Influence of sodium chloride or potassium chloride on systemic acid-base status, milk yield, and mineral metabolism in lactating dairy cows

Our objective was to evaluate the response of lactating dairy cows to dietary Na, K, and Cl while holding cation-anion balance constant. Fifteen lactating Holstein cows, blocked according to age and previous milk yield, were assigned randomly to replicated 3 x 3 Latin squares with experimental periods of 3 wk. Diets contained sorghum silage and concentrate in a 40:60 ratio (DM basis) and were formulated to provide +32 meq of [(Na + K) - Cl]/100 g diet DM via one of three variations: 1) basal concentrations of dietary Na, K, and Cl, 2) basal diet with addition of 20 meq of Na and 20 meq of Cl/100 g in the form of 1.17% added NaCl, or 3) basal diet with the addition of 20 meq of K and 20 meq of Cl/100 g in the form of 1.56% added KCl. Free proton concentration in blood was increased by addition of NaCl and KCl; however, this increase did not appear to be physiologically significant, and no other measures of acid-base status were significantly affected. Plasma K was higher and plasma Mg was lower for the diets with supplemental NaCl or KCl than for basal diet. Urine mineral excretion reflected dietary mineral concentration, except Ca and Mg excretion rates were reduced by feeding the KCl diet. Milk yield reflected DM intake, which was lowest with supplemental NaCl. Results of this study indicate that, at a dietary cation-anion balance of +32 meq/100 g of diet DM, the balance of Na and K to Cl in the diet is a more important determinant of dietary impact on systemic acid-base status than actual dietary concentrations of Na, K, and Cl.     

Airborne respirable silica near a sand and gravel facility in central California: XRD and elemental analysis to distinguish source and background quartz

Despite the potential toxicity of respirable quartz to humans, little is known about the transport of airborne quartz from sources to receptors and how to distinguish anthropogenically generated quartz from natural background in a receptor sample. Airborne quartz emissions near a sand and gravel facility were determined using PM10 and PM2.5 filter samples collected at four downwind sites (D1: 22 m, D2: 62 m, D3: 259 m, and D4: 745 m from the facility) as well as one upwind site (U1: 1495 m) during summer sampling. X-ray diffraction was used to determine quartz concentration and elemental composition was analyzed using PIXE, XRF, PESA, and HIPS techniques. Elemental composition of the PM samples was used to determine the X-ray mass absorption coefficients that are essential for accurate quartz quantification by XRD. Elemental composition was found to be a useful tool to distinguish source and background crystalline silica. Both PM10 and PM2.5 samples collected at the D1, D2, and D3 sites contained more Si, Al, and Fe and less H, Na, and S, compared to those at the U1 site, whereas site D4 sample compositions were similar to those at the U1 site. A composite variable, SOIL/(H+Na+S), where SOIL = 2.20Al + 2.49Si + 1.63Ca + 1.94Ti + 2.42Fe, was used to distinguish source materials from background. Average dry season quartz concentrations in replicate PM10 samples were 4.6 +/- 0.9) microg m(-3) at U1, 60.6 (+/- 5.4) microg m(3) at D1, 62.4 (+/- 3.6) at D2, 32.6 (+/- 2.1) microg m(-3) at D3, and 9.41 (+/- 0.9) microg m(-3) at D4. The mass fraction of quartz was the highest at the D1 site and decreased with increasing distance from the facility. The mass of PM2.5 samples was too low to determine quartz concentrations. These results identify the facility as the main source of quartz and other silicate minerals downwind of the plant and that the air quality of the most remote sampling site, located approximately 750 m downwind, was still impacted by the facility's activity.     

