Levels Of Water Deprivation Research Articles

Influence of short-term, water-deprived bermudagrass on Orius insidiosus predation and Spodoptera frugiperda larval survival and development

ABSTRACT Turfgrass is susceptible to changes in water availability, and its effects could cascade through multiple trophic levels. In some years, turfgrass is exposed to short drought spells. It is unclear if this short period of water deprivation would cascade to predator performance on herbivory on bermudagrass. Thus, the objective of this study was to determine the effects of water deprivation on predation by Orius insidiosus (Say) (Hemiptera: Anthocoridae) on Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) when mediated by drought-tolerant ‘TifTuf’ and drought-susceptible ‘Tifway’ bermudagrass. Neonates of S. frugiperda and adults of O. insidiosus were caged on bermudagrass in greenhouse conditions. Treatments were three factors: 1) water deprivation at three levels – fully, moderately, and sparsely watered; 2) predator at two levels – present or absent; and 3) bermudagrass at two levels – drought tolerant and susceptible cultivars. The survival of S. frugiperda larvae was reduced when O. insidiosus adults were present regardless of water deprivation levels and bermudagrass cultivars. Reduced larval weight, body length, and head capsule width of S. frugiperda larvae were observed with predators compared to without predators. S. frugiperda larval mortality was significantly greater with predator’s absence for the sparsely-watered treatment than for the fully and moderately-watered treatments. The levels of water deprivation had a partial impact on the survival of S. frugiperda larvae, whereas bermudagrass cultivars did not affect the survival and development of S. frugiperda larvae. Thus, during at least short-term dry spells, O. insidiosus predation can potentially reduce the S. frugiperda population on bermudagrass.

Responses of broiler chickens to incremental levels of water deprivation: Growth performance, carcass characteristics, and relative organ weights

Abstract The objective of the study was to assess the effect of varying levels of water deprivation on growth performance, carcass characteristics, and internal organ weight of broiler chickens. Ninety unsexed Ross 308 chicks 2 weeks old were randomly assigned to five water deprivation periods of 0, 6, 12, 18, and 24 h. Each treatment was replicated three times with six birds per replicate. Broiler chickens were given water ad libitum (0 h) or for 30 min at 6-, 12-, 18-, and 24-h intervals. Average daily feed intake (ADFI), average daily gain (ADG), and feed conversion ratio (FCR) were determined on a weekly basis. A negative linear relationship (P < 0.05) existed between water deprivation and ADFI. The increase in water deprivation level resulted in ADFI decreasing at an increasing rate. The R 2 value was 0.94. There was no relationship between water deprivation on ADG and FCR (P > 0.05). There was a quadratic relationship between water deprivation and cold dress mass (CDM) and warm dress mass. As the level of water deprivation increased, there were linear increases in relative weight of gizzard, spleen, heart, lungs, liver, and gastrointestinal tract (P < 0.001). The organ weights of the broiler chickens revealed the ability of birds to withstand of up to 24 h. Using differential of quadratic equations, the maximum time of water deprivation that did not negatively affect CDM was estimated to be 4 h.

Assessing the effect of water deprivation on the efficacy of on-farm euthanasia methods for broiler chickens

ABSTRACT 1. Moribund or diseased poultry requiring euthanasia are often dehydrated. To understand how dehydration influences the efficacy of various killing methods, this experiment investigated the effect of water deprivation (WD) on times to unconsciousness and death. 2. Broiler chickens (n = 179) were water-deprived for 0, 24, 48 or 72 hours to mimic dehydration, then killed via manual cervical dislocation, mechanical cervical dislocation (Koechner Euthanising Device (KED)), or non-penetrating captive bolt (Zephyr-EXL), at 8, 22, 36 or 50 d of age. Degree of WD was confirmed by skin turgor, packed cell volume and body weight loss. Method efficacy was evaluated by the time to unconsciousness and death using pupillary light (PUP), palpebral blink (PAL) and nictitating membrane (NIC) reflexes, feather erection (FE), cloacal winking (CW) and convulsions (CN). The extent of damage caused by each method was examined via radiography, gross pathology and histopathology. The main effects of WD time and euthanasia method were analysed by two-way analyses of variance (CRD, PROC MIXED, SAS 9.4) with a-priori contrasts to compare water-deprived versus non-water-deprived (NON) birds. 3. Skin turgor, packed cell volume and body weight loss had a quadratic relationship with WD, with highest values for those birds which were water-deprived for 72 h. WD level did not affect time to unconsciousness. Time to death was longer for WD birds than NON, with longer latencies to FE, CW and CN for water-deprived birds. WD only affected radiography or gross pathology scores on d 8, with the extent of subcutaneous haemorrhage within the neck decreasing as WD increased. 4. The shortest latency to PUP loss, at all ages, and to PAL and NIC loss, at 22 d, was with the Zephyr-EXL. KED had the longest time to unconsciousness (PUP, PAL and NIC), at all ages, and to death, at 36 and 50 d. 5. Overall, WD increased time to death, but did not affect the onset of unconsciousness, with no interaction between methods and WD level.

