Search

Since 10 years, EU-legislation states that ‘pigs must have permanent access to sufficient quantity of material to enable proper investigation and manipulation activities’. While much research has focused on which materials ‘enable proper investigation and manipulation activities’, little has been done to determine what constitutes ‘sufficient quantity’ and ‘permanent access’. Based on the hypothesis that a reduced level of oral manipulation of pen mates reflects an increased level of fulfilment of pigs’ behavioural need to explore, we chose oral manipulation of pen mates as target behaviour. In three batches, we investigated the relation between oral manipulation of pen mates and amount of straw provided to the pigs in order to identify the amount of straw, where additional provision of straw did not reduce the occurrence of oral manipulation of pen mates any further. From 30 to 80 kg body weight, the pigs were housed in groups of 18 animals in pens (5.48 m × 2.48 m) with concrete floor (1/3 solid, 1/3 drained and 1/3 slatted). Pens were cleaned manually twice a week and fresh uncut straw was provided daily onto the solid part of the floor. In the first batch, 48 pens were assigned to either 10, 500 or 1000 g straw per pig and day ( N = 16 pens per straw allocation). A reduction in oral manipulation of pen mates was found when pigs were given 500 compared to 10 g ( P = 0.03), but no further reduction when increasing the straw amount to 1000 g was detected. In the second and third batch, a total of 96 pens were assigned to 8 treatments (10, 80, 150, 220, 290, 360, 430 or 500 g straw per pig and day) ( N = 12 pens per straw allocation). There was a linear relation between straw amount and oral manipulation of pen mates, the latter being reduced from 8.4% to 6.7% of active time, when pigs were provided 500 compared to 10 g ( P = 0.01). Based on the concept of bioequivalence, 387 ± 10 g straw per pig and day was identified as the amount of straw where a further increase in straw provision did not reduce the oral manipulation of pen mates. Thus, the straw amount identified to meet pigs’ need to explore was close to 400 g straw per pig and day. A criterion of permanent access (defined by a minimum of 1 l (approx. 60 g) unsoiled straw in a pen 24 h after allocation) was achieved at lower levels of straw provision, especially during the initial weeks of the growing period. [ABSTRACT FROM AUTHOR]

Fear induced by exposure to humans, and anxiety induced by novel environmental changes may both function as stressors and have negative effects on reproduction in pigs. An earlier experiment indicated that reactions to humans and novelty had some repeatability between the ages of 8 and 24 weeks, thus reflecting personality traits. The present experiment therefore tested for predicted negative relationships between behaviour related to fear and anxiety measured at 8 weeks of age and later reproduction in 30 sows. Factor analysis of behaviour in a voluntary human approach test performed in the home cage and a novel object test performed in a novel arena indicated that behavioural measures related to investigation of these stimuli loaded on separate factors and may therefore reflect independent underlying dimensions. One factor related to investigation of the human was interpreted as reflecting the level of fear of humans, while another was correlated to investigation of the novel object and interpreted as indicating novelty-induced anxiety. Factor scores were generated for ‘fear’ and ‘anxiety’ and used in regression analysis as predictors of maternal behaviour and reproductive parameters. Higher levels of fear of humans were associated with longer durations of farrowing, larger variation in inter-birth intervals, and a higher number of piglets dying without milk in their stomachs. The duration of farrowing was positively correlated to the number of live born piglets dying within 3 weeks of age. Higher fear also tended to associate with a higher number of stillborn and a higher number of live born piglets dying within 3 weeks of age. High anxiety only tended to be associated with a higher number of stillborn. These results are interpreted as supporting the hypothesis that there are negative associations between fear of humans and maternal ability in sows. [Copyright &y& Elsevier]

The coping styles hypothesis states that animals have consistent behavioural and physiological coping responses that can be characterised on a continuum from reactive to proactive. According to this hypothesis, animals can be characterised by consistency in responses across social and non-social situations as well as over time. We evaluated the validity of this hypothesis for predicting the coping responses of pigs by testing for predicted correlations between responses to a variety of challenges. Animals were exposed to an immobility test at 3 weeks of age. At 8 and 24 weeks, animals were exposed to an unknown pig in the test animal’s home cage, a human in the home cage, and a novel object (bucket) in a novel arena. None of the predicted correlations were found between the duration of immobility and behaviour in the later tests. Many behavioural measures had some repeatability between the ages of 8 and 24 weeks, despite significant changes in the observed level of responses, but there were few correlations between responses to social and non-social situations. Responses to a human and novel object were positively correlated when measured at 8 weeks but not at 24 weeks. The results indicate that the coping styles hypothesis has very limited value in predicting the coping responses of pigs representing the population as a whole. The existing correlations could more parsimoniously be described as reflecting responses to specific or closely related stimuli. It is suggested that future research on pig personality should investigate the possibility that specific coping behaviours—for example, those mediated by fear and anxiety—may have consequences for different elements of coping ability related to welfare and productivity. [Copyright &y& Elsevier]

