FEEDING THROUGH LACTATION PERIOD 19 



gives, some will get more than they need while others will not get 

 enough to give the milk which they are capable of producing. As 

 the cow gets along toward the end of the lactation period her milk 

 rapidly falls off and the farmer will save much grain here by feed- 

 ing it according to production. It is a good plan to have a small 

 blackboard nailed to each cow's stanchion, on which can be 

 written the amount of grain the cow should receive. When her 

 milk shows that the amount should be changed it is very easy to 

 change the figure on the board. 



38. Vitamines in the dairy ration.— Certain other sub- 

 stances besides protein, carbohydrates, fats and minerals are 

 necessary for health and growth. These substances are called vita- 

 mines. Their importance has been principally worked out in the 

 diet of humans, but we do know that our farm animals may suffer 

 from a lack of them. Further, the dairyman must be interested in 

 vitamines because milk is the most important source of vitamines 

 in the human diet. This fact is increasing its use and value. 



There are at least three vitamines, distinguished on the basis 

 of the effect of their absence from the food. The fat soluble 

 vitamine, vitamine A, is the one that occurs in butter fat. In 

 animal feeds it occurs in green forage and leafy roughage. Grains 

 in general contain little, but yellow corn contains considerable 

 amounts. The absence of the vitamine A affects growth and other 

 body functions and eventually causes a specific eye disease. 



The second vitamine, vitamine B, occurs abundantly in milk, 

 in grains, in green forage and in roots. Thus it occurs liberally 

 in animal feeds and is not likely to be deficient in the ration. 



The absence of another vitamine, the antiscorbutic or vitamine 

 C, results in scurvy in humans and certain animals. This vita- 

 mine occurs liberally in leafy foods and green forage and to a 

 variable extent in milk. It does not occur in grains or in dry 

 roughage. Thus it does not occur in much of the material used in 

 feeding farm animals. 



Some animals, however, are not susceptible to a lack of vita- 

 mine C, and so far as we know at present its importance is not 

 great in the case of dairy animals. 



