A total of 198, 27-day-old weanling gilts (7·7 kg) were used to study the associations between food intake characteristics measured in individual pigs but which were group-housed, and indicators of gut physiology at 5 days after weaning. All piglets were offered ad libitum access to food and water and were housed in pens (11 piglets per pen) equipped with feeding stations in order to determine the time between weaning and the start of the first food intake (latency time; h), and the increase in daily food intake (daily increase; g/kg0·75 per day) for each individual. Forty piglets were selected that either had an early (≤ 2 h) or a late (≥23 h) start of food intake and subsequently either had a relatively fast (≥18 g/kg0·75 per day) or slow (≤ 2 g/kg0·75 per day) increase in daily food intake so that there were four different groups. Five days after weaning, the 40 piglets were killed in order to determine histological (villous height, crypt depth, number of goblet cells) and functional (maltase and sucrase activities) measures in the proximal small intestine (SI), and microbial measures (ammonia and volatile fatty acid (VFA) concentrations) and dry-matter (DM) content in the distal SI, caecum and colon. Thirteen unweaned piglets were killed to serve as the reference group. Villous height/crypt depth ratio (P < 0·05), number (P < 0·01) of goblet cells on the villi and crypts, and sucrase activity (P < 0·001) in the proximal SI of the unweaned piglets were higher than in the weaned piglets. The proportion of branched-chain VFA (bcVFA; P < 0·01), ammonia-nitrogen (P < 0·001) and DM concentrations (P < 0·01) in the contents of the caecum as well as proportions of bcVFA in the contents of the colon of the unweaned piglets were higher than in the weaned piglets. Apart from a tendency towards an interaction (P < 0·1) between latency time and daily increase with regard to villous height/crypt depth ratio and number of goblet cells on the villi of the proximal SI, histology and function of the proximal SI and digesta characteristics of the distal SI, caecum and colon were not affected by latency time. Piglets with a fast increase in food intake tended to have longer villi on the proximal SI (P < 0·1), and had less acid-mucin containing goblet cells (P < 0·05) on these villi than had the piglets with a slow increase. The piglets with a fast increase had a higher DM content in the colon and tended to have a higher total VFA-concentration in the caecum than did their counterparts with a slow increase. The genotype of the piglets affected maltase (P < 0·01) and sucrase (P < 0·05) activities in the proximal SI and tended to affect the villous height/crypt depth ratio (P < 0·06). Genotype also affected total VFA concentrations (P < 0·05) and tended to affect the ammonia nitrogen (P < 0·1) in the colon and caecum, respectively. This study indicates that within the range of practical food intake levels recorded, the physiology and function of the gut is not markedly affected by the time between weaning and the onset of feeding or by the subsequent increase in daily food intake.

A series of 24-h video studies on four commercial Danish pig herds investigated the behaviour of pregnant sows kept in dynamic groups (72 to 200 sows) with electronic sow feeding (ESF). The herds mainly differed with respect to provision of a layer of unchopped straw as bedding material, the frequency of introduction/removal of animals, space allowance in the lying area, group size and number of feeding stations, and starting times for the feeding cycle. All herds had one feeding cycle per 24 h. Six 24-h video recordings in the most settled period with respect to rank relationships (2 to 12 days after the last introduction) were collected from each herd and analysed according to activity and aggressive interactions. In two of the four herds recordings were collected in two separate periods with different starting times for the feeding cycle. In all herds peaks of activity in the morning and in the afternoon were evident. Furthermore, the diurnal variation was overlaid by an increase in activity at the start of the feeding cycle. The activity and aggression in the feeding area as well as the duration per sow of the period with high feeder occupation were lowest in herds where a layer of straw bedding was provided. Changing feeding start from day time to night time was accompanied by a reduced feeder occupation in the period following start of the feeding cycle. However, in herd 1 (characterized by no litter, high stocking density and high frequency of grouping) the level of aggression was reduced, whereas it was increased in herd 2 (characterized by straw in lying area, low stocking density, low frequency of regrouping). Number of regroupings and space allowance apparently had no obvious effects on the average frequency of aggression or the aggression per sow at risk in periods between introduction of new animals, but space allowance may have improved social function by weakening the association between activity and aggression. Due to the small number of herds included the present results were descriptive rather than conclusive. However, the study supports the suggestions that provision of unchopped straw as bedding material and starting the feeding cycle in the evening for overnight feeding may improve behaviour in dynamic group housing systems with ESF. However, the benefits of starting the feeding cycle in the evening may depend on low disturbance in daytime from other management procedures.

Meat quality was studied in pigs reared in groups kept as units during the fattening period and slaughter (unmixed). The results were compared with conventionally reared pigs, which were mixed during the fattening period, at transport to the abattoir and at lairage (mixed). It is concluded that the unmixed pigs in this study had a better meat quality measured as pH,, pHu, weight loss and also fewer skin lacerations compared with the mixed groups (i.e. less development of pale, soft exudative (PSE) and dark, firm dry (DFD) in the unmixed animals). There were no significant differences in meat colour or in lean content between the unmixed and mixed pigs.

Food intake patterns of growing pigs given food ad libitum in individual and group housing were derived from food intake recordings with IVOG®-stations. The IVOG-station is a feeding station that records animal identification number, time, duration and amount of food intake during each visit of a pig to the food hopper. Data were collected in three testing batches of 90 Dutch Landrace pigs each, housed in 10 individual pens and in 10 group pens of eight pigs per batch.

Based on survival analysis theory, intervals between visits shorter than 5 min (which was used as meal criterion) were regarded as within-meal intervals and these visits were grouped into meals. In group housing, food intake per day and rate of food intake had no significantly non-normal distribution. In individual housing, rate of food intake, food intake per day and number of meals per day had no significantly non-normal distribution. In individual housing rate of food intake, food intake per day and number of meals per day had no significantly non-normal distribution. All traits were normally distributed after discarding extreme values, except food intake and eating time per visit and per meal. In group housing these traits were not significantly non-normally distributed after logarithmic transformation.

Pigs housed in groups ate faster, had a higher food intake per meal but less meals per day, less eating time per day and a lower daily food intake than pigs penned individually. During the day two peaks of feeding activity occurred, especially in group housing: one in the morning and one in the beginning of the afternoon.

A distinction was made between meals with a major contribution to daily food intake and meals of minor importance. In group housing, 69% of the daily number of meals accounted for proportionately 0·87 of daily food intake and 0·83 of daily food intake time. In individual housing 39% of the meals accounted for proportionately 0·90 of the daily food intake and 0·79 of the daily eating time.

Higher repeatabilities of day to day recordings of food intake traits, were found when estimated within 2-week periods compared with months or with the total fattening period.