PRICKLY PEAR IN U.S.A. 
Prickly Pear in U.S.A. 
Report by Professor R. D. WATT. 
|The following report, presented to the Institute of Science and 
Industry by Professor R. D. Watt on the subject of Prickly Pear Inves- 
tigations in the United States, will be read with interest. It will be 
seen that in the United States there’ is a difference of opinion as to the 
economic value of the cactus. In Australia, however, the plant has 
become such a pest, and has established itself over such an enormous 
area, that its progress has got to be checked, and the plant, if possible, 
eradicated, regardless of any slight economic value it may possess. In 
a bulletin on the subject issued by the Institute last year, it was pointed 
out that the Pest pear had a value as a fodder reserve in case of drought, 
but that experience had shown that Prickly Pear by itself did not 
contain sufficient nutriment to keep up the condition of animals fed 
upon it. The fruits are much more nutritious than the joints. | 
Before leaving for my recent trip to America and Europe, I pro- » 
mised to make ‘some inquiries in the United States with regard to the 
utilization of the Prickly Pear, especially in a desiccated form, for the 
feeding of live-stock. Owing to the delay in my departure caused by 
the strike of marine engineers, the American part of my trip was con- 
siderably curtailed, so that I was not able to make such exhaustive 
inquiries as I should have liked into this matter, but whenever I had 
the opportunity I gleaned all the information I could. 
The first man interviewed was Mr. M. E. Jaffa, Professor of Nutri- 
tion in the University of California. He was of the opinion that none 
of the dried cactus products, except those derived from the fruits of 
some species, were of any value for human food, nor did he think 
that they were of much value for feeding cattle or other domesticated | 
animals because of the low protein and fat content, the high fibre con- 
tent, and the uncertainty as to the nutritive value of the nitrogen-free 
extract which constitutes from 70 to 75 per cent. of the material. No 
actual feeding tests had been carried out to ascertain the latter point. 
He was further of the opinion that the correct place for the various 
species of Opuntia for cattle food was a reserve for dry seasons, the 
cattle cacti to be consumed by cattle in their natural succulent state 
after the destruction of the spines and spicules, if necessary; that their 
main value as feeding stuffs depended on their succulence; and that to 
manufacture concentrated products from them by desiccation was a 
mistake. He was under the impression that nearly all the cactus food 
products companies had gone out of business, although he supplied me 
with a report he had sent to one company on the value of their products 
- for human consumption, a copy of which is enclosed. 
Before interviewing Professor Jaffa, I had already written to the 
manager of this particular company, the Cactus Food Products Com- 
pany of Los Angeles, asking certain questions regarding species, pro- 
cesses of manufacture, analyses, and prices. A reply was not, however, 
' 07m 
