Theses and Dissertations

Title: Digestibility of nutrients in six semi-purified rations by channel catfish in troughs

Name: Smith, Barry Wayne

Degree: MS

Chair: Dr. Richard T. Lovell

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1970

Pages: 61

Keywords: Digestibility,Nutrients,Semi-Purified Rations,Channel Catfish,Troughs.


The digestibility of nutrients in six semi-purified rations containing variable levels of protein, cellulose, and starch by channel catfish (Ictalurus punctatus, Rafinesque) in troughs was evaluated by using chromium oxide as an inert reference substance in each feed. Excreta was collected using two methods: an indirect trough collection method and a direct intestinal collection method. Digestibility coefficients determined on excreta collected in troughs were higher than coefficients determined from excreta collected from the intestine. There was no significant difference in protein or fat digestibility from the six rations with the trough collection of excreta. All values for protein and fat were above 95%. Starch digestibility was influenced by the level of both starch and cellulose in the diet, but not by the level of protein. Values for starch digestibility ranged from 69 to 84%. In the intestinal collection method, excreta was collected from the lower third of the intestine and, separately, from four areas of the digestive tract, namely, the stomach, upper intestine, lower intestine, and rectum. The absorption of protein in two-year-old channel catfish occurred the length of the intestine up to and possibly including the rectum. Thus, digestibility coefficients determined from material taken from the intestine anterior to the rectum did not represent complete nutrient absorption. There was a significant difference in protein digestibility among the six rations for collection of excreta from the rectal area. A higher percentage of protein was digested in rations containing 40% protein than those containing 20% protein. Starch did not seem to affect protein digestibility but cellulose did. Values for protein digestibility ranged from 72 to 93%.

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