CALIFORNIA AGRICULTURAL EXTENSION SERVICE CIRCULAR 33 October, 1929 REARING DAIRY HEIFERS FREE FROM TUBERCULOSIS AND ABORTION DISEASE C. M. HARING PUBLISHED BY THE COLLEGE OF AGRICULTURE UNIVERSITY OF CALIFORNIA Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, University of California, and United States Department of Agriculture cooperating. Dis- tributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, California Agricultural Extension Service. UNIVERSITY OF CALIFORNIA PRINTING OFFICE BERKELEY, CALIFORNIA 1929 Digitized by the Internet Archive in 2011 with funding from University of California, Davis Libraries http://www.archive.org/details/rearingdairyheif33hari REARING DAIRY HEIFERS FREE FROM TUBERCU- LOSIS AND ABORTION DISEASE ^ C. M. HAEING2 To reduce disease in California cattle, the first step necessary must be a general movement among dairymen to raise healthy heifer calves. If these calves are from high-producing cows, such a movement will result in a supply of young dairy animals which will meet all require- ments, including the tests for tuberculosis and abortion disease. The constantly increasing demand for healthy dairy animals insures a market at an attractive price for all such animals. The prevention of tuherculosis in the calves of tuherculous dams has been found possible by the removal of the calf soon after birth to a non-infected place. Calves are usually healthy when bom, even though the dam may be diseased, but they may become infected with tubercu- losis shortly afterwards. If the calf of a tuberculous cow is removed from its mother within forty-eight hours after birth and thereafter kept from contact either direct or indirect with tuberculous animals, it will usuall}^ grow to maturity without having become infected. The milk which it receives must be from non-tuberculous cows or else be heated sufficiently to kill the tubercle bacilli. SPECIAL FEEDS AND DRUGS ARE WITHOUT EFFECT ON TUBERCULOSIS AND ABORTION There is no evidence that tuberculosis or abortion in a herd can be reduced by special feeds or the use of mineral supplements or drugs. If the cattle are being correctly fed for satisfactory growth and pro- duction, there is only one way in which the materials fed may help to control the spread of these diseases. That is to use feeds free from the germs of these diseases. All feed must be free from the contam- inating discharges of diseased animals. Milk may be made safe by pasteurization. 1 This circular has been prepared with the assistance of several successful dairymen and certain members of the State Department of Agriculture, Sacra- mento, of the California Dairy Council, and of the Divisions of Agricultural Extension, Dairy Industry, Animal Husbandry, and Veterinary Science of the University of California. It does not include full directions for the feeding and care of calves. For such information, apply to a county farm advisor or write to the College of Agriculture, Berkeley, for other publications on calf feeding. 2 Professor of Veterinary Science and Veterinarian in the Experiment Station. 4 California Agricultural Extension Service [CtR- 33 Carefully balanced rations and mineral supplements have no effect in preventing" tuberculosis or Bang's abortion disease in cattle. The value of balanced rations as an aid to efficient milk production is well known and the use of steam bone meal may also benefit the general condition of cattle in certain sections where there is a deficiency of lime or phosphorus, but these cannot be substituted for the necessary sanitary precautions outlined in this circular to prevent abortion and tuberculosis. Owners are specifically advised against the use of so-called tonic drugs or feeds. Until recently it was supposed that cod liver oil might be of value under certain circumstances, but recent experiments at the University of Wisconsin prove that this material is not only valueless in preventing abortions, but is actually detrimental to the milk producing function. Success in maintaining a herd free from tuberculosis or in rearing healthy calves from tuberculous dams requires constant attention to the necessary details by a capable and responsible jierson. Scrupulous attention to details is necessary reg^ardless of whether the calves are reared in small or in large numbers. The following directions if observed carefully may help dairymen to rear healthy calves and reduce disease in California dairy cattle. WHAT TO DO ON FARMS FREE FROM TUBERCULOSIS When all of the cattle on a farm are free from reactors to the test for tuberculosis, the rearing of disease-free heifers is a relatively simple problem. Care must be taken to see that they do not come in contact with outside animals or have access to food or water that has been contaminated with discharges from diseased cattle or swine. Until recent years, one of the common ways in which tuberculosis was spread from farm to farm was from the feeding of unpasteurized skim- milk from creameries. In California a law now requires that all skim milk from creameries returned to farms must first be pasteurized. Nevertheless, if a herd is free from tuberculosis it will be safer not to bring in any skim milk from a creamery or another dairy. If an outside supply is necessary and there is any possibility that it may contain live tubercle bacilli it should always be boiled or pasteurized ; and in addition the calves should be tuberculin tested every six months as a means of removing any that may have become infected through inefficient heating of the milk or the utensils in which it has been transported. Every reactor calf should be immediately sepa- rated from the others and slaughtered. 