134 AGRICULTURAL RESEARCH AND THE FARMER : 



because animals cannot live without them. Vitamin A is present 

 in cod liver oil, but is absent from oUve oil. 



In the first series of experiments a Utter of lo Berkshire pigs, 

 weaned at the age of eight weeks, was divided into five groups. 

 Group I was kept in a sty and fed on a diet consisting of the 

 constituents of whey in which olive oil (free from vitamin A) 

 replaced the fat of the whey. Group 2 was kept under similar 

 conditions and received whey and toppings. Group 3 received 

 the same kind of food as Group 2 but was kept in a portable 

 sty on pasture, since grass contains all the known vitamins. 

 Gro7tp 4 was also kept on grass, but had no whey in the ration 

 supplied. Group 5 was kept under farm conditions, being fed 

 on a mixed diet of toppings, whey and swill, and having abundance 

 of green food in addition. At the end of three months on the 

 experimental diet the hogs were slaughtered, the sows being 

 retained for further experiment. The differences in growth 

 and well-being of the hogs were marked, the dressed dead weights 

 being as follows : — Groiip i — 84 lbs. ; Group 2 — 122 lbs. ; Group 

 3 — 120 lbs. ; Group 4^103 lbs. ; Group 5 — 150 lbs. It was 

 surprising that the animals in Group i should have grown so 

 weU on a diet so deficient in vitamins, but on testing the fat of 

 the animals by feeding them to rats whose growth had been 

 brought to a standstill by a deficiency of vitamin A, a striking 

 difference in the nature of the fats was demonstrated. The 

 body fats from pigs in Groups i and 2 were found to be of no 

 value as a source of vitamin A, while the grass-fed animals 

 yielded fat containing appreciable amounts of this important 

 growth-promoting substance. 



From this experiment it would seem that whey contains 

 insufficient of the vitamin A to allow excess for storage in the 

 fat. If grass or green food is fed at the same time, this deficiency 

 is made up. There would also appear to be a value in whey (as 

 shown by the difference in weight betv/een Groups 3 and 4) 

 independent of its vitamin content. 



The experiment was continued with the sows of Groups I 

 to 4. In 48 days the weight of the sow in Group 1 had become 

 almost constant at 132 lbs. Gro2ip 2 was making little progress 

 at 144 lbs Group 3 weighed 180 lbs. and was doing well ; Group 4 

 weighed 152 lbs. At this stage in the experiment a quarter of an 

 ounce of crude cod liver oil, a substance rich in vitamin A, was 

 given to the sow of Group i. This small dose, given instead of 

 the olive oil in the diet, caused the immediate resumption of 

 normal growth. The sow in Group 2 also recovered normal 

 growth on being given 2 lbs. of lucerne per day. 



