The Stock-Feeder's Manual Part 3

4. The difference between the amount of heat evolvable by the foods before being consumed, and that actually obtained by the combustion of the egesta into which they were ultimately converted, would be the amount actually set free and rendered available within the body. The calculations would be somewhat affected by an increase in the weight of the animal's body; but it would not be difficult to keep the weight stationary, or nearly so, and there are other ways of getting over such a difficulty. An experiment such as this would be a costly one, and could not be properly conducted unless by the aid of an apparatus similar to that employed by Pettenkofer in his experiments on respiration. This apparatus, which was made at the expense of the King of Bavaria, cost nearly 600.

_Value of Manure._--It is a complication in the question of the economic feeding of the farm animals that the value of their manure must be taken into account. Of the three cla.s.ses of food const.i.tuents, two--the mineral and nitrogenous--are recoverable in the animal's body and manure; the non-nitrogenous is partly recoverable in the fat.

I shall take the case of a sheep, which will consume weekly per 100 lbs. of its weight, 12 lbs. of fat-formers, and 3 lbs. of flesh-formers.

Twelve per cent. of the fat-formers will be retained in the _increase_, but the rest will be expended in keeping the animal warm, and the products of its combustion--carbonic acid and water--will be useless to the farmer. It is, therefore, desirable to diminish as much as possible the combustion of fatty matter in the animal's body; and this is effected, as I have already explained, by keeping it in a warm place.

Of the flesh-forming substance only five per cent. is retained in the increase, the rest is partly consumed in carrying on the movements of the animal--partly expelled from its body unaltered, or but slightly altered, in composition. The solid excrement of the animal contains all the undigested food; but of this only the mineral and nitrogenous const.i.tuents are valuable as manure. The nitrogen of the plastic materials which are expended in maintaining the functions of the body is eliminated from the lungs, through the skin, and by the kidneys--perhaps also, but certainly only to a small extent, by the r.e.c.t.u.m.

The food consumed by an animal is disposed of in the following way:--A portion pa.s.ses unchanged, or but slightly altered, through the body; another part is a.s.similated and subsequently disorganised and ejected; the rest is converted into the carca.s.s of the animal at the time of its death. The undigested food and aliment which had undergone conversion into flesh and other tissues, and subsequent disorganisation, const.i.tute the excrements, or manure, of the animal. The richer in nitrogen and phosphoric acid the food is, the more valuable will be the manure; so that the money value of a feeding stuff is not determinable merely by the amount of flesh which it makes, but also, and to a great extent, by the value of the manure into which it is ultimately converted.

Corn and oil-cakes are powerful fertilisers of the soil; but the three principles which const.i.tute their manurial value--namely, nitrogen (ammonia), phosphoric acid, and potash--are purchasable at far lower prices in guano and other manures. Nevertheless, many farmers believe that the most economical way to produce good manure is to feed their stock with concentrated aliment, in order to greatly increase the value of their excreta. They consider that a pound's worth of oil-cake, or of corn, will produce at least a pound's worth of meat, and that the manure will be had for nothing, or, rather, will be the profit of the business.

The richer food is in nitrogen and phosphoric acid, the more valuable will be the manure it yields. It follows, therefore, that if two kinds of feeding stuff produce equal amounts of meat, that the preference should be given to that which contains the more nitrogen and phosphoric acid. Mr. Lawes, who has thrown light upon this point, as well as upon so many others, has made careful estimates of the value of the manure produced from different foods. They are given in the following table:--

TABLE

Showing the estimated value of the manure obtained on the consumption of one ton of different articles of food; each supposed to be of good quality of its kind.

Estimated Money Value Description of Food. of the Manure from One Ton of each Food.