1929] Dairy Heifers Tuberculosis and Abortion Free WHAT TO DO IN SMALL TUBERCULOUS HERDS If the herd is not severely infected, that is, if not more than one iji ten animals reacts to the test for tuberculosis, it is often practicable to dispose of the reacting cattle. In small tuberculous herds, facilities are usually inadequate for keeping the calves and young healthy heifers entirely separated from the infected herd. Under such condi- tions the following procedure is advised. 1. Dispose of all reactors, including any which have given doubtful or questionable reactions, as well as any non-reactors which, on physi- cal examination show symptoms of tuberculosis. A cow can be so far gone wdth the disease that she will not react to the test. F\g. 1. — ("all l";inu. J)ui iii<^r II'LM-U*i'D npproxiiiuitcly two thousand hoaltliy heifers were reared in this plant. 2. Clean and disinfect the premises thoroughly, and do not depend entirely on chemical disinfectants. Greater dependence should be placed on thorough cleaning. Remove promptly all damp manure, for the smallest particle may harbor many tuberculosis germs. The tubercle bacillus dies in a few weeks in dry manure or soil, but under moist conditions has been known to live for more than a year. 3. Have a veterinarian re-test the herd with tuberculin in 60 to 90 days. Immediately remove all reactors and again clean and dis- infect. So long as reactors are found, have a test made every six months. Even when the herd is believed to be free from reactors, an annual test is recommended. 4. Boil or heat to at least -^° F for 20 minutes all milk fed to calves and observe all other recommendations in this circular for their protection. Even though the reacting adult cattle have been 6 California Agricultural Extension Service [CiK. 8?. removed, there is a possibility that a ''spreader" or two were left that did not react to the test. If a small herd is hadly infected, that is, if more than three animals in ten react to the test for tuberculosis, the best solution would b^e for the owner to arrange to cooperate with other farmers or groups of farmers. It may be practicable for one group to undertake to milk out the reacting aged cows while another group builds up young herds of healthy heifers. In view of the threatened shortage of healthy cows in this state, every dairyman should either arrange to rear his Fig. 2. — Interior of calf barn sli iiKiiMuuai pons with ni()val)le partitions. heifers himself free from disease or employ someone to rear them for him, or sell them to someone Avho will follow the accepted procedure. In certain communities the county farm bureaus might well plan for the establishment of calf farms where an attempt could be made to raise calves free from disease at reasonable rates. When the owner of a tuberculous dairy herd undertakes to rear healthy heifers only a short distance from the diseased animals, a successful outcome is quite uncertain. However, when no other way is open the attempt should be made. When an animal first becomes infected, there is usually no danger to other animals, even though it reacts to the tuberculin test. But 1929] Dairy Heifers Tuberculosis and Abortion Free sooner or later, tuberculous cattle may begin to have infectious dis- charges. The g-erms escape through the mouth and nose, the bowels, the milk, and discharges from the genital organs and open lesions in any part of the body. When the disease is located in the lungs and discharges into the air tubes, pieces of diseased tissue and millions of germs are liberated and coughed up. Most of these are swallowed and passed out in the manure. This is the chief way in which the tubercle bacilli are discharged from diseased cattle. When the germs are being given off in. any of these ways, the disease is known as open Fig. 3. — When calves cannot be kept in separate pens six or eight may be kept in one pen, provided they are kept stanchioned for half an hour after feeding and are fed a small amount of grain. tuberculosis. Cattle in advanced stages of the disease usually have open tuberculosis. The high percentage of tuberculous cattle and hogs on certain ranches has been found to be due to the failure of the owners to remove promptly animals that develop visible indications of the disease. Bearing Healthy Heifers. — The method followed in undertaking to rear healthy heifers will vary according to the conditions prevailing on each farm, but the following procedure is suggested as a general guide for owners of small herds. 