Specific populations of the yeast Geotrichum candidum revealed by molecular typing

Geotrichum candidum is a ubiquitous yeast and an essential component in the production of many soft cheeses. We developed a multilocus sequence typing (MLST) scheme with five retained loci (NUP116, URA1, URA3, SAPT4 and PLB3) which were sufficiently divergent to distinguish 40 sequence types (STs) among the 67 G. candidum strains tested. Phylogenetic analyses defined five main clades; one clade was restricted to environmental isolates, three other clades included distinct environmental isolates and dairy strains, while the fifth clade comprised 34 strains (13 STs), among which all but two were isolated from milk, cheese or the dairy environment. These findings suggest an adaptation to the dairy ecosystems by a group of specialized European G. candidum strains. In addition, we developed a polymerase chain reaction inter‐long terminal repeat scheme, a fast and reproducible random amplification of polymorphic DNA‐like method for G. candidum, to type the closely related dairy strains, which could not be distinguished by MLST. Overall, our findings distinguished two types of dairy strains, one forming a homogeneous group with little genetic diversity, and the other more closely related to environmental isolates. Neither regional nor cheese specificity was observed in the dairy G. candidum strains analysed. This present study sheds light on the genetic diversity of both dairy and environmental strains of G. candidum and thus extends previous characterizations that have focused on the cheese isolates of this species. Copyright © 2016 John Wiley & Sons, Ltd.     

Technical note: Validation of the BHBCheck blood β-hydroxybutyrate meter as a diagnostic tool for hyperketonemia in dairy cows

Accurate cow-side blood β-hydroxybutyrate (BHB) detection meters are valuable tools for rapid diagnosis of hyperketonemia. The main objective of this study was to compare the blood BHB measured in whole blood by the BHBCheck meter (PortaCheck, Moorestown, NJ) to a previously validated meter, Precision Xtra meter (Abbott Laboratories, Abbott Park, IL) and a colorimetric laboratory assay. Samples (n = 426) were collected from postpartum primiparous and multiparous Holstein cows (n = 79 cows) enrolled in 1 of 2 experiments (Exp) with different sampling schedules (Exp 1: n = 39 cows, 58 samples; Exp 2: n = 40 cows, 368 samples). In both Exp, whole-blood samples were collected from the coccygeal vessels after morning milking, before morning feeding. Blood samples were used immediately for BHB quantification via the BHBCheck meter and the Precision Xtra meter. Blood was also collected into evacuated tubes containing no additive (Exp 1) or potassium oxalate/sodium fluoride (Exp 2), which were centrifuged for serum or plasma separation and stored at ?20°C for subsequent analysis. Laboratory quantification of BHB concentration was done by the BHB LiquiColor Assay (EKF Diagnostics-Stanbio, Boerne, TX; certified for serum and plasma). Data were analyzed by UNIVARIATE, CORR, FREQ, REG, and LOGISTIC procedures of SAS 9.4 (SAS Institute Inc., Cary, NC). Within this sample set, average parity was 3.3 lactations and DIM was 14 d. The proportion of samples classified as hyperketonemia (BHB ≥1.2 mmol/L) was 25, 28, and 31% as determined by the colorimetric assay, BHBCheck meter, and Precision Xtra meter, respectively. The correlation for BHBCheck meter BHB concentration compared with the colorimetric assay concentrations was r = 0.96, with a sensitivity of 91% and specificity of 93%. Correlation, sensitivity, and specificity of the Precision Xtra meter concentrations were 0.97, 98%, and 92%, respectively. Bland-Altman plots demonstrated minimal bias for both meters. Area under the receiver operator characteristic curve suggests adequate diagnostic accuracy of both meters. Overall, accuracy, sensitivity, and specificity of the BHBCheck meter was similar to the Precision Xtra meter and laboratory assay, indicating the BHBCheck meter is appropriate for use as a cow-side diagnostic test for hyperketonemia in dairy cows.     