1. Decorticated cotton-seed cake 6 10 0 2. Rape-cake 4 18 0 3. Linseed-cake 4 12 0 4. Malt-dust 4 5 0 5. Lentils 3 17 0 6. Linseed 3 13 0 7. Tares 3 13 6 8. Beans 3 13 6 9. Peas 3 2 6 10. Locust beans 1 2 6(?) 11. Oats 1 14 6 12. Wheat 1 13 0 13. Indian corn 1 11 6 14. Malt 1 11 6 15. Barley 1 9 6 16. Clover-hay 2 5 0 17. Meadow-hay 1 10 0 18. Oat-straw 0 13 6 19. Wheat-straw 0 12 6 20. Barley-straw 0 10 6 21. Potatoes 0 7 0 22. Mangolds 0 5 0 23. Swedish turnips 0 4 3 24. Common turnips 0 4 0 25. Carrots 0 4 0

All the saline matter contained in the food is either converted into flesh, or is recoverable in the form of manure, but a portion of its nitrogen appears to be lost by respiration and perspiration. Reiset states that 100 parts of the nitrogen of food given to sheep upon which he experimented, were disposed of as follows:--

Recovered in the excreta 583 Recovered in the meat, tallow, and skin 137 Lost in respiration 280 ------ 10000

Haughton's experiments, performed upon men, gave results which proved that no portion of the nitrogen of their food was lost by perspiration or by respiration. Barral, on the contrary, a.s.serts that nitrogen is given off from the bodies of both man and the inferior animals.

Boussingault states that horses, sheep, and pigs exhale nitrogen.

A cow, giving milk, on which he had experimented, lost 15 per cent.

of the nitrogen of its food by perspiration. The amount of nitrogen which Reiset states that sheep exhale is exceedingly great, and it is difficult to reconcile his results with those obtained by Voit, Bischoff, Regnault, Pettenkofer, and Haughton. Of course, men and sheep are widely different animals; but still it is unlikely that all the nitrogen of the food of man should be recoverable in his egesta, whilst nearly a third of the nitrogen of the food of the sheep should be dissipated as gas. I think further experiments are necessary before this point can be regarded as settled; and it is probable that it will yet be found that all, or nearly all, of the nitrogen of the food of animals is recoverable in their egesta.

Regarding, then, an animal as a mechanism by which meat is to be "manufactured," five economic points in relation to it demand the feeder's attention: these are--the first cost of the mechanism, the expense of maintaining the mechanism in working order, the price of the raw materials intended for conversion into meat, the value of the meat, and the value of the manure. In proportion to the attention given to these points, will be the feeder's profits; but they are, to some extent, affected by the climatic, geographic, and other conditions under which the farm is placed.

[Footnote 1: If the elements were only capable of combining with each other in simple ratios, the number of their combinations would be as limited as that of the letters of the alphabet; but as one, two, or more atoms of oxygen can combine with one, two, or more atoms of other elements, we can a.s.sign no limits to the number of _possible_ combinations. There are hundreds of distinct substances formed of but two elements, namely, hydrogen and carbon.]

[Footnote 2: In a paper by Professor Sullivan, of Dublin, the conversion of one of these substances into another _outside_ the animal mechanism, is almost incontrovertibly proved.]

[Footnote 3: _Experimental Inquiry into the Composition of some of the Animals Fed and Slaughtered as Human Food._ By John Bennet Lawes, F.R.S., F.C.S., and Joseph Henry Gilbert, Ph.D., F.C.S. _Philosophical Transactions of the Royal Society._ Part II., 1860.]

[Footnote 4: From the Greek _pla.s.so_, "to form." Plastic materials are sometimes termed _formative_ elements; both terms imply the belief that they are capable of giving shape, or form, not only to themselves, but also to other kinds of matter not possessed of formative power.]

[Footnote 5: The slow conversion of phosphorus into phosphoric acid takes place in the animal organism; its gradual oxidation in the open air gives rise only to an imperfectly oxidised body--_phosphorous acid_.

But the latter fact does not invalidate the general proposition, that the heat emitted by a substance undergoing the process of oxidation is proportionate to the amount of oxygen with which it combines, and is not influenced by the length of time occupied by the process, further than this, that if the oxidation be _very_ rapidly effected, a portion of the heat will be converted into an _equivalent_ amount of light.]

[Footnote 6: This statement is not absolutely correct, but the range of variation is confined within such narrow limits as to be quite insignificant.]

[Footnote 7: Doubt has recently been thrown on the truth of this belief by Frankland, Fick, and Wislicenus.]