1. Have all the animals in the herd carefully examined twice a year by a veterinarian for physical signs of tuberculosis. Dispose of 8 California Agricultural Extension Service [Cir- 33 any which he considers suspicious. The special object of these pre- cautions is to reduce as far as possible the number of cattle that are spreaders of the disease. Cows that have developed hard lumps in the udder or are seen to be giving abnormal milk should be isolated Fig. -i. — VViien small numbers of calves are reared elaborate equipment is unnecessfiry. Fig. 5. — To prevent bad habits, keep young calves apart. and the milk discarded until recovery. If tuberculosis is the cause of the udder trouble, recovery will not occur, and therefore in herds where a program for raising healthy heifers is in progress all animals showing chronic mastitis should be disposed of for beef under official 1929] Daiky Heifers Tuberculosis and Abortion Free inspection. Special care should also be taken to remove cows showing symptoms of lung- tuberculosis and any which have discharging abcesses. 2. Kemove the calves from their dams within 48 hours after birth and feed them on boiled milk that has been heated to at least 160° F for 20 minutes. Whenever practicable, the milk selected for calf feeding should be from those cows in the herd which have passed the tuberculin test. The facilities on small farms for heating milk are usually inadequate and the use of the milk from the non-reacting Fig. 6. — High-producing- healthy heifers reared according to plans outlined in this circular. cows is a desirable precaution. However, in such cases the milk should also be heated as carefully as the facilities permit, for there are some- times cows in badly infected herds that are discharging tubercle bacilli and such cows in rare instances may not react to the tuberculin test. 3. The care and feeding of the calves and the sterilization of the feeding buckets and other utensils must be done by a capable person who has a working knowledge of the principles of hygiene and sani- tation. In tuberculous herds the care of the calves must never be left to children. The caretaker must fully realize that any utensil which has been in contact with milk or other discharges of an animal 10 California Agricultural Extension Spjrvice [Cir. 33 in the tuberculous herd is unsafe for use with the calves until it has been sterilized by dry heat or with live steam or boiling water. Chlo- rine disinfectants as a substitute for heat while helpful for some purposes on a dairy, are valueless^ against tuberculosis germs. There are a multitude of other facts necessary for the person to know who is responsible for the care of the calves. Most of them will be evident to an adult person of ''good common sense" who is experienced in dairying. 4. A veterinarian should be employed to tuberculin-test the calves as a check on the methods being used to protect them from tubercu- losis. In small dairies it will usually be preferable to have this done shortly after the calves have been weaned from liquid milk. It is desirable to wean the calves at as early an age as possible, because they are in the greatest danger while receiving milk from infected cows, even though it is supposed that the milk has been sufficiently heated. On page 16 of this circular the use of dry skim milk is described as a means of removing this danger. The heating of the milk is the most iynportant part of the procedure in rearing healthy calves on the milk of tiiherculous coivs. Boiling will kill tubercle bacilli instantly, but if a lower temperature is used, a proportionately longer time is required ; for example, it requires between 15 and 30 minutes to kill tubercle bacilli in milk at a tempera- ture of 140° F. At temperatures lower than that they are not killed even by prolonged exposure. Under average working conditions, either in a creamery or on a farm, a margin of safety is necessary. It is therefore recommended that the milk for calf feeding either be brought to the boiling point or heated to a temperature of not less than 160° F for 20 minutes. Experience has shown that when a margin of safety of less than 20° is used, the dangers are greatly increased from inaccuracies in the recording thermometer or carelessness of the employees in charge. Dependence should not be placed on a record- ing thermometer alone. The attendant should also use a reliable hand thermometer. Equipment for heating milk for calf feeding will vary according to the amount of milk to be heated and the local conditions under which the equipment must be operated. When only a small amount of milk is needed (less than ten gallons), it may be heated in a double container over a direct flame. In every case a thermometer should be used to make sure that the milk remains hot for a sufficient time to kill tubercle bacilli. The feeding value