乳与乳制品中总砷测定的不同前处理方法比较

目的比较不同前处理方法的处理效果,选择适合乳与乳制品中总砷测定的前处理方法。方法分别采用湿法消解、干法灰化、微波消解对乳与乳制品样品进行前处理,利用氢化物原子荧光法测定总砷含量。结果 3种前处理方式的检测结果均满足方法学要求,湿法消解、干法灰化和微波消解的回收率分别为81.7%～86.5%,90.0%～94.4%和90.8%～95.6%,精密度分别为8.84%～9.80%,3.22%～4.37%和3.18%～4.82%;检出限分别为0.0042、0.00068、0.0028mg/kg;微波消解法处理的质控样品结果更接近于标准值。结论微波消解法操作简便、准确性好,适合乳制品企业批量产品检测。     

HACCP系统在发酵乳制品生产中的应用

探讨HACCP(危害分析与关键控制点)质量管理系统在乳制品生产中的应用。对乳制品生产过程各个环节可能造成的潜在危害进行物理、化学和生物分析,确定关键控制点、关键限值、监控措施和建立纠偏措施,将生产过程各个环节可能造成的潜在危害消除或减轻使之达到可接受水平。     

Prevalence of failure of passive transfer of immunity in newborn heifer calves and associated management practices on US dairy operations

Failure of passive transfer of immunity (FPT) in dairy replacement calves has been linked to increased neonatal morbidity and mortality and long-term decreases in productivity. The purpose of this study was to estimate the prevalence of FPT in US dairy heifer calves in 2007 and to use nationally representative data to investigate associations of FPT with colostrum and calf management practices. A cross-sectional study was conducted by the USDA's National Animal Health Monitoring System between January and August 2007. Producers from 394 operations in 17 states completed survey questions about colostrum and calf management practices, and serum samples were collected from 1,816 healthy heifer calves on those operations. Serum immunoglobulin G (IgG) levels were determined by radial immunodiffusion, and calves were classified as having FPT if the IgG concentration was less than 10 mg/mL. To investigate associations between FPT and management practices, a multivariable analysis was completed using a weighted logistic regression model. The estimated prevalence of FPT in US dairy heifer calves was 19.2%. The odds of FPT were higher for calves on operations that pooled colostrum [odds ratio (OR = 2.2)], allowed nursing (OR = 2.4), or hand fed colostrum more than 4 h after birth (OR = 2.7). The odds of FPT were also higher for calves on operations that did not provide a source of heat during cold weather for calves experiencing a dystocia (OR = 1.6), would not seek veterinary assistance when unable to correctly position a calf for delivery (OR = 2.6), or did not routinely monitor serum proteins in calves as a measure of passive transfer (OR = 13.8). The prevalence of FPT in dairy heifer calves has decreased in the last 15 yr, so progress has been made in this important area of calf management. This study identified several management practices associated with FPT that could be targeted for educational campaigns or further research.     

Reducing prepartum urine pH by supplementing anionic feed ingredients: Effects on physiological and productive responses of Holstein × Gir cows

This study compared physiological and productive parameters in 3/4 Holstein × 1/4 Gir dairy cows receiving a prepartum concentrate containing ammonium chloride to reduce urine pH near 7.0 (CON; n = 17), or a commercial anionic supplement to reduce urine pH near 6.0 (SUPP; n = 17). Nonlactating, multiparous, pregnant cows were assigned to receive SUPP or CON beginning 21 d before expected date of calving. Cows were maintained in a single drylot pen with ad libitum access to corn silage, and individually received their prepartum concentrate once daily (0800 h) before calving. Cows from both treatments completely consumed their concentrate allocation within 30 min after feeding. Cow body weight and body condition score were recorded once weekly, urine pH measured every 3 d, and blood samples collected on d ?21, ?14, ?9, ?6, and ?3 relative to expected calving date. After calving (d 0), cows were moved to an adjacent drylot pen with ad libitum access to water and a total mixed ration, and were milked twice daily (0600 and 1700 h). Cow body weight and body condition score were recorded once weekly and individual milk production was recorded daily until 30 d in milk (DIM). Blood samples were collected before each milking during the first 5 DIM, as well as at 6, 9, 16, 23, and 30 DIM before the morning milking. Based on actual calving dates, cows received SUPP or CON for (mean ± standard error) 19.2 ± 1.2 and 19.0 ± 0.9 d before calving, respectively. Urine pH was less in SUPP versus CON cows during the last 15 d of gestation (6.12 vs. 7.15, respectively). Milk yield during the first 5 DIM and throughout the experimental period was greater in SUPP versus CON cows (by 20 and 14%, respectively), whereas serum Ca concentrations did not differ between treatments during the first 5 DIM. Serum concentrations of fatty acids were greater in SUPP versus CON cows 3 d before and at calving (by 52 and 22%, respectively), whereas SUPP cows had lower serum glucose and cortisol concentration at calving (by 23 and 27%, respectively). Hence, the SUPP treatment decreased prepartum urine pH near 6.0 in Holstein × Gir dairy cows without depressing concentrate intake compared with CON, although total dry matter intake was not evaluated to fully investigate feed intake responses. Moreover, the SUPP treatment transiently affected serum glucose, fatty acids, and cortisol concentrations near the time of calving, and resulted in greater milk yield during the initial 30 DIM compared with CON.     