Ammonium chloride and ammonium sulfate for prevention of parturient paresis in dairy cows

Forty-eight Holstein cows with two or more previous lactations and no history of parturient paresis were randomly assigned to one of four prepartum diets in a 2 x 2 factorial design to determine the effect of dietary supplementation with ammonium salts and Ca intake on serum Ca concentrations at calving. Four diets provided either 53 g total dietary Ca/d or 105 g Ca/d and were either supplemented with ammonium salts [100 g/d each of NH4Cl and (NH4)2SO4] or unsupplemented. Anion-cation balance of the diets, calculated as milliequivalents (Na + K)--(Cl + S), was -75 meq/kg DM with ammonium salts and +189 meq/kg DM without ammonium salts. Experimental diets were fed from 21 d prior to expected parturition until calving. Calcium intake during the feeding period did not affect the incidence of parturient paresis or serum concentrations of ionized Ca at calving. The incidence of parturient paresis was 4% with and 17% without the ammonium salts. Cows fed diets containing ammonium salts had higher serum ionized and total Ca concentrations at parturition. Serum concentrations of Mg, P, Na, K, and Cl on the day of parturition were unaffected by dietary treatment.     

动态顶空取样-大气压化学电离质谱原位实时监测发酵乳挥发性代谢产物

采用大气压化学电离质谱法,利用动态顶空取样技术对发酵乳生产过程中产生的挥发性代谢产物进行原位实时监测。从发酵开始后3.0～4.7h连续用质谱仪记录发酵乳挥发物的离子流信号,结果表明：2,3-丁二酮(m/z 104,M+H2O+·)在前4h信号较弱,4h后开始逐渐增大,4.2h后呈快速增大的趋势;乙酸乙酯(m/z 106,M+H2O+·)信号从发酵3h后开始呈逐渐增大趋势;苯甲醛(m/z 124,M+H2O+·)信号较平稳。发酵进行到6h的质谱图中质谱信号主要有乳酸(m/z 91,MH+和m/z 108,M+H2O+·),2,3-丁二酮(m/z 104,M+H2O+·),苯甲醛(m/z 107,MH+和m/z 124,M+H2O+·),乙酸乙酯(m/z 89,MH+和m/z 106,M+H2O+·),正已醛(m/z 101,MH+和m/z 118, M+H2O+·),2-丙烯醛(m/z 74·M+H2O+·)等。未发酵的纯牛奶质谱图中有正己醛(m/z 101,MH+),苯甲醛(m/z 107,MH+和m/z 124,M+H2O+·),葵醛(m/z 174,M+H2O+·)等信号。动态顶空取样-大气压化学电离质谱技术具有快速、非破坏性等优点,在发酵食品的生产质量控制方面有一定的理论和实际应用价值。     

一平浪盐矿产蛋白酶嗜盐古菌的鉴定及其酶学性质

从分离自一平浪盐矿的嗜盐古菌中筛选产胞外蛋白酶菌株,并对所产蛋白酶的酶学性质进行初步研究。结果表明,2株高产胞外蛋白酶嗜盐古菌YPL20和YPL26为盐矿盐古球菌（Halococcus salifodinae）。YPL20胞外蛋白酶最适反应条件为50℃,p H9.0和0 mol/L Na Cl。YPL26胞外蛋白酶最适反应条件为50℃,p H7.0⁹.0和2.5 mol/L Na Cl。它们具有良好的热稳定性、酸碱稳定性和盐度耐受性。Mn²⁺、Ca²⁺对YPL20和YPL26的蛋白酶活性均有促进作用,而Cu²⁺、Zn²⁺均有抑制作用。丝氨酸蛋白酶抑制剂完全抑制YPL20和YPL26的蛋白酶活性,说明YPL20和YPL26的胞外蛋白酶是丝氨酸蛋白酶。      

