Behaviour and welfare of veal calves in relation to husbandry systems

anglais. The traditional housing of veal calves in individual crates without roughage has received prolonged and serious criticism, since it denies the animals various social activities, freedom of movement and the possibility to consume roughage and to ruminate. In order to develop an economically acceptable alternative to this housing system, which would provide a significant improvement in calf welfare, the housing of calves in groups of five was evaluated with regards to husbandry, health and ethological aspects. The present study focussed mainly on the behaviour of the calves in individual crates and group pens (chapter IV) and it was only casually concerned with the production and health of the animals (chapter III).<p/>A major problem in the group pens was the occurrence of preputial sucking and urine drinking, which had a negative influence on production, health and behaviour. The development of these activities was described (chapter V) and several experiments concerning their prevention were presented (chapter VI). The influence on lying behaviour of the tethering of the calves during the first 6-8 weeks after arrival - as a preventive measure against preputial sucking and urine drinking - was studied in chapter VII. Finally, restrictions to particular lying postures in the crates were investigated with respect to their effect on sleep (chapter VIII).<p/>In five consecutive experiments, a total of 94 calves were housed in individual crates (1,65 x 0,65 m) and provided with 100 g straw/calf/day. whereas 99 calves were kept in groups of five in pens (2,20 x 3,83 m) on concrete slatted floors with straw bedding and an ad libitum supply of straw in baskets. The group housed calves were not tethered during the first weeks after arrival.<p/>In four other experiments, a total of 47 calves were housed in individual crates (1,70 x 0,70 m) and given 200 g straw cobs/calf/day from week 7 or 9 onwards, whereas 139 calves were kept in groups of five in pens (2,40 x 3,05 m) on wooden (and in some pens partly concrete) slatted floors. 1 kg straw cobs was supplied daily from week 7 or 9 onwards in one trough per group pen. During the first 6 weeks after arrival, the calves were tethered to the feeding gate, separated individually by partitions.<p/>All calves were male and predominantly black and white (FH x HF). In three out of the nine experiments, male red and white (MRY) calves were used. The influence of this breed difference was not discussed. The calves were fed a milk replacer in open buckets twice daily at approximately 8.00 and 16.00 h.<p/>In chapter III, limited data on production, health and labour requirements of the calves in these housing systems are reported, which provide a first impression on how individual crates and group pens compare. Growth rate (about 1200 g /day) and feed conversion (about 1,5) of the calves slaughtered at a normal weight in group pens with and without straw bedding on the one hand and individual crates on the other were comparable and quite favourable. Slaughter quality, which was satisfactory in general, was also similar in these different housing systems. Haemoglobin levels at slaughter were fairly high (8-110 g/100 ml), but meat colour was still acceptable.<p/>A relatively large number of group housed calves, however, died or had to be culled or eliminated. The total of these losses amounted to 10,1 % in the group pens with straw bedding, against 4,3% in the corresponding crates; in the group pens with slatted floors the total losses were 9,4% against 2,2% in the crates. These high losses in the group pens mainly occurred because in this housing system it was difficult to treat diseased calves individually (for example by supplying a medicinated milk replacer) since they were often pushed away by penmates. When disregarding these losses, the health status of the calves, as measured by the frequency and duration of the different medical treatments imposed,<br/>seemed no worse in the group pens than in the individual crates.<p/>In the group pens, the provision of 23,3 kg strawlcalf for feeding and 106,3 kg straw/ calf for bedding took 138,7 min/calf in total during the entire fattening period, against 32,6 min/calf for supplying 7,1 kg straw/calf in the individual crates. In the group pens with bare slatted floors and the corresponding crates, the total amount of straw cobs provided from week 9 onwards (13-14 kg/calf) and the time required to do this (15-17 min/calf) were about equal.<p/>In the first series of experiments, when the calves were tethered for the first 6 weeks after arrival, preputial sucking did not occur. The muzzling of preputial suckers was not satisfactory, since it obstructed smelling, licking and the intake of straw and moreover, it did not stop the ingestion of urine. Abomasal lesions (erosions, ulcers, scars), which were mainly located in the pyloric region, were observed in calves housed in individual crates and group pens alike. In only 14-37% of the animals, the abomasums were not affected by lesions.