Sense Organs

Effects of segregation and impact of specific feeding behaviour and additional fruit on voluntary nutrient and energy intake in yellow-shouldered amazons (Amazona barbadensis) when fed a multi-component seed diet ad libitum

Parrots are commonly fed multi-component seed diets; however, both segregation and feeding behaviour might alter ingredient and nutrient composition of the offered diet. First, the nutritional impact of segregation was assessed as it occurs when multi-component diets are temporarily stored in food containers that are replenished before completely emptied and birds being fed from the upper layer. The most detrimental effect hereof was a vast decrease in mineral supplements, leading to a decrease in Ca:P ratio in the offered food in relation to the formulated diet. Next, caloric distribution shifted towards more EE energy at the expense of NFE energy, as proportion of oilseeds increased and NFE-rich seeds decreased. Next, a feeding trial was performed on six yellow-shouldered amazons (Amazona Barbadensis) in which nutritional impact of parrot-specific feeding behaviour was assessed as well as the influence of additional provision of fruit next to the seed mixture. Profound selective feeding behaviour and dehusking of seeds resulted in a vast increase in energetic density by up to 64% in the ingested fraction in relation to the offered mixture in toto. Furthermore, the already suboptimal Ca:P ratio further deteriorated and caloric distribution shifted by over twofold towards EE energy accompanied with a vast decline in NFE energy, CP energy remaining similar. Finally, provision of fruit next to the seed diet significantly lowered voluntary energy intake from 936 ± 71 to 809 ± 109 kJ ME/kg(0.75)/day, without compromising adequate protein intake. In conclusion, notwithstanding efforts of nutritionists to formulate diets to approximate estimated, species-specific requirements, nutritional composition of the actually consumed fraction of multi-component seed diets can be vastly deteriorated by both animal and management factors. Furthermore, offering of fruit next to a seed-based diet effectively reduces voluntary energy intake and can hence be applied to abate obesity.

Treatment of bilateral corneal ulceration in a Peregrine Falcon (Falco peregrinus) using 360 degree conjunctival flaps

A wild Peregrine Falcon (Falco peregrinus) was presented with extensive bilateral fluorescein positive corneal damage. Local therapy and bilateral tarsorrhaphies resulted in slow improvement over 5 weeks. When bilateral 360 degree conjunctival flaps were used subsequently, healing proceeded more rapidly over the next 8 weeks. Although bulbar conjunctival flaps have been reported as difficult in birds due to their small size and relatively immobile bulbar conjunctiva, 360 degree conjunctival flaps made from palpebral rather than bulbar conjunctiva were found to be technically feasible in a larger bird species such as the Peregrine Falcon.

Adaptations and pathologies linked to dynamic stabilization of neural circuitry

Brain circuits for infrequently employed memories are reinforced largely during sleep by self-induced, electrical slow-waves, a process referred to as "dynamic stabilization" (DS). The essence of waking brain function in the absence of volitional activity is sensory input processing, an enormous amount of which is visual. These two functions: circuit reinforcement by DS and sensory information processing come into conflict when both occur at a high level, a conflict that may have been the selective pressure for sleep's origin. As brain waves are absent at the low temperatures of deep torpor, essential circuitry of hibernating small mammals would lose its competence if the animals did not warm up periodically to temperatures allowing sleep and circuit reinforcement. Blind, cave-dwelling vertebrates require no sleep because their sensory processing does not interfere with DS. Nor does such interference arise in continuously-swimming fishes, whose need to process visual information is reduced greatly by life in visually relatively featureless, pelagic habitats, and by schooling. Dreams are believed to have their origin in DS of memory circuits. They are thought to have illusory content when the circuits are partially degraded (incompetent), with synaptic efficacies weakened through infrequent use. Partially degraded circuits arise normally in the course of synaptic efficacy decay, or pathologically through abnormal regimens of DS. Organic delirium may result from breakdown of normal regimens of DS of circuitry during sleep, leaving many circuits incompetent. Activation of incompetent circuits during wakefulness apparently produces delirium and hallucinations. Some epileptic seizures may be induced by abnormal regimens of DS of motor circuitry. Regimens of remedial DS during seizures induced by electroconvulsive therapy (ECT) apparently produce temporary remission of delirium by restoring functional or 'dedicated' synaptic efficacies in incompetent circuitry. Sparing of sensory circuitry in fatal familial insomnia seemingly owes to supernormal circuit use in the virtual absence of sleep. ECT shocks and cardioverter defibrillation may have analogous remedial influences.

