用体外产气法评价玉米秸秆、稻草、玉米秸秆青贮与精料的组合效应

本试验旨在应用体外产气法研究玉米秸秆、稻草、玉米秸秆青贮与精料间的组合效应。采用单因素试验设计,进行3次组合筛选试验:首先进行玉米秸秆与稻草组合试验,筛选出最优玉米秸秆和稻草组合(玉米秸秆-稻草)比例;再进行玉米秸秆-稻草与玉米秸秆青贮组合试验,筛选出最优玉米秸秆-稻草和玉米秸秆青贮组合(玉米秸秆-稻草-玉米秸秆青贮)比例;最后进行玉米秸秆-稻草-玉米秸秆青贮与精料组合试验,筛选出最优玉米秸秆-稻草-玉米秸秆青贮与精料组合比例。各组合均分别以100.0∶0、80.0∶20.0、60.0∶40.0、50.0∶50.0、40.0∶60.0、20.0∶80.0、0∶100.0进行体外发酵试验,每个组合设3个重复。利用体外产气法分析不同饲料组合对48 h产气量、干物质消失率(DMD)、p H及微生物蛋白(MCP)、氨态氮(NH3-N)、挥发性脂肪酸(VFA)浓度的影响。计算各组合的单项组合效应指数(SFAEI)和多项组合效应指数(MFAEI)。结果表明:1)各饲料以不同比例组合对产气量均有显著或极显著影响(P0.05或P0.01),玉米秸秆∶稻草、玉米秸秆-稻草∶玉米秸秆青贮、玉米秸秆-稻草-玉米秸秆青贮∶精料产气量的SFAEI分别在60.0∶40.0、40.0∶60.0、20.0∶80.0时达最大值;2)各饲料以不同比例组合对DMD也存在显著或极显著影响(P0.05或P0.01),玉米秸秆∶稻草、玉米秸秆-稻草∶玉米秸秆青贮、玉米秸秆-稻草-玉米秸秆青贮∶精料DMD的SFAEI分别在50.0∶50.0、40.0∶60.0、20.0∶80.0时达最大值;3)不同玉米秸秆-稻草-稻草∶精料对p H有极显著影响(P0.01);4)各饲料以不同比例组合对MCP浓度也存在显著或极显著影响(P0.05或P0.01),玉米秸秆∶稻草、玉米秸秆-玉米秸秆青贮∶玉米秸秆青贮、玉米秸秆-稻草-玉米秸秆青贮∶精料产气量的SFAEI分别在80.0∶20.0、40.0∶60.0、20.0∶80.0时达最大值;5)各饲料以不同比例组合对NH3-N浓度也存在显著或极显著影响(P0.05或P0.01),范围在20.20~31.59 mg/d L;6)玉米秸秆与稻草组合的乙酸/丙酸和玉米秸秆-稻草-玉米秸秆青贮与精料组合丁酸浓度在各比例间差异不显著(P0.05),各饲料以不同比例组合对其余VFA和TVFA浓度也存在显著或极显著影响(P0.05或P0.01)。以MFAEI进行评定各饲料组合的最优比例如下:玉米秸秆与稻草为60.0∶40.0;玉米秸秆、稻草与玉米秸秆青贮为24.0∶16.0∶60.0;玉米秸秆、稻草、玉米秸秆青贮与精料为9.6∶6.4∶24.0∶60.0。

Associative Effects of Corn Stalk,Rice Straw,Corn Stalk Silage and Concentrate Evaluated by Gas Production Technique in Vitro

This experiment was conducted to investigate the associative effects of corn stalk (CS), rice straw(RS), corn stalk silage (CSS) and concentrate (CC).Single factor experiment was started with the screening for the optimal proportion of combination of CS and RS (CS-RS), which was subsequently recombined with CSS to screen the optimal proportion of combination of CS-RS and CSS (CS-RS-CSS), finally, CC was added to screen the optimal proportion of combination of CS-RS-CSS and CC.Every combination was tested in vitro with the proportions of 100.0∶0, 80.0∶20.0, 60.0∶40.0, 50.0∶50.0, 40.0∶60.0, 20.0∶80.0 and 0∶100.0with 3 replicates, respectively.In vitro gas production method was performed to analyze 48 h gas production,dry matter disappearance rate (DMD) , pH, and the concentrations of microbial crude protein (MCP) , ammonia nitrogen (NH3-N) and volatile fat acids (VFAs), as well as to calculate single factor associative effects index (SFAEI) and multiply factors associative effects index (MFAEI).The results showed as follows: 1)feeds combined at different proportions had significant effects on gas production (P<0.05 or P<0.01), and SFAEI of gas production for CS ∶RS, CS-RS ∶CSS and CS-RS-CSS ∶CC reached the biggest at the proportions of 60.0∶40.0, 40.0∶60.0 and 20.0∶80.0, respectively;2) feeds combined at different proportions had significant effects on DMD (P<0.05 or P<0.01), and the optimal proportions of CS ∶RS, CS-RS ∶CSS and CS-RSCSS ∶CC were 50.0∶50.0, 40.0∶60.0 and 20.0∶80.0 according to the SFAEI, respectively;3) different proportions of CS-RS-CSS and CC had significant effects on pH (P<0.01);4) feeds combined at different proportions had significant effects on MCP concentration (P<0.05 or P<0.01), and the optimal proportions of CS ∶RS, CS-RS ∶ CSS and CS-RS-CSS ∶ CC were 80.0 ∶ 20.0, 40.0 ∶ 60.0 and 20.0 ∶ 80.0 according to the SFAEI, respectively;5) feeds combined at different proportions had significant effects on NH3-N concentration (P<0.05 or P<0.01) changing from 20.20 to 31.59 mg/dL;6) there were no significant differences in acetic acid/propionic acid among different proportions of combinations of CS and RS, and in butyric concentration among different proportions of combinations of CS-RS-CSS and CC (P>0.05), and feeds combined at different proportions had significant effects on the rest VFA and TVFA concentrations (P<0.05 or P<0.01).Using MFAEI to assess the optimal results of associative effect, it is conclude that the optimal proportions are as follows∶ CS ∶RS is 60.0∶40.0;CS ∶RS ∶CSS is 24.0∶16.0∶60.0;CS ∶RS ∶CSS ∶CC is 9.6∶6.4∶24.0∶60.0.