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Prairie Swine Centre is an affiliate of the University of Saskatchewan
Prairie Swine Centre is grateful for the assistance of the George Morris Centre in developing the economics portion of Pork Insight.
Financial support for the Enterprise Model Project and Pork Insight has been provided by:
Effects of density and perch availability on the immune status of broilers.
Posted in: Welfare by admin on January 1, 2002 | No Comments
Commercial broiler hens were raised from hatch to 42 days of age with 10, 15 and 20 birds per m2 in pens with or without the availability of horizontal perches to examine the effects of the housing on the immune status of the birds. The immune parameters assessed were lymphoid organ weights, antibody response to SRBC in the last 10 days of growth, heterophil:lymphocyte ratios at 32 and 42 days of age, and lymphocyte blastogenesis of peripheral blood lymphocytes collected at 32 and 42 days of age. As bird density increased, bursa weight and bursa/body weight ratios decreased. The bursa weights and bursa/body weight index were also significantly decreased by the addition of perches to the environment. No other significant effects were observed for the flock performance, morphometric data, or immunological tests between treatments. Conclusions stated that, under the conditions of the study, which tried to simulate commercial conditions, the bursal weight was the best indicator of stress related to housing density. Stress appeared to increase with the addition of perches because the birds used the perches infrequently. Therefore, there may have been a further reduction in the availability of floor space to the birds with the addition of perches.
Validation of a method for assessment of an acute pain in lambs.
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Lambs were castrated and tail docked using rubber rings and the level of acute pain was assessed using behavioural and physiological methods. Validity was determined by showing how accurately lambs were allocated to their appropriate treatment groups. The treatments were ranked before the experiment according to the amount of tissue damage and its sensitivity to pain (anaesthesia), in decreasing order of severity: 1) castration and tail docking; 2) bilateral castration; 3) unilateral castration; 4) short scrotum castration; 5) short scrotum castration with local anaesthesia; 6) handled. Another group of lambs that been tail docked only acted as a tail docking control for castration and tail docked lambs. Changes in plasma cortisol concentration; 14 postures and 11 active behaviors were recorded for 180 minutes. A principal component analysis (PCA) and discriminant analysis (DA) helped determine the combinations of indices that most accurately allocated lambs to the appropriate treatment groups. Using all individual indices available from the lambs in a PCA, the first two components accounted for 45 % of the variation while use of the DA allocated 79 % of the lambs to their appropriate groups (60 minute data). Values for 30, 90, 120, and 180 minutes were 50, 55, 48, and 48 %, respectively. Simplification of the measurement was carried out by combining indices: total – incidence of active behaviors, relating to movements of limbs, tail and head plus vocalisation; VSS – time spent dog sitting, lying normally with trembling or with partial extension of hind limbs, and statue standing; V4LL – lying with full extension of the hind limbs; AbS – abnormal standing, excluding statue standing. The accuracy of allocation was improved to 60, 79, 71, 64, and 60 % for 30, 60, 90, 120, and 180 minutes using the combined indices. The accuracy for 60 minute data was not improved when increases in plasma cortisol were included. A simplified index consisting of V4LL and REW (movements of tail and limbs) allocated 74 % (60 minute data, 64 % for 30 minute data) correctly. When the treatment groups were combined to represent severe, mild, or moderate pain, the combined indices permitted correct allocation of 91 % and the simplified indices 83 % of lambs to their appropriate groups (60 minute data).
An assessment of several potential enrichment devices for feedlot cattle.
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This study looked at four potential environmental enrichment devices for feedlot cattle over a 22 day trial. Two of the devices allowed cattle to rub and scratch different portions of their body, and these were used most extensively by the animals and by 75% of the cattle in each pen. Of the two scratching devices, the one that allowed scratching of the head and back of the animal was used the most, and increased in usage up to 16 days after the beginning of the trial. The other device allowed scratching of the sides of the animal. The other potential enrichment devices involved accessing odours by sniffing and nosing a pipe hung in the pen. These devices, using milk and lavender odours, were used very little and primarily during the first 2-3 days of the trial. The milk based devices was used slightly more than the lavender devices. The conclusion of the study is that scratching devices have greater potential as enrichment devices in feedlots than do odour based devices.