鲁梅克斯叶蛋白的抗氧化肽活性及功能性质研究

本文旨在探究鲁梅克斯叶蛋白酶解物的抗氧化性能和叶蛋白的功能性质,为鲁梅克斯叶蛋白的应用和推广辅以理论依据。研究选用碱热法获取的叶蛋白粉,分别采用胰蛋白酶和胃蛋白酶水解,对其酶解物进行自由基的清除能力和对金属离子的螯合能力评价;另外,本研究中还探讨了不同的温度、p H、Na Cl浓度对鲁梅克斯叶蛋白溶解性、持水性、持油性、发泡性及乳化性的影响。结果表明,在肽浓度分别为0.5、1、8、0.2 mg/m L时,胰蛋白酶酶解肽的还原力、对DPPH·的抑制率、对·OH的清除率和对Fe2+的螯合能力显著高于胃蛋白酶酶解肽（p<0.05）;而当肽浓度为80 mg/m L时,胃蛋白酶酶解肽对O-2·的抑制率则显著高于胰蛋白酶酶解肽（p<0.05）。二者在对自由基种类和清除效果上出现的差异,可能与酶解所得肽段中疏水性氨基酸的种类和数量有关。叶蛋白的功能性质研究表明,鲁梅克斯叶蛋白具有较高的持水性（均大于4 g/g）和发泡性（最高可达45%）,二者受温度、p H和Na Cl浓度的影响较小;而溶解性、持油性和乳化性受温度、p H和Na Cl浓度影响,表现出规律性差异,存在一定幅度上的波动。      

Minor and trace elements in different honey types produced in Siena County (Italy)

The concentrations of 23 chemical elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Th, Tl, U, Zn) were determined in 51 honey samples of different botanical origin produced in Siena County (Italy). K, Ca, Na and Mg were the most abundant elements, with mean contents of 1195, 257, 96.6 and 56.7 mg/kg, respectively. The Fe, Zn and Sr contents generally ranged from 1 to 5 mg/kg. Except for Ba, Cu, Mn and Ni, the trace element contents were below 100 μg/kg. The analytical data indicated a good level of quality of the honeys, especially with regard to the concentrations of toxic trace elements, such as As, Cd, Pb and Sb, and suggested a significant influence of the botanical origin on the element composition. Some local geological and geochemical features also seemed to affect the chemistry of the honey.     

Role of magnesium in the dietary cation-anion balance equation for ruminants

Eight midlactation Holstein cows (four primiparous) were assigned to replicated 4 x 4 Latin squares with a 2 x 2 factorial arrangement of treatments. The basal diet was formulated to contain 0 milliequivalents (Na + K) - Cl/100 g of diet DM. Treatment diets of high and low dietary cation-anion balance were achieved by adding appropriate amounts of supplemental Na + K (added on an equivalent basis) or Mg to the basal diet. Milk and protein yield were increased as well as DMI and FCM for Na + K diets The high concentration of cation increased milk fat percentage. The cation-anion balance (using Mg as a cation) had no effect on any of the production parameters observed. The higher cation-anion balances increased blood bicarbonate levels and plasma Na. Urinary Ca excretion was increased for the Mg diets. Urinary pH increased with both the source of cation (Na + K) and the concentration of cation (high) in the diet. other minerals were unaffected in milk, plasma, or urine. Responses measured in this trial reflect treatments calculated using the equation milliequivalents (Na + K) - Cl/100 g diet DM or (Na + K) - (Cl + S)/100 g diet DM, suggesting that Mg plays a minor role in dietary cation-anion balance.     

苹果果胶酯酶提取及其酶学性质探究

以国光苹果为原料,通过单因素和正交实验考察了Na Cl浓度、p H、提取温度和提取时间对苹果果胶酯酶酶活的影响,确定了苹果果胶酯酶最佳提取工艺参数,并研究了苹果果胶酯酶的酶学性质。结果表明:在Na Cl浓度为2.5mol/L、p H为8.5、提取温度30℃和提取时间为27h时,苹果果胶酯酶的酶活达到0.98μmol/min·m L;该酶反应的最适温度为40℃,热稳定性较差,最适p H为11;金属离子中Ca2+对果胶酯酶有显著的激活作用,Na+、K+和Fe2+也有一定的激活作用,而Ba2+、Mn2+和EDTA对果胶酯酶有抑制作用。      