The aim of the present experiment was to examine the effects of pre-test transport duration and animal age on the behaviour of 40 weaned pigs in a porcine elevated plus-maze (PEPM). The transport constituted of holding test animals together with pen mates in a transport trolley kept in motion by the experimenter. Multiple regression of behaviour on transport duration and animal age (between 33 and 54 days) indicated that longer duration of pre-test transport was associated with increases in the activity-related measure closed entries (CLE) in the PEPM, but was not associated with changes in the activity-related variable total entries (TE) or either of the anxiety-related behavioural elements percent open time (POT) or percent open entries (POE). Increasing animal age, on the other hand, was associated with decreases in both activity-related measures, but not with anxiety-related parameters. These results imply that animal age and the duration of transport prior to testing should be standardised across treatments in experiments in which evaluation of activity in this novel environment is important, but that measures related to PEPM anxiety are robust to the effects of variation in transport duration and animal age. [Copyright &y& Elsevier]

The success of pens which provide pigs with a bedded resting area and an area for feeding, elimination and other activities depends on pigs' ability to show discrimination in elimination behaviour and thereby keep the resting area dry and clean. The eliminative behaviour of 16 gilts was studied during the last day of gestation when motivation for prepartum nest-building was high. During gestation the gilts had been housed in stalls (n=8) or in pens (n=8). Before parturition the animals were moved to farrowing pens with a peat and straw bedded resting area and a solid floor activity area. The gilts urinated and defecated significantly more in the activity area than in the resting area (P<0.001). However, significantly more gilts which had previously been stalled defecated in the resting area than gilts which had never been confined (P<0.05). Thus, previous housing experience may influence patterns of elimination in pigs. [ABSTRACT FROM AUTHOR]

The purpose of this project was to exemplify the use of Evolutionary Operation (EVOP) technique at herd level to test the effect of change in the herd's normal management procedure. As pigs are day active animals, it is assumed that an increase in the activity level during the night will indicate that the pigs are forced to change their normal diurnal rhythm to adapt to the conditions. Thus change in the diurnal pattern of drinking was used as a potential indicator of stress/resource limitations in the pen. A three way factorial experiment with 714 crossbred pigs (34.3±4.1 kg) was carried out. The variables were: stocking density (14 or 18 pigs per pen), number of straw allocations (one allocation of 140 g straw per pig/day or four daily allocations of 35 g straw per pig) and allocation of pigs to pens (randomly or by size). The pigs were fed a libitum. Water consumption and temperature at pen level were continually measured during the experimental period (29 days). The day was divided into two 12-h periods: “day” (from 0700 h to 1859 h) and “night” (from 1900 h to 0659 h), and the proportion of the water consumption during the night of the total water consumption was calculated at pen level. Data were analysed using a linear mixed effect model. The average daily water consumption was 4.52±0.24 l per pig per day. On average, 26.0% of the total amount of water was consumed during the night. An increasing stocking density increased the proportion of water consumed during the night by 2.0 percentage points ( P =0.01). A random distribution of the pigs instead of sorting them by size at pen level reduced the proportion of water consumed during the night by 2.3 percentage points ( P =0.03), while no significant effect of the number of straw distributions ( P =0.36) or interactions was found. Looking at the daily water consumption, no effect of stocking density ( P =0.32), straw allocation ( P =0.85) or sorting the pigs (Randomly versus sorted by size, P =0.11) was found. Groups with small pigs had a lower water intake compared with groups with large or randomly sorted pigs ( P <0.01). The results show that the use of an EVOP design at herd level using change in the diurnal rhythm as response variable can be used to give a fast indication of the optimal combination of production factors within the herd. [ABSTRACT FROM AUTHOR]

