754 Summary of Agricultural Experiments, [dec, 



chopped straw, and 12 lb. hay; Lot I. received in addition 20 lb. of 

 brewers' grains and 20 lb. swedes, while Lot II. received 60 lb. 

 swedes. Feeding in this way was continued for ten weeks, when the 

 rations were reversed— that is, Lot I. received the increased quantity 

 of swedes and Lot II. the brewers' grains. The variations in the results 

 were not great, but the two series of experiments are considered to 

 point to the following conclusions : — 



(1) A moderate allowance of 20 lb. of brewers' grains per day has the 

 effect of increasing, at all events for a certain period, the daily yield 

 of milk. The period over which such increase is maintained has its 

 limit, and the practice of changing the diet is a good one. 



(2) The effect of brewers' grains on the yield is not confined to the 

 earlier period of lactation, and it is probable that by a judicious use 

 of brewers' grains the lactation period might be considerably extended. 



(3) The evidence of the experiments with regard to the percentage 

 of fat in the milk seems conclusive that, so far as the daily average of 

 fat is concerned, brewers' grains in moderate quantities produce in the 

 long run no appreciable diminution of fat, although the percentage of 

 butter fat in the morning's milk seems to be lowered more frequently. 

 Having regard to this fact and the 3-per-cent. standard brewers' grains 

 are not to be recommended where the mixed milk of a herd of cows 

 is habitually low in the morning - . It must also be borne in 

 mind that the above conclusions are based on results obtained by 

 feeding brewers' grains in moderate quantities only and with a good 

 complement of artificial foodstuffs. 



In these experiments no effect was produced by the brewers' grains 

 on the non-fatty solids, nor was the effect on the live-weight of the 

 cattle very marked. 



Transfer of Boric Acid from Food to Milk. — (Durham C.C., Educa- 

 tion Com., Offerton Bull., No. 3). — Indian cottoncake is frequently 

 treated with boric acid as a preservative, and experiments have been 

 carried out by Mr. S. H. Collins, Lecturer in Agricultural Chemistry, 

 Armstrong College, to determine whether the milk of cows fed on 

 cake thus preserved would be likely to contain boric acid. 



Two cows were fed on 5 lb. maize meal and 3 lb. decorticated 

 cottoncake, with straw chaff, and hay, while two other cows were fed 

 in a similar way, except that they received a small quantity of "boric 

 meal " made from 19 parts of maize meal and 1 part of boric acid. 

 Boric acid appeared in the milk at once, the maximum being 50 parts 

 per million — a small amount, but sufficient to render the seller liable 

 to prosecution under the Food and Drugs Acts. The amount of boric acid 

 given was by no means excessive, as it was only equal to 5 lb. of a 

 Bombay cottoncake containing 1 per cent, of boric acid, an amount 

 which might be exceeded in practice. 



Another experiment was undertaken to find out whether a smaller 

 amount of boric acid — viz., 1 per cent. — would be traceable in the milk, 

 and this was found to be so. 



There should, however, be no difficulty in distinguishing between 

 milk preserved with boric acid and milk contaminated by the use of 

 foods containing boric acid. If milk contains more than "i per cent, 

 of boric acid, it has probably been deliberately preserved, as less than 

 this quantity would not be likely to have any preservative effect. If it 



