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NS · 17 апр 2007

Пришли домой - кура валяется на полу, целая,
но какая-то немного странная. Поняли только когда подняли её и внимательно осмотрели.

ivank · 18 апр 2007

NS пишет:

Из той-же википедии:

Собака - всеядное млекопитающее из семейства псовых, одомашнено около 10 тыс. лет назад.
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Тогда и собаки всеядные
Только на их здоровье растительная диета не очень хорошо сказывается.
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Из той же, да не совсем . По моему опыту русскоязычная Википедия на порядок менее информативна и достоверна, чем англоязычная (что не удивительно).
Читаем в англоязычной версии той же статьи: http://en.wikipedia.org/wiki/Dog#Diet

Diet

At present, there is some debate as to whether domestic dogs should be classified as omnivores or carnivores, by diet. The classification in the Order Carnivora does not necessarily mean that a dog's diet must be restricted to meat; unlike an obligate carnivore, such as the cat family with its shorter small intestine, a dog is dependent on neither meat-specific protein nor a very high level of protein in order to fulfill its basic dietary requirements. Dogs are able to healthily digest a variety of foods including vegetables and grains, and in fact dogs can consume a large proportion of these in their diet. Wild canines not only eat available plants to obtain essential amino acids, but also obtain nutrients from vegetable matter from the stomach and intestinal contents of their herbivorous prey, which they usually consume. Domestic dogs can survive healthily on a reasonable and carefully designed vegetarian diet, particularly if eggs and milk products are included. Some sources suggest that a dog fed on a strict vegetarian diet may develop dilated cardiomyopathy since it lacks L-carnitine,[12] however, maintaining a balanced diet is also a factor since L-carnitine is found naturally in many nuts, seeds, beans, vegetables, fruits and whole grains. In the wild, dogs can survive on a vegetarian diet when animal prey is not available. However it has been noted, both by observation of extremely stressful conditions such as the Iditarod Trail Sled Dog Race and by scientific studies of similar conditions, that high-protein (approximately 40%) diets including meat help prevent damage to muscle tissue. (This research is also true for some other mammals.) This level of protein corresponds to the percentage of protein found in the wild dog's diet when prey is abundant; higher levels of protein seem to confer no added benefit.

Dogs frequently eat grass, which is a harmless activity. Explanations abound, but rationales such as that it neutralizes acid, or that eating grass might make the dog vomit, so dogs eat grass to remove unwanted substances from their stomachs, are at best educated guesses.
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NS пишет:

В животной пище они тоже не очень сбалансированы:
http://en.wikipedia.org/wiki/Essential_aminoacids
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Так и нужно есть наверно всего понемногу, и растительную и животную пищу.
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Из приведенной таблицы этот вывод непосредственно не следует . Можно предложить например такую комбинацию:
Источник белка Лимитирующая аминокислота
пшеница лизин
бобовые метионин (или цистеин)

Здравый смысл, конечно, подсказывает придерживаться умеренности во всем, в том числе и в соотношении животного и растительного компонента пищи. Но наука как раз интересна тем, что позволяет шагнуть за рамки здравого смысла и, в конечном счете, отчасти изменяет сам здравый смысл. ИМХО .

azur · 18 апр 2007

ivank, большое спасибо.
Любопытно, что говорит наука о принятии пусть сбалансированной, но монотонной пищи? Например, одного и того же сухого корма в течение долгого периода времени?

ivank · 22 май 2007

azur пишет:

Любопытно, что говорит наука о принятии пусть сбалансированной, но монотонной пищи?
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Долго ли, коротко ли... Вот что пока я нашел:

Bradshaw JW.
The evolutionary basis for the feeding behavior of domestic dogs (Canis familiaris) and cats (Felis catus).
J Nutr. 2006 Jul;136(7 Suppl):1927S-1931S. Review.
http://www.ncbi.nlm.nih.gov/entrez/...ool=iconabstr&query_hl=10&itool=pubmed_docsum

Я процитирую побольше про собак, т.к. это может быть интересно:

Feeding behavior and food selection in domestic dogs

It is generally agreed that dogs were the first species of animal to be domesticated, but precisely when, why, and how domestication took place is still under debate (4). Archaeological evidence suggests that dogs first became distinguishable in appearance from wolves ;14,000 y ago; their mitochondrial DNA points to a much older common ancestor, perhaps .100,000 y ago. This discrepancy can be resolved if the appearance of domestic wolves/dogs did not diverge from that of free-living wolves until the shift from hunter-gatherer lifestyles to the early stages of agriculture; at this point this is speculative. There is also argument about the purpose for which dogs were first kept by people. Whatever the details of their origin, today?s dogs are extraordinarily diverse in form, their range of sizes and conformations exceeding those of all the other species in the Canidae combined. Less visible, and less well documented, is an underlying diversity of physiology and behavior (5). It is therefore always risky to generalize about ??the dog?? when discussing any aspect of behavior. Although anecdotally some breeds and types of dogs differ from others in their feeding behavior, there is little published evidence that would enable this variation to be explained.

