间接测热法和回归法估测棉籽粕和玉米蛋白粉在蛋鸡中的代谢能和净能值

Metabolizable Energy and Net Energy Values of Cottonseed Meal and Corn Gluten Meal for Laying Hens by Using Indirect Calorimetry Method and Regression Method

本研究旨在通过间接测热法和回归法估测蛋鸡棉籽粕和玉米蛋白粉的代谢能(ME)和净能(NE)值。试验选用504只32周龄体重一致的健康矮小型粉壳蛋鸡,随机分为7个处理,每个处理2个重复,每个重复36只鸡。对照组饲喂玉米-豆粕型基础饲粮,试验组分别饲喂棉籽粕或玉米蛋白粉按不同比例(5%、10%和20%)替代基础饲粮组成的试验饲粮。测定每1种饲粮的NE值时,将2组的蛋鸡预试7 d后,分别安排到2个相同的呼吸室中测定其3 d内采食饲粮过程中的产热量(HP);当基础饲粮的测定期结束后,测定蛋鸡绝食后1～72 h的HP。绝食代谢产热可用来估测蛋鸡的维持净能需要(NEm),通过析因法计算蛋鸡对饲粮的NE摄入量,并建立饲粮ME和NE值与待测原料替代比例之间的回归方程,从而推测出其ME和NE值。结果发现:蛋鸡在绝食第3天的HP和呼吸熵值极显著低于第2天(P<0.01);随着饲粮中棉籽粕或玉米蛋白粉替代比例的提高,蛋鸡采食单位重量饲粮后的热增耗逐渐提高;饲粮的有效能值[表观代谢能(AME)、氮校正表观代谢能(AMEn)和NE]随玉米蛋白粉替代比例的提高而逐渐升高,但随棉籽粕替代比例的提高而逐渐降低;根据饲粮有效能值与待测原料替代比例之间的关系建立线性回归方程后,得到棉籽粕的AME和AMEn值分别为10.61和9.45 MJ/kg DM,玉米蛋白粉的AME和AMEn值分别为17.62和15.80 MJ/kg DM,其中棉籽粕替代组饲粮NE=-2.321X1+8.676(R2=0.739 3),玉米蛋白粉替代组饲粮NE=3.210X2+8.880(R2=0.889 4),式中X1和X2分别代表饲粮中棉籽粕和玉米蛋白粉的替代比例。因此,在(20±1)℃的环境温度下,当矮小型粉壳蛋鸡处于产蛋高峰期时,棉籽粕和玉米蛋白粉的NE估测值分别为6.35和12.09 M J/kg DM,NE/AM E分别为59.91%和68.60%。

This experiment was conducted to estimate the metabolizable energy （ME） and net energy （NE） values of cottonseed meal and corn gluten meal for laying hens by using indirect calorimetry method and regres- sion method. A total of 504 32-week-old dwarf pink-shell laying hens with similar body weight were randomly allocated into 7 treatments with 2 replicates per treatment and 36 laying hens per replicate. Hens in the control group were fed a corn-soybean meal based diet, and hens in the other groups were fed the experimental diets which was basal diet substituted by different ratios （5% , 10% and 20% ） of cottonseed meal or corn gluten meal. After a 7-day adaptation period, two groups each with 36 hens were arranged into two same respiration chambers to measure the heat production （HP） for three days during the feeding period, and measured the HP at 1 to 72 h after fasting basal diet. The equilibrium fasting HP （FHP） may provide an estimate of NE require- ments for maintenance （NEm）. The NE intake from diets was determined by factorial method and the energy values of test ingredients were estimated based on the linear regression of dietary ME and NE values on substi- tution ratios. The results showed that the HP and respiration quotient of hens were lower on the 3rd day of star- vation than those on the 2nd day （P 〈 0.01 ）. The heat increment was increased with the increase of substitu- tion ratio of cottonseed meal or corn gluten meal. The dietary apparent metabolizable energy （ AME）, AME corrected for nitrogen retention （AMEn） and NE values were increased with the increase of substitution ratio of corn gluten meal, but decreased with the increase of substitution ratio of cottonseed meal. According to the lin- ear regression equation between the dietary available energy value and test ingredients substitution ratio, the AME and AMEn values of cottonseed meal were 10.61 and 9.45 MJ/kg DM, and the AME and AMEn values of corn gluten meal were 17.62 and 15.80 MJ/kg DM. The cottonseed meal substitution group dietary NE = -2.321X1 ＋8.676 （R2 =0. 739 3）, and the corn gluten meal substitution group dietary NE =3. 210X2 ＋ 8. 880 （R2 = 0. 889 4 ） , where X1 and X2 represented the substitution ratios of cottonseed meal and corn gluten meal, respectively. In conclusion, the NE estimation values of cottonseed meal and corn gluten meal are 6.35 and 12.09 MJ/kg DM, and the NE/AME are 59.91% and 68.60% for dwarf pink-shell laying hens at egg-laying peak when the environmental temperature is （20 ＋ 1 ） ℃.