7/ La. MILK AND CREAM CONTESTS ERNEST KELLY In Charge of Market Milk Investigations, and GEORGE B. TAYLOR Market Milk Specialist, Dairy Division UNITED STATES DEPARTMENT OF AGRICULTURE DEPARTMENT CIRCULAR 53 Contribution from the Bureau of Animal Industry JOHN R. MOHLER, Chief Washington, D. C. August, 1919 WASHINGTON : GOVERNMENT PRINTINQ OFFICE : 1919 ^- MILK AND CREAM CONTESTS/ CONTENTS. Page. Contests promote better milk supplies 3 Two kinds of contests 3 Methods of scoring milk and cream 4 Score card for milk 4 Score card for cream 6 Contests in which samples are prepared by contestants 8 Preparation of samples 10 Shipping the samples 10 Handling samples at destination 10 Page. Contests in which samples are taken ou the street 11 Collecting the samples 12 File card for recording milk scores 12 Laboratory equipment for conducting con- tests 12 Methods of analyzing and testing 14 Publicity 25 CONTESTS PROMOTE BETTER MILK SUPPLIES. FRIENDLY RIVALRY among milk producers and dealers is an important feature in the improvement of the milk supplies of cities. Any factor which encourages this rivalry must be given careful consideration by sanitarians and all milk authorities. Since the inauguration of milk and cream contests, in 1906, this method of promoting friendly rivalry has been recognized. At this time, be- sides State and National contests, a number of cities use such means for gradin.g milk supplies. Milk and cream contests promote competition among the dairy- men, lead to the gradmg of milk supplies, and through pubhcity encourage the efforts of producers as well as educate the consumers regarding the value of good milk and where the best can be obtained. TWO KINDS OF CONTESTS. Milk and cream contests are of two kinds — one in which the dairy- men prepare their own samples of milk or cream especially for the contest, the date of which is known; the other in which samples are collected on the street without the knowledge of the producers. The first method may or may not indicate the dairymen who gen- erally produce the higher grades of milk. It represents only care m the preparation of samples for definitely known contests. As an educational factor, however, it is very valuable, as it teaches pro- ducers care and cleanliness in the production and handling of milk. Of course, in such contests the dairymen take extraordinary care in the production and preparation of the samples, but there is neverthe- less an educational value, as shown by the fact that dairymen con- testing during several consecutive years usually receive higher scores each succeeding contest. In National and State contests all samples 1 This circular is a revision of Department Bulletin 356. It is of interest to officials and sanitarians concerned in the control of milk supplies of cities and in a general way to producers of market milk. 2 r ^-. X -^ IX Milk and Cream Contests. a are, of necessity, prepared samples. The advertising value of a high score is so great that much interest is always aroused. On the other hand the surprise contest, especially when it repre- sents samples of milk or cream covering a definite period of time, gives a mathematical rating to each producer based on his everyday product, thereby laymg the foundation for grading a city's milk sup- ply. Such contests are valuable in bettering the local milk supply and should be instituted especially in the smaller cities when labora- tory facilities are available. There are three classes of entries in milk and cream contests — cer- tified, raw market, and pasteurized. In grading, these classes must be regarded as entirely distinct, and in the report of results each class must be given separately. METHOD OF SCORING MILK AND CREAM. The samples are scored for bacteria, flavor and odor, sediment, fat, solids not fat (m case of milk), temperature or acidity (depending on the kind of contest), and the appearance of the bottle and cap. A perfect score is 100, divided as shown in the score cards following: [Front.] united states department of agriculture, Bureau of Animal Industry. dairy division. SCORE CARD FOR MILK. Place Class . Exhibit No. Exhibitor Address . . (Signed) Item. Perfect score. Score allowed. Remarks. Bacteria 35 15 10 15 15 1 ^ 5 Bacteria found per cubic centimeter Sediment Fat TeiBperalure (street samples) [Degrees, . i or or \oi(lit\* ^■nrpnflrecl samr>los^ Bottle and cap /Bottle, . \Cap, . Total 100 Date Judges. [OVEE}. 4 Department Circular 53, U. S. Dept. of Agriculture. [Back.] DIRECTIONS FOR SCORING. Bacteria per Cubic Centimeter — Perfect Score, 35. Points. 