The development of feather pecking behaviour and targeting of pecking in chicks from a high and low feather pecking line of laying hens.
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Large individual differences between adult laying hens in their propensity for feather pecking are known to exist. However, not much research has been carried out into the individual differences concerning the development of feather pecking behaviour. The purpose of this study was to investigate whether contrasting levels of feather pecking, observed among adult birds from two lines of laying hens, already occur at an early age. Furthermore, an important question to be discussed was whether different behavioural systems may be related to the occurrence of feather pecking. Therefore, this study consisted of studying and comparing the behaviour of White Leghorn laying hens from a high (HFP) and low feather pecking (LSP) during the first 8 weeks of life. Chicks were reared in litter-floor pens and were kept in groups of five animals per line (12 groups per line). HFP chicks showed significantly higher levels of gentle feather pecking than LFP chicks at the age of 14 and 28 days. Furthermore, HFP chicks spent significantly more time preening than LFP chicks on day 14, 28, and 41. Duration of foraging behaviour and feeding behaviour was significantly higher in the LFP line compared to the HFP line. HFP chicks showed a negative correlation between gentle FP and preening. In the LFP line duration of feeding correlated negatively with gentle FP. In conclusion, differences in feather pecking behaviour between HFP and LFP chicks can already be observed at a very early age during development. Furthermore, the results indicated that HFP and LFP chicks differ in the way pecking behaviour is targeted. This difference could be related to the existence of a difference in underlying motivational system controlling the development of feather pecking between the two lines.
Decision support system for overall welfare assessment in pregnant sows A: Model structure and weighting procedure.
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An ongoing argument in the defining and assessment of farm animal welfare has been over what criteria should and should not be used. The authors constructed a computerized welfare assessment model for gestating sows, called the SOWWEL (from SOw WELfare), based on a hierarchical organization of the sows’ needs. The model was constructed using data from previous scientific studies. The housing and management systems are inputted into the model and it will generate an overall welfare score. Thirty-seven attributes associated with welfare related properties of the housing and management system are found within the model (ie: space per pen, health status, feeding levela
Influence of housing on weanling horse behavior and subsequent welfare
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Horses were monitored to measure behavioural and physiological stress markers when they were weaned individually in solid partition box stalls or in small groups housed in paddocks. Both treatment groups experienced maternal deprivation stress, but the stalled weanlings had the additive effects of social isolation, which prevented them from performing social behaviors. Weanlings of an average age of 4.5 months were weaned in individual box stalls or in groups of three in a paddock with limited grazing forage and an open shelter available. There were no distinguishable treatment differences between the 11, 17-dioxoandrostanes (indicator of glucocorticoid metabolite concentrations) of fecal samples, either immediately post-weaning or at the end of the 56-day study. All weanlings showed a 4-week post-weaning increase in 11, 17-dioxoandrostanes for reasons that were unclear. The 11, 17-dioxoandrostanes is the metabolite that has been determined to be correlated with plasma cortisol levels, and thus stress levels, in horses. Behavioral observations indicated significant differences in the behavioural time budget of stall-housed and paddock-housed weanlings. Paddock-housed weanlings behaved more like feral horses, spending more time moving and less time lying, and they showed a strong motivation to graze and be near their group mates. Stalled weanlings spent more time engaged in aberrant behaviors such as licking or chewing the stall/shed wall, kicking at the stall/shed wall, pawing, and bucking/rearing bouts. The ability to engage in strongly preferred behaviors, the freedom from aberrant behavior, and the variety of behaviors shown indicated that paddock-reared, group-housed weanlings had better welfare. However, the evidence necessary to conclude that stalled weanlings had poor welfare was insufficient.
