In order to provide information on the state of hydration of broilers during marketing, 7-week-old Ross broilers of mixed sex were kept at 17 or 23 degrees C and deprived of food, or food and water, for 24 h. Measurements were made of live weight, carcass weight, muscle moisture, packed cell volume, plasma glucose, corticosterone, total protein, osmolality and sodium. There was a decrease in live weight, carcass weight, plasma glucose and plasma total protein, and an increase in packed cell volume and corticosterone, in birds deprived of food, or food and water. Muscle moisture increased in birds deprived of food and decreased in birds deprived of food and water. Osmolality decreased in birds deprived of food, the decrease being greater in birds at 23 degrees C. Plasma sodium levels were higher in birds kept at 23 degrees C and increased only in birds deprived of food and water at 23 degrees C.

Energy conservation is a clear function of torpor. Although many studies imply that torpor is also a water-saving strategy, the experimental evidence linking water availability with torpor is inconclusive. We tested the relative roles of water and energy shortages in driving torpor, using the Siberian hamster Phodopus sungorus as a model species. To account for the seasonal development of spontaneous heterothermy, we used male hamsters acclimated to short (8L:16D, SP; n = 40) and long (16L:8D, LP; n = 36) photoperiods. We continuously measured body temperature (Tb) during consecutive 32 h of complete removal of water, food, or both, separated by 7.5 d recovery periods. We predicted that all deprivation types would increase the frequency of spontaneous torpor in SP, and induce torpor in LP-acclimated hamsters. Individuals underwent each deprivation type twice in random orders. Food and water deprivation did not induce torpor in LP-acclimated P. sungorus. Patterns of torpor expression varied among deprivation types in SP individuals. Torpor frequency was significantly lower, but bouts were ∼2 h longer and 2.5 °C deeper, during water deprivation compared to food and food-and-water deprivation. Heterothermic responses to all deprivation types were repeatable among individuals. Different torpor patterns during water and food deprivation suggest that water and energy shortages are distinct physiological challenges. Deeper and longer bouts during water deprivation likely led to higher energy and water savings, while shorter and shallower bouts during fasting may reflect a trade-off between energy conservation and food-seeking activity. The lack of a difference between food- and food-and-water-deprived hamsters suggests a higher sensitivity to food than water shortage. This supports the traditional view that energy conservation is the major function of torpor, but suggests that water shortages may also modulate torpor use. The high repeatability of thermoregulatory responses to resource deprivation suggests that these may be heritable traits subject to natural selection.

The effects of withholding food and/or water supply on the quality of meat from rex rabbits were investigated. Thirty-two rabbits were maintained under four different conditions: food and water respectively withheld 16-18 h and 6-8 h before slaughter (group 1); food withheld for 16-18 h, but water available ad libitum (group 2); food available ad libitum, but water withheld for 6-8 h (group 3); food and water available ad libitum (group 4). The pH₂₄ h (pH of meat at 24 h postmortem) increased following fasting. Withholding food or water decreased the lightness (L*-value) of meat after storage for 24 h. Group 2 had the highest redness value (a*-value). Drip loss, ripe meat ratio and tenderness were more affected by withholding water than by withholding food. Water content and intramuscular fat content were not affected by the treatment conditions (P < 0.05). Group 2 had the lowest drip loss and Warner-Bratzler shear force value, and the highest ripe meat ratio. Therefore, the best-quality rabbit meat can be obtained by withholding food for 16-18 h before slaughter, but allowing access to water ad libitum. Rabbit meat has become increasingly popular because of its high nutritional value. However, relatively little is known about the factors that affect the quality of rabbit meat, as especially few investigations have considered the effects of pre-slaughter conditions on rabbit meat quality. We were interested in knowing the effects of withholding food and/or water on rabbit meat quality, and have done some research in this field. We found that the best-quality rabbit meat can be obtained by withholding food for 16-18 h before slaughter, but allowing access to water ad libitum. This finding could be a reference value for rabbit meat production.