<p/>It was concluded that group housing with or without straw bedding is not incompatible with fast growth, favourable feed conversion and adequate slaughter quality. The high losses in the group pens may perhaps be reduced by restraining the calves at feeding with a self- yoking feeding gate, which facilitates not only the treatment of illnesses but also their detection. The latter seems particularly valuable on practical farms, when health inspection is not as intensive as in the present study. The supply and removal of straw as a bedding is extremely labour intensive and therefore wooden slatted floors without straw are preferred in further research. The study of the causation and prevention of preputial sucking and urine drinking has a high priority, since preventive tethering restricts freedom of movement, social contact and exploratory behaviour.<p/>In chapter IV, it was investigated to what extent calves in individual crates were restricted in their behaviour in comparison to calves in group pens and how they dealt with their situation. For this purpose, the behaviour of the same calves whose production characteristics were described in the previous chapter was registered.<p/>Observations were carried out on all individual calves in both housing systems over one period of 23 hours (24 hours with exception of feeding periods) in weeks 8, 12, 16 and 20 after arrival by means of instantaneous sampling in 10 minute intervals. Subsequently, an analysis of variance was executed to calculate the average frequency and trend for each behaviour and both housing systems were compared on the basis of these parameters. The percentages quoted are close approximations of average values over the second series of four experiments (with group pens on slatted floors without straw bedding and the corresponding crates).<p/>The calves in the crates spent more time lying than those in the group pens (74 against 68%). This is probably above all the result of a greater variety of stimuli in the group pens, but occasional mounting and treading of penmates may also have contributed to this difference.<p/>Lying on the side or on the brisket with both hindlegs stretched in the group pens amounted to 2 and 8% of total lying time respectively. Lying was severely restricted by the sidewalls of the crates and consequently, these postures only rarely occurred in the crates at the end of the fattening period. It is argued that these restrictions may interfere with the relaxation of the body. Moreover, these limitations seemed to affect behavioural thermoregulation; the crated calves regulated heat loss by stretching their forelegs forwards during lying (27% of total lying) or by bending them under the body, whereas the group housed calves increased or decreased body. contact with the floor often by stretching and bending their hindlegs instead of their forelegs (hindlegs stretched: 10% of total lying; forelegs stretched: 15,5% of total lying).<p/>Lying with the head turned backwards, which is the usual posture for supporting the head (in the group pens 20-25% of total lying) became increasingly restricted in the individual crates towards the end of the fattening period. In the crates, the duration of this lying posture as a proportion of total lying decreased from 25% in week 8 to 5% in week 20. Although the head was supported forwards on the floor more often (10% instead of 5% of total lying) or against the partitions (1-2% of total lying), the duration of lying with the head supported was clearly reduced in the crates in comparison to the group pens: 16% and 30% respectively. The latter percentage includes lying with the head on penmates in the group pens (5% of total lying). Since supporting the head is necessary for the relaxation of the neck muscles during certain states of sleep, the restriction of these tying postures in the crates may interfere with sleep as a physiological process.<p/>Furthermore, the licking of the belly, back, thighs or hindlegs (1,7% in the crates and 3,2% in the group pens) and the scratching of the head, neck or shoulders (0,05 against 0,16 %) were also hindered by the sidewalls of the crate, whereas rubbing (0,6-0,7 %) was not impaired. On the other hand, the licking of the forelegs (1,0 against 0,7%) and the muzzle (1,9 against 1,1 %), which are easily accessible, was more frequently performed by the crated calves than by the group housed ones. The increase of the latter activities in the individual crates may be related to conflict situations. Self stretching was reduced in the crates as compared to the group pens (0, 14 against 0,25%).<p/>In the individual crates, physical interactions between neighbouring calves were usually limited to licking and sucking at feeding times when the front was opened, whereas in the group pens mutual licking occurred regularly throughout the day (2,5%) and head butting and mounting (together 1,0%) were also performed. Preputial sucking and urine drinking were seldom in this period from 8 to 20 weeks after arrival (together less than 0,3%). Occasional licking outside feeding periods was observed in the crates as soon as the calves were able to reach over the sidewalls, which shows their desire for social contacts. Head butting against inanimate objects and jumping as an introduction to play were more frequent in the individual crates than in the group pens (together 0,4% against 0,2%), which may indicate a need for social play in the individually housed animals.<p/>Exploration by the crated calves was confined to the licking and sniffing at the front part of the crates and the surveying of the area in front of and behind the crates. As a consequence of the limited (visual) contact with the environment, the calves in the crates were quickly alarmed, in contrast to those in the group pens, which could survey the environment even when lying.