of milk for calves is not injured hy heating to a temperaturf of between 160° to 170° F for 20 to 30 minutes. The I92i>] Dairy Heifers Tuberculosis and Abortion Free 11 writer has personally supervised at the Agricultural Experiment Sta- tion, Berkeley, the rearing of 80 calves fed exclusively on milk heated for this time and at this temperature. The heating was undertaken to prevent losses from scours and septicaemia which had occurred in calves earlier in the year. The losses stopped as soon as the practice of heating the milk started. It has been reported that in England rickets has occurred in calves as a result of the prolonged feeding of heated milk but that this condition was prevented by the feeding of cod liver oil cake. It is possible that the temperatures used were much higher than those customarily used in California. In any case, it has been possible in this state to rear thousands of calves on milk heated be- tween 160° and 170° F for 20 to 30 minutes without the use of cod liver oil or other antirachitic food. It is difficult to give specific directions for the rearing of disease- free young stock on small farms where the older cattle are affected with tuberculosis or ahortion disease. It is recommended that owners of small herds read over the following recommendations for large herds and adopt such procedures as they may consider practicable. In some small herds the chances of success under conditions of incomplete segregation and occasional imperfect pasteurization are better than in large herds, because in small herds there is less chance of the existence of bad "oi)en cases" and the close attention that it is possible to give each cow may result in the early detection of '^spreaders." In large tuberculous herds, ''spreaders" are nearly always present and the mixed milk constantly contains virulent tubercle bacilli. On the other hand, on large farms facilities for complete isolation of the calves and young stock and adequate pasteurization of the milk are usually better than in small dairies. WHAT TO DO IN LARGE TUBERCULOUS HERDS Success in rearing calves in large dairies depends largely on the installation of adequate facilities, adequate organization, and last but not least, dependable employees. The management of calves during the early weeks of their lives is a matter requiring patience and scrupulous attention to details, in addition to experience. Frequently serious losses among healthy calves or great reduction in the occur- rence of disease have been observed to follow a change in calf attend- ant, while the most frequent failures to carry on successfully the proved methods of rearing healthy calves from tuberculous cows have resulted from the careless work of unreliable employees in charge of milk pasteurization. Owners will reduce losses from disease when they 12 California Agricultural Extension Service [C'ir- 33 realize more fully that the position of calf attendant is one of the more important on the dairy. They should give their personal atten- tion to the selection of such an employee. When oalves are reared in large numbers, all of the milk fed re- gardless of its source should he h oiled or pasteurized. If the source is a large non-reacting herd, there is even more danger that one or more of the animals may be tuberculous but have failed to react to the tuberculin test. If the milk fed is mixed from a large number of cows, it should be boiled or pasteurized, because the danger is multi- plied by the number of cows contributing. Milk from a cow that has an inflamed udder or has aborted or has retained afterbirth is apt to be badly contaminated with infectious discharges. It is safe when boiled or pasteurized, but not otherwise. Retained afterbirth, mastitis, cowpox, and other conditions may occur in any dairy and render the milk of certain cows unfit for human consumption. There can be little objection to feeding it to calves, provided it is first boiled or pasteurized. Boiling or pasteurizing of milk is an excellent precaution in pre- venting scours, pneumonia, septicaemia, and other infectious diseases of calves. These diseases are usually of little consequence to owners having small groups of cattle. Such men may remain in the business for years and never experience difficulty in raising calves. Neverthe- less, the danger of disease making its appearance increases in propor- tion to the size of the herd, and no owner of dairy herds numbering hundreds of breeding animals may hope to escape unless special pre- cautions are taken. One of the best precautions is the boiling or pasteurizing of all milk fed the calves regardless of its source. Where to Keep the Calves. — Complete isolation from infected cattle is the most essential requirement in locating the quarters where the calves are to be reared. One of the most common ways in which tuberculosis germs may be carried to the calves is through the use of unsterilized feeding pails and other utensils which have been in con- tact with unheated milk from diseased