Influence of pH on lipolysis and biohydrogenation of soybean oil by rumen contents in vitro

Nevel, Christian Van; Demeyer, D.

doi:10.1051/rnd:19960105

Cited by 129 publications

(96 citation statements)

References 13 publications

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“…Therefore, the increased fermentability of BBD compared with CBD would have made more dietary fat available for lipase action, which explains the greater concentrations of PUFA (LA and LNA) for BBD than CBD in the rumen. A lower pH has been reported to decrease lipase activity in vitro (Van Nevel and Demeyer, 1996); however, its influence appeared minimal in our study since the pH differences between the two diets were relatively small compared with the larger differences in rates of DM and starch degradability. The effect of grain processing on the extent of PUFA biohydrogenation was milder and could be attributed to the lack of difference in rumen pH between rolled and ground diets.…”

Section: Pufa Metabolismcontrasting

confidence: 65%

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Mohammed

Kennelly

Kramer

et al. 2010

Animal

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It was hypothesized that differences in starch degradability account for observed differences in rumen vaccenic acid (t11-18:1) and milk rumenic acid (RA) concentrations. To test this hypothesis, starch degradability was varied through grain source and by processing. Eight Holstein cows in mid-lactation were assigned to two 4 3 4 Latin squares with four 21-day periods and four diets: dry rolled barley, ground barley, dry rolled corn and ground corn. Diets contained similar starch content and were supplemented with whole sunflower seed to provide similar total polyunsaturated fatty acid (PUFA) (18:2n-6 1 18:3n-3) contents. Forage/ concentrate ratios of all diets were 42 : 58. Rumen, plasma and milk samples were collected in the third week of each period. In situ degradation rates (%/h) for rolled corn, ground corn, rolled barley and ground barley were 5.4, 8.9, 17.0 and 19.4, respectively, for dry matter (DM) and 6.3, 10.8, 25.3 and 43.8, respectively, for starch. DM intakes were greater for corn-based diets (CBD) than for barley-based diets (BBD) with no difference between rolled and ground diets. Daily minimum rumen pH was less (5.2 v. 5.5) and pH duration ,5.8 (h/d) was greater (7.4 v. 4.3) for BBD than for CBD. Milk fat content and yield were less for BBD than for CBD with greater values observed for rolling compared with grinding. Variability in milk fat yield was strongly related (R 2 5 0.55; P , 0.01) to total starch intake (45%) and milk c9t11-CLA (10%) and none of the t-18:1 isomers or CLA isomers that are typically associated with milk fat depression entered the model. The concentrations (%) of t10-18:1 and t11-18:1 were greater for BBD than for CBD in rumen contents (t10-18:1, 3.5 v. 1.3; t11-18:1, 3.2 v. 1.9), plasma (t10-18:1, 1.2 v. 0.2; t11-18:1, 0.97 v. 0.58) and milk (t10-18:1, 3.8 v. 1.0; t11-18:1, 2.6 v. 1.7) despite greater total PUFA intakes for CBD. Milk RA concentration was greater for BBD than for CBD (1.46 v. 0.89) but was not influenced by the method of grain processing. This study clearly demonstrated that the milk content and profile of t-18:1 and CLA isomers were more strongly influenced by the source of grain starch (barley . corn) than by the method of grain processing indicating that factors inherent in the source of starch were responsible for the observed differences and these factors could not be modified by the processing methods used in this study.Keywords: grain processing, vaccenic acid, conjugated linoleic acid, corn, barley ImplicationsConjugated linoleic acid (CLA) is a component of milk fat with demonstrated health benefits. It was hypothesized that a difference in rate of starch digestion, varied through source of grain and processing method (rolling v. grinding), would influence rumen PUFA digestion and thus milk CLA. Concentrations of ruminal CLA precursors and milk CLA were greater for barley-based diets than corn-based diets but were not different between rolling and grinding indicating that factors inherent in the source of starch were responsible for the observed ...

