30 
THE CULTIVATOR 
DB. PLAYFAIR'S LECTURE, 
GRAZING AND FATTENING CATTLE. 
At the request of the Royal Agricultural Society of 
England, Dr. Lyon Playfair recently delivered two 
lectures before that society, on the application of the 
principles of physiology to the grazing and fattening of 
cattle. By the kindness of our friends in London, we 
have been favored with reports of these lectures. The 
first was delivered on the 7th December, and we doubt 
whether we can occupy a page to better advantage than 
by giving this lecture to our readers: 
Dr. Playfair stated that the object of the lecture was 
to point out in what manner the principles of physiolo¬ 
gy, especially those which had been lately developed by 
the chemical researches of Liebig, might be applied to 
the grazing and fattening of cattle. In the first place, 
he should endeavor to give a clear conception of what 
the principles of physiology were, that were involved 
in the feeding and growth of animals. Vegetables, in 
their growth, derive all their food from the mineral 
kingdom, principally from the air, which had been 
called a gaseous mineral; whilst animals derived their 
principal nutriment directly from the vegetable king¬ 
dom. Vegetables effected many chemical changes in 
the food they took up, animals few. Gluten and albu¬ 
men are the nutrient principles of plants, and in chemi¬ 
cal composition they are identical with the albumen of 
the white of an egg, of the muscle of an ox, or the 
blood of a sheep. By identity was not meant similarity, 
but positively the same thing. The albumen of blood, 
of muscle, and of an egg differed in physical but not in 
chemical characters. The composition of these sub¬ 
stances, as analysed by various chemists from the animal 
and vegetable kingdom, as seen in the following table, 
prove their identity: 
Gluten. 
Casern. Albumen. 
Ox-biood. Ox-flesh. 
Boussin- 
gault. 
Scherer. 
Jones. 
Playfair. 
Playfair. 
Carbon,. 
54-2 
54-1 
5-5 
64-19 
54-12 
Hydrogen, • • • - 
7-5 
7-1 
7- 
7-5 
7-89 
Nitrogen, •••• 
1-4 
15-6 
15-7 
15-72 
16-71 
Oxygen, 
24-4 
23-2 
22-1 
22-69 
21-66 
These analyses do not differ more than the analysis of 
the same substance. Plants, in fact, contain within them 
the flesh of animals, and all the animal organization does 
in nutrition, is to put this flesh in the right place. But 
animals take up with their food other constituents of 
plants which contain no nitrogen; such are starch, su¬ 
gar, gum, &c. These are not nutritive principles; they 
do not assist in making the flesh of animals; and when 
animals are fed on these alone, they die. But animals 
possess a certain degree of heat, and their bodies have 
generally a temperature above that of the atmosphere— 
about 100 degrees of Fahrenheit’s thermometer. Whence 
then comes this heat? From the burning of the sugar, 
starch, gum, &c. The air that animals exspire is car¬ 
bonic acid, the very gas that is produced by the burning 
of wood or charcoal^n a fire. Charcoal is carbon, and 
animals take in dail*a large quantity of carbon in their 
food. It is the burning or combustion of this substance 
in the body that produces animal heat. In hot countries, 
animals on this account take less carbon. The food of 
the East Indian contains only about 12 per cent of car¬ 
bon; whilst that of the Greenlander contains 70 per 
cent. The depraved taste of the Greenlander, who 
drinks train-oil and eats tallow candles by the dozen, 
might be pitied or wondered at; but it is necessary to 
his healthy existence. Another reason for animals ac¬ 
quiring carbonaceous food in cold climates is, that the 
air is more condensed, and the same measure contained 
a greater quantity of oxygen; that gas being the agent 
which, by uniting with the carbon and forming carbonic 
acid, gave out the heat. Strong exercise also demands 
a large supply of carbonaceous food, on account of the 
oxygen taken in during the hard breathing thus pro¬ 
duced. Oxygen, when once taken into the system, 
never escapes uncombined, and would destroy the whole 
fabric of the body unless a fresh supply of material was 
given. Clothes, by keeping in animal heat, rendered 
less carbonaceous food necessary in order to keep the 
body up to its proper temperature. The following table 
exhibits the principles of food necessary for the two 
great processes of life—^nutrition and respiration:— 
Elements of Nutrition. 