This paper develops a simple and effective method for detection of sows and piglets in grayscale video recordings of farrowing pens. This approach consists of three stages: background updating, calculation of pseudo-wavelet coefficients and foreground object segmentation. In the first stage, the texture integration is used to update the background modelling (i.e. the reference image). In the second stage, we apply an “à trous” wavelet transform on the current reference image and then perform subtraction between the current original image and the approximation of the current reference image. In the third stage, the pairwise relationships between a pixel and its neighbours on a factor graph are modelled based on the pseudo-wavelet coefficients, and the image probabilities are approximated by using loopy belief propagation. Experiments have shown promising results in extracting foreground objects from complex farrowing pen scenes, such as sudden light changes and dynamic background as well as motionless foreground objects. [ABSTRACT FROM AUTHOR]

Abstract: In order to quantify the relative priorities between lying, eating and social behaviour of dairy cows in different stages of lactation, responses to time constraints were investigated in two experiments. In experiment one, 48 dairy cows, half in early and half in late lactation, had free access to lying, eating and social contact in a resource pen for 23h (2×11.5), 15h (2×7.5) or 12h (2×6) a day. Rest of the day, the cows were deprived of eating, lying and social contact. In experiment two, we examined whether the time constraint on eating alone affected feed intake and eating behaviour using 32 cows kept in tie-stalls, half in early and half in late lactation. Half of the cows had free access to feed for 24h a day and the other half had access to feed for 12h a day. Reducing the time with free access to the resources reduced the time spent on all behaviours measured, but the proportion of time spent lying increased while the proportion of eating and social behaviour remained constant. Speed of feed intake was increased when the time budget was reduced; thus, the relative reduction in feed intake was less than the relative reduction in eating time. Time constraints on access to feed alone did not reduce feed intake. Stage of lactation did not affect the relative priorities between behaviours. In conclusion, lying time had higher priority than eating time and social contact in both early and late lactation, and cows compensated to some extent for a reduction in eating time by increasing the rate of feed intake. [Copyright &y& Elsevier]

The behavioural priorities of farm animals may be quantified by demand functions generated by use of operant conditioning techniques. However, there are several aspects of this method that still need to be investigated in more detail. The aim of this study was to investigate the effect of operant response type on the demand function for food in mink. The responses examined were pressing a lever and pulling a chain. The experiment was conducted with eight mature female mink. During each of two periods, the mink were tested in four replicates of successively increasing fixed ratio (FR)-values (4, 8, 16, 25, 60, 80 and 100). The rewards were available for 24 h per day and each reward consisted of 0.5 g of food. Half of the animals worked on the lever in the first period and on the chain in the second period, the other half of the animals vice versa. The mink were weighed regularly throughout the experiment. The behaviour of the mink was video recorded continuously for 24 h on the days when they were working on FR levels 4, 40 and 100.The number of rewards and thereby the amount of food earned decreased as the FR-values increased for all animals. The demand curve for food obtained by chain pulling was steeper than the demand curve obtained by lever pressing (P<0.001). The results show that the response type can influence the slope of demand functions. One reason for the difference in slopes of the demand curves could be that the unit price paid on the chain and on the lever at a given FR-value was not the same, even though the minimum force required was 35–40 g for both types of response.The slope of the demand curve for food in mink was much steeper than previously found in mice, rats, pigs and hens. This is most likely due to the combination of high FR-values and small rewards in relation to the foraging strategy in mink. High levels of stereotypies were related to high workloads on the chain. The mink had a more restricted food intake and a higher level of stereotypies when working on the chain than when working on the lever. Frustration caused by a combination of high FR-values, small rewards and hunger may explain the significant increase in stereotypies. [Copyright &y& Elsevier]

• High piglet mortality in outdoor production conflicts with the organic principles. • A consistent problem related to mortality appears to be large litter sizes. • Optimise breeding strategies by using less prolific genetics. • Select for improved maternal behaviour and piglet robustness. The current level of piglet mortality in production systems with outdoor farrowing is high and conflicts with the ethical principles of organic farming. Over the last decade, there has been a rise in scientific studies addressing the level of piglet mortality in outdoor pig production and the causes for mortality. Therefore, the aim of this paper was to review current literature on risk factors for piglet mortality in outdoor pig production, to identify causes of mortality and possibilities for improving piglet survival. A consistent problem related to outdoor piglet mortality appears to be the use of highly prolific sow hybrids. Large litter sizes are accompanied by long parturitions and the birth of piglets displaying signs of lowered viability. Management interventions such as use of birth assistance and caretaking of less viable piglets, as is common in indoor systems, is more difficult to apply in outdoor production. Therefore, based on the present review, we suggest that use of less prolific sow genetics, in systems with outdoor farrowing, may be one way to increase piglet survival. Sows used in outdoor systems should give birth to piglets displaying signs of high vitality and the sows should be able to nurse their own litter. This solution also conforms to the organic mind-set of operating a system with the least possible human intervention. [ABSTRACT FROM AUTHOR]