[Footnote 8: The results of Savory's experiments on rats appear to prove that animals can live on food dest.i.tute of fat, sugar, starch, or any other fat-forming substance. I think, however, that animals could hardly thrive on purely nitrogenous food. The conclusions which certain late writers, who object to Liebig's theory of animal heat, have deduced from Savory's investigations, appear to me to be quite unfounded.]

[Footnote 9: So termed because it is the basis of the common oils; the fluid portion of fat is composed of oleine.]

[Footnote 10: The term _dry_ is applied to the _solid_ const.i.tuents of the food. Thus, a pig fed with 100 lbs. of potatoes would be said to have been supplied with 25 lbs. of dry potatoes, because water forms 75 per cent. of the weight of those tubers.]

[Footnote 11: The amounts of "mineral matter" are too high, owing to the advent.i.tious matters (dirt) retained by the wool.]

[Footnote 12: This pig was completely a.n.a.lysed by Lawes and Gilbert.]

[Footnote 13: The results of recent and accurately conducted investigations prove that men engaged in occupations requiring the highest exercise of the intellectual faculties, require more nutritious food, and even a greater quant.i.ty of nutriment, than the hardest worked laborers, such as paviours, and navvies. I have been a.s.sured by an extensive manufacturer, that on promoting his workmen to situations of _greater_ responsibility but _less_ physically laborious than those previously filled by them, he found that they required more food and that, too, of a better quality. This change in their appet.i.te was not the result of increased wages, which in most cases remained the same--the decrease in the amount of labour exacted being considered in most cases a sufficient equivalent for the increased responsibility thrown upon them.]

[Footnote 14: As ammonia, urea, uric acid, or hippuric acid; all of which are nearly or perfectly mineralised substances.]

[Footnote 15: The excrements of animals are capable of evolving, by combustion, enormous amounts of heat.]

PART II.

ON THE BREEDING AND BREEDS OF STOCK.

SECTION I.

THE BREEDING OF STOCK.

_Cross Breeding._--For many years past feeders have zealously occupied themselves in the improvement of their stock, and the result of their labors is observable in the marked superiority of the breeds of the present day over their ancestors in the last century. The improvement of animals designed as food for man is effected by keeping them on a liberal dietary, by selecting only the best individuals for sires and dams, and by combining the excellencies of two or more varieties of a species in one breed. A species consists of a number of animals which exhibit so many points of resemblance, that they are regarded by the great majority of naturalists to be the descendants of a single pair.

If we except the believers in the hypotheses relative to the origin of existing varieties of animals and plants, propounded by Lamarck, Darwin, and other naturalists of the "advanced school," there is a general belief in the immutability of species. The individuals of an existing species, say dogs, can never acquire the peculiar features of another species; nor can their descendants, if we except hybrids, ever become animals in which the characteristics of the dog tribe are irrecognisable. By various influences, such as, for example, differences in food and climate, and domestication, a species may be split into _varieties_, or _breeds_, all of which, however, retain the more important characteristics of the primordial type. There appears to be no limit to the varieties of dogs, yet one can perceive by a glance that there is no specific difference between the huge Mont St. Bernard dog and the diminutive poodle, or between the spa.r.s.e greyhound and the burly mastiff. All the varieties of our domestic fowl have been traced to a common origin--the wild Indian fowl (_Gallus bankiva_). Even Darwin admits that all the existing kinds of horses are, in all probability, the descendants of an original stock; and it is generally agreed that the scores of varieties of pigeons own a common ancestor in the rock pigeon (_Columba livia_).

As certain individuals are grouped by naturalists into species, so particular species, which in habits and general appearance resemble each other, are arranged under the head of genus. The horse, the a.s.s, and the zebra are formed on nearly the same anatomical plan; they are therefore cla.s.sed together, and designated the genus _Equus_, a term derived from the Latin word _equus_, a horse--that animal being regarded as the type, or perfect member of the group. Thus the horse, in the nomenclature of the naturalist, is termed _Equus caballus_; the a.s.s, _Equus asinus_; and the zebra, _Equus zebra_. By a further extension of this principle of cla.s.sification, very closely allied genera are united under the term of _family_.

