Effect Of Different Pretreatment Palm Kernel Cake On Pellet Characteristic, Nutrient Digestibility And Intestinal Microflora Of Pigs

The shortage of high quality materials such as corn and soybean meal is an important factor to hinder the healthy development of animal husbandry industryin our country.The utilization of unconventional feed materials is the priority to the reduction and replacement actions of corn and soybean meal.Palm kernel cake(PKC)has high nutritional value and comprehensive nutritional types,however,its application in dietary formulation is limited by its high content of non-starch polysaccharide(NSP).Enzymatic hydrolysis,microbial fermentation and puffing pretreatment can reduce the content of NSP in PKC and increase its application in livestock and poultry breeding.Therefore,the first purpose of this study was to optimize different pretreatment parameters of PKC.A secondary outcome of this study was to investigate the effect of different pretreatment PKC on pellet characteristics,nutrient digestibility and intestinal microflora of growing-finishing pigs.There are three experiments in this paper,and the results are as follows:Experiment 1: Optimization of pretreatment parameters of PKC extrusion,enzymatic hydrolysis and microbial fermentation.The orthogonal combination of three factors and three levels was designed to optimize the pretreatment parameters of PKC with reducing sugar release as the evaluation marker.1.During PKC extrusion,the release of reducing sugar of PKC puffing products was significantly affected by puffing temperature and water content(P < 0.05).The effect of three factors on PKC reducing sugar release was in the order of temperature > water content > feeding rate.The optimal puffing parameters of PKC were puffing temperature 100℃,feeding speed 22.34 kg/min,water content 20% and reducing sugar released 2.42%.2.During PKC enzymatic hydrolysis,the release of reducing sugar of PKC enzymatic products was significantly affected by p H and temperature.The effect of three factors on PKC reducing sugar release was in the order of p H > enzymatic temperature > enzymatic time.The optimal enzymatic hydrolysis parameters of PKC were PH 5,enzymatic hydrolysis temperature 60℃,enzymatic hydrolysis time 8 h,and the release of reducing sugar was 9.01%3.During PKC fermentation,the release of reducing sugar of PKC enzymatic products was significantly affected by fermented temperature and water content.The effect of three factors on PKC reducing sugar release was in the order of water content > fermented temperature > fermented time.The optimal processing parameters of PKC fermentation were fermented time 4 d,water content 55%,fermented temperature 36℃,reducing sugar released 6.37%.Experiment 2: Effects of different pretreatment PKC on pellet characteristics.The optimal parameters in experiment 1 were used to pretreat PKC,and the content of conventional nutrients in PKC was determined.Then,the quality of feed was determined.The five experimental groups were basal diet group,10%PKC group(PKC),10% puffing PKC group(PPKC),10% enzymatic PKC group(EPKC)and10% fermented PKC group(FPKC).The differences of PKC conventional nutrient content and hardness,flour content,flour ratio and starch gelatinization degree of pellet feed were compared between groups.The results were as follows:1.Conventional nutrients: puffing pretreatment could significantly reduce the crude fiber and ether extract contents of PKC(P < 0.01),fermented and enzymatic pretreatment could significantly increase crude protein of PKC(P < 0.01),and significantly decrease crude fiber of PKC(P < 0.01).2.Pellet characteristics: In terms of hardness,PPKC group and FPKC group were significantly higher than base diet group(P < 0.05);There were no significant differences between treatment groups and basal diet groups in powder content and pulverization rate(P > 0.05);Starch gelatinization degree in PPKC group was significantly higher than that in basal diet group(P < 0.01),FPKC group and EPKC group were significantly lower than basal diet group(P < 0.01).Experiment 3: Effects of different pretreatment PKC on nutrient digestibility and intestinal microflora of growing-finishing pigsPKC and pretreated PKC(PPKC,FPKC and EPKC)were used as main test materials.A total of 105 growing pigs with an average body weight of 28±0.5kg were randomly divided into 5 treatments with 3 replicates per treatment and 7 pigs per replicate.Treatment 1(control group)was fed basal diet.Treatment 2,3,4 and 5 were fed diets supplemented with 10%PKC,10%PPKC,10%FPKC and 10%EPKC,respectively.Nutrient levels in diets of each group were balanced.The experiment lasted for 8 weeks(4 weeks in growing pigs and 4 weeks in finishing pigs),and the application effects were discussed from the aspects of nutrient apparent digestibility,growth performance,serum biochemical indices,intestinal microflora.The results were as follows:1.Compared with ordinary PKC group,dietary supplemented with 10%pre-treated PKC significantly improved nutrient digestibility,growth performance and intestinal lactobacillus abundance(P < 0.05).2.Compared with the basal diet,there were no significant differences in nutrient digestibility and growth performance of pigs in PPKC group during growth and finishing stages(P > 0.05);The nutrient digestibility and growth performance of pigs in FPKC and EPKC groups were significantly lower than basal diet(P < 0.05),there were no significant differences in nutrient digestibility and growth performance at fattening stage(P > 0.05).In conclusion,puffing pretreatment can reduce the content of PKC non-starch polysaccharide,increase the hardness of pellet feed,and reduce the powder content and pulverization rate.Compared with fermented and enzymatic pretreatment,puffing treatment has more obvious effect on improving the growth performance of growing pigs,thus,it is more suitable to palm kernel cake.