Hygiene in Hand-milking Sheds Supplying Factories

New Zealand Journal of Agriculture, Volume 81, Issue 5, 15 November 1950, Page 465

Hygiene in Hand-milking Sheds Supplying Factories

IN the many technical links in the process of butter and cheese manufacture hygiene in the milking —both personal arid mechanical—is highly important, and it is one factor in the initial stages of dairy-produce manufacture which is controlled solely by farmers. In this article

D. I. Bowman,

Farm Dairy In-

structor, Department of Agriculture, Waimate, discusses aspects of hygiene in sheds where cows are milked by hand for factory supply. THE hygiene of a milking shed A begins in the shed surroundings, so'the site must be one which will remain efficient and sanitary no matter what subsequent farm activity or building takes place. Requirements for a dairy site,' listed in their ■order of importance, are: — A situation at least 50yds. from piggeries, 30ft. from fowlhouses, and 2 chains from a public roadway. An open space free from dust, cesspools, manure heaps, and drainage from other farm buildings. A good fall for drainage. Clean atmosphere and enough sunlight to reduce to a minimum the growth of moulds and fungus. A good water supply and reasonable proximity to the electric-power supply. The farm plan should be studied to find a site fulfilling those conditions, and it is advisable to seek the aid of a Farm Dairy Instructor. On small farms a site which incorporates all the desirable factors without much waste of land may not be found easily, but efficient sanitation must be established and maintained throughout the life of the shed. Well-laid-out, sanitary dairy premises require the minimum of work to keep the shed and equipment in order during the milking season. Printed plans and advice are obtainable from Farm Dairy Instructors of the Department of Agriculture. Maintenance of Surroundings If a milking shed is built at least the minimum specified distances from piggeries and fowlhouses, the likelihood of contamination from these sources is reduced to a minimum provided ordinary care is taken. Dust, manure heaps, and cesspools will not exist while a shed is new and the surroundings are in good order, but neglect and indiscriminate wandering of stock about the premises will soon provide a source of contamination. Mud caused by animals being herded becomes in summer contaminating dust .which blows into the shed through its ventilation. This dust will contaminate the milk and strike one of the first blows at the quality of the produce. Access by stock to the cowshed should be controlled by fenced concrete races to and from the night and

day pastures, and this factor should be considered when the shed site is chosen. The perfect arrangement of stock direction provides a grassed surrounding at all times, obviating dust in summer and odorous cesspools in winter. The concrete races should be designed to suit the conditions on the farm.- They afford very efficient sanitary control, and to seek advice from the Dairy Division on this subject is well worth while. If a good, sound dairy shed has been built in the centre of much farmyard activity, and therefore is open to numerous sources of contamination, it may be possible to rectify the position by replanning some of the farmyard arrangements. Renovation and alteration often are not as expensive as they may have appeared. The first objective would be to establish as large a grass area as possible around the shed. Piggeries and fowlhouses which are too close must be shifted, all manure heaps and odorous objects removed, drainage reorganised if necessary, and provision made for control of access by stock.. Shed ventilation may need to be modernised, drainage examined, arid broken concrete refaced. Woodwork should be examined for evidence of borer, as borer dust may fall into the milk. The existing shed may be found ideal for another farm building the erection of which is contemplated, and in such circumstances selecting a new site for a new shed may be more economic. Air-borne infection of dairy produce on farms caused by unhygienic shed sites is a serious problem and one that farmers must be prepared to eliminate. Dangers of Dust A shed with dusty, interior and surroundings is not safe even on the

calmest of days. Some farmers say: “We milk here only on wet days and use the grass paddock during fineweather”. Wet days often are windy,, and the dust danger is always present.. Dust cannot be kept from settling in. the milk and open ■ buckets in such a. shed, and such conditions cause a vast, amount of irreparable damage to New' Zealand dairy produce. Warm milk, is an excellent medium for growing: bacteria, and germs from cowshed, dust are highly undesirable. A dusty shed cannot be kept clean. For example, between milkings all the dairy equipment will become coated, with fine dust deposited from the air,, so each successive milking deposits itsshare of contamination in the cream, can. Apart from that, where there is. dust there is odour, and grade quality is affected by absorption of foreign, odours. Preparation of Cows for Milking While the cow is roaming the paddocks between milkings much dust and. bacteria-laden material is deposited.. on its body, so the flanks and legs near the udder must be cleaned as much as possible. Some types of household scrubbing brush are excellent to clean, this area down, only moderate pressure being used on the udder. The udder should then be ; washed with clean, warm water and dried with a clean cloth. No open, milk buckets should be left in the vicinity during the brushing and washing treatment, as they are sure tocollect some of the dust and splashes. Apart from its virtue of cleanliness,, gentle brushing and warm-water washing of the udder aids the letting: down of milk. The tail of the cowshould be prevented from waving about , and, if necessary, the animal, comfortably leg-roped.