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Section: Pufa Metabolismcontrasting

confidence: 65%

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Mohammed

Kennelly

Kramer

et al. 2010

Animal

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“…When concentrates comprise more than 70% of the diet, biohydrogenation is on average only 50 and 65% for linoleic and linolenic acid, respectively. This has been shown to be due to a drop in pH, limiting at first lipolysis, and thus hydrogenation which occurs only on free FA [139]. A large amount of dietary linoleic acid and a decrease in the…”

Section: The Fate Of Dietary Fatty Acids In the Rumenmentioning

confidence: 99%

Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids

et al. 2000

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-After a brief survey of metabolic pathways and nutrient fluxes involved in mammary lipogenesis, this review summarises the known effects of diet on ruminant milk fat composition. Special attention is given to fatty acids that could play a positive role for human health, such as butyric acid, oleic acid, C18 to C22 polyunsaturated fatty acids and conjugated linoleic acid (CLA). The efficiency of the transfer of C18:2, C18:3, C20:5, C22:5 and C22:6, from the duodenum to the milk, is reviewed. The main dietary factors taken into account are the nature of forages, including pasture, and the supplementation of dairy rations with protected or unprotected vegetable or fish oils. Dose-response curves of milk CLA are reviewed for different fat supplements, as well as the non-linear relationship between milk CLA and trans C18:1. The potential of dietary factors to increase the mean CLA content in cow milk fat is about 300% above basal values. There is, however, a need to evaluate how the different feeding strategies could change the other aspects of milk fat quality. ruminant / nutrition / milk / fatty acids / human healthRésumé -Plasticité de la matière grasse du lait de ruminant : contrôle nutritionnel des acides gras saturés, polyinsaturés, trans et conjugués. Après un bref rappel des voies métaboliques et des flux de nutriments qui concourrent à la lipogenèse mammaire, cette revue est consacrée aux principaux effets des facteurs alimentaires sur la composition des lipides du lait de ruminant. Un intérêt particulier est porté aux acides gras qui peuvent avoir des effets positifs sur la santé humaine, tels que les acides butyrique, oléique, linoléique conjugué (CLA) et les acides gras polyinsaturés, de 18 à 22 atomes de carbone. L'efficacité du transfert des C18:2, C18:3, C20:5, C22:5 et C22:6, du duodénum au lait est estimée à partir des données de la bibliographie. Les principaux facteurs alimentaires considérés sont la nature des fourrages, dont l'herbe pâturée, et la supplémentation des rations pour vaches laitières avec des huiles végétales ou de poisson, protégées ou non. L'augmentation potentielle

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“…Indeed, a pH sensitivity of lipases has been observed (Henderson, 1971;Faruque et al, 1974), and isomerase activity has also been shown to be dependent on pH (Kepler and Tove, 1967;Yokoyama and Davis, 1971;Troegeler-Meynadier, 2004), but modifications in bacterial populations or bacterial activity may also modify the BH process. Some authors have argued that the pH effect could be more important on lipolysis than on hydrogenation, without major effects on bacterial biomass (Van Nevel and Demeyer, 1996). In in vitro continuous cultures, the effects of pH on BH depend on other factors, including dilution rates or soluble carbohydrates (Martin and Jenkins, 2002).…”

Section: Digestion Of C18 Fatty Acids In Ruminantsmentioning

confidence: 99%

Digestion of fatty acids in ruminants: a meta-analysis of flows and variation factors: 2. C18 fatty acids

Glasser

Schmidely

Sauvant

et al. 2008

Animal

104

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In ruminants, dietary lipids are extensively hydrogenated by rumen micro-organisms, and the extent of this biohydrogenation is a major determinant of long-chain fatty acid profiles of animal products (milk, meat). This paper reports on the duodenal flows of C18 fatty acids and their absorption in the small intestine, using a meta-analysis of a database of 77 experiments (294 treatments). We established equations for the prediction of duodenal flows of various 18-carbon (C18) fatty acids as a function of the intakes of their precursors and other dietary factors (source and/or technological treatment of dietary lipids). We also quantified the influence of several factors modifying rumen metabolism (pH, forage : concentrate ratio, level of intake, fish oil supplementation). We established equations for the apparent absorption of these fatty acids in the small intestine as a function of their duodenal flows. For all C18 unsaturated fatty acids, apparent absorption was a linear function of duodenal flow. For 18:0, apparent absorption levelled off for high duodenal flows. From this database, with fatty acid flows expressed in g/kg dry matter intake, we could not find any significant differences between animal categories (lactating cows, other cattle or sheep) in terms of rumen metabolism or intestinal absorption of C18 fatty acids.

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Influence of pH on lipolysis and biohydrogenation of soybean oil by rumen contents in vitro

Cited by 129 publications

References 13 publications

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Effect of grain type and processing method on rumen fermentation and milk rumenic acid production

Ruminant milk fat plasticity: nutritional control of saturated, polyunsaturated, trans and conjugated fatty acids

Digestion of fatty acids in ruminants: a meta-analysis of flows and variation factors: 2. C18 fatty acids

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