Effects of fermentable starch and straw-enriched housing on energy partitioning of growing pigs

Both dietary fermentable carbohydrates and the availability of straw bedding potentially affect activity patterns and energy utilisation in pigs. The present study aimed to investigate the combined effects of straw bedding and fermentable carbohydrates (native potato starch) on energy partitioning in growing pigs. In a 2 × 2 factorial arrangement, 16 groups of 12 pigs (approximately 25 kg) were assigned to either barren housing or housing on straw bedding, and to native or pregelatinised potato starch included in the diet. Pigs were fed at approximately 2.5 times maintenance. Nitrogen and energy balances were measured per group during a 7-day experimental period, which was preceded by a 30-day adaptation period. Heat production and physical activity were measured during 9-min intervals. The availability of straw bedding increased both metabolisable energy (ME) intake and total heat production (P <0.001). Housing conditions did not affect total energy retention, but pigs on straw bedding retained more energy as protein (P <0.01) and less as fat (P <0.05) than barren-housed pigs. Average daily gain (P <0.001), ME intake (P <0.001) and energy retention (P <0.01) were lower in pigs on the native potato starch diet compared to those on the pregelatinised potato starch diet. Pigs on the pregelatinised potato starch diet showed larger fluctuations in heat production and respiration quotient over the 24-h cycle than pigs on the native potato starch diet, and a higher activity-related energy expenditure. The effect of dietary starch type on activity-related heat production depended, however, on housing type (P <0.05). In barren housing, activity-related heat production was less affected by starch type (16.1% and 13.7% of total heat production on the pregelatinised and native potato starch diet, respectively) than in straw-enriched housing (21.1% and 15.0% of the total heat production on the pregelatinised and native potato starch diet, respectively). In conclusion, the present study shows that the availability both of straw bedding and of dietary starch type, fermentable or digestible, affects energy utilisation and physical activity of pigs. The effects of housing condition on protein and fat deposition suggest that environmental enrichment with long straw may result in leaner pigs. The lower energy expenditure on the physical activity of pigs on the native potato starch diet, which was the most obvious in straw-housed pigs, likely reflects a decrease in foraging behaviour related to a more gradual supply of energy from fermentation processes

The relationship between psychological resilience and posttraumatic stress in young adults exposed to an earthquake

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Design of climate respiration chambers, adjustable to the metabolic mass of subjects

Open-circuit respiration chambers can be used to measure gas exchange and to calculate heat production (Q) of humans and animals. When studying short-term changes in Q, the size of the respiration chamber in relation to the subject of study is a point of concern. The washout time of a chamber, defined as the proportion of the chamber size to the rate of ventilation, needs to be minimised for accurate measurement of short term changes in Q. To date, most respiration chambers have a fixed size, limiting their use for different species, sizes and number of subjects, thus hampering studying the short term dynamics of Q. This chapter presents various approaches to the design, construction and testing of respiration chambers, adjustable to the metabolic mass inside. As investment costs for constructing respiration chambers are high, flexibility in the use of chambers can contribute substantially to an efficient use of resources. Furthermore, an outline is given to sensor criteria and calibration and finally, the validation of a whole indirect-calorimetric system is described. Air leak tolerance is defined and attention is paid to caretaking of animals, excreta collection and animal and personnel welfare and safety. Respiration facilities, recently constructed at Wageningen University are presented as an example. Briefly, four 45 m2 climate chambers can be used, e.g. for heat or cold stress experiments, to incubate eggs or as a hygiene barrier. Within each chamber, one or two smaller airtight, size adaptable respiration rooms, can be built in where ambient temperature, humidity and ventilation rate can be controlled independently. In each respiration room a wide range of ventilation flow rates can be accomplished and both hypobaric and hyperbaric air pressure control can be established, allowing energy metabolism experiments with specific pathogen free animals (hyperbaric) or trials with infectious agents (hypobaric)

Mineral absorption and excretion as affected by microbial phytase and their effect on energy metabolism in young piglets

Positive effects of dietary phytase supplementation on pig performance are observed not only when phosphorus is limiting. Improved energy utilization might be one explanation. Using indirect calorimetry, phytase-induced changes in energy metabolism were evaluated in young piglets with adequate phosphorus intake. Eight replicates of 8 group-housed barrows each were assigned to either a control or a phytase-supplemented diet [1500 phytase units (FTU)/kg feed]. Piglets were fed a restricted amount of the control or phytase diet. The diets were made limiting in energy content by formulating them to a high digestible lysine:DE ratio. Fecal nutrient digestibility, portal blood variables, organ weights, and apparent absorption and urinary excretion of ash, Ca, P, Na, K, Mg, Cu, and Fe, were also measured. A model was developed to estimate energy required for absorption and excretion, which are partly active processes. Phytase tended to improve energy digestibility (P = 0.10), but not its metabolizability. Energy retention and heat production were not affected. At the end of the 3-wk period, pancreas weight (P <0.05) and blood pH were lower (P <0.01), and CO2 pressure was higher (P <0.01) due to phytase. This suggests that phytase reduced energy expenditure of the digestive tract, and increased metabolic activity in visceral organs. The potential increases in energy retention due to phytase were counterbalanced by increased energy expenditures for processes such as increased mineral absorption (for most P <0.05), and their subsequent urinary excretion. Energy costs of increased absorption of nutrients, and deposition and excretion of minerals was estimated as 4.6 kJ/(kg0.75·d), which is 1% of the energy required for maintenance. The simultaneous existence of both increases and decreases in heat production processes resulted in the absence of a net effect on energy retention