Quantitative assessment of the effects of space allowance, group size and floor characteristics on the lying behaviour of growing-finishing pigs

To obtain quantitative information that can be later used in animal welfare modelling, the relationship between the lying behaviour of growing-finishing pigs (initial body weight (BW) between 19 and 87 kg) and different factors related to the housing conditions, with a potential negative effect on their welfare, was studied by means of a meta-analytical approach. Data from 22 experiments reported in 21 scientific publications were collected. The space allowance, expressed on an allometric basis by means of a k-value (m2/BW0.667), the group size (n) and the floor characteristics (fully and partly slatted v. non-slatted floor), as well as their significant two-way interactions were used as fixed effects, and the experiment was used as a random factor to take into account the interexperiment effect. Further regression analyses were performed on the predicted values of observations in order to improve the adjustment of data. A significant quadratic relationship was established between space allowance (k-value, P <0.05; squared k-value, P <0.01) and the percentage of time spent lying. A significant interaction between the k-value and the floor type was also found (P <0.05), showing that the relationship between space allowance and lying behaviour is affected by the presence or absence of slats. Threshold k-values were obtained using broken-line analyses, being about 0.039 for slatted floors and almost double for non-slatted floors. Compared to other studies, these values suggest that the ability to rest as space availability decreases may be compromised before a reduced performance becomes apparent. Group size did not show a significant effect. Additional information should be added to the model, as further data become available, to adjust the proposed parameters as well as to try to include the effect of other important aspects such as that of ambient temperature

Meta-analysis on the effects of the physical environment, animal traits, feeder and feed characteristics on the feeding behaviour and performance of growing-finishing pigs

A meta-analysis, using information from 45 experiments on growing-finishing pigs published in 39 manuscripts, was carried out to determine the simultaneous effects of the physical environment (space allowance, group size, flooring conditions, temperature, presence of enrichment), pig traits (initial body weight (BW) for each studied time interval, sex, genetics), feeder characteristics (water provision within the feeder, feeder design (individual/collective), feeder places/pig, presence of feeder protection) and feed characteristics (feed allowance (ad libitum/restricted), net energy content, crude protein (CP) content), as well as their potential interactions, on the feeding behaviour and performance of growing-finishing pigs. The detrimental effect of low temperature on performance was particularly evident for restricted-fed pigs (P <0.05). At reduced feeder space allowance, a reduction in the percentage of time spent eating was predicted when increasing initial BW, whereas the opposite was predicted for larger feeder space allowances (P <0.001). The reduction in visit duration to the feeder in higher BW groups became gradually more important with increasing feeder space allowance (P <0.01), whereas the increase in the ingestion rate and average daily feed intake (ADFI) with increasing initial BW became smaller with increasing feeder space (P <0.05). The model predicted a reduction in feed conversion ratio (FCR) with increasing group size (P <0.05) and floor space allowance (P <0.01) and on solid floors with or without bedding (P <0.05). In comparison with other feeders, wet/dry feeders were associated with more frequent but shorter feeder visits (P <0.05), higher ingestion rates (P <0.001) and higher ADFI (P <0.10). The use of protection within individual feeders increased the time spent feeding (P <0.001), reduced the number of visits per day (P <0.01), the ingestion rate (P <0.001) and FCR (P <0.01) in comparison with other feeder types. Sex modulated the effect of the number of feeder places/pig on FCR (P <0.05), with a gradual reduction of FCR in entire males and females when increasing feeder space allowance. Genetics tended to modulate the effect of diets’ CP content on FCR (P <0.10). Overall, these results may contribute to the improvement of the welfare and performance of growing-finishing pigs by a better knowledge of the influence of the rearing environment and may help optimize the feeding strategies in current production systems

High-Fibre feeding in gestation

Gestating sows are usually fed low levels of feed, which may not provide sufficient satiety, and does not allow sows to fully fulfil their motivation to express foraging and feeding behaviours. Feed restriction may therefore lead to high occurrences of non-feeding oral activities, including stereotypies, and restlessness and aggressive behaviour in grouphoused sows, which are interpreted as signals of sustained feeding motivation and frustration. Inclusion of fibres in the diet reduces the energy density of diets and therefore allows for larger meal sizes without increasing the energy supplied. Moreover, dietary fibres influence the mechanisms that enhance satiation and satiety at the sensory, postingestive and post-absorptive levels. This chapter reviews the impact of dietary fibres on behaviour and welfare of gestating sows, and describes their potential consequences for performance. Dietary fibres generally reduce the occurrence of stereotypies and decrease restlessness and activity, with some studies also reporting reduced aggression. These effects are most likely related to behavioural and physiological mechanisms underlying the impact of dietary fibres on satiety and feeding motivation. The extent of the response to dietary fibres is, however, variable and depends on the characteristics of the fibrous diet (inclusion rate, fibre source, physicochemical properties), housing and feeding conditions, and characteristics of the sows, especially parity, with greater effects in younger sows. Dietary fibres provided during gestation usually result in increased feed intake of sows during lactation, probably due to their effects on the size and capacity of the gastrointestinal tract. Studies on the effects of fibres on reproductive performance are scarce and show variable results, which might partly be attributed to over- or underestimation of the energy content of the diet during pregnancy. In conclusion, dietary fibres generally have a beneficial effect on the behaviour and welfare of gestating sows which are restrictedfed. The impact of high fibre diets during gestation on reproductive performance over multiple successive cycles in group-housed sows merits further research

