散养成乳牛舍环境测定

以一栋散养成乳牛舍为对象，系统地测定了舍内外的气温、气湿、风速、辐射强度、黑体温度及屋顶热流量。结果表明：从６月１日—９月１０日，舍内旬均气温都在２３．４３℃以上，舍内１４：００气温旬均值都在２８℃以上，舍内旬均ＴＨＩ都超过７１．７１；屋顶热流量曲线的斜率很大、峰值出现于１４：００，并且与舍外黑体温度呈高度的正相关；舍内与舍外的黑体温度、辐射强度分别呈中等以上的正相关；冬季舍内寒冷，同时受舍外气流影响大。笔者认为，通过增加牛舍高度、先用高热阻屋面材料和冬季防风可望改进此类牛舍的环境。     

赖氨酸修饰对梯棱羊肚菌黑色素结构和理化特性的影响

为了进一步提高梯棱羊肚菌黑色素的提取率及溶解性,本试验采用单因素、Plackett-Burman试验、响应面试验对纤维素酶-超声波协同提取梯棱羊肚菌黑色素的提取工艺进行优化研究。通过赖氨酸修饰,并对修饰前后的梯棱羊肚菌黑色素进行结构表征、理化性质及稳定性研究。结果表明,在NaOH浓度为1.54 mol/L,纤维素酶添加量为20 mg/g,纤维素酶酶解时间为78.6 min,料液比为1:30,酶解温度为40 ℃,超声时间为80 min条件下提取的梯棱羊肚菌黑色素最优。未修饰的梯棱羊肚菌黑色素不溶于水,色价值为480.24,修饰后的黑色素溶解度为1 016 g/L,色价值为1 771.18,比未修饰的黑色素在溶解性、色价值方面均有所提高。此外,在不同的温度、光照、pH条件下,修饰前后的梯棱羊肚菌黑色素均比较稳定。以上研究结果为梯棱羊肚菌黑色素的高效提取及其产品的开发利用奠定了理论基础。     

以豆粕为原料制备反刍动物饲用肽的研究

本文通过正交试验,选用碱性微生物蛋白酶,研究得出酶解法制备大豆肽的最佳工艺参数:豆粕预处理条件为90℃水浴加热10min,酶解条件为底物浓度5%(W/V)、加酶量5万单位/g蛋白质、温度50℃、pH值10、酶解时间5.5h。蛋白质水解率达到25%,平均肽链长度为4.0。制得大豆肽粗蛋白质含量66.83%(DM)。并对制得大豆肽和原料豆粕的氨基酸含量进行分析。     

Branched‐chain amino acid ratios in low‐protein diets regulate the free amino acid profile and the expression of hepatic fatty acid metabolism‐related genes in growing pigs

Liver metabolism is affected by nutrients. The aim of this study was to explore the effects of low‐protein diets (17% crude protein, CP) supplemented with branched‐chain amino acids (BCAAs), including leucine (Leu), isoleucine (Ile) and valine (Val), on hepatic amino acid profile and lipid metabolism in growing pigs. The ratio of Leu : Ile : Val in all groups was 1 : 0.51 : 0.63 (20% crude protein, CP), 1 : 1 : 1 (17% CP), 1 : 0.75 : 0.75 (17% CP), 1 : 0.51 : 0.63 (17% CP) and 1 : 0.25 : 0.25 (17% CP) respectively. Results revealed that compared to the positive control group (1 : 0.51 : 0.63, 20% CP), the low‐protein diets significantly augmented the concentrations of most essential amino acids and non‐essential amino acids (p < .05), with the greatest values observed in the 1 : 0.25 : 0.25 group. Moreover, relative to the control, the low‐protein diets with the Leu : Ile : Val ratio ranging from 1 : 0.75 : 0.75 to 1 : 0.25 : 0.25 markedly downregulated the mRNA abundance of acetyl‐CoA carboxylase (ACC), lipoprotein lipase (LPL) and fatty acid‐binding protein 4 (FABP‐4) (p < .05), and upregulated the mRNA expression of hormone‐sensitive lipase (HSL), peroxisome proliferator‐activated receptor‐g coactivator‐1α (PGC‐1α), uncoupling protein 3 (UCP3) and liver carnitine palmitoyltransferase 1 (L‐CPT‐1) (p < .05). Therefore, our data suggest that protein‐restricted diets supplemented with optimal BCAA ratio, that is, 1 : 0.75 : 0.75–1 : 0.25 : 0.25, induce a shift from fatty acid synthesis to fatty acid oxidation in the liver of growing pigs. These effects may be associated with increased mitochondrial biogenesis.     

