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Crowell-Davis, S. L., & Houpt, K. A. (1985). Coprophagy by foals: effect of age and possible functions. Equine Vet J, 17(1), 17–19.
Abstract: In colts and fillies observed from birth to 24 weeks old, coprophagy occurred from Weeks 1 to 19. Its frequency was greatest during the first two months. Coprophagy was rarely observed in mares and stallions. Foals usually ate the faeces of their mother but were observed to eat their own and those of a stallion and another unrelated mare. Urination by the foal occurred before, during or after 26 per cent of the coprophagy incidents. It is hypothesised that foals may consume faeces in response to a maternal pheromone which signals the presence of deoxycholic acid or other acids which the foal may be deficient in and which it may require for gut immuno-competence myelination of the nervous system. Such a pheromone may also serve to accelerate growth and sexual maturation. Coprophagy may also provide nutrients and introduce normal bacterial flora to the gut.
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Sufit, E., Houpt, K. A., & Sweeting, M. (1985). Physiological stimuli of thirst and drinking patterns in ponies. Equine Vet J, 17(1), 12–16.
Abstract: The stimuli that elicit thirst were studied in four ponies. Nineteen hours of water deprivation produced an increase in plasma protein from 67 +/- 0.1 g/litre to 72 +/- 2 g/litre, a mean (+/- se) increase in plasma sodium from 139 +/- 3 to 145 +/- 2 mmol/litre and an increase in plasma osmolality from 297 +/- 1 to 306 +/- 2 mosmol/litre. Undeprived ponies drank 1.5 +/- 0.9 kg/30 mins; 19 h deprived ponies drank 10.2 +/- 2.5 kg/30 mins and corrected the deficits in plasma protein, plasma sodium and plasma osmolality as well as compensating for the water they would have drunk during the deprivation period. In order to determine if an increase in plasma osmolality would stimulate thirst, 250 ml of 15 per cent sodium chloride was infused intravenously. The ponies drank when osmolality increased 3 per cent and when plasma sodium rose from 136 +/- 3 mmol/litre to 143 +/- 3 mmol/litre. Ponies infused with 15 per cent sodium chloride drank 2.9 +/- 0.7 kg; those infused with 0.9 per cent sodium chloride drank 0.7 +/- 0.5 kg. In order to determine if a decrease in plasma volume would stimulate thirst, ponies were injected with 1 or 2 mg/kg bodyweight (bwt) frusemide. Plasma protein rose from 68 +/- 2 g/litre pre-injection to 75 +/- 2 g/litre 1 h after 1 mg/kg bwt frusemide and to 81 +/- 1 g/litre 1 h after 2 mg/kg bwt frusemide.(ABSTRACT TRUNCATED AT 250 WORDS)
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Forster, H. V., Pan, L. G., Bisgard, G. E., Flynn, C., & Hoffer, R. E. (1985). Changes in breathing when switching from nares to tracheostomy breathing in awake ponies. J Appl Physiol, 59(4), 1214–1221.
Abstract: We assessed the consequences of respiratory unloading associated with tracheostomy breathing (TBr). Three normal and three carotid body-denervated (CBD) ponies were prepared with chronic tracheostomies that at rest reduced physiological dead space (VD) from 483 +/- 60 to 255 +/- 30 ml and lung resistance from 1.5 +/- 0.14 to 0.5 +/- 0.07 cmH2O . l-1 . s. At rest and during steady-state mild-to-heavy exercise arterial PCO2 (PaCO2) was approximately 1 Torr higher during nares breathing (NBr) than during TBr. Pulmonary ventilation and tidal volume (VT) were greater and alveolar ventilation was less during NBr than TBr. Breathing frequency (f) did not differ between NBr and TBr at rest, but f during exercise was greater during TBr than during NBr. These responses did not differ between normal and CBD ponies. We also assessed the consequences of increasing external VD (300 ml) and resistance (R, 0.3 cmH2O . l-1 . s) by breathing through a tube. At rest and during mild exercise tube breathing caused PaCO2 to transiently increase 2-3 Torr, but 3-5 min later PaCO2 usually was within 1 Torr of control. Tube breathing did not cause f to change. When external R was increased 1 cmH2O . l-1 . s by breathing through a conventional air collection system, f did not change at rest, but during exercise f was lower than during unencumbered breathing. These responses did not differ between normal, CBD, and hilar nerve-denervated ponies, and they did not differ when external VD or R were added at either the nares or tracheostomy.(ABSTRACT TRUNCATED AT 250 WORDS)
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Shettleworth, S. J. (1985). Handling time and choice in pigeons. J Exp Anal Behav, 44(2), 139–155.
