140 Effect of External Influences. 



ble influence which the pasturing exerts on milk production and 

 metabolism be regarded. 



Spoiled feed should be prohibited, and also foods which are 

 readily subject to decomposition (fresh residues of breweries, 

 sugar refineries, etc.). Food which is obtained through fermenta- 

 tion processes (hay, grass, clover, mangels, potatoes, green corn, 

 stored in pits in the ground) should if possible be limited, since 

 substances of odor and taste are eliminated with the milk and 

 especially food bacteria which diminish the keeping qualities of 

 the milk. Although they might not have a direct harmful influence 

 in the human organism nevertheless they may spoil the taste of the 

 milk. 



The beneficial influence of pasturage cannot alone be attributed 

 to the advantage of change of feeding, but is also the result of the 

 stimulating action of the light and air on metabolism, and of the 

 mild form of exercise. Therefore in the absence of pastures it 

 would be advisable to provide exercising paddocks for the animals. 

 According to Munk moderate exercise increases the yield of milk 

 and its proportion of solid substances. 



Excessive exercise of cows should be avoided. 



Although moderate exercise on rich pastures in connection 

 with other factors which increase metabolism, produces more 

 abundant and richer milk, increased exercise reduces the quantity 

 of milk but increases its fat contents. In over-exertion however 

 the quantity and quality of the milk are reduced, and the milk and 

 butter both develop an irritating taste (Dolgich). 



Exhausting transportation changes the milk production con- 

 siderably, especially when during that period the cows are milked 

 irregularly, or for advantage in selling the cows the udders are 

 allowed to become engorged with milk. Stasis mastitis results, 

 which may be cured only by repeated and thorough milkings. 



Excitement of any kind, such as fright, taking away the calf, 

 change of surroundings (new purchaser), and change of feed, may 

 for a longer or shorter period cause a diminution of the quantity 

 of milk and a change of its quality. 



Backhaus observed an increase of over 7% in quantity of 

 milk production and 8% of the fat content after the cows had been 

 curried; in other cases it amounted to 4 and 2y 2 %, respectively. 



In pasturing cows, sheds should be provided for shelter from 

 the strong rays of the sun and rain; otherwise according to 

 Schwenk the yield becomes diminished. Kirsten observed a dimin- 

 ution of the production of milk after prolonged rain. According to 

 Ingersoll and Duncanson, marked changes in the weather may 

 even be of significance during the season when the animals are 

 stabled. 



A rise or a fall in the temperature may cause a reduc- 

 tion in the fat content. In the morning following rainy nights the 

 milk may become richer. The influence of weather and pasture on 