500 and under 35 501-1,000 34. 9 1,001-1,500 34. 8 1,501-2,000 34. 7 2,001-2,-500 34. 6 2,501-3,000 34. 5 3,001-3,-500 34. 4 3,501-4,000 34. 3 4,001-4,500 34. 2 4,501-5,000 34. 5,001-6,000 33. 8 6,001-7,000 33. 6 7,001-8,000 33. 4 8,001-9,000 33. 2 9,001-10,000 33. 10,001-11,000 32. 8 11,001-12,000 32. 6 12,001-1.3,000 32. 4 13,001-14,000 32. 2 14,001-1.5,000 32. 15,001-20,000 31 Points. 20,001-25,000 30 25,001-30,000 29 30,001-3.5,000 28 35,001-40,000 27 40,001-4.5,000 26 4.5,001-50,000 25 50,001-.5.5,000 24 55,001-60,000 23 60,001-65,000 22 65,001-70,000 21 70,001-75,000 20 75,001-80,000 19 80,001-8.5,000 IS 85,001-90,000 17 90,001-95,000 16 95,001-100,000 15 100,001-120,000 12. 5 120,001-140,000 10. 140,001-160,000 7. 5 160,001-180,000 5. 180,001-200,000 2. 5 Above 200,000 Note. — When the number of bacteria per cubic centimeter exceeds the local legal limit the score shall beO. Plavor .\nd Odor — Perfect Score, 15. Deductions for disagreeable or foreign odor or flavor should be made according to conditions foimd. When possible to recognize the cause, it should be described under " Remarks." Sediment — Perfect Score, 10. Examination for sedunent may be made by means of a sediment tester and the resulting cotton disks compared with standards; or the sediment may be determined by examination of the bottom of the milk in the bottle. In the latter case the milk should stand undisturbed for at least an hour before tlie exami- nation. Raise the bottle carefully in its natural upright position until higher than the head. Tip slightly and observe the bottom of the milk with the naked eye or by the aid of a reading glass. The presence of the slightest movable speck makes a perfect score impossible. Further deductions should be made ac- cording to the amoimt of dirt found. AVhen possible, the nature of the dirt should be described under "Remarks." Fat in Milk— Perfect Score, 15. Points. 4.0 per cent and over 15 3.9 per cent 14 3.8 per cent 13 3.7 per cent 12 3.6 percent 11 3.5 percent 10 3.4 per cent 9 i Note. — When the per cent of fat is less tlian the local legal limit the score shall be 0. Solids Not Fat— Perfect Score, 15. Points. 8.7 per cent and over 15 8.6 per cent 13 8.5 per cent 11 8.4 per cent 9 8.3 per cent 7 Note. — When the per cent of solids not fat is less than the local legal limit the score shall be Temperature (Street Samples)— Perfect Score, 5. Points. 50° F. or below 5 5110 53° 4 54 to 56° 3 I'oiiils. 3.3 per cent 8 3.2 per cent 7 3.1 per conl 5 3.0 per cent 3 2.9 per cent 1 Less than 2.9 per cent Points. 8.2 per cent 5 8.1 percent 3 8 per cent 1 Less than 8 per cent 57 to 60°.. Above 60° Points. .... 1 .... Milk and Cream Contests. iVi [ISark— ('(intinueil.] AciDiT-^- (Pkkpakei) Samples)— Perfect Scoke, 5 I'oinis 0.2 per cent or less .'> 0.21 per cent 4 0.22 per cent .3 Point."!. 0.23 per cent 2 0.24 per cent 1 More than 0.24 per cent Hottle A.vn Cap— Perfect Score, 5. Peductions in .score .sluniltl he made for dirty or chipped bottles or for cap.s which do not cover the lips of tlie bottles or do not fit i)roperly in the cap seats. I Front.) UNITED STATES DEPARTMENT OF AGRICULTURE, Bureau of Animal Industry, haiky Dn^isioN. SCORE CARD FOR CREAM. Place Class Exhibit No. Item. Bacteria. Flavor and odor . Sediment Fat Temperature (street .samples). or Acidit y ( prejiared .samples). . . BotI le and cap Total. Perfect score. 3.5 2.") II) 20 J 00 Score, allowed. Remarks. Bacteria found \)ot culiic centime- ter Cowy, l)itter, feed, flat, strong Per cent. Degrees. . or Per cent . Cap Bottle... Exhil)itor Address.. (Signed). Date. Judges. tovEi:. 6 Department Circular 53, U. S. Dept. of Agriculture. [Back.] directions for scoring. Bacteria pee Cubic Centimeter— Perfect Score, 35, Points. Under 500 35 501-1 ,000 34. 9 1 ,001-1 ,500 34. 8 1 ,501-2,000 34. 7 2,001-2,500 34. 6 2,501-3,000 34. 5 3,001-3 ,500 34. 4 3 ,501-4 ,000 34. 3 4,001-4,500 34. 2 4,501-5,000 34 5,001-6,000 33. 8 6,001-7,000 33. 6 7,001-8,000 33. 4 8,001-9,000 33. 2 9,001-10,000 33 10,001-11 ,000 32. 8 11,001-12,000 32. 6 12,001-13,000 32.4 13,001-14,000 32. 2 14,001-15,000 32 15,001-20,000 31 Points. 25,001-30,000 29 30,001-35,000 2S 35,001-40,000 27 40,001-45,000 26 45,001-50,000 25 50,001-55,000 24 55,001-60,000 23 60,001-65,000 22 65,001-70,000 21 70,001-75,000 20 75,001-80,000 19 80,001-85,000. 18 85,001-90,000 17 90,001-95,000 16 95,001-100,000 15 100,001-120,000 12. 5 120,001-140,000 10 140,001-160,000 7.5 160,001-180,000 5 180,001-200,000 2. 5 Above 200,000 20,001-25,000 30 Note.