【作者】 焦浩鹏；

【导师】 薛白；

【作者基本信息】 四川农业大学 ， 动物营养与饲料科学， 2010， 硕士

【摘要】 本试验研究共分为三个试验：试验一,分别以豆粕、磷酸脲和矿物质缓释尿素为氮源,配置了三种等能等氮日粮,分别为豆粕组(SBM组)、磷酸脲组(UP组)和矿物质缓释尿素组(SRU组),采用注射器式体外模拟发酵装置,分别在0、1、2、4、6、8、10、14、18和24h后终止发酵,测定瘤胃培养液中pH、氨氮浓度(NH3-N)和微生物蛋白(MCP)浓度。结果表明：UP组的pH值出现峰值较早,在第4h出现最大值(6.79)；而SBM组和SRU组分别在第10h和第6h达到最大值,pH值分别为6.82和6.76。UP组其氨氮浓度在第2h便达到最大值(59.01 mg/100ml)；而SRU组在第8h才达到最大值(52.37mg/100ml)。试验各组微生物蛋白浓度变化规律相近,在24小时内缓慢上升,都在第24h达到最大值。但可以看出UP组在第24h时的微生物蛋白浓度显著低于(P<0.05)SBM组和SRU组。体外发酵试验表明,在等能等氮的条件下,矿物质缓释尿素组氨的释放速度较为平缓,矿物质缓释尿素组与豆粕组所产生的微生物蛋白无显著差异。试验二,分别以豆粕、磷酸脲和矿物质缓释尿素为氮源,配制了三种等能等氮饲料,按氮来源不同分别命名为豆粕组(SBM组)、磷酸脲组(UP组)和矿物质缓释尿素组(SRU组)。选3头体重相近的2岁瘘管牦牛,采用3×3拉丁方设计,每期12天,在试验期的第11天选取10个时间点,连续24h测定瘤胃液的pH值、NH3-N和MCP浓度；在试验的第12天食前1h采集血清,并测定动物血清尿素氮、总蛋白、血清磷和血清钙浓度。结果显示：在24小时内,试验各组pH值和氨氮浓度变化规律相近,都呈先升高,后降低,又升高的趋势。试验各组pH值和氨氮浓度都在食后第2h小时达到最大值；但在第2h,UP组的pH值和氨氮浓度极显著高于SBM组和SRU组(P<0.01),而SBM组和SRU组差异不显著(P>0.05)。试验各组MCP浓度变化规律相近,都呈先升高,后降低的趋势,并且都在第10h时达到最大值。在第10h时,UP组的微生物蛋白浓度显著低于(P<0.05)SBM组和SRU组,而SBM组和SRU组差异不显著(P>0.05)。试验各组血清Ca和血清P浓度差异不显著(p>0.05)；SRU组的血清总蛋白浓度为87.23g／L,显著高于(P<0.05)SBM组(84.27 g／L)和UP组(84.54g/L)。试验表明,在等能等氮的条件下,矿物质缓释尿素组所合成的微生物蛋白与豆粕组无显著差异,能够代替饲料中的部分蛋白源。试验三,试验选体重350kg左右西门塔尔杂交牛20头,按年龄、体重均等的原则,随机分为四组,每组5头,分别接受四种日粮处理,四种日粮按不同氮源命名,分别为：大豆粕组(SBM)、磷酸脲组(UP)、矿物质缓释尿素组Ⅰ(SRUⅠ,0.35%)和矿物质缓释尿素组Ⅱ(SRUⅡ,0.75%)试验牛在试验期第1天和最后一天早上空腹称重,称重后采集血液样品用于测定血清钙、血清磷、血清尿素氮和血清总蛋白浓度。结果表明,SRUⅠ组日增重为974.29g,比对照组、SBM组、UP组和SRUⅡ组分别高出6.81%、4.28%和0.96%,与SBM组差异极显著(P<0.01)。而SRUⅡ组日增重为965.00g,比对照组SBM组合UP组高出5.80%和3.29%,与SBM组差异极显著(P<0.01)。试验各组血氨浓度均处于正常水平。试验各组血清Ca和血清P浓度差异不显著(P>0.05); SURⅠ和SRUⅡ组的血清尿素氮与SBM组差异不显著(P>0.05),显著低于(P<0.05)UP组；尽管试验各组血清总蛋白浓度差异不显著(P>0.05),但除UP组外,其余试验组在试验期后均有所增加,其中SRUⅠ组最高,分别高于SBM组3.82%,高于UP组3.17%。试验表明,矿物质缓释尿素较豆粕组和磷酸脲组生产性能更高。矿物质缓释尿素添加量为0.35%时的生产性能较添加量为0.75%时高,其经济效益也最高。更多还原

