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Digestibility is the result of two competing processes: digestion and digesta transit. To develop or parameterise mechanistic models of digestion, both processes have to be quantified. The aim of this study was to determine the effect of insoluble dietary fibre on the transit in the gastrointestinal tract of pigs. Six barrows (33??kg initial body weight and fitted with two simple T-cannulas at the proximal duodenum and distal ileum) were used in a double 3??????3 Latin square design. Pigs were offered diets differing in total dietary fibre content (170,??220 and 270??g/kg DM) at 4??h intervals. A single meal marked with YbO2 and Cr-EDTA was used to determine the kinetics of markers concentrations of the solid and liquid phases, respectively. The mean retention time (MRT), calculated by the method of the moments, averaged 1, 4 and 38??h in the stomach, small intestine and large intestine, respectively. Increasing the insoluble fibre content in the diet had no effect on MRT in the stomach and decreased the MRT of both phases in the small intestine (P??

Abstract: The method of Boisen and Fernandez [Boisen, S., Fernandez, J.A., 1997. Prediction of total tract digestibility of energy in feedstuffs and pig diets by in vitro analyses, Anim. Feed Sci. Technol. 68, 277–286] for measuring in vitro fecal digestibility of organic matter (OMdv) or in vitro digestible organic matter content (DOMv, g/kg) was used on 113 compound feeds (79 as mash and 34 as pellets) and 66 ingredients (as mash) whose digestibility of organic matter (OMd) and energy (Ed) and digestible energy content (DE, MJ/kg) had been measured in 60kg growing pigs for all compound feeds and ingredients, and in adult sows for about 2/3 of the compound feeds (as mash); net energy (NE, MJ/kg) of these feeds were estimated from digestibility information. The repeatability and accuracy of the method were evaluated. Data obtained on compound feeds fed as mash were used to establish prediction equations of OMd, Ed, DE NE from OMdv or DOMv and chemical criteria. The levels of accuracy and repeatability of OMdv measurement were satisfactory and values for OMdv and OMd of mash compound feeds were very close and highly correlated (r =0.91). Apart from OMdv, the best prediction equations of OMd or Ed included ash content and a cell wall criterion (ADF or crude fiber); for prediction of DE, fat content had also to be considered. The coefficient of variation of all equations was below 0.02. The equations allow a satisfactory prediction of OMd, Ed or DE of the 66 ingredients fed as mash. However, the equations established on data obtained on mash feeds underestimate the in vivo nutritional value of pelleted feeds and are not applicable to prediction of energy value of feeds for adult pigs. [Copyright &y& Elsevier]

Two experiments were conducted to evaluate the impact of different energy systems in predicting the energy cost of gain of growing-finishing pigs fed diets containing different levels of dietary fat. The diets in both experiments were based on wheat, corn and soybean meal and supplemented with 0, 1.75, 3.50 and 5.25% tallow. In Experiment 1, 24 crossbred barrows (Duroc×Landrace×Yorkshire) were randomly allocated to one of the four dietary treatments to determine the digestible (DE) and metabolizable (ME) energy content of the diets and net energy (NE) was calculated from DE and ME values. In Experiment 2, 96 crossbred barrows (Duroc×Landrace×Yorkshire) were used to evaluate the effectiveness of the energy systems in predicting the energy cost of gain for growing-finishing pigs fed ad libitum. There were six pens per treatment and four pigs per pen. The results obtained in trial 1 were used for calculating the energy cost of gain in trial 2. During the growing period, there was a linear decrease (p < 0.05) in the DE and ME cost of gain, while the NE cost of gain was not influenced by level of fat. During the finishing period, neither DE, ME or NE cost of gain were influenced by the dietary fat level. For the total experiment, the DE and ME cost of gain decreased (linear effect; p = 0.001), but there was no significant decrease in the NE cost of gain. It is concluded that the NE system can predict the performance of growing-finishing pigs more precisely for diets differing in fat content than can the DE and ME systems. [ABSTRACT FROM AUTHOR]