Encoding of learned importance of sound by magnitude of representational area in primary auditory cortex

We hypothesized that learning-induced representational expansion in the primary auditory cortex (AI) directly encodes the degree of behavioral importance of a sound. Rats trained on an operant auditory conditioning task were variably motivated to the conditioned stimulus (CS) through different levels of water deprivation. Mean performance values correlated with deprivation level, validating them as a measure of the overall control and, therefore, behavioral importance of the CS. Electrophysiological mapping revealed expanded representations of the CS, compared with other frequencies in experimental subjects, but not in naive or visually trained controls that received noncontingent CS tones. Importantly, representational area showed a significant positive correlation with mean performance levels for only the CS band, with significant effects for relative area in contrast to only modest changes in absolute area. CS representational expansion was asymmetric into high-frequency zones, thus performance level also was significantly correlated with the relative anterior-posterior location of the enlarged representation. An increased representation of low frequencies, related to the acoustic spectrum of the reward delivery equipment, also was discovered in both experimental and control trained subjects, supporting the conclusion that behaviorally important sounds gain representational area. Furthermore, there was a surprising reduction in total AI area for the experimental and control groups, compared with untrained naive subjects, indicating that the functional dimensions of AI are not fixed. Overall, the findings support the encoding of acquired stimulus importance based on representational size in AI.

Effects of dopaminergic drugs on delayed reward as a measure of impulsive behavior in rats.

Impulsive individuals exhibit an exaggerated preference for immediate rewards over delayed but larger rewards, perhaps because they value the delayed rewards less. Dopamine (DA) has been postulated to mediate the incentive value of rewards, thus it may also mediate the exaggerated preference for immediate rewards in impulsive individuals. In this paper, we investigate the effects of DA agonists and antagonists on the value of delayed versus immediate rewards. The study had three main objectives: (1) to determine the effects of D1 and D2 type DA antagonists on the value of delayed rewards, (2) to determine the effect of the indirect DA agonist d-amphetamine on the value of delayed rewards, (3) to determine the sensitivity of the adjusting amount (AdjAmt) procedure to acute one-day changes in delay to reward, amount of reward, deprivation level and starting amount. In the AdjAmt procedure, rats choose between an adjusting amount of water given immediately (adjusting alternative) and a constant 150 microliters water delayed by 4 s (standard alternative). The immediate amount of water is adjusted across trials until the rat chooses both alternatives with equal frequency (indifference point). The final adjusted amount is an indicator of the subjective value of the standard alternative. The D1/D2 antagonist flupenthixol (25, 50, and 100 micrograms/kg) and the D2 antagonist raclopride (40, 80, and 120 micrograms/kg), decreased the indifference points, whereas the D1 antagonist SCH 23390 (5, 10, and 20 micrograms/kg) did not affect the indifference point. All three DA antagonists slowed responding. The indirect DA agonist amphetamine (0.5, and 1.0 mg/kg) had effects opposite to those of the DA antagonists, it decreased choice latency, increased the number of trials completed and increased the indifference point. Decreasing the water deprivation level (6, 24, and 48 h) had no effect on the indifference points but slowed responding. Increasing the delay to reward (2, 4, and 8 s) and decreasing the amount of water available for choosing the standard alternative (300, 150, 75 microliters) decreased the indifference point. The results indicate that amphetamine increased the value of delayed rewards (decreased impulsivity) and that D2 but not D1 receptor antagonists decreased the value of delayed rewards (increased impulsivity). The procedure was sensitive to acute 1-day changes in delay and magnitude of reward.