cows. Therefore, the utmost care must be used, first, that all feeding pails and other utensils are thoroughly sterilized, and second, that these pieces of equipment shall not be exposed to contamination after sterilization. They should never be tal^en into the milk house, cow barns, corrals or other places where they would be exposed to contact with untested or re- acting animals or the milk or other discharges from them. Water contaminated with the manure or other discharges of tuber- culous cattle is one of the chief sources of bovine tuberculosis in Cali- fornia. Hence, the water supply for the calves should be made safe 1929] Dairy Heifers Tuberculosis and Abortion Free 13 and the calf pens so located that there is no drainag-e to them from areas occupied by the other cattle. It is desirable, also, to locate the pens so that no dust from the cow corrals can blow into them. Construction and Care of the Calf Barn and Peyis. — The type Of construction most suitable will vary greatly with the number of calves to be reared, the local climatic conditions, and the physical situation on each individual farm. Requirements in the northwestern part of the state are entirely different from those in the southeastern, but certain general principles remain unchanged regardless of local con- ditions. Some of these may be carried out as follows : 1. Provide facilities if possible for keeping each calf separate as shown in figure 2 until it has reached the age of at least three weeks. If two or more young calves are kept in the same pen, they may become badly soiled with fecal discharges and often develop injurious habits as shown in figure 5. At six to twenty weeks of age the calves may run together in grouj^s not to exceed eight in a pen, or may be kept in larger groups in fields. 2. Provide duplicate sets or sufficient numbers of separate pens, sheds, and runs so that it will not be necessary to keep all of them constantly occupied by calves (see figure 1). At intervals of not more than two weeks, each and every pen, stall, and run should be thoroughly cleaned, disinfected^ and left vacant and exposed so far as possible to the direct rays of the sun for two or three days. 3. Take every advantage of the disinfecting and other beneficial effects of the direct rays of the sun when constructing buildings and pens. In some sections of the state it may be necessary to provide plenty of shade during the hot days, but such shade should be portable so that it may be removed at the intervals when the pens and runs are vacant as recommended in the preceding paragraph. 4. After the drying and sunning exposure, a liberal application of lime wash or whitewash is recommended. A whitewash spray pump and spray materials should be kept as a part of the calf barn 3 Disinfection requires more than simply spraying some disinfectant over all surfaces. Most of the work necessary to eliminate the germs of calf scours and other trouble making microorganisms will consist in removing all litter, manure and contaminated surface soil. The liberal use of scalding hot solution of lye will not only aid in the cleaning process but also have some disinfecting effect. After the cleaning process is completed, a disinfecting solution should be sprayed into all cracks and over all surfaces. For this purpose a saponified cresol solution which will readily mix with water is recommended. This is sold under various trade names. The concentrated solution usually contains fifty per cent cresol in which case it should be used in the proportion of at least one part to thirty parts of water. When the label indicates that less than 50 per cent pure cresol is present, proportionately more disinfectant should be added to the water mixture. 14 California Agricultural Extension Service [Cir. 33 equipment, not to be taken over to the infected bai'ns or corrals where the older cattle are kept. Fio^ure 3 shows the interior of a calf barn which has received frequent applications of whitewash. 5. Facilities must be provided for sterilizing- all receptacles and utensils which come in contact with the milk fed the calves. When only a few calves are reared, boiling water may suffice, but in a plant handling large numbers of calves there is no substitute for live steam. 6. If a large number of calves are to be reared, permanent buildings having concrete floors with adjacent and well drained out- door pens are essential (see figures 2 and 3). When only a few are reared, elaborate equipment is not necessary (see figure 4), but facili- ties should exist for carrying out the above mentioned principles of individual isolation of young calves, sterilization of utensils, and cleaning, disinfecting, drying, and sunning of buildings, pens, and ground surfaces, Miinagenient of Tuberculous Cows about to Calve. — The practice most approved by specialists in animal husbandry provides sanitary box stalls for calving. However, under average California conditions for purposes of disease control; it is sometimes better to permit the cows to calve