Effects of Casein and Zein Diets on Hymenolepis diminuta in Rats and Quantitation of Nitrogen and Amino Acids in Parasite and Host

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Abstract
Sixty rats divided among 10 groups of equal average weight were offered for 28 days 5 different diets, all equivalent except for the proteins, casein (diet C) or zein (diet Z), and supplemented amino acids missing in zein: lysine (diet ZL), tryptophan (diet ZT), and both (diet ZLT). On day 7 one group on each diet was infected with 3 cysticercoids of Hymenolepis diminuta per rat; 21 days later infected rats were killed and tapeworms and certain host materials, taken from 9 other rats fed on diets C, Z, or ZL for 28 days, were processed for chemical analyses. Physical data for tapeworms, such as point of attachment, length, and wet weight, were recorded. Weight changes of infected and noninfected rats on each diet were similar. Rats on diet C gained steadily, on diet Z lost steadily, on diets ZL and ZT losses were less, and on diet ZLT after 12 days gains above initial weight commenced, but at a slower rate. Worms from rats on all 4 zein diets were longer and of greater biomass than from diet C hosts. Homogenized worms, intestinal mucosae, walls and contents, and feces were freeze-dried and hydrolyzed in evacuated and sealed ampules in 6 N HC1 at 110 C for nitrogen and amino acid determinations. Nitrogen values were equivalent in diets C and Z, in tapeworms from all rats, and in the intestinal mucosae and walls. Percentages of amino acids determined by ion exchange chromatography were equivalent in worms, diets C and Z, and intestinal walls from rats on all 5 diets. Zein-fed hosts had greater percentages of N and amino acids in intestinal contents and feces than in diet C rats.