Falsification of matching theory: changes in the asymptote of Herrnstein's hyperbola as a function of water deprivation.

Five rats pressed levers on variable-interval schedules of water reinforcement at various levels of water deprivation. In one phase of the experiment, three deprivation conditions that replicated conditions in Heyman and Monaghan (1987) were arranged, along with three less extreme deprivation conditions. In a second phase, water deprivation was arranged so that subjects were exposed to a greater range of access to water per day. Herrnstein's hyperbola described the rats' response-rate data well. The y asymptote, k, of the hyperbola appeared roughly constant over the conditions that replicated those of Heyman and Monaghan, but decreased markedly when less extreme deprivation conditions were included. In addition, k varied systematically when the second method of arranging deprivation was used. These results falsify a strong form of matching theory and confirm predictions made by linear system theory.

Determination of discount functions in rats with an adjusting-amount procedure.

An adjusting-amount procedure was used to measure discounting of reinforcer value by delay. Eight rats chose between a varying amount of immediate water and a fixed amount of water given after a delay. The amount of immediate water was systematically adjusted as a function of the rats' previous choices. This procedure was used to determine the indifference point at which each rat chose the immediate amount and the delayed amount with equal frequency. The amount of immediate water at this indifference point was used to estimate the value of the delayed amount of water. In Experiment 1, the effects of daily changes in the delay to the fixed reinforcer (100 microliters of water delivered after 0, 2, 4, 8, or 16 s) were tested. Under these conditions, the rats reached indifference points within the first 30 trials of each 60-trial session. In Experiment 2, the effects of water deprivation level on discounting of value by delay were assessed. Altering water deprivation level affected the speed of responding but did not affect delay discounting. In Experiment 3, the effects of varying the magnitude of the delayed water (100, 150, and 200 microliters) were tested. There was some tendency for the discounting function to be steeper for larger than for smaller reinforcers, although this difference did not reach statistical significance. In all three experiments, the obtained discount functions were well described by a hyperbolic function. These experiments demonstrate that the adjusting-amount procedure provides a useful tool for measuring the discounting of reinforcer value by delay.

Water deprivation and subfornical organ activity in the pigeon a [ 14C]2-deoxyglucose study

Following varying degrees of water deprivation (0, 24 and 72 h), functional activity in the subfornical organ (SFO) of pigeons was measured using the [ 14C]2-deoxyglucose method. Increasing levels of water deprivation produced a significant increase in glucose uptake in SFO. The magnitude of the effect was systematically correlated with morphologically defined SFO subdivisions.

Are pheromones their own reward?

Hamster vaginal discharge (HVD) contains a variety of intersexual pheromones which are powerful promoters of male reproductive behavior. Males avidly investigate and then consume HVD from females or from artificial sources. We measured the reward strength of HVD and other sapid substances with operant techniques. The highest fixed ratio at which males would bar press, the break point, varied with the level of water deprivation and the volume of water reward. Break points for sucrose rewards, in undeprived animals, were higher than for water and varied with concentration. Water, vanillin and HVD solutions were comparable reinforcers irrespective of deprivation level. Sexual experience did not increase bar pressing for HVD rewards. Moreover, naive animals could not be trained to bar press for HVD. These results contrast with other evidence that HVD is highly palatable and challenge the notion that the pheromones present in it are innately rewarding. However, this conclusion may be mitigated by constraints on learning which limit the utility of operant techniques to evaluate the reinforcing properties of HVD.

Response of thirsty rats to absence of water: Frustration, disinhibition or compensation?