Several breeds of dog have a reputation for being able to consume large meals very rapidly, and it is possible that this is the
legacy of competitive feeding in the wolf. When a wolf pack makes a kill of a large mammal such as a caribou, a feeding hierarchy that allows the pack leaders (alphas) to feed first is observed; once they have withdrawn, the juveniles may have to compete with each other for the best of what remains. Rapid feeding may also be an adaptation to scavenging during the early stages of domestication (6). Dogs that retain this tendency can rapidly become obese if allowed to feed ad libitum. Although some breeds may be more prone to such behavior than others, there is also considerable variation among individuals within breeds (7).

In wild animals, food selection is a complex process that begins with the onset of foraging behavior and ends with the consumption of an item of food. In contrast to cats (see below), hunting behavior in domestic dogs was greatly modified genetically during the course of domestication, both in comparison with the wolf, and between types (6). Feral dogs generally subsist by scavenging rather than by hunting (8), suggesting that most dogs do not retain a fully functional repertoire of hunting behaviors. Occasional kills of livestock by feral or stray dogs may be accounted for by the high thresholds for flight in domestic, compared with wild animals. For most pet dogs, the selection of food provided by humans is based upon its appearance, odor, flavor, and texture. Little is known about how wolves use these senses to select among potential foods; thus, it is impossible to judge to what extent food selection behavior in dogs was modified by domestication. The taste systems of dogs and cats are based on what is probably a general carnivore pattern; certainly they are distinct from those found in rats (9) and several other omnivores and herbivores. One major distinction is the much greater sensitivity of the latter to sodium chloride, often a limiting factor in the diet of herbivores but less critical for carnivores because prey automatically contains an adequate level of sodium. Beagles appear to have little preference for salt or appetite for sodium (10), but monovalent cations, including Na+, greatly potentiate taste responses to sugars in dogs; thus, it is unclear how much of a role sodium chloride may have in food selection (11). Among the taste buds of the facial nerve in dogs, the most common units (Type A) respond primarily to amino acids, many of which, such as L-proline and L-cysteine, are described as ??sweetish?? in humans (12); these units also respond to mono- and disaccharides. Type B units, which are different from those found in rats, respond to carboxylic acids, phosphoric acids, nucleotide triphosphates, histidine, and other Brønsted acids. Type C units respond primarily to nucleotides that are associated with the ??umami?? taste in humans (13). Type D, which are not found in cats, respond to a small number of ??fruity-sweet?? compounds, such as furaneol (9). It was suggested that broad links can be drawn between these specializations and carnivory because many of the compounds mentioned occur in raw flesh and in carrion (14), but it is still unclear how the information from the taste buds is integrated into the brain or translated into feeding behavior. Odor must also play a major role in food selection because anosmic dogs show a reduced discrimination between different types of meat (15).

Although such sensory biases may predispose dogs to prefer some foods over others, these preferences must be modified by experience; however, little published research exists in this area. Dogs fed the same diet for long periods often display enhanced preferences for other diets (16,17), an example of the so-called ??novelty effect,?? which will be discussed further in relation to cats (see below). Neophobia, initial rejection of apparently palatable foods that have never been experienced before, does occur in some breeds of dogs, but not in others (14). The most powerful effects of experience on feeding behavior in any species are one-trial aversions, in which sickness following a meal induces complete and persistent refusal of the same food at subsequent encounters. Experimentally, this is often demonstrated by adding an emetic such as LiCl to a food; it was suggested that dogs are less ready to learn such aversions than are other species (18), but subsequently it was discovered that LiCl has other behavioral effects on dogs (19), including inducing aggression; thus it is possible that these effects may interfere with aversion learning.
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То есть "эффект монотонности" более характерен и/или лучше изучен для кошек, чем для собак:

Many cats do, however, show a growing aversion toward foods that have formed a large part of their diet in the past, sometimes referred to as the ??novelty effect?? but more accurately termed a ??monotony effect?? because it is the perceived palatability of the repeated food that is mainly affected. This strategy should reduce the probability that an unbalanced diet is taken because no 2 foods with markedly different flavors should contain the same nutritional deficiencies, even if these cannot be directly detected by cats. Powerful monotony effects were detected in both kittens and adult cats, and in both catteries (6,37) and free-ranging populations (38). The strength of this effect on preference appears to be greater in free-ranging cats, such as those on farms or taken in as strays, than in cats raised exclusively on nutritionally complete diets (39). Experience of the effects of accidentally taking a nutritionally incomplete diet, and subsequently correcting the imbalance by seeking out a food of contrasting flavor, may therefore increase the tendency to adopt the same strategy on subsequent occasions.
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The extent to which kittens are neophobic toward a new food appears to depend upon the degree of contrast between its sensory attributes and those of the foods they or their mother are accustomed to eating. Weaning onto varied diets results in puppies and kittens with broad food preferences (44). The simplest explanation for this is that the possibility of strong contrasts, which might trigger neophobia, is reduced because any new food is likely to show some similarity to one or other of the foods already experienced. It is unclear whether wide experience actually makes young animals less neophobic per se. Kittens and puppies raised on a single type of commercial pet food often show strong preferences for other commercial foods on the first few occasions they are offered (6); presumably, in this situation, the broad similarity between the products means that there is little or no neophobia, and the ??monotony effect?? (antiapostatic selection) dominates.
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It is less easy to generalize about dogs, however, simply because of the great diversity of form and behavior within this species, resulting from its long history of domestication and the many different functions for which dogs have been bred.
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