The Dairy Coiv — Scientific Findings. 391 



may give milk below or above the normal in richness; (602) defective, 

 unusual, or scant feed may force the cow to give abnormally rich or 

 poor milk; (603) feeding large quantities of fat may temporarily in- 

 crease the fat in milk; (606) excitement or work may cause the milk 

 to be richer or poorer than normal; (609) the shorter the period be- 

 tween milkings, the richer the milk; (615) morning's milk is usually 

 richer than night's milk; the first drawn milk is the poorest and the 

 last drawn the richest. (597) In general, all changes in environment, 

 care, or food which affect the cow are mainly reflected in the quan- 

 tity and, in some degree, in the quality of the milk she yields. Often 

 when the percentage of fat increases, the quantity of the milk de- 

 creases so that the total yield of fat is not increased. (596-9) 



619. Effects of feed on fat composition. — The fat of milk is a 

 composite of many kinds of fat, such as palmitin, olein, stearin, buty- 

 rin, etc. "While the kind of feed given the cow does not materially 

 change the total per cent of fat in her milk, it does in some cases 

 seem to alter the relative proportion of the several component fats 

 or in some way change the composition of the fat, as shown by the re- 

 sultant butter. We know that butter produced from cows fed cotton- 

 .seed meal is hard and tallowy, with a high melting point, while lin- 

 seed meal and soybeans tend to produce a soft butter with a low 

 melting point. 



]\rany years ago investigators began diligently to study the influ- 

 ence of feed on the composition of the fat of milk, and their work 

 is still in progress. No basic conclusions have yet been reached, and 

 we are forced to agree with Frear,^ who years ago, after reviewing 

 all available data, wrote: "They (the data) do not, however, suffice 

 either for the framing of a theory as to the relation of the several 

 food constituents to the fats of milk, or for the quantitative meas- 

 ure of the influence of a given food." (605-6, 643) 



620. Flavor, odor, and color. — Milk and its products possess qual- 

 ities cognizable only to sight, taste, and smell. The Guernsey breed 

 excels in producing a milk with a yellow fat. The grain of corn, pas- 

 ture grass, carrots, and some other feeding stuffs impart a yellowish 

 tinge to milk fat. Due to minute quantities of volatile oils they con- 

 tain, onions, leeks, turnips, rape, etc., impart an objectionable flavor 

 to milk, possibly apparent to all people, while the flavors imparted 

 by green rye or corn silage are detected by some but pass unnoticed 

 by many. (362) Wlien cows are first turned to pasture, we at once 

 observe a grass flavor in the milk and butter, tho it soon disappears ; 



^Agr. Science, 1893. 



