MILKING QUALITIES.

Waipa Post, Volume III, Issue 104, 23 April 1912, Page 4

MILKING QUALITIES.

DISCUSSED ON SCIENTIFIC LINES.

An interesting interview appears in a recent issue of the Agricultural. Gazette (England), which states that as yet nothing has been published as to the inheritance of quality in milk, further than a paper based upon the analyses of the yields of about 3000 Ayrshire cows, which showed that quantity and quality are inherited separately and independently, but we know that, among full-sized cows like Shorthorns, milk yield is inherited in a manner similar to the inheritance of coat colour in Shorthorns. So writes Professor James Rutherford in Hoard’s Dairyman, and he goes on to add that it would be well to mention the amount of caution that must be exercised before the figures usually .published as to milk yields can be made use of. First of all, it ought to be stated that milk yields are very sensitive, and fluctuate with such things as food, weather, shelter, comfort, and, above all, the individual cow’s health. If such causes as these are operating seriously they ought to be left out of count altogether. Great caution is necessary when a cow has been in milk beyond the normal period. The usual interval between the births of successive calves is twelve months, which brings the normal lactation period to nine or ten months. If the interval he longer than twelve months, then by so much is it longer the lactation period is increased beyond the normal; and the yield is enhanced. We must therefore reduce our thou-sand-gallon cows by something round about 100 gallons for every month they run beyond the twelve before having their next calf. The reduction must be made with some judgment, because for one month only it ought to be more per month than if it were made for half a dozen. For cows giving about 750 gallons in the normal lactation the reduction is about 70 gallons a month, and for cows‘giving 500 gallons it ts about 45.

THE COW’S AGE

Another point that must be considered,is the cow’s age. A cow is not mature till she is five or six years old, and at that time her yield is about 50 per cent, greater than when she had her first calf at about three years old. These are the chief facts to be considered before we can reduce yields to a normal. But when all things are considered we must still keep in mind that statements as to yields can only be rough approximates. We speak of a thousand-gallon cow; but the “ thousand ” is a flexable figure, expanding occasionally, under favourable circumstances, and in exceptional circumstances, to 1200, and contracting perhaps to 900; and we must allow a similar flexability when speaking of 500gallon cows. With these short explanations it may now be said that mature cows fall into three grades: Ihe 1000 7 gallon grade, the 700 to 800 gallon grade, and the 500-gallon grade, and that the middle grade is intermediate between the extremes in the same way as roan is intermediate between red and white. In breeding for milk, therefore, we need only follow the lines laid down already in considering how a white herd could be converted into red. We have only to find some 1000-gallon bulls—if we may be allowed to speak in this way —and mate them with low and intermediate cows. If mated with low-grade cows, the progeny will be medium grade ; if mated with medium grades, half the progeny will be high grade; and if mated with high grades, the progeny will all be high grade. THE BULL QUESTION.

There is one serious difficulty, however, and that is to identify the 1000-gallon, bulls. A white bull or a red can be told by the naked eye; but a iooo-gallon bull cannnt be told in this way. As yet he can only be told by the way in which he breeds — that is, by the yields of his daughters, and before that can be done he has usually gone to the butcher. But this might be suggested, that no son of a 1000gallon cow should be sent to the butcher until his grade is known. He will be either high grade or medium, and in cither case he is of value as a breeder. But when it is found that all his daughters by low-grade cows are medium grades, or that half his daughters by medium cows arc high grades, or that all his daughters by high-grade cows are high grades, then he should never go to the butcher at all. And it should be remembered further that as soon as a bull is identified as a high grade, his sons by highgrade cows are all high grades also. One odier point need only be mentioned. Our present method of describing cows as giving so many gallons during a lactation is very cumbrous and by no means accurate. It is always unsatisfactory to have to use “corrected ” figures. There is a better method of describing a cow’s yield, and it is liable to fewer uncertainties. Besides, it can be used when the cow is only two hionths calved. It will be 4 '

noticed that about half the cow’s total yield for a normal lactation is given by about Lhe end of three months. This part of the yield, too, is subject to less variation that the remaining part. Even increased food has less proportional effect upon it, probably because the cow is drawing upon what she had saved up in fat before the calf was born.