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Four crossbred castrated male (Large White x Pietrain) pigs (initial weight about 10 kg) were used in a 4*4 Latin square arrangement to compare 4 sources of protein in a basal diet of sugar cane juice: the protein sources were: SB, soybean meal to provide 10% crude protein in diet DM (control); GT30, fresh leaves of Giant Taro replacing one third of the soybean; GT60, fresh leaves of Giant Taro replacing 60% of the soybean; and GT100, fresh leaves of Giant Taro replacing 100% of the soybean. The rest of the diet was sugar cane juice and a mineral supplement in quantities to provide a total daily amount of feed equivalent to 50 g DM / kg live weight. The experimental periods were 10 days, 5 for adaptation and 5 for collection of faeces and urine.
Apparent digestibility coefficients for SM and crude protein decreased linearly from 94 to 84% for DM and 82 to 61% for crude protein, as the proportion of protein from taro leaves increased. Total intakes of N were higher on the diets with 100% soyabean due to the analyhsed protein content of the soybean being higher than that used in the calculations of diets. After adjusting the data to constant N intake, there were no differences in daily N retention. N retention as percent of digested N was higher on diets containing taro leaves compared with only soybean as protein source.
The implications from the data are that the protein in taro leaves is less digestible but has higher biological value than the protein in soybean meal.