species and variety of herbage affects release of cell contents during ingestive mastication in dairy cows fed indoors

Acosta

Animal Feed Science and Technology

2007

The release of intracellular constituents from fresh ryegrass (Lolium perenne L.) during ingestive mastication in dairy cows: effect of intracellular constituent, season and stage of maturity

Animal Feed Science and Technology

2001