Abstract: According to optimal foraging theory, animals should prefer food items with the highest ratios of energy intake to handling time. When single items have negligible handling times, one large item should be preferred to a collection of small ones of equivalent total weight. However, when pigeons were offered such a choice on equal concurrent variable-interval schedules in a shuttlebox, they preferred the side offering many small items per reinforcement to that offering one or a few relatively large items. This preference was still evident on concurrent fixed-cumulative-duration schedules in which choosing the alternative with longer handling time substantially lowered the rate of food intake.
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Shettleworth, S. J. (1985). Foraging, memory, and constraints on learning. Ann N Y Acad Sci, 443, 216–226.
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Cook, M., Mineka, S., Wolkenstein, B., & Laitsch, K. (1985). Observational conditioning of snake fear in unrelated rhesus monkeys. J Abnorm Psychol, 94(4), 591–610.
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Packer, C., & Pusey, A. E. (1985). Asymmetric contests in social mammals: respect, manipulation and age-specific aspects. In P. J. Greenwood, M. Slatkin, & (Ed.), Evolution: Essays in Honour of John Maynard Smith (pp. 173–86). Camebridge: Camebridge University Press.
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Chase, I. D. (1985). The sequential analysis of aggressive acts during hierarchy formation: an application of the `jigsaw puzzle' approach. Anim. Behav., 33(1), 86–100.
Abstract: The `jigsaw puzzle' approach is a general method for investigating how interactions among individuals cumulate to form the overall patterns of dominance behaviour in groups. Here, the model is used to discover how aggressive interactions between pairs of individuals modify subsequent interactions with bystanders or third parties. The model indicates that four sequences of successive, aggressive acts are possible in component triads of larger groups: two ensure transitive attack relationships and two can lead to either transitive or intransitive relationships. An application of the model to 14 groups of four hens demonstrates that the two sequences guaranteeing transitivity make up 77% of all sequences. More specifically, hens attacking one group member usually go on to attack a second member, and hens receiving one attack frequently receive a second attack from a bystander. In contrast, an attacked hen rarely `redirects' an attack to a bystander, and a bystander rarely attacks a group member who has just attacked another individual. The application of the jigsaw puzzle approach to aggressive sequences in other species is discussed. Data available for several primate species corroborate the findings in hens and provide support for the method as a general tool for investigating the proximate mechanisms of hierarchy formation.
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Terrace, H. S. (1985). Animal Cognition: Thinking without Language. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences (1934-1990), 308(1135), 113–128.
Abstract: Recent attempts to teach apes rudimentary grammatical skills have produced negative results. The basic obstacle appears to be at the level of the individual symbol which, for apes, functions only as a demand. Evidence is lacking that apes can use symbols as names, that is, as a means of simply transmitting information. Even though non-human animals lack linguistic competence, much evidence has recently accumulated that a variety of animals can represent particular features of their environment. What then is the non-verbal nature of animal representations? This question will be discussed with reference to the following findings of studies of serial learning by pigeons. While learning to produce a particular sequence of four elements (colours), pigeons also acquire knowledge about the relation between non-adjacent elements and about the ordinal position of a particular element. Learning to produce a particular sequence also facilitates the discrimination of that sequence from other sequences.
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Kamil, A. C., & Roitblat, H. L. (1985). The Ecology of Foraging Behavior: Implications for Animal Learning and Memory. Annual Review of Psychology, 36(1), 141–169.
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