Chemical composition, amino acid profile and metabolizable energy value of pasta refusals, and its application in broiler diets in response to feed enzyme

The present trials were conducted to evaluate the chemical composition and nutritional value of different samples of maize, wheat and pasta refusals for broiler chicks in response to a crude enzyme preparation. The different samples of maize, wheat and pasta refusals were force fed to the 48-wk-old Leghorn cocks with or without enzyme (with predominant xylanase activity). The apparent dry matter digestibility was significantly (P < 0.01) different among the three feedstuffs with the highest values obtained for the pasta refusals. Similarly, the apparent nitrogen retention was different (P < 0.001) among the feed ingredients with the more negative values allocated to the cocks on maize samples. The average AMEn values of maize, wheat, and pasta refusals samples were determined to be 14.1, 12.6, and 15.5 MJ kg−1, respectively. The enzyme inclusion improved (P < 0.05) the AME and TME values of wheat and pasta refusals samples. A broiler trial was performed to investigate the effect of xylanase supplementation of wheat- and pasta refusals-containing diets on performance of broiler chicks. A total of 864 Ross 308 broiler chicks of 7 days-old were used to compare 18 experimental diets according to a 2 × 3 × 3 factorial arrangement of treatments with two test ingredients (wheat or pasta refusals), three inclusion levels (200, 400, and 600 g kg−1 of diet), and three supplemental enzyme levels (0, 500 or 1000 U xylanase kg−1 of diet). Dietary inclusion level of wheat and pasta refusals had a significant (P < 0.05) effect on average daily feed intake (ADFI) throughout the experimental period, and increase in dietary wheat content was associated with ADFI reduction, resulting significant (P < 0.01) test ingredient × inclusion interaction. On the other hand, supplemental enzyme increased ADFI during the periods of 36–49 (P < 0.01) and 7–49 (P < 0.05) d of age. The average daily weight gains (ADWG) were influenced by dietary inclusion level (P < 0.01) of wheat and pasta, as well as by enzyme level (P < 0.01) and respective interaction (P < 0.05). The highest ADWG values were observed for the chicks on 400 g kg−1 pasta refusals-containing diets supplemented with 1000 U kg−1 xylanase. Dietary inclusion of pasta refusals in the expense of wheat significantly (P < 0.05) improved feed conversion ratio (FCR) during grower period. In addition, dietary supplementation of at least 500 U kg−1 xylanase improved FCR values during both 7–35 (P < 0.01) and 7–49 (P < 0.05) d periods. Although increase in dietary inclusion level of wheat and pasta refusals was associated with marked (P < 0.01) increases in viscosity of both ileal and jejunal contents, enzyme supplementation properly decreased (P < 0.01) digesta viscosity. These findings suggest that the broilerʹs response to feed enzymes depends on age and dietary inclusion level of wheat or pasta refusals. Results indicate that pasta refusals can be used as a main energy source in broiler diets with the beneficial effects on performance traits.