Effect Of Pelleting And Grinding On The Pellet Quality, Feed Nutritional Value And Growth Performance Of The Broilers

The current study was conducted to evaluate the influence of pelleting and grinding onthe pellet quality and nutrient utilization and growth performance of broilers. This studyconsisted of three parts as following:The effect of pelleting and grinding on the pellet quality: The effect of pelleting andgrinding on the pellet quality: The study of different storage time (60d), transportingdistance (124.3km), quantity of loading and unloading times(6times) on the percentage ofpowder of pellets indicated: The storage time and the quantity of loading and unloading timeshad no effect on the percentage of powder, and the positive correlations between thepercentage of powder and the distance of transporting were showed (P <0.05). Two type ofdiets (maize-and wheat-based) in broilers and pelleting temperature (80,85,90℃) wereselected to evaluate the effect of on pellet quality. The result indicate: From80to90℃canimprove PDI, hardness and gelatinised starch in both maize-and wheat-based diet (P <0.05),especially in wheat-based diet(P <0.05). To study the effect of particle size (378,430,516,590, μm) on the pellet quality, four kinds of screen (1.0,1.5,2.0,2.5, mm）were used togrinding the corn, wheat and soybean meal and found that the particle size had no effect onthe pellets quality (P>0.05).The effect of pelleting and grinding on feed nutritional value:14410-d-old AAbroilers were selected and randomly placed into8treatments (1broilers per cage,3birds perreplication,6replications per treatment). Two diet types (maize-and wheat-based), two typesof intake (conventional total collection method in free intake and force intake) and two feedform (mash and pellet) were adopted to evaluate nutrient utilization. The results show: Themash diets had greater (P <0.05) nutrient and energy digestibility than the pellets. Diet typehad no effect on the nutrient utilization (P>0.05), however the force intake resulted ingreater true nutrient digestibility and TME (P <0.05) than the free intake (P>0.05).10810-d-old AA broilers were selected and randomly distributed into6treatments (one broiler percage,3birds per replication,6replications per treatment). The experimental design wasevaluating three conditioning temperatures (80,85,90℃) and two diet types (maize-andwheat-based diet), while applying conventional total collection method in free intake. The results indicted: From80℃to90℃, the nutrient utilisation and metabolisable energy werelinearly decreasing (P <0.05) and the effects were significant (P <0.05).14410-d-old and14430-d-old AA broilers were respectively distributed into individual cages for8dietarytreatments with six replicates of18broilers for each diet. Two feed form (mash and pellets)and four kinds of particle size (378,430,516,590, μm) were selected and the nutrient andenergy digestibility were determined using a conventional total collection method in freeintake. The results indicated: The mash improve the nutrient utilization in18-21d starterbroilers (P <0.05), but pellets increase the nutrient utilization in38-41d finisher broilers (P <0.05). For the starters, increasing the particle size, the nutrient utilisation and metabolisableenergy of mash were linearly rising (P <0.05), but the effect was reversed for pellets (P <0.05). The particle size had no effect on the nutrient utilization of mash and pellets in finisherbroilers (P>0.05).The effect of pelleting and grinding on growth performance:5761-d-old AA broilerswere randomly distributed into8treatments (12birds per replication,6replications pertreatment) to evaluate the effect of feed form and particle size on the growth performance.Compared to the mash, pellets can improve ADFI and ADG (P <0.05), reduce F:G (P <0.05),promote performance. For the mash, the effect of particle size on ADFI, ADG and F:G wasdifferent (P <0.05), while the particle size had no effect on ADFI, ADG, and F:G of broilersfed on pellets (P>0.05). When the FI was similar for the mash and pellets, pellets canimprove ADG and reduce F: G.. If the body weight of broilers fed on mash and pellets wasequal, the cultivation period of mash would increase two weeks at least. This is the why thebroilers fed on mash have higher nutrient utilization and lower performance. Compared to themash, pellets resulted in higher slaughter yield, empty yield, half-empty yield, breast muscleyield, leg muscle yield and abdominal fat (P <0.05). The particle size had no effect on theslaughter performance of birds fed on mash and pellets (P>0.05). The mash had higher therelative weight of gizzard, proventriculus, duodenum, jejunum, ileum, intestine and cucemand the relative length of duodenum, jejunum, ileum, intestine and cucem (P <0.05). From378μm to590, the relative weight of gizzard was linearly increasing (P <0.05), and theeffects were significant (P <0.05).All these results indicate: The transporting distance is the main factor to cause thepowder pellet feed. Increasing the pelleting temperature can improve the pellets quality,especially in wheat-based diet. The particle size had no effect on the pellets quality. The forceintake results higher nutrient and energy utilization than the conventional total collectionmethod. The contribution of particle size on nutrient utilization can be influenced by the feed form and ages of broilers. Pellets resulted in higher growth and slaughter performance.Broilers fed on mash can receive the equal performance compared with fed on pellets, whilethe cultivation period will be increased by at least two weeks, which would increase themaintenance requirement and reduce feed efficiency. The mash will promote the developmentof digestive tract, resulting in higher nutrient utilization than pellets.