【作者】 张召辉；

【导师】 颜培实；

【作者基本信息】 南京农业大学 ， 动物营养与饲料科学， 2005， 硕士

【摘要】 体温日节律为恒温动物健康的标示,泌乳奶牛体温,呼吸数和体液酸碱度也都存在昼夜间波动性。夏季温热环境对体液酸碱度影响颇深,白天高温期间由于过高的呼吸频率产生呼吸性碱中毒,因机体过度调节又在晚上相对凉爽时导致补偿性代谢酸中毒。本研究探讨日粮阴阳离子差及其不同的调剂时间对暑热期间不同生产水平泌乳奶牛的影响。 第一部分研究在中等程度热应激情况下,DCAD不同调剂时间对中低产奶牛生产性能和体液酸碱状况的影响。选择泌乳中期奶牛10头,随机分成二组（A和B组）,A组为对照组,采用常规日粮,DCAD为32.4mEq/100g DM;B组是将A组全天精料所加盐分全部于早上一次添加。结果表明,DCAD调剂时间对泌乳奶牛生产性能具有显著影响,采食量和产奶量分别提高16.7%（P<0.05）和19.4%（P<0.01）;除非脂固型物（NFC）（P<0.01）外,乳蛋白、乳脂、乳糖以及乳中粗略矿物质含量的影响不显著;14:00尾静脉血样测定表明,血Na⁺、K⁺、Ca²⁺浓度和血pH、pCO₂和HCO₃^-组间差异不明显,B组碱储增加,为正值,但组间差异不显著;尿pH升高（P<0.05）,Na⁺、K⁺、Ca²⁺排出量有增加趋势,尿中强离子差（Strong ion difference,SID.Na+K-C1）降低。 第二部分研究不同DCAD水平和调剂时间对高产奶牛产量、体温、呼吸数和血尿参数的影响。选择高产荷斯坦奶牛18头,随机分成三组,每组6头,A组为对照组,采用基础目粮,B组在A组基础上,早上日粮精料中增加30gK₂CO₃,C组是在A组基础上早上和中午精料中各增加15g K₂CO₃+20gNaHCO₃。使A、B、C日粮DCAD分别为42.3,47.16和52.54 mEq/100g DM。结果表明,同对照组相比,B、C组产量分别提高8.9%和10.4%;试验全期B组直肠温度均低于A、C组,其中15:00和23:00体温对比差异显著（P<0.05）,A与C差异不明显;对应时间测定的呼吸数在整个试验期间差异均不明显。早上5:30尾动脉血气测定结果表明,C组HCO₃^-浓度和TCO₂显著高于A、B组,碱储在A、B均为负值,且B组显著低于A组,14:00测定的血气参数在组间差异不显著。同对照相比,血清Ca²⁺降低（P<0.05）。测定的尿参数在组间差异不显著,但尿pH同DCAD的变化趋势一致。对所选取的几个典型时段分析表明,B组在高温持续期有比A、C组相对较低的产奶量下降幅度:15:00和23:00的更多还原

【Abstract】 The rhythms in deep body temperature is a sign which indicates the homoiothermal animal is in the healthy status. There are the diurnal fluctuations in body temperature, respiration rate, and acid-base balance of lactating dairy cows under summer condition. The acid-base status of lactating dairy cows was affected in hot humid weather. During the hot part of the day, blood and urine pH were higher, and blood pCO2 and the content of HCO3" were lower, which suggested respiratory alkalasis. During the cooler part of the day, blood and urine pH fell, and the content of blood HCO₃was lower, which suggested compensated metabolic acidosis. The research aimed at determing the effects of dietary cation-anion difference and administration time-dependent on performance acid-base and mineral status under summer condition in mid and high-yielding dairy Cows.The first part of this research studied administration time-dependent influence of dietary cation-anion difference on performance acid-base and mineral status under summer condition in mid-yield dairy cows Ten mid-lactation Holstein cows were assigned randomly to A or B, A was control, which was feed basic diet and DCAD equal 32.4 mEq/100g DM. The total of salt in A concentrate was added to the morning concentrate of B. The results indicated that administration time-dependent of dietary cation-anion difference significantly influenced the performance of heat-stress dairy cows. Intake of DM and 4% FCM increased 16.7% （P<0.05） and 19.4% （P<0.01）, respectively; Expect of NFC （P<0.01）, milk fat protein lactose and rough mineral were not altered by administration time of dietary cation-anion difference; Blood samples taken from the caudle vein at 14:00 indicated that blood Na K and Ca and blood pH carbon dioxide partial pressure and HCO3’ concentration were not altered by the administration time, Blood base excess increased in B, but the difference between groups was not significant. Urine pH was increased （P<0.05） ,and the excretion of urinary Na K and Cl had the tendency to be raised. And the urine strong ion difference （SID=Na⁺+K⁺-Cl^-） was decreased.The second part of this research studied the effects of dietary cation-anion difference and administration time-dependent on milk yield rectal temperature, respiration rate and blood and urinary parameters. Sixteen high-lactation Holstein cows were assigned randomly to A,B, and C. A was control, which was feed basic diet; on the base of A,B was added 30g K2CO3 to the concentrate of breakfast; C was added 15gK2CO3and 20gNaHCO3 to each the concentrate of breakfast and lunch on the base of A. The dietary cation-anion difference of A,B, and C is 42.3, 47.16, and 52.45mEq/100g DM, respectively. The results indicated that DCAD and administration time-dependent influenced the performance of heat-stress dairy cows. Milk yield of B and C increased 8.9% and 10.4%, respectively. Rectal temperature of B was lower than A and C during the experiment, and measured values at 15:00 and 23:00 lower significantly（ P<0.05 ）. Respiration rate is not significant in A, B, and C during experiment. The results of caudal artery blood gas measured at 5:30 indicated that blood bicarbonate and TCO₂ of C increase significantly. Base excess was negative value in A and B, and B lower significantly than A. The results of blood gas measured at 14:00 different insignificantly. The results of caudal vein serum ions indicated that serum concentration of Ca²+ decrease significantly compared with A. Urinary parameters different insignificantly, but urine pH was increased by DCAD. The analysis of typic periods indicated that rectal temperature , respiration rate and the level of decrease in yield in B were lower significantly during continuous hot summer, and implied that the improvement of physiological parameters and performance benefit from the fitting DCAD and administration time-dependent.更多还原