摘要
【目的】哺乳期犊牛胃肠道功能尚未健全,对日粮的消化能力不足,易导致腹泻等营养性疾病的发生,降低成活率。实施早期断奶的哺乳期犊牛日粮以液体的代乳品为主,其酸度对犊牛健康有着比成年牛更加重要的影响,但目前犊牛血气指标变化的规律、正常值范围等数据仍不成体系,无法判别日粮酸度是否适宜。本研究以48头新生荷斯坦公犊牛研究液体饲料pH值对哺乳期犊牛血气指标的影响,探索犊牛血气指标的变化规律。【方法】采用2×4因子设计,2种代乳品,其植物蛋白占总蛋白比例分别为50%和80%,代乳品乳液pH值分别调整为6.2、5.5、5.0、4.5,共计8个处理组。将48头新生荷斯坦公犊随机分配到上述8个组中,分别饲喂上述代乳品乳液。试验期63 d,其中预试期21d,正试期42 d。每两周测定犊牛体重,每日记录代乳品和颗粒料的采食量;在21、49 d抽取全血检测血液pH值、二氧化碳分压(pCO2)、氧气分压(pO2)、氧饱和度(SO2)、[HCO3-]浓度(HCO3-)、实际剩余碱量(ABE)、总二氧化碳量(TCO2)、标准碳酸氢盐浓度(SBC)和标准剩余碱(SBE)。采用SAS软件GLM或MIXED模型对生长性能或血气指标进行统计分析,以REG模型建立血气指标与代乳品乳液pH值之间的相关关系式,以正态分布检验血气指标的变化。【结果】降低代乳品乳液pH值可提高犊牛平均日增重(P<0.05);代乳品乳液pH值对犊牛血液pO2、SO2、HCO3-、ABE、TCO2、SBC和SBE皆有极显著的影响(P<0.01),对血液pH值、pCO2也具有影响趋势;随着代乳品乳液pH值的降低,犊牛血液pH值、pCO2、pO2、SO2、HCO3-、TCO2呈现出二次曲线变化规律(P<0.05),R2分别达到0.9201、0.8481、0.8600、0.9445、0.8631、0.8141,ABE、SBC和SBE则呈现出直线型改变(P<0.05),R2分别为0.9060、0.8126、0.8298。血液pH值和pCO2随日龄变化有显著改变(P<0.05);除HCO3-、ABE、SBE外,其他血气指标符合正态分布规律(P>0.05)。代乳品中植物蛋白占总蛋白的比例由50%提高到80%时,犊牛平均日增重和干物质采食量降低,但血气指标并未受到影响(P>0.05)。【结论】随代乳品乳液pH值的降低,21—63 d犊牛血液HCO3-、ABE、TCO2、SBC、SBE显著降低,可作为评价日粮酸度效果的敏感指标。
【Objective】 Due to the immature gastrointestinal function and low ability digest dietary, diarrhea or other nutritional diseases were easy to arise in suckling calves that bring about low survival rate. Compared with adult cattle, liquid milk replacer is the main feed for the early weaned calves. Thus, acidity of milk replacer emulsions has more important effect on calf health. But the change regulation, the normal value scope of blood gas parameters in calves are not in any systematic manner, so that it is unable to determine whether the appropriate dietary acidity is. To study the change regulations of blood gas parameter in calves, an experiment was carried out to investigate the variations of blood gas parameters in calves which fed liquid feed with different pH. 【Method】The pH values of a milk replacer(6.2, 5.5, 5.0 or 4.5) and the ratio of vegetable protein to total protein in the milk replacer(50% or 80%) were used to form an 2 × 4 factorial design in this experiment. Forty-eight neonatal healthy Chinese Holstein male calves were allotted into eight groups and each group was fed with one of the 8 milk replacer emulsions. The experiment lasted 63 d with 21 d for adaptation and 42 d for test. Growth performance was determined fortnightly, the intake of milk replacers and pellet diet were recorded every day. Blood samples were collected on 21 d and 49 d. The pH value, partial pressure of carbon dioxide(pCO2), partial pressure of oxygen(pO2), oxygen saturation(SO2), the concentration of [HCO3-](HCO3-), actual base excess(ABE), total carbon dioxide volume(TCO2), standard bicarbonate concentration(SBC), standard base excess(SBE) of the blood samples were determined. Data of growth performance or blood gas parameters were analyzed using the GLM or MIXED procedure of SAS software, the regression equations between blood gas parameters and milk replacer emulsion pH value were established by REG procedure, and the changes of blood gas parameters were analyzed using normal distribution test. 【Result】The results showed that the average daily gain were improved while the pH value of milk replacer decreased(P〈0.05). The pH value of milk replacer siginificantly affected blood pO2, SO2, HCO3-, ABE, TCO2, SBC and SBE(P〈0.01). pH value, pCO2, pO2, SO2, HCO3- and TCO2 showed a quadratic curve(P〈0.05) as milk replacer emulsion pH value decreased with R2 as 0.9201, 0.8481, 0.8600, 0.9445, 0.8631, 0.8141, respectively, meanwhile ABE, SBC, SBE were showed a linear turn(P〈0.05) with R2 as 0.9060, 0.8126, 0.8298. Blood pH and pCO2 were varied remarkably with the age of day increasing(P〈0.05). Blood gas parameters were in line with the normal distribution(P〈0.05) except for HCO3-, ABE, SBE. While the ratio of vegetable protein to total protein of milk replacer increased from 50% to 80%, the average daily gain and dry matter intake of calves decreased, but blood gas parameters were unaffected(P〈0.05). 【Conclusion】The blood HCO3-, ABE, TCO2, SBC,and SBE of calves aged 21 to 63 days significantly decreased with the pH value of milk replacer dropping. Blood gas parameters can be used as sensitive indices to evaluate the effect of dietary acidity on calves.
出处
《中国农业科学》
CAS
CSCD
北大核心
2014年第17期3465-3474,共10页
Scientia Agricultura Sinica
基金
奶牛产业技术体系北京市创新团队
国家科技攻关计划(2006BAD04A03-03)
关键词
犊牛
血气指标
代乳品
PH值
酸度
calves
blood gas analysis
milk replacer
pH value
acidity