产蛋期蛋鸡不同类型玉米净能研究

本试验利用禽用开放式呼吸测热装置进行能量代谢试验,通过间接测热法结合替代法测定不同类型玉米在产蛋期蛋鸡饲粮中的表观代谢能和净能。选用34周龄产蛋期海兰褐蛋鸡180只,随机分为6组,每组30只。试验选用1种玉米-豆粕型基础饲粮和5种待测饲粮。待测饲粮由5种待测玉米(3种2018年10月收获的正常玉米和2种2016年收获储存3年的陈化玉米),分别以50%比例替代基础饲粮构成。试验鸡在舍内笼养,预试期7 d,正试期27 d,其中正试期分为3期,每期9 d(适应3 d、呼吸测热3 d、绝食测热3 d)。每期试验中,从每组中选择4只试验鸡,称重后分别放入呼吸测热装置的12个代谢室(每个代谢室2只),每2个代谢室对应1种饲粮,测定气体交换和排泄物总量,呼吸测热的同时进行消化代谢试验。结果表明:与基础饲粮相比,5种玉米待测饲粮的表观代谢能显著提高(P<0.05),3种正常玉米待测饲粮的净能显著高于基础饲粮和2种陈化玉米待测饲粮(P<0.05);2种陈化玉米的表观代谢能和净能显著低于3种正常玉米(P<0.05)。本试验中,3种正常玉米的表观代谢能分别为16.19、15.85、16.17 MJ/kg,2种陈化玉米的表观代谢能分别为15.12和15.06 MJ/kg;3种正常玉米的净能分别为12.39、12.57、12.25 MJ/kg,2种陈化玉米的净能分别为11.29和12.05 MJ/kg。

Study on Net Energy of Different Types of Corn in Laying Hens

In this study,an open respiratory calorimeter for poultry was used for energy metabolism test,and the apparent metabolic energy and net energy of different types of corn in the laying hens'diet were determined by indirect calorimetry combined with substitution method.A total of 180 Hy-Line brown layers at the age of 34 weeks were randomly divided into 6 groups with 30 chickens in each group.The diets to be tested consisted of 5 corn varieties(3 normal corn harvested in October 2018 and 2 aged corn harvested and stored for 3 years in 2016),which were substituted for the basal diet by 50%respectively.The chickens were kept in a cage in the house.The pre-test period lasted for 7 days and the forward test period lasted for 27 days.The forward test period was divided into 3 phases,each of which lasted for 9 days(3 days for adaptation,3 days for respiratory heat measurement and 3 days for fasting heat measurement).In each phase of the experiment,4 chickens from each group were selected,weighed and put into 12 metabolic chambers(2 chickens for each metabolic chamber)of the respiratory calorimeter,and each 2 metabolic chambers was fed a kind of diet.The total amount of gas exchange and feces was measured,and the digestion and metabolism test was conducted while the respiration and heat were measured.The results showed that,compared with the basal diet,the apparent metabolic energy of the 5 corn diets under test was significantly increased(P<0.05),and the net energy of the 3 normal corn diets under test was significantly higher than that of the basal diet and 2 aged corn diets under test(P<0.05).The apparent metabolic energy and net energy of the 2 aged corn were significantly lower than those of the 3 normal corn(P<0.05).In this experiment,the apparent metabolic energy of 3 normal corn is 16.19,15.85 and 16.17 MJ/kg,and that of 2 aged corn is 15.12 and 15.06 MJ/kg,respectively.The net energy of 3 normal corn is 12.39,12.57 and 12.25 MJ/kg,and that of 2 aged corn is 11.29 and 12.05 MJ/kg,respectively.