CACTI AS FORAGE. Figs. 321, 322.
Stock in the southern part of the range country feed more or less on prickly pear, and under pres sure of hard circumstances will forage on many kinds of cacti. Fat cattle often eat the fruits of certain cacti, apparently from preference. Inas much as great areas of the southern range country produce cacti of many kinds and in abundance, it becomes an important question as to how far the plants can be profitably utilized for forage. The interest in the subject is naturally increasing, with the settlement of the country; and this interest has been hastened of late by the discussions regarding the breeding of spineless cacti.
So far as present investigations show, spineless cacti are of little economic importance under ex isting range conditions in the West unless grown to maturity in enclosures. The only reason why cacti can remain on the range and attain full growth is because of the protection the spines give them. On an overstocked range, spineless cacti would be consumed before they had fairly started growth. Fig. 321 shows what occurs when cattle have access to more or less spineless forms. In many sections, jack-rabbits are destructive to the spineless cacti.
The spineless cactus is not a recent development. The following fiat-jointed Opuntias are spineless in large part: 0. decumbens ; 0. tomentosa ; 0. Pes corvi ; 0. vulgaris ; 0. Rafinesguii ; 0. crassa ; 0. Ficus-Indica ; 0. fili pendula ; forms of O. robusta ; 0. rubescens.
The following Opuntias are spine less but have objectionable spicules: 0. basilaris ; 0. inanurna ; 0. iner mis ; 0. microdasys; 0. microcarpa ; 0. rufida ; 0. Treleasii.
Many spineless forms are grown in Mexico that might easily be propa gated if that kind were thought to be of any practical value. Present knowledge is not sufficient to state whether the spineless forms will grow as well as the native spiny forms in the same region.
The use of spine-bearing cacti.
The spines are of course objection able to the feeding of cacti. Whether spineless cacti will some day be regu larly bred and planted it is not neces sary now to enquire: the spines are easily and cheaply burned off.
With a gasoline blow-torch, or prickly-pear burner, as it is called, the spines have been singed from a number of species of cactus common to the Southwest. The Arizona Experiment Station tested several species in this way. (Fig. 322.) Previous to the experiment, it had been noticed that the stock was browsing on the cactus shrubs, especially on the less spiny fruits. The first fifty plants that were singed were literally devoured by the stock, the prickly pears being eaten nearly to the ground, while only the trunks and woody branches of the chollas remained. It was soon
evident that the animals were feeding entirely on the singed cacti, which they readily distinguished from the unsinged. The amount that should he fed from a plant at one time varies with species and condition of growth.
The machine used costs eighteen dollars. It con sumes eight to ten gallons of gasoline per day. One man with a machine can feed 400 head of cattle all the spiny cacti they will eat. It is esti mated that 7,000 to 11,000 pounds of cactus for age can be prepared daily in this way, at a cost of about two dollars and forty cents, not including the hire of the man. The work and the cost are justified if cattle can thereby be carried over periods of shortage. The amount of water in this forage, as estimated at the Arizona Experiment Station, is approximately 75 to 80 per cent, leav ing 20 to 25 per cent, or 1,600 to 2,500 pounds of solid matter for the day's work. This large amount of water is of considerable value to the thirsty cattle as it no doubt enables them to browse much farther from their watering places than they otherwise could.
At the New Mexico Experiment Station, experi ments were made to test the value of one kind of cactus forage for dairy cows. The spines were singed off in the way mentoned above. The cactus was then run through a root-cutter. When the cows became accustomed to it they ate forty to fifty pounds per day, in connection with a grain ration and a little hay. It seemed to be about equal in value to sugar-beets, pound for pound.
Composition of cactus forage.
Analysis of cactus stems and fruit were made at the Arizona Experiment Station, and are reported in Bulletin No. 51 of that station. The ash content of the kinds analyzed was found to be high; the fiber is low ; nitrogen-free extract is present in high average amount ; protein is more than half that contained in alfalfa hay and about the same as that in grama grass ; ether extract is high in the seeds, but the seeds are not digested by the animal ; the fiber content of the seeds is also high.
Literature.
For fuller information, the reader should consult Bull. 74 of the Bureau of Plant Industry, United States Department of Agriculture, and Bull. 91 of the Bureau of Animal Industry ; also publications of the Arizona and New Mexico Experiment Sta tions. Bull. 60, New Mexico, gives results of many analyses of leading species.