Versatile gas/particle ion chromatograph

A new, compact gas/particle ion chromatograph has been developed for measuring ionic constituents in PM2.5 (particulate matter of aerodynamic diameter < or = 2.5 microm) and water-soluble ionogenic gases. The instrument has separate sampling channels for gases and particles. In one, a membrane denuder collects soluble gases for preconcentration and analysis. In the other, a cyclone removes larger particles, a membrane denuder removes soluble gases, and a continuously wetted hydrophilic filter collects particles. A single, multiport, syringe pump handles liquid transport, and one conductivity detector measures anions and ammonium for both channels. Electrodialytically generated gradient hydroxide eluent permits 20 min chromatographic runs. Gas/particle samples are each collected for 40 min, butthe sampling intervals are staggered by 20 min. Liquid samples from the gas denuder and particle collector are aspirated and preconcentrated on sequential cation and anion concentrators and transferred respectively to an ammonia transfer device and an anion separation column. The flow configuration results in an ammonium peak before anion peaks in the chromatogram. The system measures ammonia, organic acids (such as acetic, formic, and oxalic acids), HCl, HONO, SO2, HNO3, and the corresponding ions in the aerosol phase. Low ng/m3 to sub-ng/m3 limits of detection (LODs) are attained for most common gases and particulate constituents, the LODs for gaseous SO2 to NH3 range, for example, from sub parts per trillion by volume (sub-pptv) to approximately 5 pptv.     

聚集条件对罗非鱼皮Ⅰ型胶原自聚集动力学的影响

采用Boltzmann函数拟合结合两阶段动力学模型(成核阶段和生长阶段),研究了胶原浓度、温度、溶液p H和离子强度对罗非鱼皮Ⅰ型胶原自聚集动力学的影响。结果表明:胶原浓度、温度、溶液p H和离子强度能调控胶原自聚集动力学。当浓度达到或高于0.34 mg/m L时,胶原表现明显的自聚集,且浓度越高越有利于胶原晶核的形成,过量的胶原分子能阻碍胶原纤维的生长;聚集温度越接近胶原来源原料的生活温度或溶液p H偏碱性,胶原越易自聚集;Na Cl浓度也可影响胶原的自聚集动力学,适量浓度的Na Cl有利于胶原晶核的形成,但Na Cl浓度过高却对胶原纤维的生长有阻碍作用。      

Effect of dietary cation-anion difference on acid-base status and dry matter intake in dry pregnant cows