Elements of Respiration. 
Vegetable Fibrine, 
Fat, 
“ Albumen, 
Starch, 
“ Casein, 
Gum, 
Animal Flesh, 
Sugar, 
“ Blood. 
Wine, 
Spirits, 
Beer. 
If it were not for some power or force within the animal 
fabric, it would soon become a prey to the chemical ac¬ 
tion of oxygen. The force that withstands this action is 
vitality—a principle independent of the mind, and which 
constantly opposes the destructive chemical laws to 
which the body is subject. Disease is the temporary 
ascendancy of the chemical over the vital force. Death 
is the victory of the chemical force. A dead body ex¬ 
posed to the action of oxygen is soon resolved into its 
primitive elements—carbon, hydrogen, and nitrogen, in 
the form of carbonic acid, ammonia and water; and 
these are the elements from which plants again prepare 
materials for the living body. These remarks will ex¬ 
plain many facts known to the agriculturist, and will 
assist him in insuring more certainly many of the ob¬ 
jects of his labors. It is very well known that cattle do 
not fatten so well in cold weather as in hot. The rea¬ 
son is this: The fat is a highly carbonized substance, 
formed by the animal from its carbonaceous food. In 
cold weather, the carbon in this food is consumed in 
keeping up the heat of the animal, which is at that sea¬ 
son more rapidly carried off. This is also illustrated in 
an experiment made by Lord Ducie at Whitfield. One 
hundred sheep were placed in a shed, and ate 20 lbs. of 
Swedes each per day; another hundred were placed in 
the open air, and ate 25 lbs. of Swedes per day; yet at 
the end of a certain period the sheep which were pro¬ 
tected, although they had a fifth less food, weighed 3 
lbs. a head more than the unprotected sheep. The rea¬ 
son of this is obvious: the exposed sheep had their car¬ 
bonaceous food consumed in keeping up their animal 
heat. Warmth is thus seen to be an equivalent for food. 
This is also illustrated by the fact, that two hives of 
bees do not consume so much honey when together as 
when separate, on account of the warmth being greater; 
and they have less occasion for consuming the honey, 
which is their fuel. Cattle, for the same reason, thrive 
much better when kept warm, than when exposed to 
the cold. The cause of animals getting fat is, that they 
take in more carbonaceous food than they require for 
producing animal heat; the consequence is, that it is 
deposited in the cellular tissue in the form of fat. Fat 
is an unnatural production, and its accumulation is not 
necessary for securing the health of the body. When 
stored up, however, it will serve the body for keeping 
up its animal heat, and by this means its life, till it is 
all consumed. An instance is related of a fat pig having 
been kept without food for 160 days, having been kept 
alive by its own fat. Another element necessary to be 
taken into consideration in the fattening of animals is 
motion or exercise. Every action of the body—nay, 
every thought of the mind, is attended with chemical 
change; a portion of the deposited tissues are thus being 
constantly consumed. It is on this account that when ani¬ 
mals are fattened, they are kept quiet and still. The 
cruel practice of fattening geese by nailing their feet to 
the floor, and of cooping pigeons and chickens before 
they are killed, arises from a knowledge of this fact. 
