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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:
Behavioural and physiological responses to an acute stressor in crib-biting and control horses
Posted in: Welfare by admin on January 1, 2003 | No Comments
It was observed through video-recordings that crib-biting horses perform the stereotypy for 10.4 to 64.7 % of their stabling time. Crib-biting and non-crib-biting horses (controls) were exposed to an arousal-inducing stimulus in order to study the similarities and differences in their response. For the first two days of the experiment, the horses received food from a special bucket. On day three, the food bucket was presented but the horses were not allowed to feed. During and after presentation of the food stimulus, arousal behaviour and crib-biting intensity were studied, as was plasma cortisol concentration, heart rate at rest, and heart rate variability at rest. Heart rate and arousal behaviour in crib-biters and in controls increased in response to the stimulus, but crib-biting frequency decreased. Upon examination of heart rate variability at rest, it was determined that crib-biters had a lower vagral tone (high frequency component) and a higher sympathetic tone (low frequency component) than controls. This lower basal parasympathetic activity may be indicating why crib-biting horses showed neither a significant increase in the high frequency component during presentation of the food stimulus, nor decrease in the high frequency component after presentation of the stimulus, when compared with control horses. Therefore, there may be differences in the tuning of the autonomous nervous system and in the stress reactivity of crib-biting and non-crib-biting horses. The experimental results suggest that crib-biting horses are more stress sensitive than non-crib-biting horses, and they are also physiologically and psychologically less flexible than the non-crib-biting horses.
A laser-based method to measure thermal nociception in dairy cows: Short-term repeatability and effects of power output and skin condition.
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Exposure to acute stress can lead to changes in nociceptive thresholds. Laser technique has been used successfully to measure nociceptive thresholds in cattle. This paper presents data from three experiments examining whether: 1) the method is valid as a measurement of nociceptive threshold in dairy cows; 2) there is an acceptable repeatability within 15 min (the duration of most experimental acute stressors); and 3) skin condition (intact vs. naked) affects nociceptive threshold and its variability in dairy cows. Three experiments were performed to observe the behavioural responses to a computer-controlled CO2 laser beam applied to the skin on the caudal aspect of the metatarsus. In experiment 1, effects of power output on nociceptive responses were examined on dairy cows kept and tested in tie stalls. Increasing the power output affected the latencies to respond, types of response, and behaviour during (increasing frequency of tail flicking) and between single laser exposures (increasing frequency of kicking). Therefore, behavioural responses to a laser stimulus seem to be a valid measure of nociception in dairy cows. Repeatability within 15 minutes was investigated in experiment 2. The variables’ latency to move the exposed leg and frequency of tail flicking during laser exposure showed the highest level of repeatability. Effects of power output and skin condition were examined in experiment 3. Increasing the power output and shaving off hair led to increased responses as seen by shorter latencies to respond, less non-responding, and increased kicking. In conclusion the results of these experiments suggest that behavioural responses to laser stimulation are a valid and reliable measure of nociception in dairy cows, especially when applied on naked skin.
Effects of qualitative and quantitative feed restriction on the activity of broiler chickens.
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Diurnal patterns and time courses of activity were investigated in groups of fast-growing broilers subjected to different levels of qualitative and quantitative feed restrictions. Eight groups of 225 female Ross 208 broiler chickens were reared from 1 to 57 days of age in straw-bedded floor pens (18.9 m2) equipped with drinking nipples and six circular feed troughs. The lighting schedule consisted of 7 h and 10 min of darkness preceded by 30 min dusk. Groups were fed one of two feeds (Control and Diluted), where the latter was the control feed diluted with 15% ground oat hulls. All groups were fed ad libitum between 0-7 days of age and 43-56 days of age. During the in-between period four groups were fed ad libitum and four groups were fed twice a day (meal-fed). The meal-fed groups were fed 58 and 67% of the ad libitum groups on control and diluted, respectively, calculated on a weekly basis. Activity was logged every half-a minute throughout the experimental period using passive infrared detection (PID). Number of birds feeding was counted in all groups every 4 min during 90 min after the morning meal (08.00 h) and 90 min around the afternoon meal (14.00 h). Quantitative, but not qualitative, feed restriction affected activity levels, with meal-fed chickens being more active throughout the light period. An increase in the proportion of meal-fed birds feeding following each meal was observed. Across the meal-feeing period the meal-fed chickens appeared to learn about food availability and adjusted their behaviour accordingly. General activity of the chickens peaked at 21 days for all groups. An activity increase during the dark period was found to reflect night feeding as well as the growth of the birds. The potential welfare benefit to the birds of increased activity caused by quantitative restriction was in the present experiment overshadowed by the concomitant extended periods of hunger.
