Untersuchungen zur ernährungsphysiologischen Bewertung unterschiedlich behandelter Sojabohnen in der Broilerernährung

Abstract

The objective of the present study was to evaluate the effects of differently treated soybeans on nutrition-physiological parameters in diets (Corn and differently treated soybean) for growing chicken. Considering the factors which influence the effectivity of the treatment process on feed value such as time, mechanical energy and feed structure, one batch of full fat soybean was treated in this present investigation under the following technical conditions: A: Roller mill (RM) + Conditioning (40 min.); B: RM + Conditioning (40 min.) + flaking; C: RM + Conditioning (10 min.); D: RM + Conditioning (10 min.) + Expander (20 kWh/t); E: Hammer mill (HM) + Conditioning (10 min.) + Extruder; F: HM + Conditioning (10 min.); G: HM + Conditioning (10 min.) + Expander (20 kWh/t); H: HM + Expander (20 kWh/t); I: HM + Expander (15 kWh/t) + Steam; K: HM + Expander (40 kWh/t). In a growth trial (day 7-28) with male chickens (genotype Cobb) daily feed intake, average daily gain (ADG), feed conversion ratio (FCR), energy and protein depositions (PD) were examined. After feeding the animals with experimental diets from day 21 to 28, the apparent ileal amino acid digestibility of some amino acids in the diets was determined in 4 pooled chyme samples (9 animals/pooled sample) using acid insoluble ash marker (HCl insoluble crude ash, 1 % celite added in each test diet). Further to the growth trial, a metabolism bioassay (6 male chickens genotype Cobb/treatment) was conducted from day 15 to 21 which consisted of a 6-day collection period, after a 5-day adaptation period. The excrements were collected 3 times a day. Besides the nitrogen determination in the excrements which was the basis for the N-balance measurement, the gross energy content was measured for determining the N-corrected metabolizable energy (MEn) in the feed mixture. Furthermore, the physiological protein value (PNu) as a criterion for evaluating protein quality and the lysine efficiency were derived from the data of the balance measurements. At the end of the metabolism bioassay, the animals were killed and the trypsin avtivity in the collected chyme of the jejunum was determined. The results of this experiment can be summerized as follows: 1. Depending on the given conditions of feed treatments, different trypsin inhibitor activities (TIA) could be detected in the treated soybeans. A high reduction of the TIA was found particularly in treated soybeans A, B, C, D, E, F and G. The relative remaining activity of trypsin-inhibitors in these groups varied from 16 to 27 % compared to untreated soybean. In contrast, the remaining trypsin inhibitor activity in the treated soybeans H, I and K was relatively high, resulting in a value of 75 %, 32 % and 48 % resp., compared to untreated soybean. 2. The daily feed intake , average daily gain and feed utilization of diet group H were, due to the highest activity of the trypsin inhibitor, lower than the control A and those of other diet groups (B, C, D, E, F, G and K). Similarly, the highest TIA in the soybean H led to a significantly reduced nutrient deposition. However, the influence of highest remaining activity of trypsin inhibitor in the diet H on PNu was insignificant. 3. The N-corrected metabolizable energy in the diets B (14,87 MJ/kg DM) and F (14,70 MJ/kg DM) was significantly higher than that of the control A (13,96 MJ/kg DM). The reason for an increase in metabolizable energy in the diets B and F can be due to the possible improvement of nutrient availability through flaking and expander treatments (The improvement of oil availablity as a result of damaging the cell structure of seeds could be responsible for the increasing metabolizable energy in the diets B and F). 4. Due to the relatively higher TIA, both reduced ileal apparent amino acid and nitrogen digestibility were observed in the diet H compared to control A and the other diets (B, C, D and E). However, further steam input and an additional energy supply in treated soybeans I and K resp., reduced the antinutritional factors in the soybeans.Thus significantly improving the ileal apparent amino acid and nitrogen digestibility in these groups (I und K) as compared to the group H. Despite its lower ileal apparent lysine digestibility in the diet group H compared to the control A, lysine efficiency of both groups was not significantly different. 5. Depending on the activity of the trypsin inhibitor in the treated soybeans, the trypsin activity in the chyme was influenced differently. A significantly reduced trypsin activity in the chyme was particularly observed in the diets H and K.