MILK PRODUCTION.

Stratford Evening Post, Volume XXXV, Issue 79, 10 April 1913, Page 7

MILK PRODUCTION.

QUANTITY AND QUALITY

PHYSIOLOGICAL LAWS

A great deal lias been heard of late of various phases of the question of the milk standard and the basic caus-

es of the variations in the quality of milk. A very exhaustive contribution

to this subject is contained in a book ou "Feeding of Crpps and Stock," by Dr. A. D. Hall, director of the famous Rothamsted Agricultural Experimental Station in England, which has been

in existence since 1843. Tins able work (says the Telegraph) contains a chapter on "Milk, Butter and Cheese," which deals with a great many questions connected with the production of milk, butter, and cheese, and the results of the .experiments in the variations in composition of milk are particularly interesting. As a result of about two hundred thousand anaylses, the average composition of milk, for instance, was found to be: Fat 3.9 per cent, protein 3.5, lactose 4.75, ash .75, and water 87.1. In any large number of analyses this average is very well maintained, but in some cases the fat ran as low as 1.7 per cent, and as high as 10 per cent. The author states that it is commonly supposed that the percentage of fat in milk of a given herd can be raised by feeding concentrated foods rich in fat, but he explodes this theory by citing that the proportion of fat contained in milk of a given cow is a physiological function of the cow itself, and is comparatively unaffected by food. The experiments show that if the "amount of food given be insufficient for the average requirements of the cow, the animal will lose weight and will draw the.material from its own tissues in order to keep the yield of milk and butter-fat up to .its normal percentage. When the cow has lost an appreciable amount of weight the yield and the richness of the milk begin to fall appreciably. On the other hand, an excess of rich food will cause the cow to put on fat, and as the cow gets very fat the milk will begin to fall off in quality and quantity. A high percentage of fat in the food does not make the" milk any richer in fat.

The principal ■effect of a liberal but not excessive diet appears to be to keep up the milk yield somewhat longer than the period of lactation. Slight changes of food may stimulate production temporarily, but in any case the effect does not last many days. Succulent foods have an exciting effect in "promoting milk flow, and particularly the first grass after cows are turned out gives rise to an abundant production of comparatively poor milk. Lack of green food is apt to lower the yield- and quality of milk, while an excessive quantity of watery food eventually results in thin and poor milk. Tdje principal effect of different foods is noticed in the quality of the butter. Peas, beans, and cotton-seed meal tend to harden butter, while an excess ■of-fibious foods like hay, straw, and overripe forage tends to make the butter not only hard but tasteless. .Lin.seed cake, maize, rye, oata, and gluten feeds, tend to soften the butter. Other variations in the composition of milk are due to six principal causes, namely: First, individuality; second, breed; third, period of lactation; fourth, time of milking; fifth, age; sixth, disturbance. .In a herd of the same breed, and all treated alike as regards food and housing, there will be considerable* differences in percentage of fat. These differences are found to be hereditary, so that the average composition of the mixed milk of a herd can be considerably raised by weeding out the animals yielding poor milk and breeding only from those giving milk witli high percentage of fai A tabular statement only confirms common knowledge that' Jerseys and Guernseys give the richest milk, but it appears that, there are eonsiderabh variations in the same breed in different parts of the world, Red Polls, for example, averaging 2.99 per cent in one locality and 4*34 in another. During the first flush of,milk after calving, the proportion of butter-fat is lowest next reaching an average amount, and finally rising gain' as the cow begins to dry off.

The experiments show that the time of milking is a very important faetoi in the composition of milk. When the cots were milked at 0 in the mor

ing and agaifi at 2 in the afternoon (an interval of eight hours) it was found that invariably the morning yield was larger, but there was a corresponding falling? oft' in quality, the morning milk often containing less than 3 per cent fat, while the evening milk went well over 4 per cent, in a herd that averaged about 3.5 per cent. With equal intervals 'between mill; ings, the morning milk showed 3.64 per cont fat, and the evening milk 3.45 r,er cent. With intervals of 16 and 8 hours the percentage war, 2.33 after the long interval and 4.47 after the short. For intervals of 15 and 9 hours the percentages were 2.87 and 4.26, and for intervals of 13 and 11 hairs the percentages were 3.18 and 38. Tt was impossible to get over the variations by any alteration in the fond. Invariably the morning milk rMmv grade was in excess of the evening milk sometimes by 50 per cor. 4- , thus tending still further to low •:• the whole average. By milking

't "r;u?.l intervals, the percentage can bo ke>t up to a normal average, and tliero was evidence to show that secretion of milk was stimulated by milk- '.:: ■■ ti.ree timea a day.

A vc?ry important result of the exis that the first milk drawn from tho udder differs greatly in fat :v.i'} t tal solids from that last drawn,

or r 'r'r>pings. Tested in six different rj-.rticiig, the fat varied as follows: 1.70 '>T cent, 1.76 per cent, 2.10 per cent, :2.5! per cent, 3.1 I per cent, and !/K per rent, while the total soikls

from 10.47 to 12.67 pei

While the results are not wholly conclusive, there is evidence that miik yield improves up to about eight years, a decided falling off taking place after the twelfth year. The butter-fat drops a little for the first feiv years, and then remains constant until the eleventh year, when it begins to fall rapidly. It is found that cows are extremely susceptible animals, easily disturbed both in yield and composition of milk by external exciting causes, such as change of location in a ne»v building, sudden fright, thunderstorms, or changes of temperature. In order to get an average composition of the milk produced by a herd, it is necessary to make up a composite sample during at least a week, using a preservative in the various samples, in order to retain them in condition for analysis up to the end of the week.