Technical Note: Effect of corticotropin-releasing hormone on adrenocorticotropic hormone and cortisol in steers.

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

Activation of the hypothalamic-pituitary-adrenal (HPA) axis is the defining feature of the stress response. Under the influence of both internal and external stressors, activation of the HPA axis causes increased synthesis of corticotropin-releasing hormone (CRH) in the hypothalamus. The objective this study was to determine an appropriate exogenous dose of bovine corticotropin-releasing hormone (bCRH) to stimulate the physiological effects of the HPA axis in steers as a method to test the sensitivity of the pituitary and adrenal gland. 14-month old Holstein-Friesian steers were either given saline (control) or bCRH (0.1, 0.3, 1.0 or 1.5 ìg/kg BW). Serial blood samples were collected at -15, 0, 15, 30, 45, 60, 75, 90, 105, 120, 135, 150, 165, and 180 min relative to time 0. Following administration of 0.1 ìg of bCRH/kg BW, the peak ACTH response was not significantly different from pretreatment baseline concentrations. Administration of 0.3, 1.0, and 1.5 ìg of bCRH/kg BW increased peak ACTH above pretreatment concentrations. Peak cortisol responses to all bCRH treatments were greater than those to pretreatment concentrations. In conclusion, bCRH challenge may be a useful method for testing the sensitivity of the hypothalamic-pituitary-adrenal axis in steers subjected to stressful husbandry conditions, and a minimum dose of 0.3 ìg of bCRH/kg BW is required to stimulate physiological effects of stressor hormones.

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

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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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Warming up for C.O.O.L.: American Viewpoint

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Country of Origin Labeling (COOL) has been a household name in the food sector for roughly two years and is basically now law. As of October 2004 (in the USA anyways), COOL is mandatory (law), implementation was about 2 billion USD, industry stakeholders had their input heard, and more concerning the passage of COOL into law. Reasons for supporting COOL include the fact that people have a right to know where their food came from and may pay a premium for meat of a different origin. This theory is flawed, and many think that politicians that have no real understanding of agriculture and economics passed COOL into law. In conclusion, COOL is a shortsighted attempt by anti-trade members in the US to construct a complex and costly trade barrier to trade in livestock and red meat. There is little economic merit other than consumer rights, even though consumers indicate they have no interest in the origin. The poultry industry is excluded from this, which helps it due to the fact that the costs of COOL would be highest for pork and beef.

Practicalities and Pitfalls of Semen Evaluation

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Current AI techniques utilize 2.5 to 3 billion sperm per dose, yet there are still many other factors that influence fertility with AI. Yet despite the numerous measures for semen quality, sperm concentration is still the most commonly performed test. Most studies indicate that 2 billion sperm per dose will not limit productivity but will reduce performance. Assessment of sperm concentrations is done by a cell-counting chamber and analysis by spectrophotometers. Both age and collection frequency seems to be the biggest factors when addressing sperm concentration variation. Cell-counting chambers are good because they allow for visual assessment of sperm. Despite it being a time consuming method, it is low cost and fairly accurate. Errors occur typically with sub-sampling, pipetting, filling the counting chamber, dilution of the samples, and errors in counting. Optical density is the most common and practical method used for commercial semen production. Spectrophotometers are used because of their speed and ease of use. It measures the amount of light transmitted through a sample, which is dependent on the number of sperm. Many photometers have predetermined curves that calculate the concentration or provide a chart for conversion of the reading to sperm/mL. Errors from this method can result from improper sampling, pipette error, improper sample holder, incorrect diluent, using the machine wrong, incorrect standard curve, and reading out of the range of the photometer accuracy. Knowledge of the equipment accuracy range and the concentration of the ejaculate could allow a single dilution to be performed that would provide optimal readings within the limits of the spectrophotometer for a wide range of ejaculates. Determining the range of semen concentrations range that will be encountered in the lab could help choose the labs standard dilution rate and give warning when expected values are out of the expected range and reading accuracy for the equipment. It appears that average concentrations today are consistently higher compared to earlier reports. This could be due to lower collection frequency, selection for testes size, greater maturity age, and better health/nutrition/housing. It could be beneficial to produce a grid for ejaculate volumes and concentrations for certain ages of boars. Standard curves should be generated for the optimal reading range of the equipment and investigations should occur when readings fall out of this range.

Variability in Growth, Pig Weights and Hog Marketing Decisions

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Digestible energy value of DON contaminated barley increased by de-hulling

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Infections of cereal grains by fusarium not only lead to reductions in crop yields and quality, but also lead to a reduction in the suitability of the grain as a feed source for swine. This is due to the fact that mycotoxins, most notably deoxynivalenol (DON, vomitoxin), produced by the fungi can reduce feed intake in swine, thereby increasing days to market. Current guidelines recommend keeping DON levels to less than 1 ppm in the final ration in order to avoid problems with feed refusal. The use of a commercial-scale pearling unit can turn DON (vomitoxin)-contaminated barley into a usable feed ingredient for swine diets. Pearling removes the DON and makes the grain acceptable to swine. Additionally, the digestible energy value of the grain is increased by 28% over intact barley. Therefore, commercial scale pearling may serve as a useful technique to improve the utilization of DON-contaminated barley by the swine industry.

Transportation of Early Weaned Piglets: Seasonal Effects

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Segregated early weaning (SEW) has become a standard practice in the swine industry in Canada. Piglets are weaned at an early age (14 – 20 d) and transported to a separate site to reduce the risk of transmission of disease from the sow to piglets. The relocation of early weaned piglets to a separate site necessarily involves transport. These journeys vary in length but typically, in Canada, fall within the 4-20 hr range. Initially, transport vehicles were heated in winter but the industry has moved to winter transport without heating. There is little information on the preferred transport temperature ranges for piglets or on actual temperatures experienced by early weaned piglets under commercial transport.
The objectives of this research were to:
1. Collect information on vehicle temperature in commercial vehicles transporting early weaned piglets during journeys of varying lengths and in different seasons.
2. To determine the effect of season on the behaviour and production of early weaned piglets following transport.
3. To determine the effect of transport factors other than duration and temperature on the behaviour and production of early weaned piglets following transport.
4. To determine the effect of piglet weight at weaning on the behaviour and production of early weaned piglets following transport.