The different varieties of the same species breed, as might be antic.i.p.ated, freely together; but it frequently happens that two individuals of different species pair, and produce an animal which inherits some of the properties of each of its progenitors. These half-breeds are termed _hybrids_, or _mules_, and we have familiar examples of them in the common mule and the jennet. As a general rule, animals exhibit a disinclination to breed with other than members of their own species; and although the interference of man may overcome this natural repugnance, he can only effect the fruitful congress of individuals belonging to closely allied species, being members of the same genus. Hybrids in the genus _Equus_ are very common. A cross has been produced between the he-goat and the ewe; the camel and the dromedary have bred together; and Buffon succeeded in producing a hybrid in which three animals were represented--namely, the bison, the zebu, and the ox. On the other hand, attempts to effect a cross between animals belonging to different families have generally failed; nor is it at all probable that a cross will ever be produced between the pig and the sheep, between the horse and the cow, or, most unlikely of all, between the dog and the cat.

It is the general belief that hybrids are sterile, or, at least, that they are incapable of propagation _inter se_. This may be true with respect to the hybrids of species not very closely allied; but that there are exceptions to the rule is quite clear from Roux's experiments with hares and rabbits. This gentleman, who is, or was, the president of a French agricultural society, but who makes no profession of scientific knowledge, has succeeded, after several failures, in producing a fruitful cross between the rabbit and the hare. This hybrid has received the name of leporide (from the Latin _leporinus_, pertaining to a hare), and it is different from former crosses, in being five parts hare, and three parts rabbit. M. Roux has bred this hybrid during the last eighteen years, and has not observed the slightest appearance of decay of race manifest itself up to the present, so that, for all practical purposes, the leporide may be regarded as an addition to the distinct species of animals. The leporide fattens rapidly, and with but little expenditure of food. Sold at the age of four months, it realises, in France, a price four times greater than that commanded by a rabbit of the same age; and at a year old it weighs on an average ten pounds, and sometimes as much as sixteen pounds. It breeds at four months, continues thirty days in gestation, and yearly produces five or six litters of from five to eight young. To produce this hybrid is by no means difficult. A leveret, just old enough to dispense with the maternal nutriment, should be placed with a few doe rabbits of his own age, apart from other animals. He will soon become familiar with the does, and when they attain the age of p.u.b.erty, all the rabbits save one or two should be removed. Speedily those left with the hare will become with young, upon which they should be removed, and replaced by others. After this the hare should be kept in a hutch by himself, and a doe left with him at night only. As the hare is naturally a very shy animal, it will only breed when perfect quietness prevails. The half-bred produced in the first instance should now be put to the hare, and a cross, three parts hare, and one part rabbit, obtained. The permanent breed should then be obtained by crossing the quadroon doe leporide, if I may use the term, with the half-bred buck.

I have directed attention to the production of the leporide because I believe that the problems in relation to it, which have been solved by M. Roux, have an important bearing upon the breeding of animals of greater importance than hares and rabbits. Here we find a race of animals produced by the fusion of two species, which naturally exist in a state of mutual enmity, and which differ in many important respects.

The hare and the rabbit are respectively of but little value as food, at least they are of no importance to the feeder; yet a cross between them turns out to be an excellent meat-producing animal, which may be reared with considerable profit to the feeder. It is thus clearly shown that two kinds of animals, neither of which is of great utility, may give rise to an excellent cross, if their blood, so to speak, be blended in proper proportions. A half-bred animal may be less valuable than its parents, but a quadroon may greatly excel its progenitors. The goat and sheep are so closely related that they are cla.s.sed by naturalists under one head--_Capridae_. Some kinds of sheep have hair like goats, and certain varieties of goats have fleeces that closely resemble those on the sheep. There are sheep with horns, and goats without those striking appendages. The Cape of Good Hope goat might easily be mistaken for a sheep. It would seem, judging by the results of Roux's experiments, that there is no great difficulty in the way of obtaining a cross between the sheep and the goat. I do not mean an ordinary half-breed, but a prolific hybrid similar to the leporide. Of course, it is impossible, _a priori_, to say whether or not such a hybrid race, supposing it produceable, would be valuable; but as goats can find a subsistence on mountains where sheep would starve, it is possible that an animal, essentially a sheep, but with a streak of goat blood in it, could be profitably kept on very poor uplands. Whether a race of what we might term _caprides_ be formed or not we have derived most suggestive information from M. Roux's experiments, which I hope may be turned to account in what is by far the most important field of enquiry, the judicious crossing of varieties of the same species.

