ON THE LAND

Taranaki Daily News, 8 January 1927, Page 23

ON THE LAND

THE EQUALITY OF MILK.

VALUE OF CLEANLINESS. (Contributed by the Department of Health.) This article is written more particularly for the information and guidance of dairy farmers in country districts to achieve their aim io turn out milk ns clean and free from contamination as they possibly can. Milk is one of the most nourishing and most delicate of all foods; nourishing because it supplies all the constituents necessary to support life, aiql delicate because it is prone to undergo deleterious changes if due precautions are not observed in its handling. These changes are chiefly induced by germs or bacteria, and as cleanliness is the main factor by which the number and species of such germs may be kept under control, cleanliness in the handling of milk is of the utmost importance. Except that first drawn from the teat, milk as it exists in the udder of the healthy cow may be considered to be practically free from germ life, and with proper precautions sterile milk may be drawn from the udder of a heaithy cow, but in ordinary practice milk is more or less exposed to bacterial contamination, and this is the reason souring and other changes take place. By far the greater number of bacteria in milk come from ordinary dirt, and may be kept out of the milk by cleanly methods of producing and handling milk, i Milk is one of the best media used in I the laboratory for growing bacteria, and the few bacteria that arc found in even I the best of milk may therefore multiply to millions and may make the milk unwholesome unless great care is taken to prevent their growth and increase. PRODUCTION OF CLEAN MILK. The eow must be healthy; the shed must be clean, well lighted and ventilated, and the surroundings also should be clean. Any operation likely to produce dust before or during milking, especially of hand milking, must be avoided. The cow must be clean and washing the udder and fianks with waler gives the best results—after washing the udder and teats must be wiped with a clean damp cloth. The milkers’ hands and clothes must be clean. In hand-milking, the milk pail should have as small an opening as can be used. The first stream of milk from each teat should be rejected, and tiie practice of wet-handed milking should be avoided. The milk should be removed from the cowshed immediately after milking for straining and cooling. It should be handled in a clean, airy, well-lighted shed kept solely for the purpose. The milk must be cooled to ofideg. F., where possible, otherwise to the lowest temperature obtainable. It should be kept as cool as possible in •• closed vessels during storage and transit. The milking utensils, including the cooler, should be well rinsed with cold water immediately after use and after rinsing, the utensils should be thoroughly washed and scrubbed with hot water to which soda has been added, { and afterwards rinsed in clean water and sterilised by steam. Sterilisation depends entirely on heating the utensils to a sufficiently high temperature lor a sufficient period of time. Scalding will not sterilise. After sterilisation the utensils must be protected from’ contamination until required. Straining cloths and udder cloths and everything that comes cither directly or indirectly In contact with the milk must be washed and sterilised after each milking. WHEN STRAINING SHOULD BE DONE. Straining should take place before cooling which should bo dune as soon as possible after milking and invariably in a- pure atmosphere. The value of a straining cloth is frequently overrated. The straining cloth strains out visible dirt to a considerable extent, such as particles of grit, straw, etc., from the milk, but bacteria are far too small for any straining cloth to prevent them from passing through. It is therefore useless for the purpose of 1 removing bacteria that have already gained access to the milk. If a cloth is used that has not been properly washed and sterilised since it was last used, bacteria will have bred multiplied on the cloth, and it wm thus j be a fertile source of contamination. j Where there is any risk of the straining cloth not being properly sterilised after each milking it is better to use a cotton wool disc. These d*scs are cheap enough, and after use can be thrown away. The quantity of dirt strained out of the milk is visible on ' the strainer, and is an excellent guide ’ as to the quality of the work being I done in the cowsheds. Butter muslin is an efficient strainer, even when sev- I oral thicknesses are used. A straining • cloth is far mere effective, and this j lias to be washed and thoroughly steri- ' lised by boiling or in steam and a new | one frequently used, otherwise. bad re-! suits will be obtained. The metal I gauze strainer keeps out the grosser impurities, and requires the same care as the above. Do not attempt to strain too large an amount, of milk without changing the strainer or straining material. If this is done the latter part of the milk poured on it may have the effect of washing through dirt with 'bacteria, which has strained out ! of the previous milk. The strainer may i be a means of infecting a large quantity: of good milk by a small amount of bad milk. COOLING PROCESS. It is almost impossible to produce milk free from bacteria or to destroy all bacteria by pasteurisation. It is i therefore necessary to prevent bacteria I from multiplying in milk, and the only | allowable method of preserving milk ■ ie by cooling it. A low temperaturel restrains the growth of all kinds of | bacteria. The degree of temperature! needed tp preserve milk will depend greatly on the length of time that the • milk ie to be kept. The marked ef-I fects of temperature are well recog- ■ nised, and everyone is aware that milk keeps better in winter than in summer/ The higher temperature the more readily do coliform bacteria multiply, and theses bacteria readily cause souring I and curdling of milk. Milk to bo safely kept should be cooled immediately after milking to 50deg. Fahrenheit or lower, and with the exception of the necessary heating for pasteurisation should not subsequently be permitted to exceed . that temperature. The maintenance' pf a