Equine learning: progress and suggestions for future research
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This is a review of research on learning in horses. It summarizes recent studies and identifies a number of topics for future research. Horses are very capable of learning using classical and instrumental methods. Recent emphasis has been on using instrumental methods to better understand the cognitive abilities of horses. Although horses can readily discriminate among stimuli, they appear to have difficulty forming abstract concepts that would link stimuli together by anything more than basic similarities. Horses often perform differently on different tasks, indicating that individuals may not be easily classified as ‘good’ or ‘poor’ learners. Horses that are calm will perform better on learning tasks. This suggests that sources of stress need to be better understood. These include how animals are handled prior to the task, but also how social conditions are managed. Studies on the effects of stress on learning, and on social and spatial cognition, are also needed.
Rearing veal calves with respect to animal welfare: effects of group housing and solid feed supplementation on growth performance and meat quality
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This study compared rearing veal calves in individual stalls versus group rearing in pens to determine how the different forms of rearing affect the welfare, growth performance and carcass/meat quality of the calves. Half of the group-housed calves were only fed milk, while the other half had their milk diet supplemented with corn. Raising the calves in group and supplementing the diet with grain resulted in those calves having better growth performance, as they weighed more at slaughter. This treatment also improved carcass confirmation, but did not affect the dressing percentage. The calves raised in groups had higher blood packed cell volume counts, which means reduced risk of anemia. The meat and carcass colour, as well as, the main physical and sensory traits of the meat were not affected by housing or feeding treatments. The carcasses from corn supplemented calves or those housed in stalls, had a higher fat content. Overall, housing veal calves in stalls and supplementing their diet with corn can improve growth performance, without losing the carcass or meat quality.
Evaluation of the relationship between injuries and size of gestation stalls relative to size of sows.
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Most pregnant sows in the United States are housed singly in stalls. Small stall dimensions or restricted space can cause injuries. The problem of spatial restriction increases as the size of the sow increases during pregnancy. The study was designed to determine whether there is relationship between sow injuries and size of gestation stalls relative to sow size. A total of 267 pregnant sows were randomly selected from 4 farms. Sow and stall measurements were obtained, and injuries were scored on the basis of location, number, and depth. Ratios of stall length to sow length, and stall width to sow height were calculated. The results indicated that high injury scores were associated with low ratios of stall length to sow length and stall width to sow height. In other words, when the stall size relative to sow size was decreased, pregnant sows endured more injuries.
Influence of mating ratio and group size on indicators of fearfulness and stress of hens and cocks
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Heterophil to lymphocyte ratio and duration of tonic immobility are indicators of stress and fearfulness, respectively. This study was designed to examine the effects of the male to female mating ratio on the heterophil to lymphocyte ratio and on the duration of tonic immobility in two different experiments. In the first experiment, four different mating ratios (1:11, 1:5, 1:3, and 1:1) and 10 different Spanish breeds of chickens were allocated to breeding pens of 12 birds each. Experiment two used two different mating ratios (1:11 and 1:1) and four breeds allocated to pens of 60. There were significant differences among mating ratios for the heterophil to lymphocyte ratio in females of both group sizes. Hens housed with a mating ratio of 1:1 had a higher heterophil to lymphocyte ratio than hens with a 1:11 mating ratio in the group with 12 or 60 birds. In the 1:1 mating ratio, hens had significant heterophilia and lymphopenia. The 1:5 and 1:3 ratios did not differ from the 1:11 ratio. In the 1:1 ratio, the effect of group size was significant, but it was not significant in the 1:11 ratio. Tonic immobility did not differ between the mating ratios for hens. In the mating ratio of 1:1 and in the group size of 60 birds, cocks showed a shorter duration of tonic immobility than cocks housed with a 1:11 mating ratio. Results in the study suggest that very high mating ratios should not be used in conservation populations because they increase physiological and psychological stress responses.