Study On The Production Of Single Cell Protein Feed With Citrus Byproducts And Feeding Effects In Growing Pigs

Three experiments were conducted for the prodcution of citrus-wastes single cell protein(SCP) feed and feeding effects on growing swine performance.Experiment 1 Study of strains screening and fermentation conditions for SCP produce using citrus byproductsA series trials were conducted to look ior the suitable microorganisms and fermentation conditions for using the by-products of citrus-processing industry to produce SCP feed.By compared the crude and true protein content before and after fermentation,single or combination microorganisms were inoculated into the summer orange or grapefruit by-products.A orthogonal trial was taken to determine the optimal fermentation conditions include culture time,inoculate ratio of strains,inoculation concentration and water content with three levels.Ten different microorganisms were used in the study.The results showed that the kind of microorganisms,or the water content,and fermentation time influenced the protein content significantly(P＜0.01).The suitable strain combination was Candida utilis(1807)-Aspergillus niger(2281)-Trichode-rma reesei(56765).The suitable conditions were:culture time 3～4 d with 2:1:1 or 3:2:1 inoculated ratio of the 3 strains,10%inoculated concentration,and 65%water content for the summer orange with the 3 times more CP content from 10%to 30%and true protein increased by 45%after fermentation,whereas culture time 4～5 d with 2:1:1 ratio of the 3 strains,6%inoculated concentration,and 65%water content for the grapefruit with the 3 times more CP content and true protein increased by 45%. Experiment 2 Field -scale production of SCP feed using summer orange byproductsA field sacle producution of SCP feed uning summer orange byproducts was performanced by using layer fermentation with the fermentation condition:culture time 3d(28℃) with 2:1:1 inoculated ratio of the 3 srtains(1807-2281-56765),8%total inoculated concentration,and 65%water content.After fermentation,the CP aud TP content were 34.59%and 11.42%respectively that were similar to the results under the laboratorial condition.The content of many amino acids(AA) were also increased with the total AA from 7.59%to 10.84%,increased by 42.83%;Lys,Met and Thr content from 0.35%to 0.63%,0.24%to 0.34%and 0.29%to 0.53%;increased by 80%,41.67%, 82.76%respectively.Experiment 3 The feeding effects of SCP feed for growing pigsA single factorial design was adopted to determine the effects of SCP feed on the growth performance of growing pigs.There were three treatments with 0.4%and 8% SCP feed respectively.All the diets were formulated with the same CP and DE by substituted the rapeseed meal(RSM) with SCP feed.Feeds were used in mash.18 DLY growing pigs(initial body weight 38.7±5.2 kg) were allotted randomly to the three treatments with six replicates of one pig.Pigs were fed in single pen for 28 days.During the last 4 days,a digestible trial was conducted to determine the protein digestibility by using indicator.The results were that the ADG,ADFI,F/G of the diet containing 4%and 8%SCP feed were similar to the basal feed.It was same for the serum total protein(TP),albumin(ALB),globin(GLO),and the ration of ALB to GLO(A/G) except the content of serum urea nitrogen(BUN),which were lower with the addtion of 4%SCP feed (P＜0.05).The feed costs reduced 2.48%and 4.85%respectively of the 4%and 8%SCP feed treatments,the diet costs of one kilogram weight gain reduced 0.06 and 0.23 yuan. The rsults showed that SCP feed could substitute the RSM in growing swine with lower feed cost perton or the feed cost for body weight gain.