— When the number of bacteria per cubic centimeter exceeds the local legal limit, the score shall be 0. „ . Fl.\.vor and Odor— Perfect Score, 2a. Deductions for disagreeable or foreign odor or flavor should be made according to conditions found. When possible to recognize the cause, it should be described under "RemarliS." Sediment— Perfect Score, 10. E-xamination for sediment should be made only after the cream has stood for at least an hour undisturbed in any way. Raise the bottle carefully in its natural upright position, until higher than the head. Tip slightly and observe the bottom of the cream with the naked eye or by the aid of a reading glass. The presence of the slightest movable speck makes a perfect score impossible. Further deductions should be made according to the amount of dirt found. When possible the nature of the dirt should be described tmder " Remarks." Fat in Cream— Perfect Score, 20. Points. 25 per cent or above 20 24 per cent 19. 5 23 per cent 19 22 per cent 18. 5 21 per cent 18 Points. 19 percent 17 18 percent , 16 17 percent 12 16 percent 8 15 per cent 4 Less than 15 per cent 20 per cent 17.5 Note.— When the per cent of fat is less than the local legal limit the score shall l>e Temperature (Street Samples)— Perfect Score, 5. Points. 50 degrees F. or below 5 51 to 53 4 54 to 56 3 Points. 57 to 60 1 Above 60 Acidity (Prep.4.red Samples) — Perfect Score, 5. Points. 0.23 per cent 2 0.24 per cent 1 More than 0.24 per cent Points. 0.2 per cent and less 5 0.21 per cent 4 0.22 per cent 3 Bottle and Cap — Perfect Score, 5. Deductions in score should be made for dirty, chipped bottles; for caps which do not cover the lips of the bottles or do not fit properly in the cap seats. Milk and Cream Contests. 7 CONTESTS IN WHICH SAMPLES ARE PREPARED BY CONTESTANTS. Before definitely announcing tlie time and details for holding milk and cream contests, the persons in charge should arrange to obtain prizes for the contestants. This is important, since there should be an additional incentive for the producers besides the desire of winning the contests. In local contests such city organiza- tions as the Chaml)er of Commerce, the Rotary Club, civic leagues, or women's clubs might be interested in furnisliing prizes, such as money, cups, or even dairy equipment. Interested commercial fimis may easily be persuaded to give prizes. After details of the contest are arranged, general publicity can be given tlu'ough local newspapers. It is best, however, not to depend too much upon this kind of publicity but to send preliminary notices to the dairymen themselves, as a great deal of individual effort usually is needed in interesting the producers. Each pro- spective contestant should receive an entry blank, the filling out and sending in of which must be made prerequisite to the entering of samples of milk or cream in the contest. SAMPLE ENTRY BLAXK. depaktmext of health. City of official entry blank. MILK AND (REAM CONTEST. Held at from to (Place.) Under the direction of The following classes are provided: Class I. Raw market milk. Class II. Certified milk. Class III. Pasteurized market milk. Class IV. Raw market cream. Class V. Pasteurized market cream. RULES. 1. Competition is open to all milk and cream producers and distributors supply- ing milk and cream to 2. Only one entry may be made in any one class. 3. Producers of certified milk are barred from competition in any other class. 4. All samples of certified milk must be accompanied with a certificate issued by the medical milk commission under whose super^•ision the milk is produced. 5. Entries in milk classes consist of 4 pints of milk in pint bottles. 6. Entries in cream classes consist of 4 one-half pints of cream in half-pint bottles. 7. All entries of milk and cream after scoring become the property of the depart- ment of health of 8. No contestant will be entitled to placing who does not make answer to each question herein given, sign declaration and forward this official entry blank to , (Name.) (Address.) 8 Department Circular 53, U. S. Dept. of Agriculture. HOW TO COMPETK. Milk or cream to compete in this contest must be delivered or shipped, prepaid, to In" order that all milk and cream entered by contestants may be of the same age when scored, all samples must be produced or prepared on (Date.) and shipped immediately. Bottles should be carefully packed in ice in a proper shipping box, and this box marked plainly on the inside cover as well as on the out- side with the owner's name and address. An official representative of the judges will receive all samples and place them at once in cold storage. APPLICATION AND QUESTIONS TO BE ANSWERED. Please enter for me four (pint) bottles of to com- (§ pint) pete in class in accordance with conditions herein prescribed. FOR CLASSES I, II, AND IV. 1. On what day and hour was the sample entered in this contest drawn? 