When prizes were gdven by our agricultural societies for 
fat, and not for symmetry, animals were strictly pre¬ 
vented from tailing any exercise at all. Mr. Childers 
found that sheep which were kept warm and quiet, fat¬ 
tened much faster than those that were allowed the open 
air and action. It is very difficult to fatten sheep and 
oxen in July, on account of the flies, which stinging 
them, keep them in a state of constant motion. The 
Cornish miners, on account of the laborious nature of 
their occupations, consume more food than laborers with 
lighter work. During the late riots in Lancashire the 
poor unemployed operatives found out that exercise and 
cold made them hungry; accordingly, they kept quiet in 
bed, and heaped upon themselves all the covering they 
could find. Englishmen in the East Indies are obliged 
to take a great deal of exercise, because they will insist 
on eating and drinking highly carbonized foods; and 
the heat of the climate not allowing the escape of much 
heat from the body, they are obliged to take in by exer¬ 
cise the oxygen of the air, in order to destroy the carbon 
which would otherwise accumulate in the system, and 
produce liver disease. In the Scotch prisons, the quan¬ 
tity of food given to the prisoners is regulated by the kind 
of work on which the prisoners are engaged, the hardest 
workers having the most food. The reason of the flesh 
of the stag becoming putrid shortly after its death arises 
from the quantity of oxygen which it takes into its sys¬ 
tem during the hard breathing of the chase. A hunted 
hare, for the same reason, is as tender as one that has 
been kept for a fortnight after being shot. The reason 
is the same. In both cases the action of the oxygen on 
the flesh produces approaching decomposition—in the 
one, quickly; in the other, slowly. Bacon, on the same 
principle, was, at one time, rendered more delicate by 
whipping the pig to death. Epileptic fits produce great 
emaciation, on account of the violent action to which 
they expose the body. Lord Ducie has performed some 
experiments highly illustrative of the foregoing general 
principles, and which also indicated what might be ex¬ 
pected from their application to the practice of grazing. 
1st experiment. Five sheep were fed in the open air 
between the 21st of Nov. and the 1st of Dec.; they con¬ 
sumed 90 lbs. of food per day, the temperature of the 
atmosphere being about 44 deg. At the end of this time 
they weighed 2 lbs. less than when first exposed. 2d 
experiment. Five sheep were placed under a shed and 
allowed to run about, at a temperature of 49 deg.; they 
consumed at first 82 lbs. of food per day—^then 70 lbs. 
and at the end of the time had increased in weight 23 
lbs. 3d experiment. Five sheep were placed in same 
shed as in the last experiment, but not allowed to talte 
any exercise; they ate at first 64 lbs. of food per day— 
then 58 lbs.—and increased in weight 30 lbs. 4th ex¬ 
periment. Five sheep were kept quiet and covered, and 
in the dark: they ate 35 lbs. a day, and were increased 
8 lbs. These experiments prove very satisfactorily the 
influence of warmth and motion on the fattening of cat¬ 
tle, and are still going on. 
Dr. Playfair then stated that he should proceed to ex¬ 
amine the different kinds of food of cattle. The food 
of cattle is of two kinds—azotised and unazotised—with 
or without nitrogen. The following table gives the 
analysis of various kinds of food of cattle in their fresh 
state: 
lbs. 
Water. 
Organic Matters. 
Ashes. 
100 Peas,. 
16 
804 
34 
“ Beans, . 
14 
824 
“ Lentels,. 
16 
81 
3 
“ Oats,. 
18 
79 
3 
“ Oatmeal. 
9 
89 
S 
“ Barley Meal,. 
15i 
824 
2 
Hay, . 
16 
764 
74 
“ Wheat Straw,. 
18 
79 
3 
“ Turneps, . 
89 
10 
1 
“ Swedes,. 
85 
14 
1 
“ Mangel Wurzel, . 
.89 
10 
1 
“ White Carrot,. 
87 
12 
1 
“ Potatoes,. 
72 
27 
1 
“ Red Beet,.. 
89 
10 
1 
“ Linseed Cake,. 
17 
754 
74 
“ Bran,. 
144 
804 
5 
A glance at this table would enable a person to esti¬ 
mate the value of the articles as diet. Thus every 100 
tons of Turneps contained 90 tons of water. But the 
value of the inorganic and organic matters which these 
foods contained differed. Thus Mr. Rham states that 
lOO lbs. of hay, were equal to 339 lbs. of mangel wur- 
zel. It would be seen by the table, that that quantity of 
hay contained 76 lbs. of organic matter, whilst the man¬ 
gel wurzel contained only 34 lbs. One result of feed¬ 
ing animals on foods containing much water is, that 
the water abstracts from the animal, a large quantity of 
heat, for the purpose of bringing it up to the tempera¬ 
ture of the body, and in this way, a loss of material took 
place. The mode proposed by Sir Humphi-ey Davy, of 
ascertaining the nutritive properties of plants, by me¬ 
chanically separating the gluten, is unsusceptible of ac¬ 
curacy. The more accurate way is to ascertain the 
quantity of nitrogen, which being multiplied by 6-2, 
will give the quantity of albumen contained in any given 
specimen of food. The following is a table of the equi¬ 
valent value of several kinds of food, with reference to 
the formation of muscle and fat; the albumen indicating 
the muscle-forming principle; the unazotised matters in¬ 
dicating the fat-forming principle: 
lbs. 
