蜂蜜掺假检测方法的研究进展

本文主要介绍了同位素比值分析法,高效阴离子交换色谱-脉冲安培检测法,双果糖酐检测法,傅立叶转换-拉曼光谱分析法,差示扫描量热法等方法在蜂蜜掺假检测方面的应用.     

Effect of replacing alfalfa hay with a mixture of cassava foliage silage and sweet potato vine silage on ruminal and intestinal digestion in sheep

This study aimed to investigate the effects of replacing alfalfa hay (AH) with a mixture of cassava foliage silage and sweet potato vine silage (CSP) (1:1 on a dry matter (DM) basis) on ruminal and intestinal nutrient digestion in sheep. Four wethers were fed a control diet containing 35% of AH and two treatment diets containing 15% and 30% of the CSP as substitute for AH at 1.5 times the metabolizable energy required for maintenance. Replacing AH with the CSP silage did not affect DM intake, whereas it linearly increased (P < 0.05) the intake of ether extract and acid detergent insoluble nitrogen (ADIN). Increasing the CSP substitution linearly decreased (P < 0.05) ruminal DM and neutral detergent fiber (aNDFom) digestibility; however, it did not affect total tract aNDFom digestibility. The CSP substitution did not affect nitrogen (N) intake and duodenal total N flow, whereas it linearly increased duodenal ADIN flow (P < 0.01) and decreased ruminal ammonia‐N concentration (P < 0.01), and intestinal (P = 0.08) and total N digestibility (P < 0.01). These results indicate that replacing AH with the CSP reduced the ruminal N degradation as well as the digestion of ruminal aNDFom and intestinal N.     

Dynamic changes of fatty acids and minerals in sow milk during lactation

The objective of the present study was to explore the changes in fatty acids (FAs) and minerals composition in sow milk in order to improve the knowledge about FAs and mineral requirements for piglets. The FAs and minerals composition in the sow milk samples which were collected from ten sows during a period of 16 days of lactation was analysed. The proportion of FAs in sow milk has a significant increase in C8:0, C10:0, C12:0, C14:0, C16:0, C14:1 and C16:1 FAs and the sum of saturated fatty acids (SFAs) according to the lactation period (p < 0.05). The proportion of C18:2 cis‐9,12 FA and the sum of polyunsaturated fatty acids (PUFAs) significantly decreased with the advancing of lactation (p < 0.05). The concentrations of minerals, including potassium, copper, manganese and zinc, were higher on day 1 and day 2 than those on day 13 and day 16 (p < 0.05). On the contrary, the lowest concentrations of calcium, sodium, magnesium and iron and the lowest molar calcium: phosphorus ratio emerged in colostrum (p < 0.05). In summary, our results demonstrated FAs profile and minerals concentrations were changed with lactation period. Better understanding of the changes of FAs and minerals may be valuable to swine nutritionists in the commercial industry. In addition, those results provided some meaningful information for sow's diet formulation during lactation.     

In ovo feeding of creatine pyruvate modulates growth performance,energy reserves and mRNA expression levels of gluconeogenesis and glycogenesis enzymes in liver of embryos and neonatal broilers

The effects of in ovo feeding (IOF) of creatine pyruvate (CrPyr) on the growth performance, energy reserves and mRNA expression levels of gluconeogenesis and glycogenesis enzymes in liver of late‐term embryos and neonatal broilers were investigated. After candling on 16 day of incubation, a total of 960 eggs were randomly assigned to three treatments: (i) non‐injected control, (ii) saline group injected with 0.6 ml of 0.75% physiological saline and (iii) Creatine pyruvate group injected with 0.6 ml of physiological saline containing 12 mg CrPyr/egg. After hatching, 120 male chicks with average body weight (BW) were randomly allocated into each treatment group for a 7‐day feeding trial. The results showed that broilers subjected to CrPyr treatment had higher BW than those of the control and saline groups on 1, 3 and 7 day post‐hatch, as well as the yolk sac weight on 19 day of incubation (19 E), the day of hatch and 3 day post‐hatch (p < .05). Compared with the control and saline groups, IOF of CrPyr increased the plasma creatine concentration on the day of hatch, and the plasma pyruvate concentration on the day of hatch and 3 day post‐hatch (p < .05). Moreover, IOF of CrPyr increased the liver pyruvate and glucose concentrations on 19 E and the day of hatch, and the liver glycogen concentration during the experiment (p < .05). Broilers in the CrPyr group showed increased mRNA expression levels of pyruvate carboxylase (PC), phosphoenolpyruvate carboxykinase (PEPCK) and glycogen synthase 2 (GYS2) on 19 E and the day of hatch (p < .05). These results indicated that IOF of CrPyr increased energy reserves in liver of embryos and neonatal broilers possibly through upregulating the mRNA expression levels of PC, PEPCK and GYS2, which could benefit the increase of BW in broilers on 7 day post‐hatch.     

