The effects of food and/or water deprivation at different ambient temperatures (7 or 35 °C) on stress hormone release in sheep (n = 8), were studied to provide background data for research into the effects of road transport. Blood samples were taken from catheterized animals at the start and, at 6h intervals, during 48h tests in an environmental chamber. Cortisol release was unaffected by temperature or deprivation state but was stimulated by introduction to the chamber. Prolactin secretion showed a similar tendency and levels of this hormone were generally higher in the first test, whichever chamber was used. Heat exposure also had a prolonged stimulatory effect on prolactin release, especially in the first test. Growth hormone concentrations were rather variable but tended to be greatest when the animals were deprived of food. Measurements of plasma osmolality indicated that sheep remained in water balance, even when water was withheld for 48h, unless they had access to food. The results suggest that under laboratory conditions, and over a wide thermal range, withholding food and water for 48h does not induce Cortisol or prolactin release in sheep. However, exposure to novel situations seems to have a stimulatory effect.

The effects of food restriction on the welfare of sheep are as yet unclear. An operant crate and a push-door were used to measure feeding motivation in sheep after Oh, 6h, 12h, 18h and 24h without food. In experiment 1, sheep had to push a panel with their noses to obtain a food reward. In experiment 2, sheep had to run a race and push through a weighted door to reach food; the time taken to reach various points was recorded and the work performed to push through the door was calculated.

In experiment 1, 3 out of 12 sheep became trained to push the panel and there was a difference in the mean number of rewards/session obtained by each animal (P < 0.05). There was no effect of treatment on the number of panel presses performed. In experiment 2, 10 out of 14 sheep were successfully trained. More sheep went through the push-door when deprived of food (P < 0.05), and they were quicker to enter the race, reach the push-door, and reach the food than those which had not been deprived (P < 0.0001). They also spent less time pushing the door than non-deprived sheep (P < 0.0001).

The push-door was a more appropriate method of measuring motivation to feed in sheep, as more sheep learned the task in less time than for the operant crate. As measured by the time taken to enter the race, reach the push-door, push through the door and reach the food there was an increase in feeding motivation after only 6h without food.

The spotted wing drosophila, Drosophila suzukii, is an invasive pest in Europe and North America. Access to resources may be challenging in late fall, winter and early spring and flies may suffer from food deprivation along with cold stress in these periods. Whereas a plethora of studies have been performed on the overwintering capacity of D. suzukii, the effects of starvation on the fly's cold tolerance have not been addressed. In the present study, young D. suzukii adults (reared at 25°C, LD 12:12 h) were deprived of food for various periods (0, 12, 24 and 36 h), after which chill coma recovery time, critical thermal minimum, as well as acute and chronic cold tolerance were assessed. Additionally, the body composition of adults (body mass, water content, total lipid, glycerol, triglycerides, glucose and proteins) before and after starvation periods was analysed to confirm that starvation had detectable effects. Starved adults had a lower body mass, and both lipid and carbohydrate levels decreased with starvation time. Starvation slightly increased critical thermal minimum and affected chill coma recovery time; however, these changes were not gradual with starvation duration. Starvation promoted acute cold tolerance in both sexes. This effect appeared faster in males than in females. Food deprivation also led to enhanced survival to chronic cold stress. Short-term starvation was thus associated with significant changes in body composition in D. suzukii, and these alterations could alter some ecologically relevant traits related to cold tolerance, particularly in females. Our results suggest that food deprivation during short time (<36 h) can promote cold tolerance (especially survival after a cold stress) of D. suzukii flies. Future studies should address the ecological significance of these findings as short food deprivation may occur in the fields on many occasions and seasons.

The Norway lobster, Nephrops norvegicus is a target fishery species in European waters. The stock assessment of N. norvegicus is complicated because it is caught in commercial gear only when it emerges from its burrow. Landings are lower in winter, and feeding limitations have been hypothesized as the cause. Wild large-sized male lobsters were sampled each season (winter, spring, summer and autumn), and two groups of animals were kept in captivity for 90 d (fed and food-deprived). The hepatopancreas and muscle were dissected, weighted, frozen for biochemical analyses (proximal analyses and DNA/RNA) and fixed in Bouin solution for microscopic observations. The oxygen consumption rates in the wild individuals caught in the spring and in the captive animals after the treatments were measured. Significant differences among the experimental groups were observed in the lipid concentration of the hepatopancreas and muscle, the water content in the hepatopancreas, and the numbers of vacuoles and pyknotic nuclei in the cells of the tubules of the hepatopancreas. The results showed that the wild Norway lobsters generally presented intermediate values between those observed in the food-deprived and the fed lobsters kept in captivity, but the values were closer to those obtained for the fed animals. This finding indicates that the wild animals exhibit a good nutritional condition throughout the year. Therefore, the wild males of N. norvegicus do not face food deprivation during winter as is suggested by the pattern of commercial catches, the flow of organic matter, and the moulting period/reproductive behaviour of the species.

Sheep and cattle are frequently subjected to feed and water deprivation (FWD) for about 12 h before, and then during, transport to reduce digesta load in the gastrointestinal tract. This FWD is marked by weight loss as urine and faeces mainly in the first 24 h but continuing at a reduced rate subsequently. The weight of rumen contents falls although water loss is to some extent masked by saliva inflow. FWD is associated with some stress, particularly when transportation is added. This is indicated by increased levels of plasma cortisol that may be partly responsible for an observed increase in the output of water and N in urine and faeces. Loss of body water induces dehydration that may induce feelings of thirst by effects on the hypothalamus structures through the renin–angiotensin–aldosterone system. There are suggestions that elevated cortisol levels depress angiotensin activity and prevent sensations of thirst in dehydrated animals, but further research in this area is needed. Dehydration coupled with the discharge of Na in urine challenges the maintenance of homeostasis. In FWD, Na excretion in urine is reduced and, with the reduction in digesta load, Na is gradually returned from the digestive tract to the extracellular fluid space. Control of enteropathogenic bacteria by normal rumen microbes is weakened by FWD and resulting infections may threaten animal health and meat safety. Recovery time is required after transport to restore full feed intake and to ensure that adequate glycogen is present in muscle pre-slaughter to maintain meat quality.