It is a _quaestio vexata_ whether or not the parents generally exercise different influences upon the shape and size of their offspring. Mr.

Spooner supports the supposition--a very popular one--that the sire gives shape to the external organs, whilst the dam affects the internal organisation. I have considerable doubt as to the probability of this theory. The children who spring from the union of a white man with a negress possess physical and intellectual qualities which are nearly if not quite the _mean_ of their parents; but the offspring of parents, both of the same race--be it Caucasian, Mongolian, or Indian--frequently conform, intellectually and corporeally, to either of their progenitors.

Thus, of the children of a tall, thin, dark man, and a short, fat, fair woman, some will be like their father, and the others will resemble their mother, or, perhaps, all may "take after" either parent.

Sometimes a child appears to be in every respect unlike its parents, and occasionally the likeness of an ancestor appears in a descendant, in whom no resemblance to his immediate progenitors can be detected. It is highly probable that both parents exercise, under most circ.u.mstances, a joint influence upon the qualities of their offspring, but that one of them may produce so much greater an effect that the influence of the other is not recognisable, except perhaps to a very close observer. But I doubt very much that any particular organ of the offspring is, as a rule, more liable to the influence of the sire than of the dam, or _vice versa_; and the breeder who believes that the sire alone is concerned in moulding the external form of the offspring, and who consequently pays no attention to this point in the dam, will often find himself out in his reckonings. In order to be certain of a satisfactory result, the dam should in every respect be equal to the sire. In practice, however, this is not always the case, for as sires are so few as compared with the number of dams, the greatest efforts have been directed towards the improvement of the former.

There is, or ought to be, a familiar maxim with breeders, that "like begets like, or the likeness of an ancestor." This is a "wise saw," of which there are many "modern instances:" the excellencies or defects of sire or dam are certain to be transmitted through several generations, though they may not appear in all. As a general rule, good animals will produce a good, and defective animals a defective, offspring, but it sometimes happens that a bull or cow, of the best blood, is decidedly inferior, whilst really good animals are occasionally the produce of parents of "low degree." If the defects or excellencies of animals were ineradicable there would be no need for the science of breeding; but by the continual selection of only the most superior animals for breeding purposes the defects of a species gradually disappear, and the good qualities are alone transmitted. As, however, animals that are used as food for man are to some extent in an abnormal condition, the points which may be excellencies in that state, would not have been such in the original condition of the animal. We find, therefore, that the improved breeds of oxen and sheep exhibit some tendency to revert to their original condition, and it is only by close attention to the diet, breeding, and general management of these animals that this tendency can be successfully resisted. Sometimes, however, an animal of even the best breed will "return to nature," or will acquire some undesirable quality; such an animal should be rejected for breeding purposes, for its defects would in all probability be transmitted to its descendants, near or remote. A case, which admirably ill.u.s.trates this point, is recorded in the _Philosophical Transactions_ for 1813, and it is sufficiently interesting to be mentioned here:--

Seth Wright, who possessed a small farm on the Charles River, about sixteen miles from Boston, had a small flock, consisting of fifteen ewes and one ram. One of these ewes, in 1791, produced a singular-shaped male lamb. Wright was advised to kill his former ram and keep this new one in place of it; the consequence was, the formation of a new breed of sheep, which gradually spread over a considerable part of New England, but the introduction of the Merino has nearly destroyed them again. This new variety was called the Otter, or "Ankon" breed. They are remarkable for the shortness of their legs, and the crookedness of their forelegs, like an elbow.

They are much more feeble and much smaller than the common sheep, and less able to break over low fences; and this was the reason of their being continued and propagated.