Highlights • When inside the hut sow surface temperature increased with increasing hut temperature. • Sows without alternative shade appeared to seek shade in the farrowing hut. • Sows lay down more in the shade of the poplars at increasing hut temperature. • Piglets followed the sow around in the farrowing paddock. Abstract The hut temperature in outdoor pig production during summer can exceed the upper critical temperature of lactating sows. Therefore, sows may experience hyperthermia, a condition which has several adverse consequences for the welfare of both sow and piglets. Thus, the aim of the current study was to investigate possible benefits of providing sows with access to an alternative shaded area, apart from the huts, constituted by an area with poplar trees within the farrowing paddock. The study consisted of two parts: Part one was an experimental study investigating the effects of providing sows with access to poplars. Fourteen sows with access to poplars and 14 sows without access to poplars were included. In the second part of the study, including 57 sows, the sows' use of the poplars was studied. In both study parts, sows were studied during four periods: pre-partum (day 2 pre-partum until, and including, the day of farrowing (day 0), early postpartum (day 1 to 4 postpartum), late postpartum (day 5 to 7 postpartum) and late lactation (two observation days, 13 and 28 days after expected farrowing, range day 11 to 31 postpartum). Access to poplars affected the sows' use of the farrowing hut, and an interaction was found between temperature and treatment (access to poplars or no access) so that access to poplars resulted in a decreased use of the hut at higher hut temperatures. No effect of temperature was seen for controls. Maximum surface temperature of sows was only affected by hut temperature and increased with increasing temperature, whereas wallowing was affected by parity group and period. The odds of wallowing were higher for parity group 1 and pre-partum. Whether the sows chose to enter the poplar area was unaffected by hut temperature but higher pre-partum and in late lactation compared to early and late postpartum. Once inside the poplars, sows lay more when hut temperature increased. Sow location had a major impact on the location of the piglets after removal of the fender, and the piglets followed the sow into the hut and the poplar tree area. In conclusion, sows lay more in the poplar area when hut temperature increased, but the sows total use of the poplars was unaffected by temperature, suggesting, poplars in the farrowing field may serve several purposes this could be as an area for thermoregulation, exploration and foraging. [ABSTRACT FROM AUTHOR]

Infrared thermography may be used for pig health screening and fever detection. In order to achieve the necessary accuracy for this purpose, it is necessary to know emissivity of the skin surface. Previous investigations attempting to find the emissivity of pig skin revealed numbers from 0.8 to 0.955. Such discrepancies can result in measured surface temperatures differing by several degrees Celsius. An unacceptable discrepancy if used for fever screening. In this study we determined the emissivity of three skin locations in ten sows when they were alive and dead: the ear base, udder and shoulder. The shoulder was investigated with and without (clipped) hairs. Emissivity for ear base, udder, and shoulder (hairy) was 0.978 ± 0.006, 0.975 ± 0.006 and 0.946 ± 0.006, respectively. Clipping the hairs of the shoulder tended to increase the emissivity ( p = 0.07). Emissivity of the hairy shoulder was significantly lower than for the ear base ( p < 0.001) and the udder ( p < 0.005). Emissivity of the three skin areas with no blood perfusion (after euthanasia) tended to be lower ( p = 0.06) compared with the emissivity of the skin areas when perfused with blood. The results of this study confirm that it is valid to use the human skin emissivity value of 0.98 for infrared skin measurements on sows. However, when studying hairy skin areas or skin with no blood perfusion, the emissivity value is lower. [ABSTRACT FROM AUTHOR]