Vegetation Responses to Fixed Stocking Densities in Highly Variable Montane Pastures in the Chinese Altay

Variability in aboveground herbaceous biomass and its quality were studied in response to three different stocking densities during a 2-yr grazing experiment with sheep on a montane summer pasture in the Chinese Altay. We determined herbaceous cover and aboveground biomass in 16 paddocks of 0.25 ha each. Vegetation cover showed high spatial variation, prompting us to implement a randomized block design. Forage intake of one male sheep per paddock was quantified four times per grazing season by collection of total feces and estimation of diet digestibility. Sheep weight was recorded every 3 wk. Aboveground herbaceous dry mass (DM) was characterized by pronounced annual variation. Biomass quality declined with progressing season and increasing sheep density. Daily organic matter intake per sheep ranged from 0.7 to 1.4 kg, which was paralleled by a biomass removal of 710 ? 1 560 kg DM/ha at densities of 8 ? 24 sheep/ha. At 8 sheep/ha, animals gained weight throughout each grazing period, whereas weight losses of 40 ? 100 g/d occurred at higher densities. These results challenge the presently followed concept of a fixed stocking density for summer pastures in Altay Prefecture, Xinjian, China. Such practice may result in low herbage allowances and thus deficient sheep nutrition in one year, as well as underutilization of forage resources in another. Flexible adjustment of stocking densities is also advisable for montane pastures where spatiotemporal variability, although less pronounced than in desert steppes of the Altay foothills, is nonetheless highly relevant.     

淮河橄榄蛏蚌营养成分及矿物质元素季节性变化分析

为评估橄榄蛏蚌的营养价值,以淮河橄榄蛏蚌为材料,采用常规营养成分分析及生化方法测定了软体部营养成分及矿物质元素含量的季节变化。结果显示：在3月、6月、9月、12月含肉率在58.03%~62.61%,6月含肉率显著低于12月(P<0.05),与3月、9月无显著性差异(P>0.05),12月与3月、9月含肉率无显著性差异(P>0.05);水分、粗脂肪无显著季节性差异(P>0.05),粗蛋白在6月、9月、12月无显著性差异(P>0.05),均显著低于3月(P<0.05),灰分在6月、9月、12月无显著性差异(P>0.05),均显著高于3月(P<0.05);淮河橄榄蛏蚌软体部（干物质）含必需氨基酸7种,非必需氨基酸10种,总氨基酸含量在52.12%~54.31%之间,必需氨基酸含量在20.57%~21.94%,呈味氨基酸含量在19.09%~19.43%,总氨基酸、必需氨基酸、呈味氨基酸含量在4个季节无显著性差异(P>0.05);所检测元素中,Hg因含量低而未检出,检测结果显示Mn、Fe、Zn、Cu、Pb、Cd这6种元素在4个季节无显著性差异。本研究结果表明淮河橄榄蛏蚌具有较高的营养价值和较好的食用价值。     

油用牡丹种子采摘始期预报模型研究

为探讨油用牡丹种子成熟采摘期受气象条件影响的变化规律,依据菏泽市2008—2019年油用牡丹物候观测资料和生育期间气温、光照及降水量等气象要素,利用Microsoft Office Excel 2013、DPS统计软件,采取相关分析、回归分析、滑动平均等数理统计方法,分析了气象条件对油用牡丹生长及种子成熟期的影响。结果表明：油用牡丹花期年变化趋势和种子采摘始期年变化趋势基本一致,个别年份因出现特别的气候异常除外;影响种子采摘始期的气象因子主要是温度,包括平均气温、积温、最高最低日较差等,相关性达显著性检验。光照、湿度、降水等与种子采摘始期相关不显著,但这些气象因子对牡丹生长的影响不容忽视;选取相关显著的气象因子,采用回归方法,建立了油用牡丹种子采摘始期预报模型,分别于7月11日、7月21日制作并发布种子采摘始期预报。模型历史回代,并对2019、2020年进行预报检验（允许误差均在±1天）,准确率均为100%,拟合和试报效果较为理想,研究结果可为花农适时采摘优质牡丹种子提供科学参考依据。     

脱脂椰子种皮的蛋白质功能性质研究

提取了脱脂椰子种皮中的蛋白质,对其功能性质,如溶解性、持水力、乳化性以及蛋白消化率等进行测定。结果表明,提取所得的脱脂椰子种皮蛋白质持水力(1.50 g/g)以及蛋白消化率(25.63%)均较低;pH对脱脂椰子种皮蛋白质的溶解性、起泡性及乳化性的影响较大,在pH4.0时,脱脂椰子种皮蛋白质的溶解性和乳化性最低;而不同浓度的蛋白质起泡性均在pH4.0时最高。     

北京林区森林经营近自然度评价方法的研究与应用

通过对北京地区森林的近自然评价,构建了适合北京森林环境条件和自然规律的森林经营策略.首先根据现地植被情况和立地条件,对植被群落分级,然后再依据近自然度评价结果,绘制群落生境图,在此基础上设计了林分作业体系,该体系的应用可节约至少30%的造林经费,提高林分生长量25%以上.