Supplements to a milk diet for dairy calves

The two factors probably responsible for the inability to raise calves on a ration of whole milk alone are the development of rickets and anemia. Tetanic convulsions in calves probably arise in association with rickets. None of the calves in the experiments reported in this bulletin developed tetany as they were protected against rickets by feeding cod-liver oil and bone meal. Blood pictures of the calves on a milk diet disclosed an anemic condition as measured by a reduced quantity of hemoglobin, a subnormal erythrocyte count and a lower specific gravity of the blood. The calves also became dyspneic, showed great weakness and lacked color around the tongue and muzzle. These conditions improved markedly upon feeding the roughages, alfalfa hay and straw. The blood also returned to normal. Feeding of alfalfa hay and grain for a period before feeding a diet of whole milk allowed storage of iron in sufficient quantities to prolong the time of apparent good health. Blood pictures at the end of the trial were subnormal even tho the animal appeared vigorous. When minimum amounts of milk were fed, supplemented with alfalfa flour, the calves retained the healthy appearance of hide and had no convulsions, which were displayed by calves in other experiments on a whole milk diet. The calves on the minimum milk-alfalfa flour diet were under-fed and many of them died of starvation. Calves on milk diets grew faster in skeletal development than normal and when allowed optional amounts of milk were above normal in weight. Calves are capable of consuming adequate quantities of liquid whole milk to maintain normal or better than normal growth curves

Length and floor construction of dairy stalls

One of the problems confronting the designer of a dairy barn is to determine the proper length of the stall platform. Cows vary considerably in length, and the stall length should vary to to meet the requirements of individual cows. Stalls that are too short make uncomfortable beds, force the cows to stand with one or both hind feet in the gutter and cause them, in reaching for hay in the manger, to carry manure to the stall floor. Long stalls are equally objectionable as the droppings fall on the platform rather than in the gutter. Adjustable stanchions are available but not in general use. Where installed, the tendency is to set adjustable stanchions at the time of installation and not change them as the occupants of the stall change. Even with adjustable stanchions it would seem desirable to make the stall length approximate the needs of the herd

Normal growth in dairy cattle

Male calves of all the breeds studied weighed more at birth than female calves. The birth weights of female calves were as follows: Holsteins, 89 pounds; Guernseys, 65 pounds; Ayrshires, 63 pounds; and Jerseys, 50 pounds. There was considerable variation among individuals in their live weights. Coefficients of variation ranged from above 15 percent in calves to less than 10 percent in 2-year old heifers. The data show that the time of first freshening marks the greatest change in the rate of growth in live weight. Very little difference can be observed in the relative rates at which animals of the different breeds approach mature size. Mature growth values are approached most rapidly in height at withers. This measurement is not even doubled from birth to maturity. Holsteins, Ayrshires and Jerseys are wider in relation to depth than Guernseys. The average weight for mature Holsteins in the Iowa Experiment Station herd may be considered as 1,405 pounds; Ayrshires, 1,111 pounds; Guernseys, 1,072 pounds; and Jerseys, 950 pounds. Gestation and lactation are shown to have considerable influence upon live weight. Late freshening heifers weigh more than heifers calving at the usual time but after freshening the weights of both groups are quite comparable

If Hay Mows Are Empty

Dairy cows fed plenty of silage, properly balanced with a grain mixture, will produce just as well and keep in as good condition as those fed both alfalfa hay and silage as roughage. In other words, apparently cows do not need a dry roughage along with silage

Efficiency of dairy rations containing various quantities of grain

The dairy cow is particularly well adapted for consuming and utilizing large quantities of roughages, though she responds well to grain feeding. The relative quantities of roughage and grain that should be fed are usually determined by the physiologic effects and economic efficiencies of such rations when fed to dairy cattle. One would hardly expect high.producing cows to maintain a high yield when consuming roughage alone, because such a ration is so bulky that it prevents the intake of sufficient nutrients for maximum production. And yet, very good results have been obtained in certain areas by such a system of feeding. Then, too, the nutrients of roughage crops are usually produced at considerably less cost than those of grain crops (17) (3). Furthermore, rough. ages are more plentiful on most farms than grain crops, especially in recent years when there has been a marked increase in the production of hay and pasture crops at some sacrifice of grain production. Under these conditions the advisability of supplementing roughage rations with grain becomes a question of interest to dairy farmers

Cows Are Good Bean Market

Dairy cows will produce more butterfat on a ration in which whole (cracked) soybeans provide the protein supplement than on an ordinary ration of mixed grains which uses such a protein supplement as soybean oilmeal

The use of water bowls in the dairy barn

1. Dairy cows, watered by means of water bowls, drank approximately 18 percent more water and yielded 3.5 percent more milk and 10.7 percent more butterfat than cows that were watered twice per day at an outside tank. 2. Cows watered with water bowls drank an average of about 10 times in each 24 hours. Approximately two-thirds of the water was consumed in the daytime, that is between 5 a. m. and 5 p. m., and the other one-third at night. 3. Cows watered at the outside tank frequently drank but once per day. This occurred about 30 percent of the times the cows were offered water. This refusal to drink more than once per day was distributed among all of the cows, although certain cows showed a greater disposition to drink but once per day than did others. The inclination to drink but once per day was not consistently correlated with the quantity of milk yielded. 4. One unusual observation was that when the cows were watered with water bowls, they usually yielded not only more milk but milk containing a higher percentage of butterfat. A mathematical treatment of the data shows that the probability is only about 4 in 100 that a result as large and consistent could have come by chance alone. 5. The temperature of the water apparently did not influence the water consumption as greatly as did atmospheric temperature. The relative consumption of water increased as temperature rose

New Use for a Corn By-product

Iowa farmers can expect satisfactory results when Iowa-produced hydrol is fed to dairy cows

Superlattice with hot electron injection: an approach to a Bloch oscillator

A semiconductor superlattice with hot electron injection into the miniband is considered. The injection changes the stationary distribution function and results in a qualitative change of the frequency behaviour of the differential conductivity. In the regime with Bloch oscillating electrons and injection into the upper part of the miniband the region of negative differential conductivity is shifted from low frequencies to higher frequencies. We find that the dc differential conductivity can be made positive and thus the domain instability can be suppressed. At the same time the high-frequency differential conductivity is negative above the Bloch frequency. This opens a new way to make a Bloch oscillator operating at THz frequencies.Comment: RevTeX, 8 pages, 2 figures, to be published in Phys. Rev. B, 15 Januar 200