豆粕对乌鳢肠道菌群组成及微生物氨基酸代谢酶活性的影响

为研究豆粕替代鱼粉对乌鳢生长、肠道菌群组成和微生物相关氨基酸代谢酶活性的影响,分别用豆粕替代0、25%、50%和75%的鱼粉配制4组等氮等能的饲料饲喂初始体质量为(8.65±0.25) g的幼鱼(分别命名为G1、G2、G3和G4组),养殖实验在室内纤维玻璃钢桶中进行,实验周期为21 d。结果显示,各组间幼鱼成活率无显著性差异;G4组乌鳢幼鱼的生长性能显著低于G1和G2组,而G3组幼鱼生长性能与其余3组差异不显著。厚壁菌门在G1和G2组乌鳢肠道中的比例显著高于G3组,且在G4组中的比例最低;变形菌门在G1和G2组中的比例显著低于G3和G4组;G4组中乳球菌属、杆菌属、假单胞菌属、链球菌属、芽孢杆菌属和不动杆菌属的比例显著低于其余3组。另外,G4组幼鱼肠道微生物谷丙转氨酶、腺苷脱氨酶活性显著高于其余3组,而G1组乳酸脱氢酶的活性最高。研究表明,豆粕替代鱼粉除了对乌鳢幼鱼的生长产生影响外,也显著影响了肠道微生物组成及微生物相关氨基酸代谢酶的活性,本研究结果对于从微生态角度进一步理解豆粕在乌鳢配合饲料中的应用提供了理论依据和参考。     

臭氧在大菱鲆亲鱼养殖回用水系统中的应用

以臭氧在大菱鲆亲鱼养殖回用水系统中的工程实例数据,分析臭氧在养殖水处理系统中的杀菌效果、脱除转化氨氮的效能。结果表明,臭氧在该工艺流程中杀菌率可达51．82％,对氨氮 亚硝酸氮的平均去除率达56．30％,这表明臭氧应用于工厂化养殖水处理中具有较好效果。     

Physicochemical,Structural and Antioxidant Properties of Collagens from the Swim Bladder of Four Fish Species

This study aimed to isolate and characterize pepsin-solubilized collagen (PSC) from marine and freshwater fish swim bladders. The physicochemical properties, protein pattern, amino acid composition, structure, thermal denaturation temperature, and antioxidant activity of PSC from four different swim bladder sources were investigated and compared. The results demonstrated that the four types of collagen extracted were all type I collagen. The yield of PSC extracted from grass carp (GCSB-PSC), bighead carp (BCSB-PSC), grouper (GSB-PSC), and monkfish swim bladders (MSB-PSC) were 38.98, 27.97, 18.16, and 10.35%, respectively. Compared to the other three PSCs, BCSB-PSC has the highest thermal denaturation temperature (38.60 °C). Based on FTIR spectroscopy and circular dichroism (CD) analysis, the extracted PSCs retained the triple helix and secondary structure well. Antioxidant studies showed that in the swim bladders of four species the swim bladder PSC could scavenge DPPH and ABTS radicals. Overall, swim bladders from marine and freshwater fish can be utilized as raw materials for collagen extraction, and the extracted collagen has potential commercial applications.