2. How many cows contributed to the sample of milk entered? 3. What kind and quality of feed was given cows daily during the week preceding the production of the sample? 4. How were cows cleaned previous to milking? 5. AVhat kind of pail was used, small-top or open? 6. How were the utensils sterilized? 7. What method of straining was used? 8. How was the milk cooled? How long after milking? To what temperature? 9. Have you previously exhibited milk or cream at any local. State, or National show 10. (Additional for cream). How was the sample separated? How was the separator cleaned? 11. (Additional for certified.) Give name and address of medical milk commission certifying to your product FOR CLASSES HI AND V. 12. When was the sample pasteurized? 13. What was the average age of the product at the time of pasteurization?. 14. Did you use a clarifier? 15. To what temperature was the product heated? 16. How long was it held at that temperature? 17. Do you use automatic temperature control and recording thermometers? 18. To what temperature was the product cooled? 19. How was the pasteurizing apparatus cleaned? I, , do hereby declare each and every statement in answer to the foregoing questions to be true. I do furthermore declare that the product submitted by me is the pure natural product, free from preservatives, and (for Classes I, II, and IV) that it has not been heated or changed in any way. Date (Name) (Address) Do you wish shipping box returned at your expense? Milk and Cream Contests. 9 PREPARATION OF SAMPLES. The person in charge of the contest should issue detailed instruc- tions regarding packing and delivery. Express charges should be paid by consignor. Contests with prepared samples would be fairer and results more valuable if the sample represented the milk of the entire herd. In some contests this is required. Generally, however, entries representmg the product of one or more cows may be furnished. Usually great care is taken to obtain the sample under as near sterile conditions as possible. Thorough washing of the udder and the hands of the milker is necessary, and a properly sterilized, small-top pail should be used. Sterile absorbent cotton or filter cloth is the best material to use for straining milk. It is not advisable to pour the milk, while still warm, mto the final container, as the shrinkage when cold leaves some space between the milk and the cap. This may detract from the appearance of the bottle, and churning may result. It is suggested that the milk be stramed mto a sterile contamer and cooled, special care being taken to avoid contamination. The milk, after mixing, may then be poured into sterile phit bottles and the caps put on. Caps may be sterilized by dipphig into melted paraffin, but care should be taken not to heat the paraffin too much, as it gives off odors at high temperatures. Wlien the cap is placed firmly into the cap seat of the bottle, some melted paraffin may be poured on. The top of the bottle should be protected by means of a cap cover. When filled and capped the bottles must be packed immediately m ice and kept cold but not frozen, until ready for examination. An ice-and-salt mixture for cooling should nev(n* be used, as it may freeze the samples. SHIPPING THE SAMPLES. If the samples are to be shipped, special care must be taken in labeling and packing. In local contests the contestants usually bring in their own samples, properly iced, but when shipping is neces- sary great care should be taken to pack the samples so that they will remain cold and there will be no breakage. One method is to place the samples m a small, close-fitting contamer, which, in turn, is securel}' fastened in an insulated box containmg cracked ice. The outer box may be insulated with cork or sawdust. The owner's name and address should be plainly written on the inside of the cover of the outer box. The package must be plainly addressed on the outside to the consignee and bear the sender's name and address. HANDLING SAMPLES AT DESTINATION. As soon as received at the place where the contest is to be held the sample should be put into cold storage at a temperature between 35° and 40° F. until ready for exammation. When the