Memory, sleep and the evolution of mechanisms of synaptic efficacy maintenance

The origin of both sleep and memory appears to be closely associated with the evolution of mechanisms of enhancement and maintenance of synaptic efficacy. The development of activity-dependent synaptic plasticity apparently was the first evolutionary adaptation of nervous systems beyond a capacity to respond to environmental stimuli by mere reflexive actions. After the origin of activity-dependent synaptic plasticity, whereby single activations of synapses led to short-term efficacy enhancement, lengthy maintenance of enhancements probably was achieved by repetitive activations ("dynamic stabilization"). One source of selective pressure for the evolutionary origin of neurons and neural circuits with oscillatory firing capacities may have been a need for repetitive spontaneous activations to maintain synaptic efficacy in circuits that were in infrequent use. This process is referred to as "non-utilitarian" dynamic stabilization. Dynamic stabilization of synapses in "simple" invertebrates occurs primarily through frequent use. In complex, locomoting forms, it probably occurs through both frequent use and non-utilitarian activations during restful waking. With the evolution of increasing repertories and complexities of behavioral and sensory capabilities--with vision usually being the vastly pre-eminent sense brain complexity increased markedly. Accompanying the greater complexity, needs for storage and maintenance of hereditary and experiential information (memories) increased greatly. It is suggested that these increases led to conflicts between sensory input processing during restful waking and concomitant non-utilitarian dynamic stabilization of infrequently used memory circuits. The selective pressure for the origin of primitive sleep may have been a resulting need to achieve greater depression of central processing of sensory inputs largely complex visual information than occurs during restful waking. The electrical activities of the brain during sleep (aside from those that subserve autonomic activities) may function largely to maintain sleep and to dynamically stabilize infrequently used circuitry encoding memories. Sleep may not have been the only evolutionary adaptation to conflicts between dynamic stabilization and sensory input processing. In some ectothermic vertebrates, sleep may have been postponed or rendered unnecessary by a more readily effected means of resolution of the conflicts, namely, extensive retinal processing of visual information during restful waking. By this means, processing of visual information in central regions of the brain may have been maintained at a sufficiently low level to allow adequate concomitant dynamic stabilization. As endothermy evolved, the skeletal muscle hypotonia of primitive sleep may have become insufficient to prevent sleep-disrupting skeletal muscle contractions during non-utilitarian dynamic stabilization of motor circuitry at the accompanying higher body temperatures and metabolic rates. Selection against such disruption during dynamic stabilization of motor circuitry may have led to the inhibition of skeletal muscle tone during a portion of primitive sleep, the portion designated as rapid-eye-movement sleep. Many marine mammals that are active almost continuously engage only in unihemispheric non-rapid-eye-movement sleep. They apparently do not require rapid-eye-movement sleep and accompanying non-utilitarian dynamic stabilization of motor circuitry, because this circuitry is in virtually continuous use. Studies of hibernation by arctic ground squirrels suggest that each hour of sleep may stabilize brain synapses for as long as 4 h. Phasic irregularities in heart and respiratory rates during rapid-eye-movement sleep may be a consequence of superposition of dynamic stabilization of motor circuitry on the rhythmic autonomic control mechanisms. Some information encoded in circuitry being dynamically stabilized during sleep achieves unconscious awareness in authentic and var

Effects of short- and long-term feeding of zinc oxide-supplemented diets on the mature, female domestic fowl with special reference to tissue mineral content

1. In Expt 1, the effects on laying hens of diets supplemented with zinc oxide providing up to 20 g added zinc/kg were compared. In Expt 2 the diets contained up to 6 g added Zn/kg. 2. In both experiments, food intake, body-weight, egg number, and liver, oviduct and ovary weights/kg body-weight were significantly reduced by added ZnO; gizzard weight/kg body-weight was significantly increased. In Expt 2, pancreas weight was significantly reduced by added ZnO. 3. Liver, kidney and pancreatic Zn and iron concentrations were significantly elevated in both experiments. 4. In both experiments, liver, kidneys and pancreatic copper concentrations gave quadratic responses to added ZnO.

Effects of water temperature on short-term water intake and medullary neuronal responses in the hen

1. The daily water intake of adult Brown Leghorn hens was measured at water temperatures of 0, 10, 20, 30, 40 and 45 degrees C. The electrical activity of neurones in the nucleus ventro-lateralis anterior solitarii (NVLAS) of the medulla was also measured when the mouth was stimulated with water at the same temperatures. 2. There was a significant decrease in water intake when the temperature of the water was 10 or 45 degrees C. 3. There was an increase in activity of some of the NVLAS neurones with decreasing water temperature and this activity was in response to specific "cold" receptors. 4. Some NVLAS neurones were identified which showed an increase in activity at temperatures of 45 degrees C and more; it was concluded that these represented responses to thermal pain. 5. It is concluded that the effects of temperature on water intake may in part be explained by the behaviour of the oral receptors.

Effects of the protracted feeding of copper sulphate-supplemented diets to laying, domestic fowl on egg production and on specific tissues, with special reference to mineral content

1. Two experiments are reported. In both experiments a cereal-based diet containing 5 mg copper/kg was fed to two breeds of laying hens for 336 d. In Expt 1 four other groups were given this diet with the addition of CuSO4.5H2O to give added levels of 200, 400, 600 and 800 mg Cu/kg diet. In Expt 2 the levels of added dietary Cu used were 100, 200, 300 and 400 mg/kg. 2. In Expt 1 records were kept of food intake, water intake, body-weight and egg production for eight 28 d periods and body-weight and egg number only were recorded for the full twelve periods. In Expt 2 full records, excluding water intake, were taken for all twelve periods. 3. Food and water intake showed a quadratic response to level of added dietary Cu, being enhanced at lower levels and depressed at higher levels of addition. 4. There was a quadratic response of total egg weight, mean egg weight and egg number to added dietary Cu. In Expt 1 egg number was maximum at 235 mg added Cu/kg diet for Warren Studler SSL (breed 1) and at 170 mg added Cu/kg diet for Shaver 288 (breed 2). In Expt 2 no breed effect occurred, the maximum egg number being calculated to occur at 176 mg added Cu/kg diet. 5. Depression of body-weight gain occurred at high levels of Cu addition. The depression of liver and oviduct weight found at high levels of addition appeared to be directly related to body-weight. A marked amount of feather loss also occurred at a high inclusion of CuSO4 in the diet. 6. The reproductive systems of the hens did not appear to be adversely affected at the levels of additive used. Gross and microscopic examination of specific tissues revealed no pathological effects although gizzard and intestinal weights were increased and caecal weight decreased by high levels of added Cu. THose aspects of the blood chemistry examined did not reveal any consistent effect between the two experiments. 7. The liver Cu analyses indicate that between 600 and 800 mg added Cu/kg diet the liver Cu concentration rises sharply. Both liver Fe and Zn concentrations showed a positive linear response to added dietary Cu. In the kidney Cu and Zn concentrations were increased but only to a limited extent, while the concentration of Fe was unaffected.