【Abstract】 This study contained three trials:Trial 1:Three diets containing different N source were used to determine the effect of N source on in vitro fermentation characteristics. The diets were formulated to be iso-energy and iso-nitrogen, with slow-release urea (SRU), urea phosphate (UP) and soybean meal (SBM) as N source. Samples were taken at 0,1,2,4,6,8,10,14,18 and 24hr incubation, for the determination of gas production, NH3 and MCP concentration. Results were:The pH peak of UP (6.79) appeared at 4h incubation; while that of SBM (6.82) and SRU (6.76) appeared at 10h and 6h incubation, respectively. The maximum ammonia-N concentration of UP (59.01 mg/100ml) and SRU (52.37 mg/100ml) were at 2h and 8h incubation, respectively. Microbial protein concentrations in all groups, increased slowly within 24 h incubation. However, the microbial protein concentration of UP was significantly lower than that of SRU and SBM at 24h (P<0.05). The trial in vitro fermentation under iso-energy and iso-nitrogen conditions indicated that the ammonia release speeds in SRU were more gentle and there was a similar productivity in microbial protein between SRU and SBM.Trial 2:Three rumen-fistulated yak were used in a 3 x 3 Latin square experiment with three periods, each of 12 days, consisting a 11-day adaptation period, and 1 day for rumen fluid collection. Three iso-nitrogen and iso-energy diets were formulated, using slow-release urea (SRU), urea phosphate (UP) and soybean meal (SBM) as N source. Rumen fluid samples began collected at the beginning of the 12th day in each period, Ten samples were collected in consecutive 24 h for the determinination of the effect of N sources on rumen pH, NH3-N and microbial protein concentration. Blood samples were collected on the 12th day in each period to measure the serous urea nitrogen, total protein, serous phosphorus and serous calcium concentration. Rumen pH and NH3-N in all the groups increased first, then decreased, and increased again in 24h and reached the maximum value which attained at 2h after feeding. Rumen pH and ammonia-nitrogen of UP group were significantly greater (P<0.01) than that of SBM and SRU at 2h after feeding. There was no difference (P>0.05) on rumen pH and ammonia-nitrogen between SBM and SRU group. Rumen microbial protein concentration in all groups increased first, then decreased, and increased again till the maximum value which attained at 10 h after feeding. Microbial protein concentration in UP group was significantly greater (P<0.01) than that in the other two groups, while that in SBM group kept similar (P>0.05) to that in SRU group. There was no difference (P>0.05) in serous Ca and serous P among the three groups. Serous total protein in SRU group (87.23g/L) was greater (P<0.05) than that in SBM (84.27 g/L) and UP group (84.54 g/L). The trial under iso-energy and iso-nitrogen conditions indicated that there was a similar productivity in microbial protein between SRU and SBM and the minerals slow-release urea can replace a part of protein source in feed.Trial 3:20 Simmental crossbred beef cattle with similar age and weight were randomly divided into four groups which were also randomly assigned to four dietary treatments. The 4 groups were therefore named, according to N source, as soybean meal group (SBM), urea phosphate group (UP), mineral slow-release urea groupⅠ(SRUⅠ,0.35%) and mineral slow-release urea groupⅡ(SRUⅡ,0.75%), respectively, with the fist 2 groups served as control group. Diets in all groups were iso-nitrogen and iso-energy, except for that in SRUⅡgroup, which was greater in N content because of the greater value of SRU addition. All the cattle were weighed at the beginning and the end of the 28-day feeding trial. Blood samples were collected at the last day before feeding for the measurement of serous calcium, serous phosphorus, serous urea and total serous protein. The average daily gain of cattle in SRUⅠgroup was 974.29 g, which was 6.81%,4.28% and 0.96% higher than, that in SBM (P<0.01), UP (p> 0.05) and,SRUⅡ(P>0.05) group, respectively. The average daily gain of cattle in SRUⅡgroup was 965.00g, which was 5.80% and 3.29% higher than that in SBM (P<0.01) and UP (P>0.05). The blood ammonia concentration in all groups kept at normal level. There were no difference (P>0.05) on serous Ca and serous P concentrations among the four groups. The serous urea in SRUⅠwas similar (P> 0.05) to that in SURⅡand SBM, and significantly lower (P<0.05) than that in UP group. Even though there was no significant difference (P>0.05) in serous total protein among four groups in the beginning and end of trail, serous total protein concentrations in SBM, SRUⅠand SRUⅡgroup were higher (p<0.05) in the end of the trial than that in the beginning of the trial, and in the end of trail the serous total protein concentration in SRUⅠgroup was the highest, which was 3.82% and 3.17% higher than that in SBM and UP group, respectively. The trial showed that the performance in SRU was greater than that in SBM and UP groups. The performance and benfits in 0.35% minerals slow-release urea was better than that of 0.75% minerals slow-release urea.更多还原