The objective was to determine if the reduction in dry matter (DM) intake of acidogenic diets is mediated by inclusion of acidogenic products, content of salts containing Cl, or changes in acid-base status. The hypothesis was that a decrease in intake is mediated by metabolic acidosis. Ten primigravid Holstein cows at 148 ± 8 d of gestation were used in a duplicated 5 × 5 Latin square design. The dietary cation-anion difference (DCAD) of diets and acid-base status of cows were manipulated by incorporating an acidogenic product or by adding salts containing Cl, Na, and K to the diets. Treatments were a base diet (T1; 1.42% K, 0.04% Na, 0.26% Cl; DCAD = 196 mEq/kg); the base diet with added 1% NaCl and 1% KCl (T2; 1.83% K, 0.42% Na, 1.23% Cl; DCAD = 194 mEq/kg); the base diet with added 7.5% acidogenic product, 1.5% NaHCO₃, and 1% K₂CO₃ (T3; 1.71% K, 0.54% Na, 0.89% Cl; DCAD = 192 mEq/kg); the base diet with added 7.5% acidogenic product (T4; 1.29% K, 0.13% Na, 0.91% Cl; DCAD = ?114 mEq/kg); and the base diet with 7.5% acidogenic product, 1% NaCl, and 1% KCl (T5; 1.78% K, 0.53% Na, 2.03% Cl; DCAD = ?113 mEq/kg). Periods lasted 14 d with the last 7 d used for data collection. Feeding behavior was evaluated for 12 h in the last 2 d of each period. Reducing the DCAD by feeding an acidogenic product reduced blood pH (T1 = 7.450 vs. T2 = 7.436 vs. T3 = 7.435 vs. T4 = 7.420 vs. T5 = 7.416) and induced a compensated metabolic acidosis with a reduction in bicarbonate, base excess, and partial pressure of CO₂ in blood, and reduced pH and strong ion difference in urine. Reducing the DCAD reduced DM intake 0.6 kg/d (T1 = 10.3 vs. T4 = 9.7 kg/d), which was caused by the change in acid-base status (T2 + T3 = 10.2 vs. T4 + T5 = 9.6 kg/d) because counteracting the acidifying action of the acidogenic product by adding salts with strong cations to the diet prevented the decline in intake. The decline in intake caused by metabolic acidosis also was observed when adjusted for body weight (T2 + T3 = 1.75 vs. T4 + T5 = 1.66% BW). Altering the acid-base status with acidogenic diets reduced eating (T2 + T3 = 6.7 vs. T4 + T5 = 5.9 bouts/12 h) and chewing (T2 + T3 = 14.6 vs. T4 + T5 = 13.5 bouts/12 h) bouts, and extended meal duration (T2 + T3 = 19.8 vs. T4 + T5 = 22.0 min/meal) and intermeal interval (T2 + T3 = 92.0 vs. T4 + T5 = 107.7 min). Results indicate that reducing the DCAD induced a compensated metabolic acidosis and reduced DM intake, but correcting the metabolic acidosis prevented the decline in DM intake in dry cows. The decrease in DM intake in diets with negative DCAD was mediated by metabolic acidosis and not by addition of acidogenic product or salts containing Cl.     

不同发酵剂与发酵条件对鲊鱼生物安全性的影响

旨在探明不同发酵剂和发酵条件对鲊鱼（一种发酵草鱼）生物安全性的影响。以不同的菌株——植物乳杆菌（Lactobacillus plantarum,Lp）、戊糖片球菌（Pediococcus pentosaceus,Pp）、木糖葡萄球菌（Staphylococcus xylosus,Sx）、酿酒酵母（Saccharomyces cerevisiae,Sc）为发酵剂,按1∶1∶1（v/v/v）进行混合（Lp+Sx+Sc、Lp+Pp+Sc、Sx+Pp+Sc）,控制不同的发酵条件,定期测定有害微生物和生物胺含量。研究结果表明:相对于自然发酵（NF）,接种发酵（IF）对鲊鱼中有害菌的抑菌效果明显好于前者（p<0.01）;与NF相比,IF能有效控制生物胺的积累,差异极显著（p<0.01）,3种混合发酵剂中,Lp+Sx+Sc对生物胺形成的抑制效果最好（p<0.05）;以20%（m/m）KCl替代Na Cl,对生物胺形成的抑制效果均显著提高（p<0.05）,最佳复合盐添加量为2.4%Na Cl+0.6%KCl;从对生物胺控制和生产效率的角度综合考量,发酵温度以20℃较适宜;综合对味感的要求与对生物胺控制的需要,混合糖添加量以5.0%为佳;在上述最佳条件下接种发酵50 d,既可使鲊鱼总生物胺含量控制在较低水平（43.50 mg/kg）,又能获得优良发酵风味和感官品质。研究结果提示,采用优良混合发酵剂并控制适宜发酵条件,有利于保证鲊鱼产品的生物安全性。      

X-ray Fluorescence Determination of Element Contents in Milk and Dairy Products

The concentrations of minerals (Na, Mg, P, S, Cl, K, and Ca) and trace elements (Mn, Fe, Ni, Cu, Zn, Rb, Sr, and Br) in different types of milk, dairy products, and infant formulas have been determined using wavelength-dispersive X-ray fluorescence analysis (WDXRF). Freeze-dried samples pressed as tablets of 4 g have been analyzed. Calibrations have been established using both plant and milk standard reference materials. The matrix correction method based on the power function of Compton scattered intensity was applied. The paper provides calibration data, detection limits for each element, and testing the accuracy of the proposed technique. The elemental compositions of the samples obtained by WDXRF were compared with the previously reported data from different countries.     

