| Sumario: | Studies on cactus carried out mainly in Mendoza plain, Argentina, and in other country
areas were reported. Variations in nutrient contents with three cladode age classes were
examined for seven Opuntia forage clones. For all age classes combined, clones showed
high organic matter: 84.4%, in vitro organic matter digestibility: 78.9% and low crude
protein (CP) content: 4.0%. High doses of fertilizer almost doubled the mean CP content
of the cladodes from O. ficus-indica (L.) Mill. x O. lindheimerii Engelm. cross when it was
compared with the treatment in which no fertilizer was added (7.8 and 4.3%, respectively).
The response to fertilization at the highest application rate was near 4-fold increase over
the biomass of the zero fertilization treatment, 3.2 to 12.7 kg DM plant-1.
Of this cross, clone 42 produced a dry matter (DM) biomass of 40 t DM ha-1 in
4 years with a total of 625 mm rainfall which is the greatest DM production recorded
to date for such a low rainfall. O. spinulifera Salm-Dyck f. nacuniana Le Houér. appears
to be the most promising species for forage production in areas with extremely cold
winters. Clones 46, 80, 83, 89 and 94 had zero frost damage. Economic analysis of
Opuntia plantations and the use of cactus for replacing corn in small ruminant diet
were included. The cost-benefit relationship of using pre-emergent herbicides on
biomass production and fertilizer application on biomass production and protein
levels were analyzed. The cactus/corn cost relationship indicated the possibility of
replacing corn by cactus in small ruminant diet.
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