shipping 122545°— 19 2 10 Department Circular 53, U. S. Dept. of Agriculture. boxes are opened the name and address of the consignee (producer) are taken and each of the bottles tagged with its class and number. The name of the contestant, the class of the product, and the number given are placed m an envelope and the envelope sealed. On the outside of this sealed envelope the number of the sample and the class are placed. The person in charge of the contest should keep the records, and it is desirable for the judges to know the samples only by numbers. As there are four bottles in each entry one may be used for chem- ical analysis; one for bacteriological examination and sediment; one for judging flavor, odor, and appearance; and one held ui reserve to be placed on exhibition. This method may be varied to meet special conditions. Tlie best sample in each class must be declared the winner of that class, provided, of course, that all conditions have been complied with. In case of ties in the total score, the entry having the lowest bacteria count should outrank the others. Samples of high merit that have not won a prize may be awarded a diploma or cerfificate bearing the seal of the health department. The following form may be used: DIPLOMA OF MERIT. The Health Department of the City of Awards a Diploma of Merit to For a sample of scoring , exhibit a% the held at Judges: (Signed) [seal.] Superintendent of Contest. Tlie persons in charge of the contest should furnish contestants with detailed copies of their scores, and be ready to answer questions regarding them. As the prmcipal reason for holding the contests is to improve the milk supply, authorities should take advantage of the data furnished by dairymen to point out faults in the production and handling of the milk or cream and advise ways to improve the quality. CONTESTS IN WfflCH SAMPLES ARE TAKEN ON THE STREET. Tliis method of conducting milk contests, if properly carried out, furnishes a basis for grading the milk supply of cities. As in the contests with prepared samples, the three classes — pasteurized and raw market milk and cream and certified milk — must be kept separate. Milk and Cream Contests. 11 COLLECTING THE SAMPLES. At least once a month, and oftener if possible, the health depart- ment should collect 2 pint bottles of milk and 2 half-pint bottles of cream from each person delivering milk or cream in the city. At the time of coUectiou one of the samples should be well mixed, the bottle opened, and the temperature of the milk or cream taken. This sample should be properly marked so as not to be used for bacterio- logical examination, but used later for chemical determinations. Both samples should be placed immediately in ice until ready for analysis. The following detenninations are made: Bacteria, sedi- ment, specific gravity, fat, solids not fat, flavor and odor, and con- dition of bottle and cap. Careful records of the determinations as well as the temperature of the milk or cream at time of collection should be made and prop- erly filed. FILE CARD FOR RECORDING MILK SCORES. Name of dairy Claaa Name of owner Place P. O. address Date sample taken. Bacte- ria per cubic centi- meter. Flavor and odor score and remarks. Sedi- ment score. Specific gravity at 00° F. Fat. Solids not fat. Tem- pera- ture on street. De- grees F. Bottle and cap score. Remarks. Per cent. Per cent. 1 '""/.'.'.\'.'.'.'..'... i After a definite period of time — for example, 3, 6, or 12 months — the determinations made on the samples of each dairyman are aver- aged; these averages constitute a new record which is transferred to the milk or cream card and scored. The scores allowed each point are added together to make the total score. At the end of the period the names of the dairymen are pubhshed m the order of their scores, the highest in each class commg first. For the purpose of grading, the dairymen of each class scoring above 90 may be put in the same grade; those scoring between 80 and 90 in another grade; and those scoring below 80 in another, thus making thi-ee grades in each class. LABORATORY EQUIPMENT FOR CONDUCTING CONTESTS. It is evident that the health department of a city must have proper laboratory equipment in order to conduct milk and cream contests. The following is a guide for the equipment of an average laboratory for doing such work. Quantities of the supplies may be varied according to the amount of work to be done. 12 Department Circular 53, 11. S. Dept. of Agriculture. CHEMICAL EQUIPMENT, Babcock milk tester, 8 to 24 bottles, for