Effects of dietary fibre on behaviour and satiety in pigs

During the past decades there has been considerable interest in the use of dietary fibre in both animal and human nutrition. In human subjects dietary fibre has been studied intensively for possible effects on body-weight management and health. In animal nutrition the interest in dietary fibre has increased because it can be used as a cheap source of energy and because of its potential to improve animal welfare and reduce abnormal (mainly stereotypic) behaviour. Animal welfare is impaired if the diet does not provide sufficient satiety, combined with an environment that does not meet specific behavioural requirements related to natural feeding habits (e.g. rooting in pigs). A considerable proportion of the behavioural effects of dietary fibre are thought to be related to reduced feeding motivation. It has been hypothesized that: (1) bulky fibres increase satiety and thereby decrease physical activity and stereotypic behaviours immediately following a meal in pigs; (2) fermentable fibres prolong postprandial satiety and thereby reduce physical activity and appetitive behaviours for many hours after a meal. The validity of these hypotheses is examined by considering published data. In sows dietary fibres (irrespective of source) reduce stereotypic self-directed behaviours and substrate-directed behaviours, and to a lesser extent overall physical activity, indicating enhanced satiety shortly after a meal. Furthermore, fermentable dietary fibre reduces substrate-directed behaviour in sows and physical activity in sows and growing pigs for many hours after a meal. Evidence of long-term effects of poorly-fermentable fibre sources is inconclusive. The findings suggest that highly-fermentable dietary fibres have a higher potential to prolong postprandial satiet

Origins of Chevron Rollovers in Non-Two-State Protein Folding Kinetics

Chevron rollovers of some proteins imply that their logarithmic folding rates are nonlinear in native stability. This is predicted by lattice and continuum G\=o models to arise from diminished accessibilities of the ground state from transiently populated compact conformations under strongly native conditions. Despite these models' native-centric interactions, the slowdown is due partly to kinetic trapping caused by some of the folding intermediates' nonnative topologies. Notably, simple two-state folding kinetics of small single-domain proteins are not reproduced by common G\=o-like schemes.Comment: 10 pages, 4 Postscript figures (will appear on PRL