Effects Of Starch Sources On Growth Performance,Blood Biochemistry And Intestinal Physiology Of Broilers

This experiment was conducted to study the effects of starch source replacing corn in equal proportion on growth performance,nutrient utilization,blood biochemical indexes,intestinal development,intestinal pH,chyme viscosity,intestinal permeability and expression of intestinal glucose transporter of broilers,and to reveal the effects of different starch sources on intestinal digestion and absorption of broilers from different levels,and provides a theoretical basis for the rational application of feeds such as corn,wheat,cassava,sorghum and peas in poultry feed.The experiment used a total of 360 healthy and free from disease male Cobb broilers at 1 day of age were randomly divided into 5 groups with 6 replicates in each group and 12 broilers in each replicate.The experimental group was fed corn diets,and the other four experimental groups were fed equal energy and equal nitrogen diet with 25%wheat,cassava,sorghum and pea.The total experimental period was 42 d,which was divided into the starter(0～21 d)and finisher periods(22～42 d)of the experiment,and the main results were as follows:(1)Starch source diets had no significant effect on feed/gain of broilers(P>0.05).The average daily gain and average daily feed intake of broilers(1～21 d)fed cassava diet were significantly lower than those fed wheat diet,sorghum diet and pea diet(P<0.05).The average daily gain of broilers(1～42 d)fed cassava diet were significantly lower than those fed wheat diet,sorghum diet and pea diet(P<0.05).The broilers fed pea diet exhibited greater the early apparent metabolizable energy(P<0.05).The nitrogen utilization rate of sorghum diet was significantly lower than that of corn diet,wheat diet and pea diet(P<0.05).Starch sources had no significant effect on the utilization of dry matter,organic matter,calcium and phosphorus in the starter and finisher periods(P>0.05).Broilers fed diets included sorghum diet and pea diet were exhibited lower the spleen weight and spleen index compared with corn diet and wheat diet(P<0.05),and the bursa of fabricius weight and bursa of fabricius index of fabricius were exhibited lower compared to cassava diet(P<0.05).(2)Broilers fed sorghum diet had higher the lactic acid concentration of serum compared with corn diet and cassava diet(P<0.05).The concentration of blood glucose and triglyceride in broilers on fasting was the lowest(P<0.05),and the concentration of lactic acid was significantly higher than other time points after 1 h and 2 h of broiler feeding(P<0.05).The concentration of low density lipoprotein showed a slow downward trend after broiler feeding(P<0.05).(3)Compared with corn diet,the length and weight of ileum and total intestinal length of cassava diet were reduced,but the weight and relative living weight of cecum and colorectum was increased(P<0.05).The ileum relative living weight and relative total intestinal weight of the sorghum diet is lower than that those of the corn diet(P<0.05).Corn diet was exhibited lower the length of jejunum relative to total intestinal(P<0.05)and increased the length of ileum relative to living weight and total intestinal weight(P<0.05).The pH of the proventriculus chyme of corn diet and wheat diet was higher than that of cassava diet,while the pH of cecum chyme was higher than that of sorghum diet and pea diet(P<0.05).The viscosity of the proventriculus and gizzard chyme of cassava diet and wheat diet was higher than that of pea diet(P<0.05).(4)Broilers fed sorghum diet exhibited lower the duodenal short circuit current and potential difference compared with corn diet,cassava diet and pea diet(P<0.05);the jejunum short circuit current of cassava diet and sorghum diet was exhibited lower than that of corn diet and pea diet(P<0.05),but the ileum tissue conductance was the opposite(P<0.05);the ileum potential difference of sorghum diet was exhibited lower than that of corn diet and pea diet(P<0.05).The cassava diet exhibited superior the permeability of FITC in the small intestine of broilers(P<0.05).Compared with the cassava diet and sorghum diet,the pea diet exhibited reduced the permeability of FITC in the ileum of broilers(P<0.05).With the extension of the test time,the electrical conductivity of the small intestinal epithelial tissue,the ileum short circuit current and the potential difference of the broiler chickens all showed a decreasing pattern,and there were significant differences at different time points(P<0.05).There were no significant effects interactions between the test time and the starch source(P>0.05).(5)The relative expression levels of SGLT-1 and GLUT-2 m RNA in the duodenum of pea diets were lower than those of corn diets(P<0.05).In the jejunum,compared with corn diet,the relative expression of SGLT-1 m RNA in pea diet was up-regulated,and the relative expression of GLUT-2 m RNA was down-regulated(P<0.05).The relative expression level of SGLT-1 and GLUT-2 m RNA in ileum of cassava diet was lower than that in pea diet(P<0.05).Therefore,25% pea and wheat can be used to replace corn in the same amount to feed broilers.The growth of broilers may be negatively affected by the replacement of corn with25% sorghum.When cassava is used to replace corn,the replacement amount should be less than 25%,and it needs to be made into pellet feed to feed broilers after removing anti nutritional factors.