10 DEPARTMENT OF AGRICULTURE. 



(5.) Improperly cleaned separators and milking utensils: 



(6.) Keeping the cream or butter at too warm temperature and in poorly con- 

 structed, ill-ventilated storage: 



(7.) Cream too old or too ripe before churning and too much buttermilk retained 

 in the butter: 



(8.) Impure water, cows drinking from stagnant ponds or the seepage from 

 barnyards : 



(9.) Result of the growth of injurious bacteria, yeasts, and moulds. 



BACTERIA. 



Like other plants, bacteria require food, warmth, and moisture for growth. 

 They absorb their food from the material in which they grow. The food elements 

 they require are present in the constituents of milk, and they are in a readily avail- 

 able state. Nitrogen, carbon, oxygen, and mineral matter are essential and are 

 furnished by the casein, milk-sugar, and mineral salts. 



SOURCES OF BACTERIA IN MILK. 



Milk may be contaminated by bacteria from within the udder, or introduced 

 into the milk by dust falling from the stable air, by hair, small particles of skin, 

 or manure falling into the milk-pail from the flanks and udder of the cow, and by 

 dirt from the hands and clothing of the milkers. The greater part of this filthy 

 matter dissolves in the milk, giving it not only undesirable odours and taints, but 

 also inoculating it with the various kinds of bacteria. These germs may also have 

 been gathered from stagnant water, muddy pools, or miry yards. While the 

 majority of them may not be disease-producing or especially harmful, should they 

 be transmitted to the human system, yet, to say the least, they are factors in 

 bringing about decomposition of the milk. 



HOW TO KEEP MILK PURE. 



Filth and disease germs go hand in hand; the same carelessness that allows 

 the one is likely to give access to the other. Hence it is of the highest importance 

 that the cow and her surroundings be kept as clean as possible. This can be accom- 

 plished by brushing off all the loose dirt and dust from the flanks and udder. This 

 will take but a moment, and will prevent large quantities of filth from getting into 

 the milk. The amount of dirt that gets into the milk is one of the chief causes of 

 its rapid spoiling, and the contamination from dissolved filth can never be entirely 

 eliminated. 



THE HERD. 



The first requisite for pure milk is healthy cows. Any animal suspected of 

 being sick or out of condition should be at once separated from the herd and not 

 allowed to remain near the dairy. Milk should never be used until five days after 

 calving, nor from a sick cow nor one with a diseased udder. 



BARNS AND STABLES. 



Costly barns or stables are not essential to the production of clean milk or to 

 the maintenance of a dairy herd at its highest efficiency. To obtain the best results, 

 however, it is important that the cows be kept comfortable at all times. The 

 barnyard should be well drained and covered with gravel, stone, or cement. The 

 contamination which a cow gets from muddy " manury " barn lots and stagnant 

 pools of water is especially bad. A tight, reasonably smooth floor, with a gutter 

 suitably located, should be provided, and the stable thoroughly cleaned and swept 

 at least twice daily. It is advisable to haul the manure directly to the field from 

 the barn, but if this is not feasible it should be removed at least 40 feet from the 

 barn. In no case must it be allowed to accumulate against or near the dairy-barn. 