low bacteria content unless the milk is clean to start with, but on the. other hand maintenance at a comparatively high temperature, such as GOdeg. to 70deg. Fahrenheit, is likely to result in a high count even with an originally ‘'clean” milk. During a part, of tiie winter months there may be little difficulty to cool to sOdeg. Fahrenheit, but in summer months, this temperature in many cases, especially in the North Island, is only possible with the use of iee. Observations in Auckland hgve shown that for six months of the summer the average temperature on delivery of raw milk was 7Odeg. Fahrenheit, and for six months 5/deg. Fall, renheit. Where the water supply is derived from a .deep well the difficulty is less. If a demand for iee could be. established, possibly the cost of production of ice might be lowered and its use encouraged, especially at farms within easy access of a city. If the temperature of the milk is lowered sufficiently at the farm, the temperature of the outer air does not affect it markedly during transit except when it is exposed to the. direct sun’s rays or in an excessively warm atmosphere. Milk-cans are frequently left by farmers at the side of the road to await collection by the depot wagons and are frequently exposed to the direct rajv of the sun and to dust. This is frequently the case also at railway stations. Covered motor wagons are fortunately superseding open carts, and by this means transport to the cities is accelerated.

In retailers' premises in the towns there should be no difficulty in imposing a definite standard of ofldeg. F., at which the temperature of all milk for sale should be kept. In house the use of the ice chest for storage of milk should be mure general. It is important for the public to recognise it has a duty also in the matter of storing the milk in thoroughly clean receptacles and keeping it stored at a low temperature,. and protected from flies, dust, and odours. MILK COOLERS. Milk coolers offer a large surface for the contamination of the milk. If the cooling is carried out in a proper dairy where the air is pure the number of organisms gaining admission is small, but in cases where cooling is carried out in a dirty cowshed or in dusty places serious pollution has to be considered. On the other hand, coolers are frequently found in a dented or damaged condition, which makes it practically impossible to keep them clean. Many have repeatedly been repaired with solder, and it is seldom that a smooth surface has been left. It is advised that coolers be fitted with metal covers; these covers fit one on each side of the cooler and protect the milk from dust while in use. They are easily removed for cleansing, and they do not interfere with the cleansing of the cooler itself. In regard to cooling on a large scale, where certain types of pasteurisers are used, milk can be left in the pasteuriser after having been heated to the requisite temperature for the required time, and cooled by passing the cooling mixture through the coil. This means less handling, and also prevents exposure of the milk to large surfaces or to the air, and is a great improvement in this respect on the use of the ordinary surface coolers. It seems hardly necessary to point out the injurious effects of the addition of stale milk to fresh milk, but fresh milk is often spoiled in this way. The mixing occurs where a milkman mixes the remnants of his morning delivery with the. fresh milk received by him in the afternoon or the following day. The consequence is an immediate increase in the number of bacteria, and a considerable reduction of the period during which the milk remain useful. Apart from this, indiscriminate mixing of various grades of milk at milk depots, etc., results in comparatively clean nii : k being depreciated by dirty ones. THE QUALITY OF MILK. (From A Correspondent.) When we consider that 36 per cent, of the Dominion exports are derived from the dairying industry, it is naturally a matter of much concern to the actual farm worker.as to the best manner of keeping* the herds well fed and healthy, and by breeding, testing and culling to increase the returns per cow to the utmost limit. In the past we have had a great advantage over our rivals from the fact that the northern countries have a long, cold winter, necessitating the preparation of large stores of winter feed at heavy expense. These advantages have, to a certain extent, disappeared 'with our increased land values and the heavy overhead charges. We are all familiar with the exceptional cow that is always doing well under any conditions, but she in no way affects the and the first consideration would seem to be to ascertain with absolute certainty the most suitable breed of cows for our To obtain a uniformly high yield of milk it is necessary to provide a plentiful supply of good, succulent feed, but as our lands in North Taranaki are generally of a light nature, and two or three days of warm wind dries up our feed, and the milk yield is immediately adversely affected —although, the yield of butter-fat per cent, usually increases, especially in the high testing breeds—and| although on particularly heavy country the larger breeds of cows may excel in quantity, it is generally recognised that upon the same country the high testing breed will also attain to a much larger size and milking capacity, and with her superior butter-fat quality compare favourably on this ideal dairy country. The general trend of dairy endeavour has been in the direction of breeding into the Jersey, with the object of obtaining the higher maximum amount of milk with a high percentage of butterfat. In all endeavours to increase but-ter-fat content of milk it has been found that the greatest gain has been made with the Jersey breed. A few years ago a six per cent, test was considered wonderful, whilst now we have authentic eases of up to nine per cent,, to say nothing of whole herds doing over 5 per eent. The size and weight of a cow is a matter for consideration in an economic review of the value of any particular breed. The Holstein carries off most of the records for highest milk and butterfat production over all periods, and the two leading Holsteins in butter-fat and. quantity of milk for twelve months were respectively 1800 and 20001 b live weight;

