Effects of feeding level of milk replacer on body growth,plasma metabolite and insulin concentrations,and visceral organ growth of suckling calves

The objective was to evaluate effects of feeding level of milk replacer on body growth, plasma metabolite and insulin concentrations, and allometric growth of visceral organs in suckling calves. Holstein bull calves (n = 8; 3–4 days of age) were fed either a low amount (average 0.63 kgDM/day, LM) or high amount (average 1.15 kgDM/day, HM) of high protein milk replacer until they were slaughtered at 6 weeks of age. Body weight (BW) at 4, 5, and 6 weeks of age, feed intake, average daily gain, and feed efficiency were higher in the HM than LM calves. The HM group had higher plasma glucose at 3 and 4 weeks of age and insulin levels after the age of 4 weeks compared with LM calves whereas no effect was detected on plasma nonesterified fatty acid or urea nitrogen concentrations. The HM calves had greater empty body weight (EBW), viscera‐free BW and most of the organs dissected than LM calves. Relative weights (% of EBW) of liver, spleen, kidneys, and internal fat were higher, whereas head and large intestine was lower in HM than LM calves. The results suggest that increased milk feeding levels would accelerate the growth of the body and specific organs.     

益生菌Lactobacillus casei Zhang在马乳中发酵特性及人工消化液耐受性研究

将益生菌L．casei Zhang以2．0×10^7cfu／g的接种量接种在马乳中进行发酵,测定其发酵特性及28d贮藏期间人工消化液的耐受性。结果表明,在发酵结束（pH4．5）时,活菌数较接种时增加了1．11个对数单位。在28d贮藏期间,发酵马乳样品pH降低了0．35个单位,滴定酸度增加了16°T,活菌数保持在10^8cfu／g以上。贮藏28d后,发酵马乳样品中L．casei Zhang在pH2．5和2．0人工胃液消化3h后,其存活率分别为100．6％和46．22％,又经人工肠液消化8h后,存活率分别降为74．83％和11．04％。L.casei Zhang保持良好的贮藏稳定性及较好的人工消化液耐受性,显示了其应用于发酵乳制品中良好的潜力。     

玉米皮膳食纤维乳饮料的研制

通过单因素试验研究了甜味剂、酸味剂、玉米皮SDF的用量对乳饮料产品感官品质的影响,确定了甜味剂用量为白糖4%、安赛蜜0.01%、甜蜜素0.04%,酸味剂用量为柠檬酸0.2%、苹果酸0.1%、乳酸0.1%,玉米皮SDF添加量8%.通过正交试验研究了几种单体稳定剂对产品稳定性的影响,确定了复合稳定剂为CMC-Na 0.35%、黄原胶0.08%、PGA 0.03%、复合磷酸盐0.02%.     

挤奶厅挤奶卫生检测的关键点分析

挤奶设备和挤奶厅的卫生对原料乳的质量有着重要的影响。作者介绍了挤奶厅检测的几个关键点：挤奶机奶衬、挤奶机真空压水平、挤奶机滤膜、挤奶机脉动管和脉动器及挤奶后挤奶机的洁净度;挤奶厅的卫生及挤奶操作和储奶管的清洗。通过加强挤奶厅关键点的检测从而保证原料乳质量。     

小肽对反刍动物乳蛋白合成影响的研究进展

小肽能被乳腺组织有效利用,用于弥补乳蛋白合成过程中游离氨基酸供应的不足,因此有必要研究小肽在反刍动物体内的代谢及其在乳蛋白合成过程中的作用,加深人们对反刍动物利用氨基酸的了解。作者从肽的概念、乳蛋白对小肽的利用、乳腺对小肽的吸收机制、影响乳腺对小肽利用的因素及其研究展望等方面对反刍动物乳腺的小肽代谢进行了综述。     

牛奶挥发性成分的GC-MS分析

研究4种牛奶挥发成分,经水蒸气蒸馏所得的油状物,采用GC-MS法对4种牛奶的挥发性成分进行了分离鉴定.经气质连用检出4种牛奶中含有苯并噻唑、丁化羟基甲苯、二苯胺、十二烷、十六烷、十八烷、十九烷、二十一烷、2-壬酮、2-呋喃甲醇、戊酸等.     

贮存温度对超高温灭菌乳黏度的影响

为了确定贮存温度对超高温灭菌乳黏度的影响,从而达到在较短的时间内评价超高温灭菌的货架期目的。该文采用TA AR-G2型流变仪测定了20～45℃温度变化范围内超高温灭菌乳的黏度变化,利用1stOpt1.5 Pro软件对试验数据进行拟合处理,探索Arrhenius模型对该过程的适用性,以期建立可描述温度对超高温灭菌乳黏度影响的精确模型,并结合Stocks方程为建立超高温灭菌乳货架期加速试验模型奠定基础。试验结果表明,κ-卡拉胶与酪蛋白形成的弱凝胶会显著影响Arrhenius模型对提高温度改变超高温灭菌乳黏度的拟合度,但随着温度升高至25℃会使得弱凝胶体系变弱,从而使得黏度随温度的变化与Arrhenius模型高度吻合（R2=0.908）;降温会导致黏度逐渐升高,此过程与Arrhenius模型拟合度较好（R2=0.942）。因此,Arrhenius模型适于描述温度对超高温灭菌乳黏度的影响。