Young horses' reactions to humans in relation to handling and social environment.
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In this experiment Forty Danish warmblood colts were used to investigate the effect of housing and handling in the rearing period on the reactions to humans. The horses entered the experiment after weaning and were housed either individually or in groups of three. Half of the horses from each housing group were handled three times per week for a period of 10 min. Approach tests were performed in the home environment when the horses were 6, 9, 12, 18, 21, and 24 months old, and an Arena and Human Encounter test was performed in a novel environment when the horses were 12 and 24 months old. In the home environment, single-housed horses approached sooner and were more easily approached by a human than group-housed horses where no effect of handling was observed. In the Arena and Human Encounter test, single-housed horses expressed less restless behaviour, more explorative behaviour, and less vocalization than group-housed horses. Handled horses showed lower increase in heart rate during the test than non-handled horses. There was no difference between the number of times single or group-housed horses touched an unfamiliar person in the Arena and Human Encounter tests but handled horses approached sooner than non-handled horses. It is concluded that the social environment affected the way horses reacted to humans when tested in the home environment but not in a novel environment. In contrast, handling affected the reactions to humans when tested in the novel environment but not in the home environment. However, handled horses also reacted less to the novel environment in general, thus indicating that handling is a mean of avoiding potential dangerous situations.
Optimum versus maximum lysine levels for weanling pigs.
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Rapid improvements in lean growth potential, health status and management of the weaned pig have resulted in changes in the energy and amino acid requirements such that previous recommendations or diet formulations used in the past may no longer result in maximum performance. In addition, recent research showing increases in nursery exit weights will double by marketing places even greater importance on maximizing weight gain of the weanling pig. So, we ask the question: .How much lysine is enough and how much is too much, and how much lysine in the starter is economical? Currently, recommended lysine:energy ratios vary from as low as 2.8 to as high as 5.0 g total lysine/Mcal DE for pigs up to 25 kg. In 1998, the National Research Council (NRC) recommended 3.5 g total lysine/Mcal DE for pigs above 5 kg live weight. Two experiments were conducted to determine the optimum ratio of total lysine/ DE for the weaned pig. In experiment 1, a total of 240 pigs at weaning were fed a standard commercial SEW diet for 5 days followed by a transition diet for 8 days. Pigs were then fed the experimental diets for a 28-day period starting on day 13 postweaning. The six experimental diets contained total lysine/DE ratios of 2.7, 3.0, 3.3, 3.6, 3.9 or 4.2g total lysine/Mcal, equal to 0.95%, 1.05%, 1.16%, 1.26%, 1.37% and 1.47% total lysine, respectively. Growth rate and feed efficiency increased with increasing lysine/DE ratio. There was no effect of lysine/DE on feed intake. Because growth rate increased linearly to the highest level (4.2 g/Mcal; 1.47 % total lysine), we concluded that the required lysine/DE ratio for the weaned pig is at or above this level and thus may be higher than most literature values and recommendations. A second experiment was therefore necessary. In experiment 2, a total of 240 pigs were fed two levels of DE; low energy (LE, 3.4 Mcal DE/kg) or high energy (HE, 3.6 Mcal DE/kg), at 5 lysine/DE ratios (3.7, 4.0, 4.3, 4.6, and 4.9 g total lysine/Mcal). Thus, 10 diets, ranging in total lysine content from 1.26% to 1.76%, were investigated. The lysine/DE ratios were selected to bracket existing literature values for the weaned pig and included higher values than those used in experiment 1. Pigs were fed one of the 10 experimental diets starting on day 7 post-weaning for a 28 day period. Growth rate increased and feed efficiency improved with increased lysine:DE ratio. Overall, the level of DE did not influence growth rate. However, pigs fed the high-energy diets ate 13% less feed than those fed the low-energy diets in week 1 and had 12% lower growth rate. Overall feed intake was 4% lower on the high-energy diets, but DE intake was similar for both DE levels. The lysine:DE ratio that maximized performance was calculated from the regression equation. We concluded that for pigs growing from 7.5 to 22.5 kg, the requirement is 4.65 g total lysine/Mcal DE, equal to 1.60% total lysine. The existing recommended ratios for the weaned pig are inadequate to support its full growth potential, so the results of experiment 1 were confirmed. Increasing the lysine level of a starter diet from 1.30% to 1.60% will cost about $80 per tonne using current feed costs. With actual total feed intake of pigs on lysine:DE levels for this period, the feed cost per pig will increase by $1.86 at the optimum lysine level. Assuming this additional lysine increases nursery exit weights by 1 kg, and assuming, based on previous research at the Prairie Swine Centre, that this improvement will increase weights at 20 wk of age by 2 kg, we calculated the change in net income per pig by using ratios above 3.7 g/Mcal. The maximum benefit is obtained at 4.30 g/ Mcal (1.5%) when hog market prices are above $1.75 (Table 3), but lowers levels of 1.3% to 1.4% optimized financial returns at lower market prices. Clearly, hog market prices dictate the benefit of using optimum versus maximum lysine:DE ratio in the starter diet and provide further support for the logic that feeding programs must be developed in the context of changing economic conditions.