Compare this with Holly Oak Annie, with a record of only 471 b less and a live weight of 7001 b. The dairyman who possesses a highproducing cow, no matter what her breed may be, has a' treasure which he ought to prize, but it is in the matter of breeding heifers for the upkeep of the herd that there should be no deviation from the hard and fast rule of selecting your breed and adhering to it. It is from her blood lines that a cow reproduces, and the purer the blood the more prepotent the animal is to beget in its offspring the best characteristics of its breed. Now, which is the most profitable breed for supplying milk for cheesemaking purposes’ According to all records, both practical and theoretical, the cow giving the good average quantity of milk with the high average butter-fat content, say 301 b of milk with a 4.5 to 5 per cent, test, is the most suitable. This is explained.in the table of butterfat and casein content of milk with its cheese yield per lb of butter-fat or lOJlb of milk. We find that the low-testing milk has on an average (relatively) low casein content, and the reverse is the ease with the high-testing milk, giving a much greater weight of fat and solids to the 1001 b of milk. In the early part of the season when the milk is at its lowest fat and solid content, the cheese from a vat of milk may be eight or nine, increasing to eleven or twelve as the season advances, the milk then showing higher percentages of fat and casein. If we take the pounds of cheese to the fat content per 1001 b of milk, we find a higher payout with the higher the test ; but when we analyse the matter we find that a given quantity of milk with a less fat content from the low-testing breeds gives as much cheese as a quantity of milk with much higher test with an equal butter-fat content. This amounts roughly to Id more cheese per lb butter-fat in the low-testing milk, varying according to yield and cheese prices. As milk is pooled at the factory it is paid for on its fat content and the low-testing supplier is losing one halfpenny per lb butter-fat. Does he gain any compensation in other ways? We have been repeatedly assured that the higher the fat content of cheese, the higher the market price. We are also assured by those in the trade that the grade being right, fat content receives the buyer’s greatest consideration. Thus it may prove that there is a compensation in quality values. It is well recognised by factory managers that the richer the‘milk the more difficult it is to incorporate the fat in the cheese, and the greater the danger of losing a higner per cent, of fat which will.have to be sold as whey butter. When milk has reached a 4.5 test the eheesemaker’s skill -is' taxed to the utmost, and it is then a question of cheese versus buttermaking to give the greater payout.