Influence of physicochemical properties of fibrous diets on behavioural reactions of individually housed pigs

Gut capacity of broiler breeder hens

1. Broiler breeders are subjected to qualitative or quantitative feed restrictions to prevent obesity, which causes major health and welfare problems. Diluting their feed by adding inert or low nutrient, bulky materials can reduce obesity, but the capacity of the gut needs to be determined to apply this strategy successfully. Two trials were conducted to measure the bulk capacity of Ross 308 broiler breeders prior to and after the onset of lay. The trial was completely randomised, with nine individually-caged breeders, with each cage as a replicate, totalling 189 birds per trial2. Birds were given ad libitum access to one of 21 maize-soyabean based feeds, an undiluted control or progressive dilution (10, 20, 30 and 40%) with either cellulose fibre, rice husk, sand, vermiculite or sawdust. Feeds were analysed for density, crude-, acid detergent- and neutral detergent-fibre, water-holding capacity (WHC), cation-exchange capacity and oil-holding capacity.2. In general, feed intake (scaled to body weight^0.67) increased and then declined as the proportion of each diluent increased. Intake increased linearly when rice hulls and sand were used as diluents.3. Water holding capacity was the most appropriate measure to define the gut capacity of broiler breeders.4. The trial data was used to estimate the maximum-scaled feed intake (SFI_max) in broiler breeders, which was 240-56.1WHC + 4.34WHC² g/kg^0.67/d.

Relation between feeding behaviour and energy metabolism in pigs fed diets enriched in dietary fibre and wheat aleurone

Feed intake and its daily pattern are regulated both at a short and a long term by several control pathways, including energy balance regulation. This trial aimed to determine the effect of dietary fibre (DB) (mix of wheat, soy and sugar beet pulp fibres) and aleurone supplementation and their interaction on energy and nitrogen balances in growing pigs with ad libitum access to feed. Forty pigs (BW: 35 kg) were fed diets differing by fibre concentration (NDF concentration: 10% or 14% DM) and aleurone supplementation (0, 2 or 4 g/kg) during 3 weeks. Pigs were housed individually in a respiration chamber during the last week to record feeding behaviour and measure energy and nitrogen balances (n = 36). Glucose oxidation was studied on the 6th day with an injection of [U-13C] glucose and measurement of 13CO2 production. There was no significant interaction between DB inclusion and aleurone supplementation on any variables characterizing feeding behaviour. Pigs had less but longer meals with high level of DB, with an increased interval between two meals without effect on daily feed intake. The meal frequency significantly decreased when aleurone supplementation increased. Total tract apparent digestibility coefficient of DM, organic matter, ash, nitrogen and gross energy decreased when pigs received high DB level. Dietary fibre level increased significantly faecal excreted nitrogen. Aleurone supplementation decreased nitrogen retention. Free access to the feed induced a great individual variability not only in feed intake level (from 784 to 2290 g/day) but also in feeding behaviour (from 5.5 to 21.5 meals per day). This variability can be linked with the importance of underlying feed intake regulation pathways and difference in energy balance and metabolism efficiency. Several profiles of metabolism efficiency can be discriminate, thanks to a clustering based on feeding behaviour and pre-prandial concentrations of metabolites and hormones. In conclusion, DB inclusion decreased meal frequency, increased average meal size, decreased total tract apparent faecal digestibility coefficient of nitrogen and gross energy. Supplementation of aleurone decreased average daily feed intake with a reduction of the meal number per day, without modification of average meal size. Aleurone supplementation decreased nitrogen retention and nutrient deposition. Independently of experimental diets, the high individual variability permitted discriminating different profiles with different metabolic strategies. Efficient pigs with a high energy retention as protein and lipid seem to be able to adapt their metabolism according to energy sources.

Feeding behaviour and pre-prandial status affect post-prandial plasma energy metabolites and insulin kinetics in growing pigs fed diets differing in fibre concentration

Variations in feeding behaviour between animals result from individual variations in their metabolism as affected by diet composition. The study aimed to link the within-day dynamics of voluntary feed intake and those of blood metabolites and insulin in growing pigs having ad libitum access to feed and receiving diets differing in dietary fibre levels and aleurone supplementation. A total of forty pigs (body weight: 35 kg) had access to diets provided ad libitum, which differed by fibre content (13 or 18 % neutral-detergent fibre) and aleurone supplementation (0, 2 or 4 g/kg). Feeding behaviour was individually recorded for 1 week. The kinetic of plasma metabolites and insulin was followed for 1 h after a voluntary test meal. Dietary fibre level did not affect the daily feed intake but increased meal size and meal duration. Aleurone supplementation (4 g/kg) decreased the daily feed intake and number of meals. Dietary fibre level only decreased insulin concentration measured 15 min after meal beginning. Aleurone supplementation (4 g/kg) decreased glycaemia in the first hour after the meal and insulinaemia 15 min after the meal. Free access to feed led to high variability in pre-prandial metabolites and insulin concentrations, resulting in different test meal size irrespective of diet composition. Animals were then spread over different profiles combining feeding behaviour and fasted status to explain different profiles of regulation of feed intake. Plasma metabolites and insulin kinetics were affected by diet composition but also by animal characteristics. Individual variability should be considered when diet composition is used to modulate feeding behaviour.

Relationship between time spent eating and nutritionally related blood metabolites of growing pigs fed on diets containing graded levels of fibre

The objective of the study was to determine the relationship between time spent on eating and nutritionally related blood metabolites in growing pigs fed on fibrous diets. Eighteen growing pigs (initial bodyweight 14.2 ± 1.20 kg) were used in a 5-week study period. The pigs were penned in metabolism crates and subjected to different treatment diets with maize cob included at 0, 80, 160, 240, 320 and 400 g/kg in a diet. Time spent eating and drinking was observed by use of video cameras. Blood was collected from the jugular vein at the end of the trial for determination of glycosylated haemoglobin, total protein, urea, uric acid, albumin and creatinine kinase concentrations. Glycosylated haemoglobin, albumin, globulin, total protein and uric acid concentrations in blood influence time spent eating (P < 0.05). Time spent eating increased linearly with an increase in uric acid, total protein, albumin and globulin concentrations and started decreasing at higher concentrations (P < 0.05). A negative relationship was observed between time spent eating and glycosylated haemoglobin concentration. There were curvilinear responses between time spent drinking and concentration of the nutritional metabolites (albumin, globulin and total protein) (P < 0.05). In conclusion, the blood metabolites can be used to predict time spent eating by pigs fed on fibrous diets. They have a direct relationship with pigs’ nutritional status. The nature of the relationships may allow feed compounders to determine the quantity of maize cobs to include in diets by focusing on feeding patterns and metabolism of pigs.