Feed Pellet Qualities Are Affected By The Processing Way And The Processing Parameters

Different processing technology and processing parameters are important factors that influence theprocessing quality and utilization rate of feed. The research aimed to study the effect of different starch sourcesand particle sizes on processing quality and utilization rate of extruded pellet feed. Surveying、sampling,analyzing test in the enterprise to study the different processing technology and parameters on the quality ofthe pellet. There are three parts in this study; the results were respectively summarized as follows:Experiment one: Starch sources significantly affected extruded diet pellet quality and apparentdigestibility of Nile tilapia (Oreochromis niloticus, GIFT strain)The study investigated the effects of three starch sources (corn, wheat flour and cassava) on floatingextrusion diet qualities (bulk density, expansion, hardness, starch gelatinization and water stability), anddietary apparent digestibility（dry matter,crude protein and gross energy）of Nile tilapia (Oreochromis niloticus,GIFT strain).Five diets were prepared by using40%corn (D1),40%wheat flour (D2),40%cassava (D3),35%wheat flour+5%cassava (D4),35%corn+5%cassava (D5), respectively. Each diet was fed to fourreplicates of30fish of an initial weight of95g for70days. The results showed that starch sources significantlyaffected pellet quality of each diet, in which cassava as sole starch source (D3) showed the highest expansion(99.3%), gelatinization degree (99.2%) and the lowest bulk density and hardness. D1(corn) showed lowestexpansion (56.3%) and SG (92.9%) and with highest bulk density and hardness. Low level of cassava (5%)could improve the expansion and decrease the bulk density of those diets with corn or wheat flour as mainstarch sources. A close correlation between amylopectin content and expansion was observed, the increasingtrend of expansion showed signs of leveling off, when the content of amylopectin up to27.8%. A negativerelationship（R12=0.737）was found between expansion and bulk density. There was no difference on waterstabilities (20min）of all diets. Apparent digestibility of protein and energy of diets were significantly differentamong groups, in which wheat flour (D2)or wheat flour+cassava diets(D4) showed higher protein and energydigestibility than those of D1and D3. D5with corn+cassava showed higher protein digestibility than that ofD1, which with corn as sole starch source. In the present study, we recommended use mixed wheat flour withcassava as starch source for tilapia floating diet.Experiment two: Effect of ingredient particle sizes on extruded diet pellet quality and apparentdigestibility of Siberian sturgeon（Acipenser baeri Brandt）The study investigated the effects of ingredient particle sizes on extruded diet pellet quality, such as bulkdensity, expansion, hardness, starch gelatinization (SG) and water stability, and dietary apparent digestibility（protein，gross energy，dry matter, total phosphorus）of sturgeon. Six experimental diets were used sameformula with different ingredient particle sizes（609um,348um,237um,191um,148um,130um）, named D1、D2、D3、D4、D5、D6，respectively. Each diet was fed to three replicates of12fish of an initial weight of395gfor60days. The results showed that pellet bulk、hardness、starch gelatinization (SG)、 water stability、 sinking rate and pellet durability, were significantly enhanced (P<0.05) by reduction of ingredient particlesize from609um to130um；expansion decreased first，then increased gradually. A strong（R21=0.979，R222=0.988，R4=0.968） negative relationship between starch gelatinization (SG)、water stability、hardnessand particle size was observed. There was a significant (R23=0.993) positive relationship between waterstability and starch gelatinization (SG),the same trend was found between PDI and hardness(R25=0.955). Theenergy required to grind increased sharply from191um to130um. A significant （R26=0.9728）negativerelationship between electricity consumption and particle size. Apparent digestibility of protein、totalphosphorus and energy of diets were significantly different among groups. As the particle size decreased,apparent digestibility of protein、total phosphorus and energy of diets were significantly enhanced(p＜0.05).Apparent digestibility of dry matter was no significant difference among groups（p＞0.05）.In thepresent study, it might be better to grind ingredient particle between237um and348um generally in view ofthe electricity consumption、pellet quality and apparent digestibility.Experiment three: Screening high-efficiency and low-consumption product processing lineThis experiment researches and records the different production line of machining process parameters aswell as the important section of sampling test the pellet quality analysis, respectively in zhuhai dragon ofgroup of haid and zhuhai RongChuan; Evergreen stake of zhanjiang evergreen, lianjiang evergreen, hainanevergreen and zhuhai evergreen; Jiangsu YuDa. The results show that the pellet quality of differentmanufacturers of the different processing technology has significant difference. Due to the high temperatureand pressure, the water stability and gelatinization of extruded feed was maximum, of course the powerconsumption was also maximum. The water stability and gelatinization of shrimp feed was significantly higherthan the pellet feed of fish, because of post curing process. There was no difference between extruded feed andshrimp feed.