Abstract: It has previously been shown that when sows lie down in the open there is a much greater risk of piglet crushing than when they lie down alongside a wall, probably because the wall provides support and/or a piglet escape zone. Therefore, walls in farrowing pens should be attractive to the sow, so that she chooses to use them when lying down. EU-regulations state that farrowing pens must be given “some means of protecting the piglets, such as farrowing rails”. Walls with farrowing rails may, however, not be the most appropriate option as they may be unattractive to the sows. We tested sow preferences for lying down alongside a plain wall, a sloping wall or a wall with a farrowing rail. Beforehand, we tested preferences for three sloping wall designs (plain, curved and multiple bars) in order to use the preferred one in the later choice experiment. In both experiments, 4×6 pregnant second–seventh parity individually housed sows were used over a 3-day training and a 4-day testing period. In both experiments, the three types of walls were balanced on position in the pen. In both tests, the sows predominantly lay down alongside the walls (on average, 80±4 and 86±3% of lying down events, respectively). In the test of the three sloping wall designs, the sows had no significant preferences for wall designs. For practical reasons the plain sloping wall was used in the subsequent test. Here, there was a significant effect of wall type (on average, 16±5% of lying down events alongside the wall with the farrowing rail, 48±8% alongside the plain wall and 36±8% alongside the plain sloping wall (P <0.025)). The sows lay down alongside the wall with the farrowing rail less than alongside the plain or the plain sloping wall (P <0.01), but the preference for the two latter wall types did not differ significantly. Irrespective of the wall type, the sows had a significant preference for the back wall of the pen (P <0.001 in both experiments). In conclusion, walls with farrowing rails appear to be less attractive to lie down against than other wall designs. Although farrowing rails provide piglets with escape zones they may not be optimal for piglet survival because they do not encourage the sow to lie down alongside a wall, rather than in the open. Moreover, they may not be optimal from a sow welfare perspective due to lack of support for the sow when lying down. [Copyright &y& Elsevier]

Repeated deprivation of lying down was used as a model to study the effect of long-term stress on performance, meat quality and metabolic changes in young bulls. Sixteen Danish Friesians were included and assigned to either control treatment or deprivation of lying down from 07:00 to 14:00 and 15:00 to 22:00 every day for 10 weeks. Feed intake was recorded daily. Blood was taken weekly to study changes in hormone and metabolite concentrations. On days 5 and 55 of the treatment, the sensitivity of the pituitary to growth hormone-releasing factor was tested. Repeated deprivation of lying down did not affect voluntary feed intake or meat quality. Likewise, feed efficiency and daily intake did not differ statistically, but numerically the reduction was in accordance with the hypothesis that long-term stress depresses performance. Between-animal variation appears to be markedly increased for traits such as daily gain and feed conversion ratio, indicating individual adaptation to long-term stress. Stressed animals tended to have lower circulating levels of insulin-like growth factor-I but no effect was observed on the sensitivity of the pituitary. [ABSTRACT FROM AUTHOR]

• One sow did not allow foster piglets to suckle within 24 h. • Milk yield dropped for four of the nine sows who accepted the foster piglets. • Latency to the first milk ejection for foster piglets ranged from 1 to 8 h. • Foster piglets had lower growth, more competition and longer nursing intervals. • Sow nutritional status was not compromised - dietary protein appeared oversupplied. Selection for increased litter size has led to the use of so-called nurse sows in several European countries. A nurse sow receives new piglets after having weaned her own. Nurse sows are often made in two-steps. In the two-step strategy, new-born piglets are given to a sow 4–7 days into lactation. Her 4–7 days old piglets are given to a so-called intermediate sow 21 days into lactation whose piglets are weaned at day 21. The use of nurse sows has been associated with welfare problems caused by an extended length of crating and/or by the disturbance of the nursing pattern by moving and mixing of foster piglets. The aim of this study was to investigate growth and welfare indicators (latency to suckle after transfer, teat fighting, snout- and knee abrasions) of ten foster litters at the intermediate sow and to compare these with the sows' own litter at the same age as well as to compare the sows' milk production, nutritional status and fat mobilisation in the period where she nursed her own piglets compared to the foster piglets. One of the ten sows did not accept the foster litter. The results on the remaining 9 litters showed reduced growth, increased teat fighting and missing milk letdown for the foster piglets compared to the sows' own litter at the same age (P < 0.05) and more udder abrasions on the sows after transfer (P < 0.05). There were signs of milk intake being insufficient (i.e. lower growth rate of foster piglets) as the foster piglets experienced longer nursing intervals (P < 0.05) and four of the sows' milk yield dropped considerably after transfer. The sows' nutritional status did not seem to be compromised but the study indicated an oversupply of dietary protein after becoming nurse sows. In conclusion, there were signs of impaired welfare and growth of foster piglets reared by intermediate nurse sows and indications of a mismatch between sow milk yield and piglet milk removal. [ABSTRACT FROM AUTHOR]

