粪便收集方式对异育银鲫表观消化率测定的影响

消化率的高低是评价饲料营养价值的重要指标,但是粪便的不同收集方式会影响消化率的测定结果。研究观察了异育银鲫摄食后的排粪高峰以及排粪持续时间,探讨了粪便的不同收集方式对异育银鲫(Carassius auratus gibelio)(约100 g)表观消化率(Apparent digestibility coefficient,ADC)测定结果的影响。饲料中加入1%三氧化二铬(Cr2O3)作为指示剂,实验采用3种粪便收集方法(积粪器法、虹吸法和后肠取粪法),并且在积粪器法和虹吸法中设置了不同的收粪时间。结果表明,正常投喂的异育银鲫摄食后的排粪高峰出现在摄食结束后的5—10h;饥饿2d的异育银鲫恢复摄食后的排粪高峰出现在摄食结束后的7—9h;饲料的干物质表观消化率(ADC of dry matter,ADCd)和蛋白表观消化率(ADC of protein,ADCp)在排粪初始阶段较低,随着排粪高峰的出现而升高。粪便的不同收集方法和不同收集时间对ADCd和ADCp的测定结果均存在显著影响(P<0.05)。采用虹吸法收集粪便测得的ADCd与在排粪高峰时段内积粪器法的测定值相当;后肠取粪法收集粪便测得的ADCd低于积粪器法排粪高峰期的测定值。采用虹吸法收集粪便测得的ADCp略低于在排粪高峰时段内积粪器法的测定值;后肠取粪法收集粪便测得的ADCp低于积粪器法各时间段内的测定值。因此,在选择挑选新鲜完整粪便的前提下,在排粪高峰期采用虹吸法收集粪便用于ADC的测定是一种方便可靠的方法,反而后肠取粪法由于操作误差容易带来更大偏差。

EFFECT OF FAECES COLLECTION METHODS ON ESTIMATION OF APPARENT DIGESTIBILITY COEFFICIENT IN GIBEL CARP (CARASSIUS AURATUS GIBELIO)

Digestibility is an important index for nutrition estimation of fish feed,but different faeces collection methods have been reported to result in great difference of apparent digestibility coefficient(ADC) estimation.This experiment investigated the faecal production fastigium and duration for gibel carp(Carassius auratus gibelio)(about 100 g);and compared the difference among the ADC values from different faeces collection methods.Chromic oxide(Cr2O3) at 1% was added as a marker.We chose three different faeces collection methods: faeces collector,siphoning from the tank bottom and intestine dissection;and set different faeces collection times in faeces collector and siphoning methods.The results revealed that,faecal production fastigium of normally feeding gibel carp was 5―10h after feeding;faecal production fastigium of pre-fasted gibel carp was 7―9h after feeding;ADC of dry matter(ADCd) and ADC of protein(ADCp) of gibel carp was low in initial phase of defecation,and then increased with the appearance of faecal production fastigium.Different faeces collection methods and times has significantly affected the determination of ADCd and ADCp for gibel carp(P<0.05).The ADCd for siphoning was similar to that for faeces collector at faecal production fastigium;the ADCd for dissection was lower than that of siphoning and faeces collector at faecal production fastigium.The ADCp for siphoning was lower than that of faeces collector at faecal production fastigium;the ADCd for dissection was lower than that of siphoning and faeces collector at all sampling times.On base of selecting fresh and complete faeces,siphoning was a convenient and credible faeces collection method for ADC determination.But dissection may induce more deviation facility,because of procedural errors.