Effects of increased supplementation of n-3 fatty acids to transition dairy cows on performance and fatty acid profile in plasma, adipose tissue, and milk fat

The objective of this study was to determine the effects of feeding an increased amount of extruded flaxseed with high proportions of n-3 fatty acids (FA) to transition dairy cows on performance, energy balance, and FA composition in plasma, adipose tissue, and milk fat. Multiparous Israeli-Holstein dry cows (n = 44) at 256 d of pregnancy were assigned to 2 treatments: (1) control cows were fed prepartum a dry-cow diet and postpartum a lactating-cow diet that consisted of 5.8% ether extracts; and (2) extruded flaxseed (EF) cows were supplemented prepartum with 1 kg of extruded flaxseed (7.9% dry matter)/cow per d, and postpartum were fed a diet containing 9.2% of the same supplement. The EF supplement was fed until 100 d in milk. On average, each pre- and postpartum EF cow consumed 160.9 and 376.2 g of C18:3n-3/d, respectively. Postpartum dry matter intake was 3.8% higher in the EF cows. Milk production was 6.4% higher and fat content was 0.4% U lower in the EF group than in the controls, with no differences in fat and protein yields. Energy balance in the EF cows was more positive than in the controls; however, no differences were observed in concentrations of nonesterified fatty acids and glucose in plasma. Compared with controls, EF cows had greater proportions of C18:3n-3 in plasma and adipose tissue. The proportion of n-3 FA in milk fat was 3.7-fold higher in the EF cows, and the n-6:n-3 ratio was decreased from 8.3 in controls to 2.3 in the EF cows. Within-group tests revealed that the C18:3n-3 content in milk fat in the EF cows was negatively correlated with milk fat percentage (r = –0.91) and yield (r = –0.89). However, no decrease in de novo synthesis of less than 16-carbon FA was found in the EF group, whereas C16:0 yields were markedly decreased. It appears that the enrichment of C18:3n-3 in milk fat was limited to approximately 2%, and the potential for increasing this n-3 FA in milk is higher for cows with lower milk fat contents. In conclusion, feeding increased amounts of C18:3n-3 during the transition period enhanced dry matter intake postpartum, increased milk production, decreased milk fat content, and improved energy balance. Increased amounts of EF considerably influenced the FA profile of plasma, adipose tissue, and milk fat. However, the extent of C18:3n-3 enrichment in milk fat was limited and was negatively correlated with milk fat content and yield.     

实施HACCP的必要基础程序(待续)

为推动我国HACCP的实施，从GMP、化学品控制、清洗和消毒、微生物控制、水的安全、空气的安全、卫生设计、预防性维护、产品溯源和回收、虫害控制、接收、贮存和运输控制、供应商控制、食品安全培训、设备的校准、消费者食品安全的投诉及审核和监督程序16个方面阐述了必要基础程序所包含的具体内容，尤其是对生产控制中容易忽视的过敏原问题进行了较为详细的阐述。为食品生产企业建立食品安全保障体系提出了一些建议，可作为卫生监督员的现场审核的参考。     

Study of Phase Transition in Hard Microcrystalline Waxes and Wax Blends by Differential Scanning Calorimetry

Phase transition temperature and associated energies in hard high melting microcrystalline waxes and its various blend with paraffin wax (melting range from 60 to 97°C) have been determined by DSC in both heating and cooling mode. The dependence of these on the composition and properties of waxes have been analyzed. The solid liquid transition temperature obtained by DSC has been compared with ASTM drop melting point of these wax samples. The present study has demonstrated that DSC can be of great use in identifying whether the wax sample is blend of different waxes or not.     

复合表面活性剂NF-201的性能与驱油效果

实验考察了驱油用复合表面活性剂NF 201的应用性能及驱油效率。NF 201由30%复合非离子表面活性剂,25%～30?～C12一元脂肪醇及多元醇,20%石油磺酸盐HF 8903A,20%～25%添加剂组成。由30℃张力曲线求出,NF 201在水溶液中分别有临界胶束浓度3 0g/L和5 0g/L,对应的表面张力为21 2mN/m,油(煤油)水界面张力为3 3×10-3mN/m。NF 201的耐温性为120～130℃。5 0g/LNF 201水溶液在Ca2 Mg2 浓度分别为1g/L或<0 6g/L时,或pH值变化范围为1 0～14 0时,均维持低表面张力和超低界面张力。在65℃下在填石英砂模型上驱替含饱和剩余水的饱和模拟油时,地层水(矿化度73g/L,Ca2 Mg2 浓度2 8～3 0g/L)、1 5g/LNaOH溶液及2 5%共聚物PSS溶液的驱油率分别为47 19%、49 30%、62 04%,加入5 0g/LNF 201使3种驱替液的驱油率分别增加10 10%、8 50%、5 61%,而加入石油磺酸盐HF 8903A使驱油率分别增加2 75%、5 11%、3 35%。在NF 201中加入2%络合剂NF可使抗钙镁能力达到3 0g/L。NF 201是一种耐温抗盐抗钙镁,适应性强,驱油效率高的表面活性剂体系。图6表2参3。     

Seasonal effects on Ca(2+) transport of sarcoplasmic reticulum and on meat quality of pigs with different malignant hyperthermia status

