Resistant starch (RS) has been suggested to prolong satiety in adult pigs. The present study investigated RS-induced changes in behaviour, satiety-related hormones and metabolites in catheterized growing pigs to explore possible underlying mechanisms for RS-induced satiety. In a cross-over design with two 14-day periods, 10 pigs (initial BW: 58 kg) were assigned to two treatments comprising diets containing either 35% pregelatinized starch (PS) or 34% retrograded starch (RS). Diets were isoenergetic on gross energy. Pigs were fed at 2.8 × maintenance. Postprandial plasma response of satiety-related hormones and metabolites was measured at the end of each period using frequent blood sampling. Faecal and urinary energy losses were measured at the end of each period. Behaviour was scored 24 h from video recordings using scan sampling. Energy digestibility and metabolizability werẽ 6% lower in RS compared with PS diet ( P < 0.001), and metabolizable energy (ME) intake was~3% lower in RS-fed than in PS-fed pigs ( P < 0.001). RS-fed pigs showed less feeder-directed ( P = 0.001) and drinking ( P = 0.10) behaviours than PS-fed pigs throughout the day. Postprandial peripheral short-chain fatty acid (SCFA) levels were higher in RS-fed than in PS-fed pigs ( P < 0.001). Postprandial glucose and insulin responses were lower in RS-fed than in PS-fed pigs ( P < 0.001). Triglyceride levels were higher in RS-fed than in PS-fed pigs ( P < 0.01), and non-esterified fatty acid levels did not differ between diets ( P = 0.90). Glucagon-like peptide-1 (GLP-1) levels were lower in RS-fed than in PS-fed pigs ( P < 0.001), and peptide tyrosine tyrosine (PYY) levels did not differ between diets ( P = 0.90). Blood serotonin levels were lower ( P < 0.001), whereas monoamine oxidase activity ( P < 0.05) and tryptophan ( P < 0.01) levels were higher in RS-fed than in PS-fed pigs. Despite a lower ME intake, RS seemed to prolong satiety, based on behavioural observations. Possible underlying mechanisms for RS-induced satiety include increased 24 h plasma SCFA levels, and decreased postprandial glucose and insulin responses. GLP-1 and PYY seemed not to play a role in RS-induced satiety. Low blood serotonin levels in RS-fed pigs suggested a difference in intestinal serotonin release between treatments. Increased postprandial plasma triglyceride levels corresponded with increased SCFA levels, but it is unclear whether triglycerides may have signalled satiety in RS-fed pigs.

Pen enrichment for broiler (meat-type) chickens is one of the potential strategies to stimulate locomotion and consequently contribute to leg health and welfare. This study was designed to evaluate effects of using a plethora of pen enrichments (barrier perches, angular ramps, horizontal platforms, large distance between feed and water and providing live Black Soldier fly larvae in a dustbathing area) on tibia characteristics, locomotion, leg health and home pen behaviour of fast and slower-growing broiler chickens. The experiment was set up as a 2 x 2 factorial arrangement with a total of 840 male broiler chickens in a complete randomized design (7 replicates per treatment and 30 chickens per replicate) with the following treatments: 1) pen enrichment (enriched pen or non-enriched pen); 2) broiler strain (fast-growing Ross 308 or slower-growing Hubbard JA 757). Home pen behaviour and use of enrichment were observed. At approximately 1400 and 2200 gram body weight, two chickens per pen were randomly selected and slaughtered, to investigate tibia morphological, biophysical and mechanical characteristics and leg health. Pen enrichment positively affected tibia biophysical characteristics, e.g., osseous volume (?=1.8 cm3, P=0.003), total volume (?=1.4 cm3, P=0.03) and volume fraction (?=0.02 %, P=0.002), in both fast and slower-growing chickens, suggesting that pen enrichment particularly affects ossification and mineralization mechanisms. Accordingly, locomotion and active behaviours were positively influenced by pen enrichment. However, pen enrichment resulted in lower body weight gain in both strains, which might be due to higher activity or lower feed intake as a result of difficulties of crossing the barrier perches. Regarding the strain, slower-growing chickens showed consistently more advanced tibia characteristics and more active behaviour than fast-growing chickens. It can be concluded that pen enrichment may lead to more activity and better bone development in both fast and slower-growing chickens.