Urban versus remote air concentrations of fluorotelomer alcohols and other polyfluorinated alkyl substances in Germany

Neutral, volatile polyfluorinated alkyl substances (PFAS) were measured in environmental air samples at two different sites in Northern Germany in spring 2005. The sampling locations were chosen to cover a metropolitan and a rural site, the Hamburg city center, and Waldhof, a background monitoring site. An optimized and validated analytical protocol was used to analyze two sets of parallel high-volume air samples. For both sampling locations as well as for individual samples, field blanks were taken to monitor possible background contamination. Gas chromatography coupled to mass spectrometry using positive chemical ionization (GC/ PCI-MS) was used for quantitative analyses. This article describes the first air concentration data of volatile PFAS outside North America reported in the peer-reviewed literature. The wide distribution of fluorotelomer alcohols (FTOHs), fluorinated sulfonamides, and sulfonamidoethanols (FOSAs/FOSEs) in German environmental air is presented. Furthermore, two volatile PFAS, i.e., N-methyl fluorooctane sulfonamide (NMeFOSA) and 4:2 FTOH, were determined for the first time in environmental air. Minimum-maximum sigmaFTOH concentrations of 64-311 pg/m3 (remote) up to 150-546 pg/m3 (urban) and minimum-maximum sigmaFOSA + FOSE concentrations between 12 and 54 pg/m3 (remote) and 29 and 151 pg/m3 (urban) were determined. 8:2 FTOH and 6:2 FTOH were found to be the predominant POPs determined in Waldhof so far. Blank contamination was found to be negligible. A significant correlation was found with the ambient temperature for the partitioning of airborne FOSEs between the gaseous and particulate phase (R = 0.853), whereas FTOHs and FOSAs were almost exclusively found in the gaseous phase. Furthermore, highest airborne PFAS concentrations were determined at relatively high ambient temperatures. Correlation coefficients (R) for sigmaFTOH and sigmaFOSA + FOSE concentrations with temperature were 0.954 and 0.968, respectively. Finally, the PFAS concentrations determined in this study are set into context with levels of "classical" persistent organic pollutants (POPs) in the same region and PFAS data available for North America.     

氯化钾、氯化钙和氯化镁部分替代食盐腌制对风鸡品质影响的研究

研究了氯化钾、氯化钙和氯化镁部分替代食盐进行腌制对风鸡品质的影响。使用不同比例的氯化钾、氯化钙和氯化镁部分替代食盐在4℃条件下腌制样品3 d之后,在15℃风干3 d得到风鸡产品,然后测定鸡胸肉的p H、色泽、质构、TVBN值、水分含量以及感官特性等指标。结果表明:与对照组(100%Na Cl)样品相比,各替代组腌制样品的p H都显著降低(p<0.05)。而在风干结束时,各个替代组样品的水分含量、剪切力和TVBN值显著高于对照组(p<0.05)。替代组样品的亮度、红度和黄度与对照组相比并无显著差异(p>0.05)。随着Na Cl的比例降低和KCl含量的提高,出现明显的苦味而对感官品质带来负面影响。因此在保持风鸡原有感官品质的基础上,合理选择氯化钾、氯化钙和氯化镁的替代比例,将有利于降低钠盐的使用量。      