<p/>Eating and ruminating were clearly enhanced in the group pens with straw bedding and ad libitum straw for feeding (7 and 22% respectively) as compared to the group pens with slatted floors and a limited supply of straw cobs (1,5 and 9,5% respectively) or the individual crates with small gifts of straw or straw cobs (1 -2% and 8-12% respectively).<p/>The performance of stereotypies such as the licking (4-5%) or scraping (2-3%) of objects and tongue playing (2%) was not affected by individual or group housing as such, but these activities were somewhat reduced when straw supply was ad libitum instead of restricted. Wooden slatted floors were slippery and uneven in comparison to concrete slatted floors with straw bedding although this probably did not interfere with the mobility of the calves, for instance during head butting and mounting.<p/>As a first step in finding ways of preventing preputial sucking and urine drinking, it is described in chapter V how the orientation of sucking behaviour develops in calves which are loose housed in groups of five upon arrival.<p/>Initially, sucking was orientated towards physical objects or body parts of congeners other than the prepuce. Most calves preferred a certain body part or (more seldom) a physical object for sucking, such as the ears, mouth, legs or scrotum of penmates, the rim of a bucket or a horizontal bar. These preferences differed among individual calves and usually changed over time. In the second and third week after arrival, many calves showed a preference for sucking at the prepuce of congeners. In reaction, the sucked calf usually started to urinate, while the sucking calf held on to the prepuce and ingested most of the urine. This preputial sucking was observed in the first 6-8 weeks after arrival; thereafter, the frequency of this behaviour and of the other sucking activities was strongly reduced in all calves. Seven out of the 30 calves in this study never sucked the prepuce and two only seldom.<p/>In most calves, preputial sucking took up several hours per day, whereas sucking at physical objects or other body parts lasted one hour per day at most. Moreover, preputial sucking occurred during several activity periods throughout the day and night, whereas other sucking was concentrated at feeding times. Individual preferences or aversions for sucking at the prepuce of particular penmates were uncommon.<p/>Persistent preputial sucking resulted in the loss of hair around the muzzle and cases of poor growth among the sucking calves, whereas hairloss of the prepuce and avoidance reactions occurred among the calves which were sucked. Urine drinking, the licking of the urine jet of a urinating calf, was relatively harmless and infrequent; it was performed by preputial suckers as well as non-preputial suckers.<p/>On the basis of this information, two hypotheses were proposed. The first one implicated that the attraction of preputial sucking as compared to other sucking was connected to the intake of urine during this activity. The second one suggested that the absence of preputial sucking in some calves had to do with their early sucking experience. Both hypotheses were tested in chapter VI.<p/>In a pilot study (chapter VI.1), several sucking and drinking devices were presented in different combinations to calves in group pens which had been fed during the first day of their life either with open buckets, with teat buckets or by the mother cow. All calves were fed a milk replacer in open buckets twice daily. The drinking and sucking behaviour of the calves was registered during one 24 hour period in weeks 2, 3 and 4 after arrival.<p/>Teats connected to a water reservoir were sucked more than empty teats, which suggests that the release of fluid from the sucked object is an incentive in sucking. This indirectly supports the idea that the excretion of urine stimulates preputial sucking. Furthermore, 11 out of 22 open bucket reared calves and 2 out of 10 cow reared calves started preputial sucking, whereas all 8 teat bucket reared calves refrained from this activity, which tentatively shows that early sucking experience may influence the frequency of preputial sucking. Next (chapter VI.2), it is argued that the provision of only small amounts of milk replacer during the first weeks of the fattening period (3-4 l/calf/day) may lead to a fluid deficit which may be one of the causes of preputial sucking. Therefore, the effect of extra water supply on the incidence of preputial sucking was investigated. In three replicate experiments, 3-5 l water (25-35°C) was provided two or three times per day in open buckets to a total of 60 calves in groups of five, whereas 60 other group housed calves did not receive extra water.<p/>Total fluid intake (milk replacer + water) was on average two to three times higher in the extra water groups than in the control groups of calves (for instance in week 3: 14 l against 5 l/calf/day). Nevertheless, in extra water groups 10 calves started preputial sucking against 14 calves in the groups without extra water; there was no significant influence of an extra supply of water on the incidence of preputial sucking.<p/>In one of the three replicates, drinking intensity of all individual calves was measured every two days by recording latency till drinking and drinking rate in separate "drinking tests". Surprisingly, the drinking intensity of calves provided with extra water was no less than that of calves without extra water. Moreover, those calves which drank the maximum of 15 l of water daily showed the highest drinking intensity. This raises some interesting questions concerning water intake regulation in these young calves.