Lying characteristics as determinants for space requirements in pigs.
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Questions concerning the minimum space requirement for intensively kept pigs in relation to their welfare have been an issue of interest for many decades. Recently, the discussion about these questions has intensified, as there is a growing concern among western societies about the welfare of intensively kept pigs. Most studies on space allowances or requirements have been assessed in experiments where the performance of the pig is predominant measure. This suggests that there is no need to house pigs at an area larger than the area below which production decreases. However, from a welfare perspective this is questionable. This study focused on the lying postures, space occupation and percentage of space-sharing in pigs, in order to develop a theoretical framework on spatial requirements for pigs, e.g. for pen design legislative purposes. Pigs were housed at thermoneutral conditions, on 60% solid and 40% slatted floors, in groups of eight from 25 to 100 kg live weight. Behaviours of the pigs were recorded at approximately 30, 50, 80 and 100 kg live weight, in order to gain an insight into their space use and space requirements. The results showed that pigs of all weight categories lie down for a greater part of the day. Based on the behavioural observations carried out, present study confirmed that the floor area occupied by lying pigs at thermoneutral conditions should on average be based on the estimated floor area for half recumbent pigs (the animal is lying half on the side and half on the belly), i.e. area = 0.033 x body weight0.66 which in turn exceeds the recommended minimum space requirements for commercial practices in EU. The present study however, does of course not answer the questions whether pigs actually need an amount space that goes beyond recommendations generally based on production performance studies. Additional validation experiments, studying the welfare relevancy of those behavioural expressions should be carried out in order to answer this question.
Evaluation of nonfeed removal methods for molting programs.
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Induced molting of laying hens is a widely utilized management technique in the commercial egg industry to extent the productive life of a hen. This experiment was conducted using 336 White Leghorn hens (60 wk of age) randomly assigned to one of four treatments that consisted of feed removal for 4 or 10 days or no feed removal with ad libitum access to 95% wheat middlings molt diets that contained supplemental minerals and vitamins. At the end of the 4 day or 10 day feed removal period, hens on these treatments were provided with the corn molt diet for 24 or 18 days respectively. Hens on the corn or wheat middlings treatments were fed the diets for 28 days. At day 28, hens on all treatments were fed a corn-soybean meal (16% CP) layer diet for 40 wk (64 to 104 wk of age). Both feed removal and the wheat middlings treatments resulted in total cessation of egg production within 8 days. Egg production of hens fed the corn molt diet had decreased to 3% by day 28. Body weight loss for hens fed the corn or wheat middlings diet was approximately 15 and 8% at day 28, respectively. Hens fed the wheat middlings diet returned to production slightly faster than hens on the other treatments. Postmolt egg production and egg mass (wk 5 to 44) were generally higher for the wheat middlings and 10 day feed removal treatments. There were no consistent differences in mortality, egg weight, egg specific gravity, feed efficiency, and layer feed consumption among treatments. This research indicates that diets with high corn or wheat middlings, particularly wheat middlings, are effective nonfeed removal methods for molting hens.
Testing responses to novelty in cattle: behavioural and physiological responses to novel food.