A meta-analysis of the combined effect of housing and environmental enrichment characteristics on the behaviour and performance of pigs

To quantify the combined effect of housing conditions and environmental enrichment on the behaviour and performance of pigs, a meta-analysis was performed using information from 45 experiments in 42 published manuscripts. Multiple regression models were applied to evaluate the effects of space allowance per pig (k-value; m2/BW0.667), group size (n), floor characteristics (solid, partly, or totally slatted floor), bedding (presence or absence), and the number and presentation sequence of point-source objects (no object, one object, two simultaneous objects, two alternated objects, three or more simultaneous objects or three or more alternated objects) on the general activity, enrichment and object-directed exploratory behaviour, social behaviour, and productive performance. A non-linear relationship between space allowance per pig and time spent sitting and lying was found (P <0.10 and P <0.01 for the k-value and its quadratic term respectively). Total time spent in exploration increased with space allowance per pig when bedding was present (P <0.01), and time spent exploring other pen items decreased with increasing space allowance per pig if no bedding was provided (P <0.001). Total time spent in exploration increased with group size (P <0.001). The lowest predicted total exploration time (least squares mean ± standard error) was found in the absence of bedding and point-source objects (13 ± 3%; P <0.05), and the highest when bedding (18 ± 3%) or point-source objects (19 ± 3%) were present. Time exploring point-source objects was higher when different objects were provided (P <0.001). Suspended (P <0.05) and deformable (P <0.05) enrichment items increased the time spent manipulating them. Time spent exploring point-source objects was predicted to be higher in the absence of slats and bedding (32 ± 6%; P <0.05), and lower when bedding (8 ± 9%) or slats (12 ± 4%) were present. Time engaged in negative social behaviours decreased in the presence of point-source objects (P <0.01), and increased with group size in the absence of bedding (P <0.001). Time engaged in positive social behaviours tended to decrease in the presence of point-source objects (P <0.10), and when space allowance per pig increased in the absence of bedding (P <0.10). Slight trends towards lower FCR were predicted when point-source objects (P <0.10) and bedding (P = 0.10) were present. This information can be utilised in the determination of the general effects of production systems on the welfare of pigs as well as in the development of new production systems

A meta-analysis of the combined effect of housing and environmental enrichment characteristics on the behaviour and performance of pigs

To quantify the combined effect of housing conditions and environmental enrichment on the behaviour and performance of pigs, a meta-analysis was performed using information from 45 experiments in 42 published manuscripts. Multiple regression models were applied to evaluate the effects of space allowance per pig (k-value; m2/BW0.667), group size (n), floor characteristics (solid, partly, or totally slatted floor), bedding (presence or absence), and the number and presentation sequence of point-source objects (no object, one object, two simultaneous objects, two alternated objects, three or more simultaneous objects or three or more alternated objects) on the general activity, enrichment and object-directed exploratory behaviour, social behaviour, and productive performance. A non-linear relationship between space allowance per pig and time spent sitting and lying was found (P <0.10 and P <0.01 for the k-value and its quadratic term respectively). Total time spent in exploration increased with space allowance per pig when bedding was present (P <0.01), and time spent exploring other pen items decreased with increasing space allowance per pig if no bedding was provided (P <0.001). Total time spent in exploration increased with group size (P <0.001). The lowest predicted total exploration time (least squares mean ± standard error) was found in the absence of bedding and point-source objects (13 ± 3%; P <0.05), and the highest when bedding (18 ± 3%) or point-source objects (19 ± 3%) were present. Time exploring point-source objects was higher when different objects were provided (P <0.001). Suspended (P <0.05) and deformable (P <0.05) enrichment items increased the time spent manipulating them. Time spent exploring point-source objects was predicted to be higher in the absence of slats and bedding (32 ± 6%; P <0.05), and lower when bedding (8 ± 9%) or slats (12 ± 4%) were present. Time engaged in negative social behaviours decreased in the presence of point-source objects (P <0.01), and increased with group size in the absence of bedding (P <0.001). Time engaged in positive social behaviours tended to decrease in the presence of point-source objects (P <0.10), and when space allowance per pig increased in the absence of bedding (P <0.10). Slight trends towards lower FCR were predicted when point-source objects (P <0.10) and bedding (P = 0.10) were present. This information can be utilised in the determination of the general effects of production systems on the welfare of pigs as well as in the development of new production systems