The Research On Key Technology And Processing Quality Evaluation Of Hard Pellet Feed

The objective of this study was to investigate the influence of different feed processing conditions on the processing quality of hard pellet feed,and the nutrients of hard pellet feed was evaluated by in vitro bionic digestion.The main contents were as following:(1)The effect of cold pelleting on the processing quality of hard pellet feedThe corn-soybean diet of broiler compound feed was used to study the effect of cold pelleting on the processing quality of hard pellet feed.Feed moisture(10%,12% and 14%),mould ring(1,2 and 3)and cooling time(0 min,30 min and 60 min)were set to 3×3 orthogonal experiment.The hardness,moisture,starch gelatinization degree,soluble proteins,and other indexes of pelleted feeds were analyzed.The results showed that the gelatinization degree of the starch in pellet feed was increased with the increasing of moisture,but there was no effect on the content of soluble protein,and the hardness of the pellet feed was reduced.The hardness of the feed was improved by increasing the mould ring length-diameter.The cooling time had little effect on the hardness of the pellet feed within 60 min.(2)The effect of conditioning pelleting on the processing quality of hard pellet feedThe conditioning pelleting experiments were carried out at 60 s,90 s,and 120 s with steam pressure of 0.2 MPa.Two different mould ring(1 and 2)were used for pelleting and the pellet feed was cooled in natural conditions for 0 h,12 h,and 24 h.The hardness,moisture,starch gelatinization degree,soluble proteins of pelleted feeds were analyzed.The results showed that the degree of starch gelatinization was improved to a certain extent with increasing of conditioning time,and the moisture of feed was increased significantly,but the soluble protein and the hardness of pellet feed without cooling or shorter cooling time were reduced.The moisture of pellet feed was reduced effectively and the hardness of pellet feed was enhanced by prolonging cooling time.Pellet feed hardness was highly correlated with PDI.Compared with cold pelleting,the hardness of pelleted feed could be increased by conditioning pelleting.(3)The effect of ether extract and conditioning temperature on the processing quality of hard pellet feedThe corn-soybean diet of piglet compound feed was used to study the effect of ether extract and conditioning temperature on the processing quality of hard pellet feed.In this research,the conditioning temperature of 60℃,70℃,and 80℃ were set,and 3 diets with 3.37%,4.00% and 4.65% ether extract were used to process 9 kinds of pellet feed,then stored in room for 0~2 d with natural withering,and the moisture,hardness,pellet durability index(PDI),gelatinization degree of starch were analyzed.The results showed that the starch gelatinization degree and the hardness of feed pellet were improved with increasing conditioning temperature,but the content of soluble protein was reduced.In addition,the hardness of the pelleted feed could be increased by reducing the ether extract or moisture content in the feed.(4)The effect of different feed processing conditions on nutrients of hard pellet feedThe corn-soybean diet of broiler compound feed was used to study the effect of different feed processing conditions on nutrients of hard pellet feed.7diets included powder,cold pellet feed,and 5 pellet feeds with conditioning time of 60 s,90 s,and 120 s,were used to determined the in vitro digestibility of dry matter,energy and crude protein.The results showed that: There was no significant difference in digestibility by in vitro methodbetween powder and pellet feed.Comparing with the powder,the digestibilities of the feed were improve by cold pelleting and conditioning pelleting processes,and the conditioning pelleting process was better than the cold pelleting.In addition,the in vitro digestibility of the pellet feed was improved with increasing the mould ring length-diameter.The in vitro digestibility of dry matter,crude protein and energy of pelleted diets were higher when the conditioning time was 90 s,this may be better for livestock to digeste.