Sampling artifacts of acidity and ionic species in PM2.5

Although sampling artifacts of acidity, ammonium, nitrate, and chloride in airborne particulate pollutants can be reduced by the use of denuders to absorb interfering gases, artifacts due to interparticle interactions still remain. In this study, the contribution of individual artifact reactions to particle evaporation and the effects of aerosol composition on the extents of sampling artifacts in PM2.5 were investigated. Samples were collected using a Harvard honeycomb denuder/filter-pack system at an urban site and a rural site in Hong Kong. The results show that the formation of artifacts can be categorized into two regimes: ammonium rich (AR) samples with a molar ratio [NH4+]/ [SO4(2-)] greater than 1.5 and ammonium poor (AP) samples with a molar ratio [NH4+]/[SO4(2-)] less than or equal to 1.5. The urban samples were all AR samples, and they were characterized by high nitrate and low in situ free acid concentrations. In contrast, the rural samples were all AP samples and they were characterized by low nitrate and high in situ free acid concentrations. We have developed a methodology to estimate the contribution of each artifact reaction to the sampling loss of nitrate, chloride, ammonium, and acidity. In the AR samples, the evaporation of HNO3 and HCl and concomitant evaporation of NH3 were the principal reactions in determining the extent of the sampling loss of nitrate and chloride. In the AP samples, the evaporation of HNO3 and HCl alone was the principal reaction instead, especially at high sampling loss. The in situ free acid concentration, a function of aerosol composition and ambient conditions, is a more useful parameter than strong acidity in understanding the sampling loss of acidity, nitrate, and chloride from the collected particles.     

Chlordanes in the mid-Atlantic atmosphere: New Jersey 1997-1999

To characterize the atmospheric dynamics and behavior of chlordane compounds in the mid-Atlantic region of the United States, atmospheric concentrations were measured in 1997-1999 at three New Jersey locations as part of the New Jersey Atmospheric Deposition Network (NJADN) project. Observed concentrations of sigma-chlordanes (cischlordane + trans-chlordane + cis-nonachlor + transnonachlor) are log-normally distributed, with a geometric mean concentration of 77.1 pg m(-3) and range from 6.1 to 481 pg m(-3). Gas-phase species comprised 83% (+/-23%) of the sigma-chlordanes species across all samples at all location. Gas-phase sigma-chlordane concentrations are inversely proportional to temperature, with higher concentrations during periods of warmer air temperatures. Observed concentrations do not correlate with wind direction or air mass history, which suggests that observed concentrations in the New Jersey atmosphere are due to volatilization from soils and surfaces on the regional scale.     

The effect on egg production of adding sodium bicarbonate and potassium carbonate to a practical-type layer's diet

Eighty laying hens (40 Hisex white, 40 Hisex brown) were given, for ten 28-day periods, a control diet and four experimental diets in which the relationship between Na, K and Cl (Na+K? Cl) expressed as mEq kg^?1 diet was elevated by adding increasing amounts of NaHCO₃ and K₂CO₃. Increasing the (Na+K? Cl) mEq kg^?1 diet had no significant effect on any of the parameters measured but the breed x diet interaction significantly affected mean egg weight.     

Dietary cation-anion difference effects on performance and acid-base status of lactating dairy cows: a meta-analysis

A meta-analysis was conducted to examine potential empirical relationships between dietary cation-anion difference (DCAD) (Na + K - Cl) and the response of lactating dairy cows. The database was developed from 12 studies published between 1984 and 1997 that included a total of 17 trials, 69 dietary treatments, and 230 cows. Results indicated that DCAD affected performance of lactating dairy cows. Maximum milk yield and feed intake were reached when DCAD was 34 and 40 meq/100 g of feed dry matter, respectively. Blood pH and HCO3 concentrations increased with DCAD, indicating an improved acid-base balance of lactating dairy cows. Changes in urinary pH and urinary excretion of Na, K, and Cl were consistent with varying DCAD, thus dietary acidity or alkalinity. The effects of DCAD were likely mediated via modification of acid-base status in the cows.