<p/>In the last section (chapter VI.3), it was investigated if early sucking experience indeed affected the development of preputial sucking as suggested by earlier data. In the first experiment 20 bucket reared, 15 teat bucket reared and 5 cow reared calves were kept in groups of five and fed twice daily from open buckets. 13 out of 20 bucket reared calves and three out of five cow reared calves started preputial sucking, whereas again none of the 15 teat bucket reared calves engaged in this behaviour. The difference between bucket and teat bucket reared calves was significant (p(one-tailed) = 0,028).<p/>In the second experiment, eight bucket reared and nine teat bucket reared calves were observed, but preputial sucking did not occur. In this experiment, the contacting and sucking of a teat was studied by presenting a non-nutritive teat to each calf individually for 5 minute periods, six times a day. Four out of eight bucket reared calves usually failed to suck the teat, whereas all nine teat bucket reared ones nearly always attached to the teat and sucked. The average duration of sucking of those calves which contacted the teat was similar in both groups.<p/>The fact that in three experiments none out of a total of 32 teat bucket reared calves engaged in preputial sucking, compared to 24 out of 50 bucket reared and 5 out of 15 cow reared calves, strongly suggests that early sucking experience influences the development of preputial sucking. Furthermore, the failure of some of the bucket reared calves to attach to the teat may indicate that such calves are less likely to find the teats of an automatic feed dispenser on their own as compared to teat bucket reared calves. The practical consequences of these findings should be investigated further with a larger number of animals.<p/>Although the previous results advanced the understanding of how preputial sucking develops and what factors are involved in its causation, they did not provide an instant method for preventing this unwanted behaviour. Since at present, tethering the calves and separating them by small partitions during the first 6-8 weeks after arrival seems the only effective and practical way to avoid preputial sucking, different tethering methods were evaluated regarding their consequences for calf behaviour (chapter VII).<p/>Stalls (i.e. spaces where single calves were tethered between partitions) of 0,48 m and 0,58 m in width were equipped with either 0,48 m long chains with contraweights (0,2 kg) which were guided through openings in the feeding gate or fixed chains of medium length (0,40 m); in a second experiment, the long chains with contraweights were replaced by short fixed chains (0,34 m). Different lying postures and patterns of standing up and lying down were recorded, mainly from 6 to 9 weeks after arrival, just before the calves were untethered.<p/>The tethering of calves in 0,48 m wide stalls restricted lying on the side or on the brisket with the hindlegs stretched at 6 and 8 weeks to about the same extent as housing in 0,70 m wide crates at 8 weeks; in 0,58 m wide stalls, both lying postures were hindered less. The stretching of the forelegs in these different types of stalls was not impaired.<p/>Stalls of 0,48 m in width restricted the lying with the head turned backwards in contrast to stalls of 0,58 m in width, but these restrictions were not serious. The use of chains of 0,34 m in length and chains provided with contraweights to prevent entanglement of the forelegs was unnecessary and moreover, it hindered the turning of the head backwards during lying; these chains should not be used.<p/>In all tethering stalls, the space in front of the calves was insufficient to swing the head forwards freely when standing up. Casual contacts with the partitions or restrictions by the chains were of minor importance, since they did not really interfere with standing up and lying down. In general, standing up and lying down occurred without great difficulty, but the calves' performance deteriorated in cold conditions.<p/>Moreover, at temperatures below approximately 8 °C, which is the lower critical value for veal calves of 4-10 weeks of age, they experienced discomfort, as appeared from the shivering of the animals and extreme postural changes including the tucking in of all legs and the burying of the head in the flank. Therefore, such low temperatures are clearly disagreeable.<br/>The support of the head while lying, which is necessary for the relaxation of the neck muscles during paradoxical sleep (PS), was diminished in the individual crates as a result of restrictions to lying with the head turned backwards. The consequences of this impairment for the performance of PS in calves of about one week old were examined in chapter VIII.<p/>Lying with the head turned backwards was obstructed for 24 hours by the use of a short halter and the performance of PS was measured before, during and after this obstruction. Twitches of the eyes, muzzle, mouth, legs and ears were successfully employed as indicators of ongoing PS. Ear twitches in particular were useful, since they could easily be recognized from videotapes and they represented a major part of PS.