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Novel stimuli can lead to negative emotions such as fear. The welfare of an individual animal depends on its coping capacity with environmental challenges and presentation of novel stimuli have been used to evaluate the welfare or the tendency to display fear reactions in farm animals. In order to develop a behavioural test as well as gain information about behavioural response to novel food, we performed four experiments with cattle kept in tie-stalls and observed the behaviour after provision of novel food. In experiment 1, the effects of the novelty of the feeding method were tested using nine heifers provided with 2 kg of their usual food from the usual fodder truck or from a basket made of plastic. The novel feeding method induced increased sniffing, decreased duration of eating and increased self-grooming. The effects of the degree of novelty of a food were examined in experiment 2 using heifers and three concentrations of fish oil (1.5, 6, or 24 g/kg) and eucalyptus oil (5, 20, 80 drops per kg) added to the usual food. Increasing the concentration of eucalyptus oil in the food led to changes in behaviour, while the addition of fish oil led to a less clear response. However, both suggested that the behaviour reflected the degree of novelty in the food. Behavioural responses to two novel foods (4kg carrots vs. 80 drops per kg of eucalyptus oil added to the usual food) as well as individual characteristics and repeatability within 72 h were examined in experiment 3. the behavioural responses to the novel foods differed, showing a higher level of approach and attempts to eat the carrots, and responses to the two different novel foods were not correlated. At the second provision, the acceptability of the carrots was greater, however responses to carrots showed an acceptable repearability. Finall, the cardiac (heart rate) and behavioural responses to usual food and novel food (4 kg carrots) were compared in experiment 4. Provision of novel food led to behavioural signs of motivational conflict and neophobia while the heart rate ended to be lower than when the cows were provided with usual food. These results provide evidence that behavioural responses to novel food in cattle include signs of motivational conflict between eating motivation and neophobia, reflecting the degree of novelty in the test situation including the feeding method. However, palatability of the food might also affect the responses, and the data on heart rate suggest that novel food is not a fear-inducing stimulus.
Influence of social status on the welfare of sows in static and dynamic groups.
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This study examined the aggression that occurs when sows are regrouped. In this study the sows were grouped twice, first immediately after weaning twelve groups of four sows were mixed. This was classified as a static group, as no new sows were ever added to the group of four. Five weeks later, three static groups were mixed into a dynamic group, which contained approximately 40 sows and remained in this group for eleven weeks. In the dynamic groups, twelve sows were removed and twelve new sows were added at three-week-intervals. Upon mixing into the static pen, aggressive and submissive behaviours were recorded for the first nine hours after mixing. The social status of the sows was subsequently ranked based on their aggressiveness and the outcomes of their aggressive interactions. On the day of mixing and one week later, injuries were recorded and salivary cortisol samples were taken for both static and dynamic groups. Injuries were also recorded prior to the sows being moved into the dynamic pen. Individual sow behaviour, the order in which the sows went through the electronic feeder and where the sow rested within the pen was recorded throughout the study. The levels of sow injuries increased significantly after the sows were moved into the dynamic group from the static group. Sows with lower social status had lower bodyweights and higher levels of injuries one week after being mixed into both the static and dynamic groups. A lower social status also resulted in those sows having a lower position in the feeding ordering and they were unable to rest in the kennel area (prime lying area). Lower ranking sows were displaced from the feeder queue and drinker more often than higher-ranking sows. Social status did not have an effect on salivary cortisol levels. The results indicated that in both static and dynamic groups the welfare of the sows with a lower social rank was impaired.
The effects of air transport on the behaviour and heart rate of horses
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There is little information on the behavioural and physiological experiences of horses during air transport. Long and short haul air transports were compared to determine if there were differences in behaviour and heart rates. Resting heart rates were determined prior to transportation. Body postures and social activities were recorded during the air transport. The behaviour and physiology of 16 horses were recorded during short haul flights (3-4 hours). Loading and unloading the truck and aircraft, and during ascent and descent, resulted in significantly higher heart rates compared to resting values or when in flight. During flight, the horses had close to resting heart rates and also sometimes doze and rest. However, during ascent and descent aggression and submission would increase and postural changes would occur to maintain balance. There were no differences in behavioural and physiological responses in the 19 horses that were studied during long haul flights (10-15 hours). Based on these results, horses seem to adapt well to air transport. The transitional stages appeared to result in increased agitation, but did not occur or last long enough to be considered a welfare concern.