fat determinations. Westphal Ijalance or accurate lactometer with cylinder for specific gravity deter- mination. Milk-test bottles, 8 per cent, for fat in milk. Cream-test Iwttles, 9 grams, 50 per cent, for fat in cream. Cream-test scales for weighing cream. Pair dividers. Pipettes, 17. G culnc centimeters, for measuring milk or acid. Combined acid ]>ottle and pipette. Burette, 50 cul>ic centimeters, glass stopcock, graduated in tenths, for acidity deter- mination. Glass stirring rods for acidity determination. Burette holder. Beakers, 100 cul)ic centimeters, for flavor and odor and acidity. Sediment tester for dirt in milk. Cotton disks f(»r sediment. Fahrenheit dairy thermometers for temperature of samples on collection. Bunsen burners, gas, with rubber tubing. Commercial sulphuric acid for fat determination. Sodium hydroxid, tenth-normal solution, for acidity. Phenolphthalein indicator for acidity determination. BACTERIOLOGICAL EQUIPMENT. Autoclav, medium size, for steam sterilization. Sterilizing oven for dry-air sterilization. Incubator, for growing Ijacteria. Water bath for melting agar tubes. For preparation of media: Balance, with weights to 5 kilos. Double boiler, one-half gallon. Funnel glass, 6 inches in diameter. Burette, 50 cubic centimeters, glass stopcock, graduated in tenths. Gas stove, single burner. 1-cubic centimeter pipettes to deliver between 2 marks, graduated in tenths with extra tenth above mark, for measuring dilutions. Test tubes, lipless, for holding 10 cubic centimeters media. Test-tube baskets. For measuring liquids : 5 cubic centimeter pipette. 10 cubic centimeter pipette. 25 cubic centimeter pipette . 50 cubic centimeter pipette. 100 cubic centimeter cylinder, graduated. 500 cubic centimeter cylinder, graduated. 1,000 culjic centimeter cylinder, graduated. Petri dishes for plating samples. Glass bottles, 8-ounce, for sterile dilution water. Thermometer ( — 10° to -f 110° C.) for temperatures in laboratory operations. Thermometer (-10° to -|-200° C.) for dry-air ovens. Pipette boxes, copper orgalvanized iron, for holding 1-cubic centimeter pipettes. Milk and Cream Contests. 13 For counting bacteria: Reading glass, 4-inch, 21- magnifications. Counting plate. Tally machine. Wax pencil. Al)sorbent cotton for filtering media. Nonabsorbent cotton for plugging test tubes. Canton flannel for filtering media. For making media: Peptone; beef extract; agar, shredded. For adjusting media: Sodium hydroxid, normal. Sodium hydroxid, tenth normal. Hydrochloric acid, tenth normal. Phenolphthalein indicator. METHODS OF' ANALYZING AND TESTING. It is of special importance in all analytical work that the standard methods prescribed be followed. No attempt is made here to give details of milk analysis, as every laboratory equipped to do this kind Fig. 1.— VVestplial balance and lactometer far determining specific gravity of milk. of work must certainly contain the proper reference books. Besides the usual books found in all health or food laboratories the analyst should have the following pamphlets: Chemical Testing of Milk and Cream, Bureau of Animal Industry, liCaflet A 12, U. S. Department of Agricidture, Washington, D. C. Official and Pro-sasional ^Methods of Analysis, Association of Official Agricultural Chemists, Bvueau of Chemistry Bulletin 107, Revised. JJ. S. Department of Agricul- tme, Washington, D. C. Testing IMilk and Cream for Butterfat, Circular 78, Purdue University Agricidtural Experiment Station, l.a l*'ayette, Ind. 14 Department Circular 53, U. S. Dept. of Agriculture. Standard Methods of Bacteriological Analysis of ]\Iilk, Pro\'isional Report of the Laboratory Section of the American Public Health Association, 126 Massachusetts Avenue, Boston, Mass. SPECIFIC GRAVITY. The determination of specific gravity should be made either by a Westphal balance or by an accurately graduated lactometer. (Fig. 1 .) Tlie importance of accuracy in taking the specific gravity is better un- derstood when it is realized that from the specific gravity and the fat found, the total solids or solids not fat are calculated. As most of the lactometers are standardized to 60° F. (15° C), it is important that the temperature of the milk to be tested should closely approxi- mate this temperature. If it is necessary to take the readings at some other temperature, the following table of correction, by Dr. Paul Vieth, should be used. Table for correcting the specified gravity of milk according to temperature. Degrees of lac- Degrees of thermometer (Fahrenheit). tometer. 