The intracellular Ca(2+) concentration is mainly regulated by the sarcoplasmic reticulum (SR). A disturbed regulation leads to an increased metabolism and ultimately to inferior meat quality. In this study, pigs with normal and mutated calcium release channels (referred to as MHR and MHS, respectively) were used. One batch of pigs was slaughtered in winter months and another in summer months. The intention was to elucidate the impact of season on the Ca(2+) transport of SR and on meat quality in dependence of the MH-status. The results show an impact of MH-status and of season on the meat quality with inferior values in summer months, and in MHS pigs. Immediately after slaughter the rate of Ca(2+) sequestration of the SR with biochemically closed and with opened calcium release channels (CRC) was not different between experimental groups. However, with basic CRC (not biochemically manipulated) the Ca(2+) uptake rate of MHR muscle of summer pigs was significantly reduced and at the level of that of MHS pigs. The results indicate an impact of summer season on the ability of SR to regulate Ca(2+) concentration properly even in pigs with a normal CRC. This disturbed Ca(2+) regulation is correlated with diminished meat quality.     

Detection of cauliflower mosaic virus by the polymerase chain reaction: testing of food components for false-positive 35S-promoter screening results

 Today DNA-based techniques are very common for the detection of genetically modified organisms (GMOs) in food products. For fast and easy detection of GMOs, polymerase chain reaction (PCR) screening methods, which amplify common transgenic elements, are applied in routine analysis. These techniques do not allow differentiation between GMOs and the natural occurrence of transgenic elements, such as the 35S-promoter of cauliflower mosaic virus (CaMV) or the NOS-terminator of Agrobacterium tumefaciens, and thus may result in false-positive detection of GMOs. In this study we evaluated three different existing 35S screening systems and report the development of two new CaMV-specific PCR systems. These PCR systems based on CaMV-specific genes allow the identification of positively screened 35S food samples as naturally virus-infected products or plants. Seven food samples tested positive in routine 35S screening analysis and negative in GMO specific systems were investigated using the new virus-specific PCR systems. In all seven samples CaMV was detected. Received: 26 April 1999 / Revised version: 28 June 1999     

Investigations of peptides and proteases in green coffee beans

Cof. canephora var. robusta. The coffee types were not significantly different in peptide content, but were significantly different in peptide composition. Peptides with weakly acid pI values were mainly found in the Cof. robusta samples. In comparison, peptides from Cof. arabica samples ranged evenly from the weakly acidic up to the weakly basic pH range. The apparent molecular masses of the peptides in the two groups of samples lie between 4 kDa and 10 kDa. The cysteine content of the peptides was relatively high. Model roastings permitted the assumption that peptides make a contribution to coffee flavour. Peptides are already available in freshly harvested coffee. Model tests have suggested that processing after the coffee harvest has an influence on peptide composition but not on the amounts of peptide. All coffee samples contained some extractable proteases. The electrophoretically obtained enzyme patterns of Cof. arabica and Cof. robusta were different. Received: 6 September 1999     

Kinetics of active sucrose transport in Saccharomyces cerevisiae

The kinetic analysis of active sucrose-H+ uptake by Saccharomyces cerevisiae revealed the presence of two transport systems with high and low affinity for sucrose. The MAL2T permease has a low affinity (K(m) = 120 +/-20 mM) for sucrose, while the alpha-glucoside transporter encoded by the AGT1 gene is a high affinity sucrose-H+ symporter (K(m) = 7.9+/-0.8 mM) that increases the specific growth rate of cells growing on sucrose.     

Interaction of Vanillin with Soy and Dairy Proteins in Aqueous Model Systems: A Thermodynamic Study

ABSTRACT: Interactions of vanillin with soy, casein, and whey proteins were studied in aqueous model systems using a thermodynamic approach. Vanillin-protein binding was examined at 12 and 4 °C using 3 proteins and 6 vanillin concentrations. The results were analyzed using a Klotz plot. Number of binding sites (n) and dissociation constants (K_d) were derived from the plots. The thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for the bindings were calculated. Under identical experimental conditions, whey protein was found to have higher affinity to vanillin than the other 2 proteins. Bindings of vanillin with casein and whey protein were enthalpy driven, while the interaction of vanillin with soy protein was highly entropy driven. The results inferred that conformational changes of soy protein might be important in binding of vanillin.     

Limnology and culture-based fisheries in non-perennial reservoirs in Sri Lanka

This study was carried out to investigate the possibility of using the limnological characteristics of non‐perennial reservoirs in Sri Lanka for the future management of culture‐based fisheries. Forty‐five reservoirs were randomly selected to study their limnology, out of which 32 were stocked with fish fingerlings of Chinese and Indian carps, tilapia and freshwater prawn at stocking densities ranging from 218–4372 fingerlings ha^?1. Of these, 23 reservoirs were harvested at the end of the culture period (6–10 months). Thirteen limnological parameters were measured during the water retention period of each of the 45 reservoirs between November 2001 and January 2004. The mean values of the limnological parameters were used to ordinate the reservoirs through principal component analysis. Ordination showed a productivity gradient among reservoirs where Secchi disc depth, total phosphorus, chlorophyll‐a, inorganic turbidity and organic turbidity were identified as key factors. The total fish yield of culture‐based fisheries was positively correlated to the scores of the first principal component axis. This study reveals that it is possible to classify non‐perennial reservoirs in Sri Lanka based on the above limnological parameters in order to develop culture‐based fisheries and that they could be applicable in comparable water bodies elsewhere in the tropics.