at pasture. Calving at pasture is especially desirable if the available stalls and corrals are not relatively free from manure and dust. The calf is less liable to contract tuberculosis, scours, pneumonia, or septicaemia if born in the comparative cleanliness of a large field than in the usual type of corral or stall. When possible a sei)arate '' maternity pasture" for cows about to calve should be provided. If the practice is followed of having cows calve in stalls, the stalls must be very thoroughly cleaned and disinfected after each occupa- tion and a liberal supply of clean straw or other bedding provided. Using the same barn for sheltering cows about to calve and also for cows affected with retained placenta, metritis or mastitis, is highly objectionable. If no other shelter is available for the sick cattle, it is better to have the healthy pregnant cows remain out in a field separate from other cattle or in a clean isolated corral than to bring them near diseased animals at a time when both the dam and her offspring are in a very susceptible condition. The dam is especially likely to con- tract some form of genital disease or mastitis and the calf to die of scours, pneumonia or other form of stable infection. If it escapes these, there is still the chance of its contracting tuberculosis, a risk which is much greater than if born in the open fields. On some dairy farms it has been found practicable to construct a maternity hospital consisting of one to several box stalls. The build- ing should be so constructed that each stall Oi)ens only to the OTitside. 11>L>!>| DaIKV IIeIFEHS Tirp.EKClTLOSIS AND AbOKTION FhEE IT) The intei^ior should l)e finished with concrete floor and smooth tongue and trroove, or cement walls so that it may be disinfected easily follow- ing each maternity case that is placed in it. This is not a laborious practice to carry out when the building is properly constructed, and it prevents the newborn calf from coming at once into infected sur- roundings, as would generally be the case if born in a corral. Harmful results from the excessive medical treatment of cow and calf in maternity stalls have recently been reported from several large dairies in California. If no losses are occurring in cows from retained afterbirth, metritis, or mastitis, and disease is not common in the calves, it is better for the cow and calf to be left without medical treatment. If abortion disease is prevalent in the herd, a blood test of the cows for this disease and the disposal or separation of the reactors may i)revent much loss at calving time, both in cows and calves. When to Separate the Cow and Calf. — Many dairymen prefer to remove the calf from its dam before it has nursed in order to hasten the procedure of teaching the calf to drink. From the standpoint of protecting the calf from tuberculosis, this is also desirable. However, under average conditions it is often impossible to have an attendant present at the birth of every calf ; furthermore, when calves are born at pasture, a day or two may elapse before the fact is discovered. While there is some danger that during this period the calf will con- tract tuberculosis, snch cases are rare and can be detected by the use of the tubercnlin test before the disease develops to a stage that is transmissible to other calves. When the calf is removed immediately, it is nsnally better to permit it to go unfed for at least eight hours after which it is given about a pint of warm raw colostrum. The feeding of pasteurized milk is repeated twice or thrice daily and the amount gradually increased until on the fifth day it receives three to five per cent of its weight at a feeding, depending upon the vigor of the calf. Care should be taken not to overfeed. On some dairies more calves have been lost from over-feeding than from any other cause. The feeding of Colostrum. — A difference of opinion exists among veterinarians regarding the necessity of allowing the newborn calf to receive colostrum. There is positive evidence that this thick yellow secretion given off by the udder just after calving contributes sub- stances lacking in ordinary milk which are beneficial to the calf. On the other hand, it has been possible on certain California dairies to rear calves successfully without the use of colostrum. On these dairies the practice of heating all milk fed to the calves has been 16 California Agricultural Extension Service [Cm. 33 followed. The heating of the milk doubtless greatly reduced the num- ber of harmful bacilli received by the calves. Under average California conditions the pasteurization of colo- strum is impracticable and the writer recommends either omitting the colostrum, or preferably feeding it unheated, and depending upon two tuberculin tests administered between the ages of two and six months, to detect any calves that may have become infected with the unpasteurized colostrum. These, if any, can then be removed before the disease has usually spread to any of the associated calves. Dry