The evaluation of protein supplements for the growing chick

The nutritive values of hydrolyzed feather meal (HFM) and blood meal (BM), supplied by a commercial rendering company, were evaluated using broiler-type growing chicks. The sample of HFM (89% crude protein), which was processed at 2.81kg/cm² of steam pressure for 40 minutes with continuous agitation, contains 1.4, 1.5 and 3.2% available histidine, lysine and cystine, respectively, and is well utilized by the growing chick. With methionine and lysine supplementation, up to 37% of the dietary protein could be supplied by HFM in chick starter rations. On the other hand, a crude protein content of 95% was obtained from the BM sample processed at 190°C for five minutes at a pressure of 1.41kg/cm². Even though BM contains 8.1 and 10.7% of available lysine and leucine, respectively, it is not efficiently utilized by broiler chicks. With arginine, isoleucine, methionine and cystine supplementation, only 17% of the dietary protein could be supplied by BM in chick starter rations. A combination of 2.5% BM and 7.5% HFM was satisfactory for chicks at the starting phase. The results indicated a possible relationship between protein source and dietary protein concentration on amino acid availability (AAA). However, no valid conclusion could be drawn from the present investigation, since there were no consistent trends on the AAA with different dietary protein concentrations. Regression equations, established from the relationships between alpha-cellulose intakes and amino acid excretions, were reliable for the corrections of metabolic and endogenous amino acids in the AAA assay. This should provide a basis for future studies involved in the development of a universal method for the estimation of endogenous amino acids in the growing chick that will save tedious labor, time and expense. Finally, an eight-hour fecal collection period, with the regression endogenous correction method, was sufficient for the calibration of AAA for HFM and soybean meal.Land and Food Systems, Faculty ofGraduat