Predicting aspects of pork quality becomes increasingly important from both a nutritional and a technological point of view. Little information is, however, available concerning the quantitative relation between nutrient intake and fatty acid (FA) deposition at the whole-animal level. In this study, eight blocks of five littermate barrows were used in a comparative slaughter trial. At 24 kg body weight (BW), one pig from each litter was slaughtered to determine the initial FA composition. The other littermates were assigned to one of four feeding levels (ranging from 70 % to 100 % of intake ad libitum) and were given a diet containing 0??36 g/kg lipid and 0??22 g/kg FA. The temperature for each block was maintained at either 23 or 30??C. At 65 kg, the pigs were slaughtered and the body lipid and FA composition was determined. Seventy per cent of the digested n-6 FA and 50 % of the n-3 FA were deposited. The average composition of de novo synthesised FA corresponded to 1??7, 30??3, 2??4, 19??7 and 45??9 % for 14: , 16: , 16: 1, 18: and 18: 1 FA, respectively. At 23??C and for feeding ad libitum, 33 % of 16: FA was deposited, 1??7 % shortened to 14: , 63 % elongated to 18: and 2??8 % unsaturated to 16: 1. Twenty-eight per cent of 18: FA was deposited and 72 % unsaturated to 18: 1. At 30??C, 18: FA desaturation was reduced by 3??5 %. Feed intake and temperature independently affected the elongation of 16: FA. A reduction in feed intake increased the elongation rate, whereas the increase in temperature reduced the elongation rate. [ABSTRACT FROM PUBLISHER]

To assess the acclimation of pigs to heat stress, the effects of high (33??C) or thermoneutral (23??C) constant temperatures on feeding behaviour and components of energy balance were studied in group-housed young pigs. Three groups of five pigs were used at each temperature. After 1 week of adaptation, voluntary feed intake (VFI) and heat production (HP) were recorded for thirteen consecutive days. Animals were fed ad libitum. Fasting HP was measured on the last day. Average initial body weights (BW) were 21??4 and 20??9 kg at 23 and 33??C respectively. Feeding behaviour was measured individually and rate of feed intake and characteristics of feeding behaviour were calculated. The O2 consumption, CO2 production and physical activity of the group were used to calculate total HP (HPtot) and its components, i.e. fasting HP (HPfas), HP due to physical activity (HPact) and thermic effect of feed (TEF). The BW gain and VFI were reduced by 37 and 30 % respectively at 33??C. The decrease in VFI corresponded to reduced consumption time (-34 %) and size of the meals (-32 %). Feeding behaviour was mostly diurnal (66 % of the VFI), and the rate of feed intake (28 g/min) was not affected by temperature. Daily HPtot, HPfas and TEF, expressed per kg metabolic weight (BW0??60), were significantly decreased at 33??C by 22, 18 and 35 % respectively, whereas HPact was not affected; TEF expressed per g feed was not affected (2 kJ/g). The decrease in HPtot at 33??C was caused by a reduction in TEF and HPfas (kJ/d per/kg BW0??60), which are both related to reduction in VFI. [ABSTRACT FROM PUBLISHER]

A dynamic model was developed to study the effects of diet composition on lipid deposition and fatty acid (FA) composition in pigs. A basic model of protein and lipid deposition was used. Deposited lipids originate from dietary FA and de novo synthesized FA. It is hypothesised that 0.85 of absorbed FA are deposited as-is, and that the composition of de novo synthesized FA was constant throughout growth. Sensitivity analysis indicated that feed intake, efficacy of dietary FA storage and partitioning of de novo synthesized FA had a major impact on FA composition. Evaluation of the model indicated that predictions of protein, lipid, and backfat mass were insufficient, mainly due to the assumption of a constant ratio of lipid to protein mass in the basic growth model. Nevertheless, predictions of the FA composition of backfat and perinephric tissue were reasonable. Differences in FA composition between different tissues could only partly be explained by differences in tissue development. Development of this conceptually simple model was hampered by the limited availability of experimental data on the contribution of dietary lipids to purposes other than lipid deposition, the composition of de novo synthesized FA and the partitioning of FA between different depot sites. [Copyright &y& Elsevier]