MACROSCOPIC ALGAE (SEAWEEDS) 11 



ing contrast with those of certain microscopic algae to be discussed in 

 another section. 



While the direct nutritional utility in humans has been limited, the 

 readily available hundreds of thousands of tons of seaweed might well 

 be more effectively exploited in agriculture and industry. Seaweed has 

 been used as a fertilizer in the coastal portions of southeast Asia for 

 many centuries. Even in the fourth century, Pallidus mentioned the use of 

 seaweeds in western lands as a partial substitute for manure. 73 To this 

 day, particularly in Brittany, Normandy, and the Channel islands, algae 

 are used in soil conservation. Marrett 74 has attributed the small size and 

 small bones of Jersey cows to a calcium deficiency associated with the high 

 iodine content of the grass, a state resulting from the application of sea- 

 weed fertilizer to the ground. The iodine content of algae is highest in 

 the fall and lowest in the spring, with marine specimens containing much 

 more than freshwater ones. According to Lunde and Closs, 75 iodine — 

 whether derived from seaweed fertilizer or meal — causes an increase in 

 the iodine content of the cow's milk, but this changes neither the quantity 

 nor the quality of the milk. That the cattle on the Isle of Jersey are free 

 from bovine tuberculosis, hoof and mouth disease, and brucellosis is 

 attributed by some to the use of algal fertilizers; it seems more reason- 

 able, however, to explain it on the simpler basis of relative isolation from 

 contagion. 



On the Pacific coast of the United States, Desmarestia, a brown sea- 

 weed, is believed to be poisonous to cattle, possibly because of the free 

 sulfuric acid present in the plant. 76 This has doubtless acted as a deterrent 

 to the wider employment of other algae in that area. 



Many forms of algae have been used as dietary supplements for live- 

 stock. Caesar, in his "Commentaries," tells of saving a crucial battle by 

 feeding dried seaweed to his hungry horses when the supply of grain 

 became exhausted. A series of reports from 1745 to 1884 indicates that 

 livestock in the northern British Isles and in the North Sea areas were 

 encouraged to feed on algae washed up on the shore; in addition, the 

 natives collected and mixed the seaweed with conventional fodder. 65 

 Large aquatic plants reportedly have also been used as forage for cattle 

 in Yugoslavia for many years. 4 It was not until World War I, however, 

 when the French were confronted with a shortage of oats and other 

 grains, that any strong interest was manifested in the provender value of 

 seaweed. The military service then began studies on the nutrient effect 

 of seaweeds on horses and cows. 



