糊化淀粉尿素对奶牛生产性能和氮利用率的影响

Effects of starea on production performance and nitrogen utilization in lactating dairy cows

试验以5头装有瘤胃瘘管的、处于泌乳中后期荷斯坦奶牛为研究对象,采用5×5拉丁方试验设计。对照组饲喂不含尿素日粮,U-16%组用尿素氮替代日粮总氮的16%,S-16%、S-24%和S-32%组分别用糊化淀粉尿素氮替代日粮总氮的16%、24%、32%。第1期适应期14d,以后每期适应期7d,采样期5d,共67d。比较研究尿素氮和糊化淀粉尿素氮替代日粮总氮的不同水平对泌乳奶牛生产性能、氮利用率的影响。结果表明糊化淀粉尿素氮替代日粮总氮的16%、24%,与对照组相比奶牛生产性能均没有显著影响(P>0.05)。当糊化淀粉尿素氮替代水平达32%时,显著降低干物质采食量(P<0.05),并降低了产奶量,但差异不显著(P>0.05);奶牛血液尿素氮随着不同糊化淀粉尿素氮替代水平的增加而提高,但差异不显著(P>0.05),对乳中尿素氮的影响在各组间差异也不显著(P>0.05);糊化淀粉尿素氮替代日粮总氮的不同水平对氮排放的影响上。当替代水平为16%时,糊化淀粉尿素与尿素相比能降低氮排放,但差异不显著(P>0.05),但是当糊化淀粉尿素氮替代日粮总氮水平达24%和32%时,排放总氮占摄入总氮的比例显著高于其他各组(P<0.05),会降低日粮氮的利用率,增加氮排放。结果揭示在同时保证奶牛生产性能和不增加氮排放的基础上,在泌乳奶牛上糊化淀粉尿素氮替代日粮总氮的适宜比例为16%,不宜达到24%。

Five mid-late lactating Holstein cows with rumen fistula were divided into five groups in a 5 × 5 latin square test design,cows of the five groups were fed with control diet without urea,U- 16% diet with replacing 16% of the total nitrogen of control diet with non protein nitrogen from urea,S-16%,S-24%and S-32% diet with replacing 16%,24%and 32;/60 of the total nitrogen of control diet with non protein nitrogen from starea. The first adaptive phase is 14 d and the other phase is 7 d,the sampling period in every phase is 5 d,all of the experiment lasted 67 d. Results indicated that,replacing 16% and 24% of the total nitrogen of control diet with non protein nitrogen from starea could not affect the production performance significantly （P;0.05）,but the S-32% group reduced the dry matter intake and milk production （P ; 0. 05）. The blood urea nitrogen （BUN） increased with the level of starea but there were no significant differences in BUN and milk urea nitrogen （MUN） （P〈0.05）. There were no significant differences （P;0.05） in nitrogen emisssion between starea and urea, which replaced 16 % of the total nitrogen, but when the starea nitrogen replaced 24% and 32 % of the total nitrogen,the total nitrogen excretion of nitrogen intake was significantly higher than other groups （P〈0.05）,it can reduce the nitrogen utilization of the diet and increase the pollution of nitrogen in environment. Therefore, we can come to a conclusion that,in the premise of not increasing the nitrogen emission,the proper proportion of replacing the total nitrogen of diets with starea nitrogen is 16% ,and being unfavorable to 24%.