Behaviour and claw health in tied dairy cows with varying access to exercise in an outdoor paddock.

Posted in: Welfare by admin on January 1, 2004 | No Comments

This study was conducted on 52 cows that were tied during a 6 month period of winter housing. Four exercise treatments were imposed providing cows with either daily exercise, exercise 2 days each week, once each week, or no exercise. The exercise consisted of being released into an outdoor paddock for one hour. Observations were made of the activity of the cows during exercise, their standing-lying behaviour while tied, and claw health at the end of the winter. In treatments involving longer periods between exercise (twice or once per week) the animals used the exercise time to walk and trot more, and to thoroughly explore the paddock. There were no differences in time required to lie down while tied among treatments, nor in milk production. Exercise had a positive effect on claw health, due in part to increased wear of the claws. Regular exercise had some advantages in terms of claw health, and the differences in behaviour during exercise suggests that animals use the exercise time to achieve some degree of activity and for exploration.

Acute and longterm effects of chronic intermittent noise stress on hypothalamic-pituitary-adrenocortical and sympatho-adrenomedullary axis in pigs.

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Noise has been shown to be a potential source of stress for pigs. The aim of this study was to determine the effect that chronic exposure to noise would have on pigs’ stress hormone levels and behaviour. Twenty-four barrows were divided into three treatments: N1 was exposed to 2h of broad-band noise (90dB) daily, N2 was exposed to the same source of noise but only three times a week, and the third treatment were handled in a similar manner but were never exposed to the noise. Blood samples were taken weekly before, during and after exposure to the noise. The blood samples were analyzed for adrenaline, noradrenaline, ACTH and cortisol concentrations. The behaviour of the pigs was documented using video recordings. The first exposure to the noise caused a change in the pigs’ behaviour, the showed increased movement and lied down less, but this did not coincide with a change in the pigs’ stress hormone concentrations. After four days of exposure to the noise, the pigs in the N1 treatment showed an increase in plasma ACTH and cortisol levels, while the same hormone concentrations did not increase until day 11 (third exposure) in the N2 treatment. The pigs in the N1 had an increase in the noradrenaline/adrenaline ratio of the eleventh day of exposure. Once again, the N2 treatment experienced a delay and the ratio did not increase until day 18 or the fourth exposure. In both treatments exposed to the noise, the amount of social behaviour (ie. nosing other pigs) decreased and the amount of time they spent lying increased. Both of these treatments also experienced a decrease in daily gain. Further examination using sixteen barrows found that chronic exposure to noise resulted in a time dependent shift in the adrenocortical and sympathetic neural systems response. When challenged cortisol concentrations rose and fell at a faster rate. When the pigs were restrained the adrenaline, noradrenaline and ACTH concentrations increased and decreased at a faster rate while elevation of cortisol concentrations was delayed. The authors concluded that repeated exposure of pigs to noise levels should be avoided, as it can be a potential source of stress for pigs.

Responses of young red jungle fowl and White Leghorn layers to familiar and unfamiliar social stimuli

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This study examined the social preferences and reactions to strangers in young White Leghorns and red jungle fowl. Chicks were tested in two runway tests. In the first test, the chicks could choose between familiar and unfamiliar breed members. In the second test, the chicks could choose between unfamiliar chicks of their own breed and the other breed. An open field test was used to assess spacing and agonistic interactions of 28 pairs of chicks per breed (in half the pairs, chicks were unfamiliar to each other). Leghorns showed preferences for familiar chicks and avoidance of unfamiliar social stimuli during the first runway test. During the second runway test, both breeds showed preferences for their own breed members, but this was more pronounced in Leghorns. During the open field test, the Leghorns were more involved in agonistic interactions than red jungle fowl chicks. The results of this study help explain why Leghorns are less able to cope with novel social and environmental stimuli. Therefore, their welfare might be compromised in situations where they encounter unfamiliar birds.

Improving management for higher reproduction accelerates genetic improvement in closed herd of swine

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Modeling the effects of stressors on the performance of populations of pigs.

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A simulation model predicting effects of social, physical, and nutritional environments on pig food intake and performance was extended to account for individual variation. The goal was to investigate the effects of between animal variation on the performance of a population of growing pigs. It has been previously suggested that pigs with a leaner, more modern genotype may be less able to cope when exposed to social stressors. Similarly, it has been suggested that a pig’s position within the social hierarchy may affect ability to cope with social stressors. In the model, it was assumed that larger, more dominant pigs would be better able to cope when exposed to social stressors. The model showed that increasing initial body weight variation and the number of stressors increased the variation in pig performance. In commercial operations, where population variation may affect the profitability of the enterprise, this model may be an important practical consideration. The way a stressor effects performance determines whether the mean population response and the average individual response will be the same. If all the pigs in a group were affected at the same intensity by the stressor, then predicted mean and average individual responses would be the same. If the intensity of the stressor affected each pig differently, then differences between the individual and mean population responses would be predicted. Variation in initial body weight and social stressors were better determinants of the variation in growth response than a variation in growth potential was when pigs were housed in conditions similar to those found in commercial environments. In conclusion, decreasing the variation in initial body weight and improving the ability of pigs to cope may be a better for improving pig performance than selecting for increased growth potential alone.