When a cow has been milked the milk should be removed immediately to the milk-house or dairy. If the bucket is put down while a cover is thrown on the animal, shed and body dust will be distributed, resulting in contamination of the milk. Cloths used for udder washing should be non-woolly, kept for the one purpose, and boiled for 15 minutes daily. A piece of an old coat or sack or some dirty old rag is most unsuitable for this operation. Use and Misuse of Teat Salves The dairyman with a herd of cows under his care will certainly find the use of teat salves necessary sometimes for the treatment of teat and udder complaints. Most medicated salves are highly odorous and therefore dangerous to milk quality, and their use is prohibited by the Dairy Produce Regulations. Cows under treatment should have their udders cleansed of all salve before being milked and be treated again before being turned out. Such cows are best milked last. Some milkers like to use a lubricant to facilitate hand milking. Odourless salves are manufactured for this purpose, but as little as possible should be used. Milk and cream absorb odours as blotting paper does ink, and serious taints can be given to dairy produce by the careless use of odorous salves. Milk should never be used as a milking lubricant. Cleaning Equipment The cream separator is a machine of many metal parts, some of which come into direct contact with the milk. It is very important that it be thoroughly cleaned twice daily. A separator must be taken apart to be cleaned; no amount of flushing can possibly clean it. The practice of running a kettle of boiling water through the machine after one milking and taking it apart after the next is hygienically wrong and worse than not touching it at all. In every separator a slime is deposited on the inside of the bowl cover by centrifugal force. Hot water bakes the solids from milk on to the tinware and, as high temperatures greatly facilitate bacterial growth, a first-class incubation device for growing all the unwanted bacteria is formed. ’ A separator bowl so treated will remain hot for hours, gaining every minute millions of contaminating germs to be washed into the cream can by the milk from the following milking. Dairy tinware should be cleaned not with cloths but with the correct brushes, which factories can supply. The correct procedure with all dairy tinware, including separator discs and bowl pieces, is first to scrub it with a brush in cold or lukewarm water, a process which cuts the milk from the tinned surface very efficiently; next, to scrub all parts with reasonably hot water containing washing soda; and, last, and most important, to immerse all the tinware in boiling water and lay it out on a convenient rack away from dust to dry by its own heat. Buckets, metal cream stirrers, creamcollecting receptacles, and cans should all be washed and scalded by the same method, and brushes should be washed and placed in the sun to harden.

A rule always to be observed, in cleaning tinware is to wash it with cold water before hot to minimise the baking of milk solids on to the tinware. The scalding water must be boiling or all tinware will be left with a fat deposit and a greasy feel; this grease film is laden with bacteria and fatty acids which contaminate milk. Dael/in nt Tmu/ara uesign o. iin ware The ideal dairy 'tinware would be glass-smooth, of simple construction, and as nearly cornerless as possible. Scratched, pitted, or rusted metal surfaces provide lodging places for bacteria and reduce the ease of cleaning. Such faults should be remedied by replacement or retinning as soon as they appear. Galvanised buckets and receptacles are totally unsuitable for dairy use because their surfaces are rough and subject to a chemical action between milk acids - and the galvanising. The basic metal of much dairy equipment is tinned copper or brass, The surfaces of these metals should be kept well tinned to protect them from the effect of milk acids. Tins in which household products have been canned , are quite unsuitable as receptacles for collecting cream. Their metal is of the wrong type and their seams cannot be cleaned. The ideal receptacles for cream collection are made of good glazed crockery, enamelware, stainless steel, or well-tinned and seamless metalware. Metal surfaces which are brass, copper, or rusty can affect dairy pro-

duce by the cumulative incorporation of very small portions of the metals in the cream supply. , Disposal of Skimmed Milk J „ ~ , • , x One of the most odorous and contaminating substances which may influence the hygiene of dairy premises fermented skimmed milk; therefore the disposal of skimmed milk directly from the separator and with the least possible time lag is most important. If a large quantity is involved, a pump and pipeline to the piggeries undoubtedly is the most. efficient arrangement. The fixtures to the pump to lead in the skimmed milk must be detachable for cleaning, and no gal-vanised-iron pipe must be used on the suction side of the pump. The pipeline of such apparatus requires similar hygienic attention to milkingmachine pipelines. Frequent washing with suitable detergent solutions is necessary, though care must be taken that the washing solution does not reach the pigs. A plug fitting the dairy end of the pipeline to close this opening between milkings prevents gases detrimental to cream from reaching the dairy. Gravitation methods are not satisfactory for the disposal of skimmed milk because the pipeline cannot be cleaned efficiently. A pump can be used to force cleaning solution through in large quantities, but the pipeline of a gravitation system would always be odorous. In a small shed clean cans removed after separation is finished provide a satisfactory method of disposing of

HYGIENE IN HAND-MILKING SHEDS . . .