• Larger piglets within-litter drank milk replacer as a supplement to suckling. • Few smaller piglets with low suckling success compensated with milk replacer. • In larger litters; more compensated for low suckling success with milk replacer. • Piglets were not weaned early and nourished solely on milk replacer. • Sub-optimal milk cup design and/or milk replacer for smaller piglets. Due to genetic selection for large litters in pig production, piglets are often supernumerary to the teats on the sow. Providing milk replacer as a second feed source is increasingly being used to rear large litters. This results in increased competition at the udder when all piglets remain at the sow. We hypothesise that larger litter size and being amongst the smaller piglets within-litter (irrespective of absolute weight) is associated with increased likelihood of drinking milk replacer as a supplement to suckling or to compensate for low suckling success. The study design was 2 × 2 factorial with two standardised litter sizes at day 1 (LSD1) of either 14 piglets (LS14) or 17 piglets (LS17) and two housing conditions in either crates (CRATE) or loose housing (LOOSE). If piglets died, they were not replaced. The piglets' suckling and drinking behaviour along with their growth rate was recorded weekly. The results showed a clear preference for suckling the sow over milk replacer. None of the piglets changed entirely to drink milk replacer. LS17 compared to LS14 was associated with more piglets with low suckling success (P ≤ 0.05) and the risk of having low suckling success was higher for the smaller piglets within-litter (P ≤ 0.05). About half of the piglets with low suckling success were able to compensate and sustain growth by drinking milk replacer (P ≤ 0.05). The largest piglets within-litter were more likely to drink milk replacer as supplement to high suckling success compared to only suckling (P ≤ 0.05). When taking into account the absolute weight of the piglets in the start of the week, piglets drinking milk replacer in addition to suckling had a higher growth rate in the following week compared to piglets who did not supplement suckling with milk replacer (P ≤ 0.05). Thus, the present study could confirm that some of the piglets experiencing a competitive disadvantage at the udder could compensate with milk replacer. However, the milk replacer was mainly used by the larger piglets within-litter and as a supplement to increase growth of piglets who had access to a teat. Several factors may have affected the piglets' ability to use the milk replacer: high effort to drink from the milk cup due to inadequate design, poorer nutrient quality of milk replacer than of sow milk, and/or suckling the sow satisfies other behavioural and physiological needs than solely nourishment. [ABSTRACT FROM AUTHOR]

• Increasing litter size increased sibling competition at the udder. • Smaller piglets had a competitive disadvantage. • Commercial milk replacer and loose housing only minimally reduced competition. Litter sizes where piglets are supernumerary to teats leads to the practice of fostering to nurse sows or to artificial rearing systems, which is associated with compromised welfare. An alternative strategy is to leave the supernumerary piglets with their own dam and provide milk replacer in the farrowing pen. To provide sufficient space around the sow's udder, loose housing could be an alternative to the use of farrowing crates. However, large litters have been associated with increased teat fighting, abrasions on sows and piglets and signs of hunger. The aim of this study was to investigate whether provision of milk replacer and/or loose housing could alleviate signs of hunger and sibling competition at the udder. Ninety-eight litters were studied in a 2 × 2 factorial design. The sows were housed in crates or loose (CRATE/LOOSE), and litters had access to milk replacer or no milk replacer (+MILK/-MILK). The litter size was either 14 or 17 piglets on day 1 postpartum but decreased as piglets died. Recordings included drinking bouts of milk replacer, teat fighting, udder massage and abrasions on sow and piglets. On day 3, at least one observation of milk replacer consumption was observed in 90% of the litters in +MILK but at less than five bouts per litter/12 h in all except two litters. On days 7, 14 and 21, 59-65% of the piglets in +MILK consumed milk replacer at least once with a mean frequency of 0.4-1.9 bouts/h/piglet. Increasing litter size resulted in more piglets involved in teat fighting, having low suckling success and snout abrasions (P < 0.05). The risk for all indicators were generally higher for smaller compared to larger piglets. Access to milk replacer reduced risk of piglet snout abrasions (P < 0.05), but not of teat fighting (P> 0.1). Loose housing reduced the risk of udder abrasions (P < 0.05) and tended to decrease udder massage (P < 0.10). Thus, milk replacer and loose housing minimally reduced litter competition in litters from hyper-prolific sows, indicating that supplementing large litters with milk replacer can be associated with compromised welfare. The welfare consequences of using milk replacer appear comparable to when surplus piglets are fostered by nurse sows or artificially reared. Before supplementing milk replacer to large litters is further applied under commercial conditions, research and innovation is needed to improve quality of milk replacer and cup design to alleviate the negative impact on welfare. [ABSTRACT FROM AUTHOR]