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 20 19.0 19.9 20.9 21.9 22.9 23.8 24.8 25.8 26.7 27.7 28.6 29.5 30.4 31.3 32.2 33.0 19.0 20.0 21.0 22.0 22.9 23.9 24.9 25.9 26.8 27.8 28.7 29.6 30.5 31.4 32.3 33.1 19.1 20.0 21.0 22.0 23.0 24.0 24.9 25.9 26.8 27.8 28.7 29.6 30.5 31.4 32.3 33.2 19.1 20.1 21.1 22.1 23.1 24.0 25.0 26.0 26.9 27.9 28.8 29.7 30.6 31.5 32.4 33.4 19.2 20.2 21.2 22.2 23.2 24.1 25.1 26.1 27.0 28.0 28.9 29.8 30.7 31.6 32.5 33.5 19.2 20.3 21.2 22.2 23.2 24.1 25.1 26.1 27.0 28.0 29.0 29.9 30.9 31.8 32.7 33.6 19.3 20.3 21.3 22.3 23.3 24.2 25.2 26.2 27.1 28.1 29.1 30.0 31.0 31.9 32.9 33.8 19.4 20.3 21.3 22.3 23.3 24.3 25.2 26.2 27.2 28.2 29.1 30.1 31.1 32.0 33.0 33.9 19.4 20.4 21.4 22.4 23.4 24.4 25.3 26.3 27.3 28.3 29.2 30.2 31.2 32.1 33.1 34.0 19.5 20.5 21.5 22.5 23.5 24.5 25.4 26.4 27.4 28.4 29.3 30.3 31.3 32.3 33.2 34.2 19.6 20.6 21.6 22.6 23.6 24.6 25.5 26.5 27.5 28.5 29.4 30.4 31.4 32.4 33.3 34.3 19.7 20.7 21.7 22.7 23.6 24.6 25.6 26.6 27.6 28.6 29.6 30.5 31.5 32.5 33.5 34.5 19.8 20.8 21.8 22.8 23.7 24.7 25.7 26.7 27.7 28.7 29.7 30.6 31.6 32.6 33.6 34.6 19.9 20.9 21.9 22.8 23.8 24.8 25.8 26.8 27.8 28.8 29.8 30.8 31.7 32.7 33.7 34.7 19.9 20.9 21.9 22.9 23.9 24.9 25.9 26.9 27.9 28.9 29.9 30.9 31.9 32.9 33.9 34.9 21 22 23 24 25 26 27 28 29 . 30 31 32 33 34 35 Degrees of lactometer. 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 Degrees of thermometer. 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 20.1 21.1 22.1 23.1 24.1 25.1 26.1 27.1 28.1 29.1 30.1 31.2 32.2 .33.2 34.2 35.2 20.2 21.2 22.2 23.2 24.2 25.2 26.2 27.3 28.3 29.3 30.3 31.3 32.3 33.3 34.3 35.3 20.2 21.3 22.3 23.3 24.3 25.3 26.3 27.4 28.4 29.4 30.4 31.4 32.5 33.5 34.5 35.5 20.3 21.4 22.4 23.4 24.4 25.4 26.5 27.5 28.5 29.5 30.5 31.5 32.6 33.6 34.6 35.6 20.4 21.5 22.5 23.5 24.5 25.5 26.6 27.6 28.6 29.6 30.7 31.7 32.7 33.8 34.8 35.8 20.5 21.6 22.6 23.6 24.6 25.6 26.7 27.7 28.7 29.8 30.8 31.7 32.9 33.9 34.9 35.9 20.6 21.7 22.7 23.7 24.7 25.7 26.8 27.8 28.8 29.9 30.9 31.8 33.0 34.0 35.0 36.1 20.7 21.8 22.8 23.8 24.9 25.9 27.0 28.0 29.0 30.1 31.1 32.0 33.2 34.2 35.2 36.2 20.9 22.0 23.0 24.0 25.0 26.0 27.1 28.1 29.1 30.2 31.2 32.2 33.3 34.3 35.3 36.4 21.0 22.1 23.1 24.1 25.1 26.1 27.2 2S.2 29.2 30.3 31.3 32.4 33.4 34.5 35.5 36.5 21.1 22.2 23.2 24.2 25.2 26.2 27.3 28.3 29.4 30.4 31.5 32.5 33.6 34.6 35.6 36.7 21.2 22.3 23.3 24.3 25.3 26.4 27.4 2S.4 29.5 30.5 31.6 32.6 33.7 34.7 35.8 36.8 21.3 22.4 23.4 24.4 25.5 26.5 27.5 28.6 29.7 30.7 31.8 32.8 33.9 34.9 36.0 37.0 21.5 22.5 23.5 24.6 25.6 26.6 27.7 28.7 29.8 30.9 31.9 33.0 34.0 35.1 36.1 37.2 21.6 22.6 23.7 24.7 25.7 26.8 27.8 28.9 29.9 31.0 32.1 33.1 34.2 35.2 36.3 37.3 The milk to be tested for specific gravity should be well mixed either by gently inverting the bottle several times or by pouring back and forth from the bottle to a beaker. In mixing the milk, as Milk and Cream Contests. 15 well as in pouring into a cylinder for the determination of the specific gravity, care should be taken to avoid the formation of air bubbles. In using the lactometer a meniscus is formed at the point where the stem comes in contact with the milk. The point to be read is at the actual surface of the liquid and not at the top of the meniscus. MILKFAT (BUTTERFAT). In order to distribute the fat evenly the bottle of milk or cream must be well mixed, preferably by pouring back and forth from the bottle to a beaker. This should be done just before the product for analysis is measured out. The charge of milk consists of 17.6 cubic centimeters and is measured; the cream charge consists of 9 or 18 grams and is always weighed. /-I ' ~-r A. ^^—e c- E— 5 =— ^^^^ ^^^ ^^ loooo * 111- the latter case, however, the analyst will know from his own experience just what dilutions to make. A blank contaming media and dilution water should be run side by side with the regular samples. Plates must not be poured until the temperature of the melted media averages between 106° and 113° F. (41° and 45° C). The plates must be left in the incubator for 48 hours, and the temperature of the incubator should be kept at about 100° F. (37.5° C). For counting colonies, a counting plate and a reading glass magnifymg 2^ diameters should be used, and in report- ing the counts the standard methods should be strictly followed. In cities where the continuous contest is in operation, and where the results are averaged every 3, 6, or 12 months, there will be from 4 to 24 bacterial counts to average. It is generally conceded that the arithmetical average may give results which are too high, especially Milk and Cream Contests. 