Effect Of Conditioning Temperatures And Particle Sizes On Quality And Utilization Rate Of Broiler Pellet Feed

Conditioning temperature and particle size are important factors that influence the processingquality and utilization rate of feed. This research aimed to study the effect of different conditioningtemperatures and particle sizes on processing quality and utilization rate of broiler pellet feed. There arethree parts in this research:1. Effect of different conditioning temperatures on processing quality andnutritive value of broiler pellet feed.2. Effect of different particle sizes on processing quality andnutrition value of broiler pellet feed.3. Effect of different conditioning temperatures and particle sizeson utilization rate of broiler pellet feed.The first part, in this research,65℃,70℃,75℃,80℃,85℃and90℃are selected to study theeffect of conditioning temperature on processing quality and nutritive value of corn-miscellaneousmeals broiler pellet feed. The results suggested that with the conditioning temperature increased，PDI,hardness, the gelatinization degree of starch showed significantly increased (P<0.01),and thecorrelation coefficient between PDI and hardness is0.9108.The gelatinization degree of starch afterpelletizing compared to which after conditioning increased by about3%-5.22%. The temperatureaffected the phytase activity significantly, and it’s only5.67%at80℃. Protein digestion rate in vitroshowed a upward trend with the rise of conditioning temperature65to80℃,and arrived at the bestvalue,82.72%, when under80℃.The reducing sugar content showed a significant downward trendwhen under80℃(P<0.01). Salmonella was not detected, the total number of bacteria, mold andcoliform group showed a significant downward trend with the conditioning temperature increasing, theinactivation rate of microorganisms in feed more than99%when under75℃,close to100%when under80℃.The second part, in this research, the test diets is corn-miscellaneous meals broiler pellet feed.4different sieve pore sizes (1.5mm、2.0mm、2.5mm、3.0mm) and2different conditioning temperatures(75℃、85℃) are selected to study the effect of particle sizes on quality of broiler pellet feed. Theresults suggested that with the conditioning temperatures changing form75℃to85℃, the PDI,hardness and gelatinization degree of starch increased respectively by1%,2-4N and1%-2%. Thedecrease of particle size could also increase the PDI, hardness and gelatinization degree of starchrespectively by1%-2%,4-6N,2%.With the particle sizes from890μm to820μm, from900μm to700μm,the energy consumption increased respectively by40%and70%. The particle sizes have no significanteffect on content of crude protein, dry matter and amino acid.The third part, in this research,864Avian broilers4d of age are allocated into8groups, each grouphave6replications with18broilers per replication to study the effect of particle sizes (1.5mm、2.0mm、2.5mm、3.0mm) and conditioning temperatures (75℃、85℃) on utilization rate of corn-miscellaneous meals broiler pellet feed. The results showed that:Feed conditioning under75℃:Particle sizes have no significant effect on apparent digestibility of crude protein and dry matter. Atearly period, ADG and ADFI showed a downtrend with particle sizes increased, but F/G showed no significant change(P＞0.05). F/G and amino acid apparent digestibility showed the best value at825μmgroup. At later period, particle sizes have no significant effect on ADG,ADFI and F/G(P＞0.05). F/Gand amino acid apparent digestibility showed the best value at892μm group.Feed conditioning under85℃:ADG and ADFI showed an upward trend first then downward with the rise of particle sizes. Atearly period, F/G showed the best value1.41at825μm group and has significant difference compare tothe latter two groups(P＜0.01). Dry matter, crude protein and amino acid apparent digestibility alsoshowed the best value at825μm group. At later period, F/G showed the best value1.87and hassignificant difference compare to other groups(P＜0.01). Dry matter, crude protein and amino acidapparent digestibility showed the best value at892μm group.The apparent digestibility of crude protein and amino acid at75℃group showed the better valuecompared to which under85℃group. The conditioning temperatures have no significant effect onbroiler growth performance and dry matter apparent digestibility.