Albumen. 
Unazotised matter. 
100 Flesh, . 
25 
0 
“ Blood,. 
29 
0 
“ Peas, . 
£9 
514 
“ Beans, . 
31 
52 
“ Lentils, . 
33 
48 
“ Potatoes,. 
2 
244 
“ Oats,. 
104 
68 
“ Barley Meal,. 
14 
68 
“ Hag,. 
8 
684 
“ Turneps,. 
1 
9 
“ Carrots,... 
2 
10 
Red Beet,. 
14 
84 
The analyses in this table, are partly the result of Dr. 
Playfair and Boussingault’s analysis, and partly Dr. Play¬ 
fair’s own analysis. The albumen series indicate the 
flesh forming pi-inciples, and the unazotised series indi¬ 
cate the fat-forming principles. By comparing this ta¬ 
ble with the former, it will at once be seen which foods 
contain not only the greatest quantity of organic matter, 
but what proportion of this organic matter is nutritive, 
and which is fattening; or that which furnishes living 
tissue and that which furnishes combustible material. In 
cold weather, those foods should be given which con¬ 
tain the larger proportion of unazotised matters, in order 
to sustain the heat of the body. Thus it will be seen that 
potatoes are good for fattening, but bad for fleshening. 
Linseed cake contains a great deal of fattening matter, 
and but little nutritive matter; hence, barley meal, 
which contains a good deal of albumen, may be advan¬ 
tageously mixed with it. Dumas, a French chemist, 
states that the principle of fat exists in vegetables, as in 
hay and maize, and that, like albumen, it is deposited in 
the tissues unchanged. But Liebig regards fat as trans¬ 
formed sugar, starch, gum, &c., which has undergone a 
change in the process of digestion. This is why linseed 
cake is fattening: all the oil is squeezed out of the seed, 
but the seed-coat, which contains a great deal of gum, 
and the starch of the seed is left, and these are fattening 
principles. The oxygen introduced by respiration into 
the lungs, is destined for the destruction of carbonaceous 
matter, but there is a provision made for taking it into 
the stomach with the food, and this is done by the sali¬ 
va. The saliva is always full of bubbles, which are air 
bubbles, which carry the oxygen of the atmosphere into 
the stomach with the food. The object of rumination 
in animals, is the more perfect mixing of the food with 
the oxygen of the air. This is why chaff should not be 
cut so short for ruminating, as for non-ruminating ani¬ 
mals, as the shorter the chaff is, the less it is ruminated, 
and the less oxygen it gets. Chaff is cut one inch for the 
ox, half an inch for the sheep, and a quarter for the 
horse. Some might, in consequence of this, suppose 
that cutting food is then of little use; but when it is con¬ 
sidered that rumination is a strong exercise, or that an 
animal will not be eating more food that is ruminating, 
it will easily be seen how cutting facilitates fattening. 
In order that food may be properly ruminated, it requires 
a certain amount of consistency and bulk; hence all wa¬ 
tery foods, as turneps, and mangel wurzel, should be 
mixed with straw. The opinion is very correct, that an 
animal “ cannot chew its food without straw.” An im¬ 
portant inorganic constituent of the food is salt; it is a 
chloride of sodium. Whilst the chlorine goes to form 
the gastric juice, which is so important an agent in di¬ 
gestion, the soda goes to form the bile, which is a com¬ 
pound of soda. The bile is, in fact, a secondary combi¬ 
nation, by which the carbonaceous matter is brought in 
contact with the oxygen, in order to be burnt. It is thus 
that common salt becomes so important and necessary an 
article of diet. In the series of changes by which the 
oxygen of the air is brought in contact with the carbona- 