23 when one of the counts is much higher than the others. On that ac- count the followmg table of per cent ratings has been prepared, the use of which, it is thought, will give a fair average of bacteria in counts of 4 or more. Briefly, the method consists in arranging the ratings and not the bacterial counts, and is more fully explained by an example following the table: Per cent ratings for various bacterial counts. Bacteria per Bacteria per Bacteria per Bacteria per cubic Rating. cubic Rating. cubic Ratuig. cubic Rating. centimeter. centimeter. centimeter. centimeter. Per cent. Percent. Per cent. Per cent. 100.0 28,000 76.3 66.000 63.4 140,000 47.0 500 99.0 29,000 75.9 67,000 63.1 150,000 45.1 1,000 97.2 30,000 75.5 68,000 62.9 160,000 43.3 1,500 96.0 31,000 75.1 69,000 62.6 170,000 41.5 2,000 94.6 32,000 74.6 70,000 62.4 180,000 39.8 2,500 93.8 .33,000 74.2 71,000 62.1 190,000 38.2 3,000 93.0 3 J, 000 73.9 72,000 61.9 200, 000 36.6 3,500 92.2 35,000 73.5 73,000 61.6 210,000 35. 1 4,000 91.2 .36,000 73.1 74,000 61,4 220,000 33.6 4,500 90.8 37,000 72.8 75,000 61.1 230,000 32.1 5,000 90.2 38,000 72.4 76,000 60.8 240,000 30.6 5,500 89.6 39,000 72.0 77,000 60.6 250,000 29.2 6,000 89.0 40,000 71.6 78,000 60.3 2{i0,000 27.8 6,500 88.6 41,000 71.3 79,000 60.0 270,000 26.5 7,000 88.2 42,000 70.9 80,000 59.8 280,000 25.2 7,500 87.6 43,000 70.6 81,000 59.6 290,000 23.8 8,000 87.2 44,000 70.2 82,000 59.3 300,000 22.4 8,500 86.8 45,000 69.9 83,000 59.1 310,000 21.2 9,000 86.4 46,000 69.6 84,000 58.8 320,000 20.0 9,500 86.0 47,000 69.2 85,000 58.6 330,000 18.8 10,000 85.6 18,000 68.9 86,000 58.3 340,000 17.4 11,000 85.0 49,000 68.6 87,000 58.1 350,000 16.2 12,000 84.4 50,000 68.3 88,000 57.8 360,000 15.0 13,000 83.8 51,000 68.0 89,000 57.6 370,000 13.8 14,000 83.2 52,000 67.6 90,000 57.4 380,000 12.6 15,000 82.6 53,000 67.3 91,000 57.2 390,000 11.5 16,000 82.0 54,000 67.0 92,000 56.9 400,000 10.4 17,000 81.4 55,000 66.7 93,000 56.7 410,000 9.4 18,000 81.0 56,000 66.3 94,000 56.4 420.000 8.2 19,000 80.4 57,000 66.0 95,000 56.2 430,000 7.2 20,000 80.0 5'<,000 65.7 96,000 56.0 440,000 6.2 21,000 79.4 59,000 65. J 97,000 55.8 450,000 5.2 22,000 79.0 60,000 65.2 98,000 55.6 460,000 4.0 23,000 78.6 61,000 64.9 99,000 55. 4 470,000 3.0 24,000 78.2 62,000 64.6 100,000 5.5.1 480,000 2.0 25,000 77.6 (>3,0CH) 64.3 110,000 53.0 490,000 1.0 26,000 77.2 64,000 64.0 120.000 50.8 5(X).000 0.0 27.000 76. S 65.000 63.7 130. onn 48.8 The bacterial average is determined thus: Suppose the following bacterial counts are the result of five counts from samples taken from dairyman "A": 11,000, 65,000, 80,000, 18,000, 450,000. Tliese are arranged in order with their corresponding per cent ratings taken from the table. The ratings are then added and divided by the number of samples. Bacteria counts. 11,000 65,000 80,000 18,000 450,000 Per cent ratings. 85. 63.7 .59.8 81.0 5.2 5 )294.7 .58.9 24 Department Circular 53, 11. S. Dept. of Agriculture. The average per cent rating is 58.9. By consulting the table it is found that the rating closest to 58.9 is 58.8; therefore the average bacteria count for samples from A's dairy is 84,000. By contrast it may be noted that the arithmetical average of the bacterial counts would be 125,000. PUBLICITY. Proper publicity has a valuable place in promoting milk and cream contests. It is not only necessary to give newspaper publicity to prepared contests, but the results of all contests should be an- nounced in a popular, readable way. In prepared contests the names of the winners of each class, with their scores and the prizes won, should always be given. In the continuous contest, when the results are announced at definite periods of time, the winners of prizes with their scores may be given. It is thought advisable, however, in con- tinuous contests to group the dairymen in classes, as A, B, and C, and publish these groupings. For instance, all the dahymen scoring between 90 and 100 could be placed in Class A, those scoring between 80 and 90 in Class B, etc. In connection with the announcement of winners in contests where the samples are taken on the street, it is advisable to arrange a meet- ing of producers to discuss in a practical way methods for producing better milk. Consumers may also be interested, not only in pub- hcity but by meetings at which milk questions of interest to them are discussed. LIBRARY OF CONGRESS III I iiili iiil iSi'll iii'il fill! I!l!' ! 'I <■■>■ iiiJi ■iiHiii 000 895 572 4 % m: omaer Gaylord Bros. Inc. Makers Syracuse, N. Y. PAT. JAN 21, I30B