Further evaluation of nonfeed removal methods for molting programs

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Laying hens that have completed a 40 week laying period may be put through a molt (loss of feathers and cessation of lay) and then begin a second laying period. Many methods used to induce this temporary stoppage of lay involve dramatic if not complete feed withdrawal. This raises serious welfare concerns. Alternative methods of inducing a molt have been developed. In this study several nonfeed withdrawal methods were compared with conventional programs (10 day withdrawal). The nonfeed withdrawal methods involved changing the diets to 94% corn, 94% wheat midlings, 71% wheat midlings:23% corn, 47% wheat midlings:47% corn, 95% corn gluten, and 94% distillers dried grains. The feed withdrawal programs achieved complete cessation of lay within a few days. With the exception of the distillers dried grains, all of the nonfeed withdrawal treatments reduced egg production to less than 6% during the program. Once laying was re-induced by the provision of a high quality laying diet there were no differences among treatments on egg production or quality. The results indicate that several nonfeed withdrawal programs are effective in inducing a molt and that subsequent production is unaffected.

Emotional reactions to learning in cattle.

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It has been suggested that when an animal’s own actions result in a reward, the animal shows signs of excitement and pleasure. Therefore, the expectation of a reward might be just as exciting as the realization that they themselves have contributed to the delivery of the reward. Information about this phenomenon would provide more insight into animal self-awareness. The current study involved a yoked control experiment involving the acquisition of an operant task. The aim was to distinguish between the reactions of animals that had learned on their own versus those that just received a food reward. Heifers were studied in pairs, each pair had a control and experimental animal. Experimental heifers were conditioned for 14 days to open a gate by pressing a panel, which gave them access to a food reward. For control heifers the gate opened after a delay equal to their matched partner’s latency to open it. Improvements in learning by the experimental heifers resulted in higher heart rates and more vigorous movements towards the food reward than the control heifers. There is some indication that a cow’s own learning improvement may result in an emotional reaction.

Effect of chronic clenbuterol administration and exercise training on immune function in horses

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Effects of longitudinal exercise training and acute intense exercise (simulated race test) on immune function have not been reported in horses. This study investigated the interaction of 8 week of exercise training with or without 12 week of clenbuterol administration in horses. Twenty-three untrained standardbred mares were used and divided into four experimental groups. Horses given clenbuterol plus exercise and clenbuterol alone received 2.4 ìg/kg BW of clenbuterol twice daily on a schedule of 5 days on and 2 days off for 12 weeks. Mares given exercise alone were aerobically trained for 3 days/week, and the control group remained sedentary. Lymphocyte proliferative response was not affected by clenbuterol or exercise treatment. From the present experiment it was apparent that horses demonstrated responses to bouts of acute exercise as noted with other species, namely humans and rodents.

Excess cortisol interferes with a principal mechanism of resistance to dehydration in Bos indicus steers.

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This study investigated the effects of excess cortisol on physiological mechanisms that resist dehydration in Bos indicus steers during a 90-h period. Steers were assigned randomly to one of four groups: 1) no water/ no cortisol, 2) water/no cortisol, 3) no water/cortisol, and 4) water/cortisol. Animals in the cortisol group were given a 0.1 mg.kg BW-1.h-1 of hydrocortisone suspended in isotonic saline for the duration of the study. Total body water, osmality, hematocrit, urine out put, feed and water intake, and plasma concentrations of arginine vasopressin (AVP), angiotensis II (AII), electrolytes, total protein, and albumin were determined at 24-h intervals for 90h. The results of this study highlight the complexity of endocrine interactions associated with water balance. Excess cortisol has a suppressive effect on the rennin-angiotensin-aldosterone axis; however it does not affect the circulating concentration of arginine vasopressin. In the presence of water deprivation, cortisol may serve to protect and maintain water balance at times of stress.

Chronic increase of dietary L-tryptophan decreases gentle feather pecking behaviour.

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The neural transmitter serotonin (5-HT) and the serotinergic system are involved in several abnormal behaviour patterns in animals. In this study the authors examined the relationship between this system and the incidence of feather pecking in 7 week old chickens. 5-HT is derived from tryptophan and they increased serotonin levels by increasing dietary tryptophan. Chicks were fed either the control diet with 0.16% tryptophan, or the treatment diet with 2%. Two lines of laying birds were used. Tryptophan reduced the incidence of gentle feather pecking, but only a trend in the same direction was found for severe feather pecking. Physiological measures confirmed that the high levels of tryptophan increased blood levels of the amino acid and increased serotonin in the central nervous system. High tryptophan also resulted in an increase in cortisol levels in the blood, which has been reported as a physiological effect of the amino acid previously. High levels of dietary tryptophan was effective in reducing levels of feather pecking in young chicks.