skim milk is a good substitute for pasteurized skim milk for feeding calves. Any tubercle bacilli and other harmful bacteria in the original milk are killed by the standard process of manufacturing skim-milk powder. In some of the best conducted dairies, the calves are fed on pasteurized whole milk until five or six wrecks of age, after which they are gradually taken off the whole milk and given instead a reconstituted skim milk. This is made by adding one part of skim- milk powder to nine parts of water. The solution of the powder can best be accomplished by adding it slowly to warm water with constant stirring. Wean the calves from liquid pasteurized milk as early as possible, when the original source of the milk is a tuberculous herd. As long as living tubercle bacilli are in the original raw milk, there is always the chance that some careless employee w^ill fail to bring the milk up to the proper pasteurization temperature. At a large dairy, cooperat- ing witli the Division of Veterinary Science, over 2,000 disease-free heifers have been reared between 1921 and 1929. The original herd consisted of about 700 cattle, nearly all of which were infected with tuberculosis. The only unsatisfactory result at this dairy in the raising of healthy calves with pasteurized milk occurred in 1927, when about ten per cent of the young calves reared in the spring, reacted to the tuberculin test. This was traced directly to the carelessness of an unreliable employee in charge of pasteurization. It is always advisable, therefore, that weaning from pasteurized milk be arranged at as early a date as possible. The time of weaning will vary widely in individual calves. At the University Experimental Dairy in Berkeley it has been possible to put calves on a reconstituted skim milk diet at three to five weeks of age, depending upon the vigor of the calf, and at eight to ten weeks to wean them to alfalfa hay and a calf meal consisting of ground barley 4 parts, wheat bran 3 parts, dry skim milk 3 parts, and salt 1 per cent. The proportion of dry skim milk was gradually reduced in the grain mixture as the calves aged. An immediately adjacent supply 1929] Dairy Heifers Tuberculosis and Abortion Free 17 of water was found necessary to assist the calves in masticating the dry milk grain mixture. A number of calves so fed have grown into large productive dairy cows and there is no evidence that the early weaning stunted or injured them in any way. Equal success in the early weaning of calves has been attained in several other dairies in this state where a mixture of dry skim milk and grains in various proportions has been used. Pasteurization at not less than 160° F for 20 minutes of milk to be fed to calves is desirable, even when the heating is done with modern equipment in a well managed creamery. The only apparent damage from heating at this temperature is the effect on the cream line as seen through a glas>s bottle. For that reason market milk is usually pas- teurized at 140° to 145° F for 30 minutes, but it is just as easy and much safer to pasteurize the calf milk at a higher temperature. When antiquated pasteurizing tanks without flush valves are used, a tem- perature of 170° F or above is essential and the precaution should be taken to draw off any cold milk standing in the outlet pipe after the milk in the tank has reached the pasteurizing temperature."* The tuberculin test should be used as a means of detecting ineffi- cient pasteurization for weeding out any calves which may have become infected before removal from the dam or later. The ideal time for the first test is when the calves reach the age of two months. They should again be tested shortly after weaning. In order to avoid the expense, however, of too frequent visits of the veterinarian, the tests may be made at any time before the sixth month of age. An interval of at least sixty days should elapse between the two tests. When no reactors are found, further retests may be made annually. The tuberculin test is an especially reliable and satisfactory method of diagnosing tuberculosis in calves and young heifers. When the calves are iveaned, the problem of protecting them from infection simply consists in their complete isolation from tuberculous cattle and from feed or water contaminated with the excretions of such cattle. If it is necessary to keep them in fields adjacent to diseased cattle, they should be protected by double fences having aii interval of at least eight feet. When the heifers reach breeding age, care should be used to select disease-free bulls. Use only bulls from herds known to be free from tuberculosis. Preferably, they should be animals that have been reared with the same precautions as the young disease-free heifers 4 Another publication is in preparation on methods of pasteurizing milk for calf feeding. 