skimmed milk, but such receptacles must receive the same hygienic cleaning as do dairy utensils and be kept odourless. A receptacle on wheels is also efficient. Whatever method of disposal is used, accumulation of skimmed milk from successive milkings is highly undesirable. Under such conditions skimmed milk sours and ferments quickly and will cause contamination by air-borne inducement of the bacteria of fermentation, as well as attracting house flies. Cooling of Cream The bacterial content of milk from a normal, healthy cow at the moment of milking is quite low, but after milking rapid germination of contaminating bacteria begins; hence the importance of each link in the chain of control the farmer exercises in the care of milk and cream on the farm. For control of germ growth all sources of contamination must be eliminated. If the shed is very dirty, a highly sanitary milk-house next door cannot be effective, for irreparable damage would be done to the cream in the shed portion of the premises. The object of keeping a dairy

scrupulously clean would be defeated by habitually neglecting to wash the separator twice daily. An odorous skimmed-milk bucket where all else was clean would neutralise much of the good work done in other directions. When the cans arrive from the factory they should be sterilised with boiling water and placed canted on a rack with their lids off to dry out by their own heat. The cream should be cooled from the separator by an efficient cooler fed by a cold water supply, artesian for preference. Luke-warm water from an overhead sun-heated tank is useless in a cream cooler. Reducing the temperature'of cream at the moment of separation effectively controls bacterial growth, and therefore some method of mechanical cooling is most desirable. The temperature of the cream or milk should be reduced to 65 degrees F., or lower if possible. Cream from a small dairy can be cooled by being stood in cold water, but the surrounding water must be cold and in ample quantity, and the cream must be stirred with a metal stirrer, until it is cool. A small quantity of cream can be cooled quickly and efficiently in this manner,

which is, certainly better than leaving it to be cooled by the air. However, leaving cream to stand in cold water without stirring it or paying attention to the water temperature is almost useless; the water near the cream receptacle rises in temperature and the cream cools slowly from the outside inward, leaving that in the centre still warm. • • • '

Cooling of cream or milk aerates the liquid and helps to liberate the volatile gases and animal odour sometimes present.

Collection of Cream

Though hot and cold cream should never be mixed, the contents should be stirred every time cream is added to the can, which should be covered with clean, loosely woven linen or gauze.

If the stirrer is left in the can, yellow scale is likely to form on the shaft and fall into the cream. A wooden stirrer should not be used, because butterfat completely permeates the wood and the stirrer then causes contamination by introducing the bacteria of rancidity and fermentation into the cream, with the same effect as adding yeast to dough in bread making.

The consistency of cream for delivery to the factory during hot weather should be about that of wellmixed paint and the cream should contain not more than 45 per cent, of fat, a safe range being 42 to 45 per cent. In a liquid of this viscosity agitation during transport is minimised and sampling at the factory is of maximum efficiency. A fat content of 38 to 42 per cent, is recommended during cold weather. . .

While cream is being held on the farm the can is best stood in cold water, running if possible. Hygiene is best served by keeping the temperature of cream low and storing it in the cleanest of atmospheric conditions.

Roadside Stands

Because of transport difficulties and the demands of farm duties cream from many. farms must wait at the roadside for some time. In scattered districts in which collection rounds are restricted the last hour spent by the cream at the gate in the heat of the sun frequently controls the farmer’s quality record. Efficient protection from the heat of the ■ sun should be provided to minimise this fault.

Cans delivered and left in the. sun for hours become highly unsanitary and should be scalded and placed to cool immediately they have been removed to the dairy.

The adopting of a tradesmanlike attitude to dairying on a farm is essential. Every farmer whose routine and technique are developed on a sound hygienic basis must save himself much money over the years and also contribute to economic stability in the industry.

HYGIENE IN HAND-MILKING SHEDS

I OCKING the two brake pedals of a tractor together is advisable when working on hills and essential when working on roads so that when the machine's speed is to be reduced pressure is exerted evenly on the brake drums. It may be argued that as . the two brake pedals are close together they may both be depressed by placing the foot down evenly across them. Though that is so if • a determined effort is made, in an emergency when the driver stamps on the brakes in a split second he cannot be sure of hitting both pedals evenly and in many cases hits .only one; if the tractor is travelling at.speed, it wifi swerve violently to one side, -to the danger of humans or animals in its path, or may even overturn. Realising this danger, manufacturers have provided a latch or a pin with which the. brake pedals ■ can be locked , together. However, even that does not ensure equal pressure on the brake drums, for the linkage mechanism between,the pedals and the brake bands may be out of adjustment. Therefore the brakes should be checked regularly to ensure that equal depression of the pedals 'results in equal pressure on the drums. . ’ When a tractor is used at a high speed the brake pedals should be locked together. The brakes should be checked regularly for wear and even pressure on the drums. . —C. J. CROSBIE, Farm Machinery Instructor, Department of Agriculture, Christchurch.