Water-deprived rats were allowed to drink in an experimental chamber during a series of training trials, and were then presented with an empty water spout during a single test trial. Their initial response to absence of water was to bite, sniff and paw at the empty spout (spout-directed behaviour), after which they engaged in activities such as eating, grooming and exploration of the chamber. By comparison with control animals that had no expectation of water, experimental rats performed these latter activities in a bizarre ‘speeded-up’ manner, which was quantifiable as an increase in local rate. Both the occurrence of spout-directed behaviour and the increase in local rate of other activities were enhanced by increasing the prior level of water deprivation and by offering a more palatable fluid during training. The results are discussed in relation to current models of behavioural switching.

Rate dependent effects of imipramine. Effects of imipramine on operant behaviour in rats at various levels of water deprivation.

The behavioural effects of 1.0, 3.10 and 6.0 mg/kg imipramine injections on lever pressing of rats were studied. Lever pressing was reinforced according to a continuous reinforcement schedule at 0, 24, and 48 h of water deprivation, according to fixed ratio schedules with 22 1/2 h of water deprivation, and according to differential‐reinforcement‐of‐low‐rate schedules with 22 1/2 h of water deprivation. The mean rate of responding per min increased significantly at 1.0 mg/kg on the continuous reinforcement schedule at 24 h of deprivation. Otherwise, a dose‐related significant reduction in the mean response rate per min occurred on the fixed raito schedules and partly on the differential‐reinforcement‐of‐low‐rate schedules, thus lending support to the idea that rate dependent effects may be produced only on schedules of reinforcement such as the fixed ratio, the fixed interval and the variable interval. The results also indicate that depenent effects may be produced only at moderate levels of water deprivation. Some critical comments are made on concepts of rate dependency in view of the results and of previous finding.

Continuous reinforcement of responding for water in rats with medial or dorsolateral septal lesions: Effect of deprivation level

The purpose of the present study was to examine differential effects of medial and dorsolateral septal lesions and level of water deprivation on lever pressing for water using a continuous reinforcement schedule. Five levels of water deprivation were used: 0, 6, 12, 24, and 48 hr. In addition to lever presses for water, responses on a second lever which were reinforced by onset of the cue lights above this lever and the amount of time the rat spent in the part of the cage where there were no levers were also recorded. The results showed that rats with dorsolateral, but not medial, septal lesions were significantly hypoactive when little deprived. These rats had reduced water-reinforced lever-press response rates when the level of deprivation was either 6 or 12 hr; they had reduced rates of sensory-reinforced (light-onset) responses and spent less time in the part of the cage most distant from the levers. Neither of the groups differed in ad libitum water intake. It is concluded that rats with dorsolateral, but not medial, septal lesions are hypomotivated when the level of water deprivation is low.

Effects of motivational variables and contextual stimuli on schedule-induced behavior

Hooded rats were trained in two experiments on either DRL 10- or 30-sec schedules of reinforcement to assess the effects of deprivation level, deprivation state, and available environmental stimuli on schedule-induced behavior. The reinforcer was an 8% sucrose solution, and the adjunctive inducing stimuli provided were air tubes and wood blocks. The effects of water deprivation level were studied in Experiment 1 by comparing water-deprived and nondeprived conditions in an ABA reversal procedure. Deprivation state, hunger or thirst, was assessed similarly in Experiment 2. In both studies, air licking developed spontaneously as an excessive, schedule-induced adjunctive activity only under thirst states, and diminished with decreased deprivation levels. Wood gnawing did not develop as an excessive or schedule-induced behavior but occurred more frequently under hunger states. The findings suggest that when state-appropriate environmental stimuli are provided during intermittent reinforcement schedules, relevant, redirected behaviors rather than irrelevant displacement activities emerge.

Behavioral contrast and responding during multiple food-food, food-water, and water-water schedules

Five pigeons pecked lighted keys for food reinforcers delivered by several multiple variable interval 2-min variable interval 2-min schedules. At different times, the components of the multiple schedule both supplied food reinforcers, both supplied water, or one supplied food and the other supplied water. Rates of responding during the water component of the food-water schedule were lower than the rates during comparable components of the water-water schedules (negative contrast). But, the rates of responding during the food component of the food-water schedule were not greater than the rates of responding during comparable components of the food-food schedules (absence of positive contrast) at two different levels of water deprivation. These results raise questions about several theories of behavioral contrast, and they may restrict the scope of any theory that attributes positive and negative contrast to symmetrical factors.