<p/>When the turning of the head backwards was thwarted by haltering, the head was supported forwards instead. Nevertheless, PS as estimated on the basis of ear movements was somewhat reduced during haltering in comparison to before and after haltering (5,8 against 7,5% on average). This indicates that in terms of PS performance, lying with the head forwards is not an equivalent substitute for lying with the head turned backwards. Since however, this small decrease in PS during haltering was not recovered after release of the halter, physiological processes occurring during PS were probably not disturbed. In this respect, the calves seemed to deal adequately with the restrictions imposed.<p/>In chapter IX, some points from previous chapters were discussed more comprehensively. It is argued that sucking is probably essential to establish satiety after drinking and that it may therefore constitute a reinforcing activity; this reinforcement may play an essential role in the development of individual preferences for sucking at certain body parts and objects; an individual calf may associate the reinforcement from sucking as such with some randomly chosen part of a penmate's body or a physical object on which the sucking can be performed.<p/>Although the details of these preferences seem coincidental, some general cues for the orientation of the sucking response may exist, such as stimuli connected to the smell, shape, temperature or position of the sucked object, fluids released from it and the caloric value of these fluids. Such cues may be used to prevent preputial sucking, for instance in the feeding with automatic teat dispensers.<p/>Teat feeding of calves was encouraged: not only because it reduces the occurrence of preputial sucking but also because it facilitates normal regulation of sucking behaviour and it promotes various digestive processes. The possible inhibitory influence of a relatively shortlasting experience with teat bucket feeding immediately after birth on the occurrence of preputial sucking was explained on the basis of imprinting processes during a sensitive period in the first days of life.<p/>As paradoxical sleep is concerned, it was mentioned that the adaptation to restrictions to lying with the head turned backwards may be more difficult to calves in individual crates than to haltered ones, since the performance of head forwards postures seems impaired in the crates and the head is supported less than during haltering. The conditions in the crates are probably inadequate for resting and maybe also for sleeping, due to restrictions to the support of the head during lying, to the lying on the side or on the brisket with the hindlegs stretched and to comfort behaviours which are partly associated with resting, such as self licking and stretching.<p/>Finally, it was shown that the housing of calves in groups of five, as presented in this study, respects the basic principles of veal calf rearing since it maintains individual feeding of an iron deficient milk replacer which is crucial to the efficient production of white meat. At the same time, it achieves a significant improvement in the welfare of the calves by removing some serious behavioural restrictions which occur in the crates, concerning the ability to lie on the side or on the brisket With both hindlegs stretched, to support the head during lying, to groom, to interact with congeners and to explore the environment. Furthermore, the provision of straw cobs in the group pens allows roughage intake and rumination. In spite of the fact that most of these benefits do not apply until the calves are untethered at 6-8 weeks after arrival, this group housing system marks a very important step in the direction of improved calf welfare.<p/>The limited data on production, management and health aspects, described in the present study, suggest that the keeping of veal calves in small groups may be competitive to the traditional housing of veal calves in individual crates. The economic feasibility of group housing on farms, however, depends eventually on the competence and attitude of individual farmers, who may now demonstrate that they realize and accept the responsibility for the welfare of their calves.

néerlandais; flamand. Als een van de alternatieven van de traditionele huisvesting van vleeskalveren in individuele boxen zonder ruwvoer werd de huisvesting in groepen van vijf kalveren vergeleken met die in individuele boxen ten aanzien van produktie-, gezondheids- en ethologische aspecten. Het hier gepresenteerde onderzoek hield zich voornamelijk bezig met het gedrag van de kalveren in beide huisvestingssystemen en slechts zijdelings met hun produktie en gezondheid. Een belangrijk probleem in de groepshokken was het optreden van preputiaalzuigen en urinedrinken, wat een negatieve invloed had op de produktie, de gezondheid en het gedrag van de kalveren. De ontwikkeling van beide gedragingen werd beschreven en ook werden enige mogelijkheden ter preventie van deze activiteiten beproefd. In de praktijk worden de dieren gewoonlijk gedurende de eerste 6-8 weken van de mestperiode met een halsketting vastgezet aan het voerhek en van elkaar gescheiden door tussenschotjes om het optreden van preputiaalzuigen en urinedrinken tegen te gaan. De invloed van verschillende vastzetmethoden op het liggedrag van de kalveren werd onderzocht. Bij enkele van deze methoden, maar vooral bij het houden van kalveren in individuele boxen werd het aannemen van bepaalde lighoudingen belemmerd en het effect van deze belemmeringen op de slaap nagegaan