18 California Agricttltural Extension Service i^^^- -^^ that they are to serve. Each bull should have passed the tests for both tuberculosis and abortion disease. Unless healthy young cattle ore kept in disease-free herds, the care used in reaHng them will have heen wasted. Owners who may be con- sidering measures to rear heifers free from tuberculosis and abortion disease should plan some way to continue to carry out isolation and preventive measures after the animals become milk producers. In large herds this problem has been solved by the arrangement of sepa- rate bams and pastures for the young heifers. Suitable temporary milking sheds can be built at a low cost. As the aged cows in diseased herds reach the end of their periods of profitable production, they should not be replaced with young animals. Gradually the old diseased herd is eliminated and eventually only herds of healthy cattle remain on the place (see figure 6). The present relatively high })rice of dairy cows when sold for beef makes this an opportune time to disi)ose of cattle from diseased herds. The existing systems of federal, state and municipal meat inspection fur- nish an adequate protection to the public and there is no reason to object to the slaughter for beef under official inspection of tuberculous or abortion-infected cattle. BANG'S ABORTION DISEASE The prevention of Bang's abortion disease in heifers is not difficult, even when the older cows are aifected. Calves are not susceptible to abortion disease until they reach breeding age and may be fed on the raw milk of abortion-infected cows without predisposing them to infection after maturity. The abortion bacilli which they may swallow with the milk eventually die or are eliminated in the excretions, so that soon after weaning, heifers are usually free from abortion infec- tion. As they approach maturity, they become increasingly suscepti- ble and are likely to become infected and abort during their first pregnancy if they come in close contact with infected cows. However, the detection of infected cows by blood test is now easy and practicable under average dairy conditions. The methods used to build up a young herd free from tuberculosis will also usually result in eradicat- ing abortion disease. A California dairy herd consisting of approx- imately eight hundred purebred and high-grade cows which had been operated for many years under the handicap of extensive tubercu- losis and abortion disease was freed from tuberculosis in five years by the isolation of the calves from the diseased dams. At the end of the period, the heifers were found to be also free from abortion disease. 1929 Dairy Heifers Tuberculosis and Abortion Free 19 Under the average conditions of dairying in California, Bang's abortion disease is easier to control than tnbercnlosis. Control con- sists in isolating those cattle which have been shown by blood tests to be infected with the disease. It is desirable to have blood tests for Bang's abortion disease made on all dairy animals of breeding age at least once a year. The blood test for abortion disease may be ar- ranged with any veterinarian. He simply draws a small amonnt of blood from the jugular vein or from the ear and applies the test at his hospital or ships the sample to a laboratory. Blood tests for abortion disease are at present made free at the Veterinary Science Labora- tories of the Division of Veterinary Science at Berkeley and at Davis. Information concerning this test and other means of controlling in- fectious abortion may be obtained by writing to the Division of Veterinary Science at Berkeley or at Davis. An Extension Veterinarian has been employed by the University to help reduce losses from abortion and sterility by cooperation with veterinary ])ractitioners in establishing demonstration herds in various dairy centers. agricultural extension service circulars No. 1. Series on Califorina Crops and Prices: Peaches. 2. Home Preparation of Jelly and Marma- lade. 3. Feeding Beef Cattle in California. 4. Irrigation by Overhead Sprinkling. 5. Series on California Crops and Prices: Lettuce. 6. Care and Management of the Milk Goat. 7. Suggestions on Grapefruit Culture in Imperial Valley. 8. Diseases and Parasites of Poultry in California. 9. Rabbit Raising. 10. The Home Preparation of Fruit Candy. 11. Cauliflower Production. 13. The Manufacture of Monterey Cheese. 14. Selection and Care of Electrical Equip- ment Used in Dairy Manufacturing. 15. Pork Production in California. 16. Irrigation of Orchards bv Contour Fur- rows. No. 17. 19. 20. 21. '^2 23". 24. 26. 29. 30. 32. 33. 34. 35. Liver Fluke and Stomach Worm of Sheep. Artificial Incubation of Eggs. Pear Blight Control in California. Bovine Tuberculosis. Thinning Sugar Beets. Strawberry Culture in California. Enterprise Efficiency Studies on Cali- fornia Farms. Bush Fruit Culture in California. The Home Vegetable Garden. Control of Pocket Gophers and Moles in California. Elements of Grape Growing in Cali- fornia. Powdery Mildew of the Grape and Its Control in California. What to Do About Bovine Tuberculosis. Rearing Dairy Heifers free from Tuber- culosis and Abortion Disease. Plum Growing in California. Alfalfa Production.