Development of sucrose preferences under two levels of water deprivation.

Although both highly (23.5 hr.) and moderately (18 hr.) water deprived rats preferred sucrose solutions to water at fixed locations, less thirsty animals developed higher preferences more rapidly. Amount of experience with each incentive but not concentration of sucrose solution affected the development of such preferences in the more thirsty rats.

Incidental cue utilization as a function of its incentive-produced validity under two levels of water deprivation.

Moderately (18 hr.) water-deprived rats were able to utilize an incidental cue of floor-texture following learning of brightness of a goal door better than highly water-deprived (23.5 hr.) animals only when water and sucrose liquids were paired with attributes of the new cue. These findings along with results from three subsidiary experiments indicate that drive level influences utilization of incidental cues by determining the differential incentive value of rewards predicted by attributes of those cues. This formulation is contrary to the drive level-focus of attention model of Tolman (1948) and Easter-brook (1959).

Effects of water deprivation on dry licking for shock avoidance and food reinforcement in the rat

One group of rats was trained on a signaled free-operant avoidance procedure to dry lick on a tungsten rod (lickometer) in order to avoid shock while water deprived or satiated. Avoidance performance was poor, and water deprivation level had no significant effect on licking performance. A second group of rats was operantly conditioned to dry lick for food pellets while water deprived or satiated. Licking for food reinforcement was effective, and there was a significant effect of water deprivation level on licking performance. The data suggest that effective licking for shock avoidance must be supported by fluid ingestion and that dry licking for food reinforcement is affected by other consequences in addition to food rewards.

Behavior of rats with septal lesions during low levels of water deprivation

The purpose of the present experiment was to investigate why rats with septal lesions show reduced response rates for water, compared to control rats, when the level of water deprivation is low. Two alternative explanations were tested experimentally: Caplan's (1973, Behavioral Biology , 9 , 129–167) “relativist” hypothesis and a “changed-motivation” hypothesis. The predictions from the two hypotheses were tested using a procedure in which the baseline was a variable-interval schedule of water reinforcement and several water-deprivation levels were used. In addition to lever presses for water, the following responses were recorded: Responses on a second lever which were reinforced by onset of the cue lights above this lever, and amount of time the rat spent in the part of the cage where there were no levers. The results showed that following septal lesions the rats were hypoactive when little deprived: In addition to reduced rate of lever pressing for water and reduced rate of water reinforcements, the rats stopped moving to the part of the cage where there were no levers and had an extremely low rate of lever pressing for light onset. These results were in accordance with the changed-motivation hypothesis; rats with septal lesions were hypomotivated when the level of water deprivation was low.

A comparison of operant licking and lever pressing in the rat

Two groups of rats were trained on a signaled, free-operant, avoidance procedure to lick or to lever press in order to avoid shock while water-deprived or satiated and, in the case of licking, while ingesting deionized water, isotonic saline, or 10% sucrose. The most effective avoidance licking occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for shock avoidance. Two other groups of rats were operantly conditioned to lick or to lever press for food pellets while waterdeprived or satiated and, in the case of licking, while ingesting deionized water or 10% sucrose. The most effective licking for food reinforcement occurred while the rats were water-deprived and ingesting 10% sucrose. Water deprivation level had no effect on lever pressing for food reinforcement. The data indicated that effective operant licking must be supported by factors related to water regulation and taste palatability.

Incentive preference under two levels of water deprivation in the rat

Rats under high (23.5 h) or moderate (18 h) water deprivation were required to learn a simultaneous goal door discrimination with S+ position correlated with incentive (water and 20% sucrose). A series of free choice trials with S+ simultaneously present at both incentive positions followed the initial discrimination. Moderately deprived animals made more errors and ran more slowly to S+ when it occurred on the water side than when on the sucrose side during discrimination trials. Highly water-deprived animals displayed less consistent and less differentiated speeds between incentives. Both deprivation groups preferred sucrose to water on free choice tests, but only moderately deprived animals tended to exclusively choose sucrose. The results were interpreted as indicating that the two deprivation levels substantially created different thirst arousal conditions in the animals.