EFFECT OF TREATMENT TEMPERATURE ON DIETARY QUALITY OF AMMONIA FIBER EXPLOSION (AFEX) TREATED CASEIN FOR RATS

Dietary quality of casein treated by the ammonia fiber explosion (AFEX ) process was evaluated in weanling Sprague-Dawley rats. Two 19 day tr ials were conducted, in which four animals received one of the four (f irst trial) or five (second trial) treatment diets. Animal performance , nitrogen digestion characteristics and biological value were determi ned for diets (protein content 18%) containing untreated casein or cas ein AFEX treated at 40, 60, 80, or 100 degrees C. AFEX treatment at te mperatures of 40-1 00 degrees C did not detrimentally effect (P>0.10) feed intake, weight gain, or nitrogen intake. AFEX treatment at 60 deg rees C increased (P<0.05) feed efficiency by 7% over controls. Higher (P<0.05) fecal (0.23 vs. 0.15 g per 5 days) and urinary nitrogen (1.26 g vs. 1.12 g per 5 days), as well as reduced (P<0.05) apparent nitrog en digestibility (91.4% vs. 94.2%), nitrogen retention (43.6% vs. 49.4 %), and biological value (47.8% vs. 52.4%) were observed for diets con taining casein treated at 60 degrees C and higher temperatures vs, con trols. Results from this study suggest decreased casein digestion and absorption, and decreased utilization of absorbed nitrogen with AFEX t reatments of 60 degrees C and higher.