| Extrusion and steam conditioning are two important means of feed processing.The aim of this study was to investigate the effects of extrusion and steam conditioning on the feed pellet quality and growth performance,nutrient digestibility,intestinal physiology and microbiology of meat rabbits under suitable extrusion parameters.The results provide basic data and theoretical basis for the application of extrusion and steam conditioning technology in rabbit feed production.This study was divided into two experiments:Exp.1,the orthogonal form L9(34)was adopted to design three factors and three levels orthogonal test.Barrel temperature,material moisture content and feed rate were selected as test factors.The vegetable raw materials mixture(maize,soybean meal,rapeseed meal,wheat bran,alfalfa meal,peanut shells)was extruded.Acid detergent fiber(ADF)content was selected as main evaluation index to research the optimum extrusion parameters.The results were as follows:1.The barrel temperature significantly decreased the ADF content of rabbit dietary(P<0.01),the priorities influencing the ADF content of rabbit dietary were barrel temperature>material moisture>feed rate.2.The optimum extrusion parameters of meat rabbit feed processing were barrel temperature 125 ?.moisture content 16%and feed rate 9 Hz.Exp.2,the 2×2 two-factor design was adopted to study the effects of extrusion and steam conditioning on growth performance,nutrient digestibility,and intestinal physiology of meat rabbits.Extrusion(with,without)and steam conditioning(with,without)were the main effects,and rabbit diet adding antibiotic(with steam conditioning,without extrusion)was preparation.The growth trial and digestion trial were respectively carried out.Growth trial:A total of 130 healthy and 30-day-old "Hycole" rabbits with similar weight(918.16±6.83g)were randomly assigned to 5 groups with 13 replicates in each group and each replicate contained 1 rabbit.The adaptation period lasted for 7 d and the formal period lasted for 35 d.Digestion trial:A total of 50 healthy and 42-day-old "Hycole"rabbits with similar weight(1066±78 g)were randomly assigned to 5 groups with 10 replicates in each group and each replicate contained 1 rabbit.The adaptation period lasted for 7 d and the digestion trial lasted for 4 d.The results showed as follows:1.Extrusion and steam conditioning can improve the pellet quality of rabbit feed.Extrusion and steam conditioning very significantly decreased powder percentage,pulverization ratio and protein solubility(P<0.01),very significantly improved hardness and starch gelatinization degree of rabbit feed(P<0.01),they both had significant interaction effects on the processing quality of rabbit feed(P<0.05).2.Extrusion significantly improved average daily gain(ADG)of 1-14 d by 17.17%(P<0.05),reduced feed/gain(F/G)of 1-14 d by 16.01%(P<0.05).Average daily feed intake(ADFI),ADG and F/G in all stages of meat rabbits were not significantly affected by steam conditioning(P>0.05).Extrusion and steam conditioning had a significant interaction effect on ADFI of 15-35 d and 1-35 d(P<0.05).3.Extrusion + steam conditioning significantly reduced the health risk of 1-35 d(P<0.05).Diets supplemented with antibiotics reduced mortality of 1-14 d.Extrusion reduced the health risk of 1-14 d by 59.98%(P>0.05).Extrusion + steam conditiong can achieve the effect of reducing the mortality by antibiotics in 1-14 d,and reduce the health risk greater.4.Extrusion significantly improved the apparent digestibility of DM,GE(P<0.05),Extrusion and steam conditioning both very significantly improved the apparent digestibility of CF,ADF and NDF(P<0.01).Extrusion significantly improved the content of total protein,globulin and the activity of lipase(P<0.05),significantly reduced the content of urea nitrogen(P<0.05);Steam conditioning significantly improved the content of total protein,albumin(P<0.05).Extrusion and steam conditioning both very significantly reduced the activity of cellulose,increased the activity of hemicellulose and pectinase(P<0.01).5.Extrusion significantly increased v/c in duodenum(P<0.05),steam conditioning significantly reduced the depth of duodenal crypt(P<0.05).Extrusion and steam conditioning both very significantly reduced the content of NH3-N(P<0.01),significantly increased the number of bifidobacteria(P<0.01)and the number of lactobacilli(P<0.05).Conclusion:The optimum extrusion parameters of the rabbit feed processing are barrel temperature 125 ?,moisture content 16%and feed rate 9 Hz.Extrusion can improve the feed pellet quality,nutrient digestibility,promote the development of intestinal tract and the secretion of digestive enzymes,promote the growth of beneficial bacteria in the intestines,reduce the health risk index and improve the growth performance of meat rabbits.Raw materials extrusion and steam conditioning treatment effect is the best,and can achieve the effect reducing rabbit diarrhea and mortality by adding antibiotics to its dietary. |
PDF Full Text Request