高效毛细管电泳法测定奶制品中三聚氰胺含量

目的：建立奶制品中三聚氰胺的含量测定方法。方法：采用高效毛细管电泳法测定,以30mmol/L 磷酸盐缓冲液(pH5.0)为电泳介质,未涂层石英毛细管(75μm× 78cm,有效长度70cm)为分离通道,紫外检测波长240nm,分离电压10kV。结果：三聚氰胺在10.0～50.0μg/mL 范围内线性关系良好,r=0.9992。平均加标回收率为97.04%,平均RSD 为1.24%(n=3)。结论：该方法快速简便、灵敏度高、重现性好,可用于奶制品中三聚氰胺含量的测定。     

乳制品依新鲜度定价模型的建立

建立起一种按照新鲜度给乳制品定价的模型，通过价格调节的机制，削弱甚至消除新鲜度对消费者需求的影响，从而可以达到促进需求．优化库存管理以及减小资源浪费的目的。该定价模型从价格调节的角度给乳制品的销售和管理提供了一种新的思路。     

A 100-Year Review: A century of dairy heifer research

The years 1917 to 2017 saw many advances in research related to the dairy heifer, and the Journal of Dairy Science currently publishes more than 20 articles per year focused on heifers. In general, nutrition and management changes made in rearing the dairy heifer have been tremendous in the past century. The earliest literature on the growing heifer identified costs of feeding and implications of growth on future productivity as major concepts requiring further study to improve the overall sustainability of the dairy herd. Research into growth rates and standards for body size and stature have been instrumental in developing rearing programs that provide heifers with adequate nutrients to support growth and improve milk production in first lactation. Nutrient requirements, most notably for protein but also for energy, minerals, and vitamins, have been researched extensively. Scientific evaluation of heifer programs also encouraged a dramatic shift toward a lower average age at first calving over the past 30 yr. Calving at 22 to 24 mo best balances the cost of growing heifers with their production and lifetime income potential. Increasingly, farms have become more progressive in adopting management practices based on the physiology and nutrient needs of the heifer while refining key economic strategies to be successful. Research published in the Journal of Dairy Science has an integral role in the progress of dairy heifer programs around the world.     

Supplemental Smartamine M or MetaSmart during the transition period benefits postpartal cow performance and blood neutrophil function

The onset of lactation in dairy cows is characterized by severe negative energy and protein balance. Methionine availability during this time for milk production, hepatic lipid metabolism, and immune function may be limiting. Supplementing Met to peripartal diets with adequate Lys in metabolizable protein (MP) to fine-tune the Lys:Met ratio may be beneficial. Fifty-six multiparous Holstein cows were fed the same basal diet from 50 d before expected calving to 30 d in milk. From −50 to −21 d before expected calving, all cows received the same diet [1.24 Mcal/kg of dry matter (DM), 10.3% rumen-degradable protein, and 4% rumen-undegradable protein] with no Met supplementation. From −21 d to expected calving, the cows received diets (1.54 Mcal/kg of DM, 10% rumen-degradable protein, and 5.1% rumen-undegradable protein) with no added Met (control, CON; n = 14), CON plus MetaSmart (MS; Adisseo Inc., Antony, France; n = 12), or CON plus Smartamine M (SM; Adisseo Inc.; n = 12). From calving through 30 d in milk, the cows received the same postpartum diet (1.75 Mcal/kg of DM and 17.5% CP; CON), or the CON plus MS or CON plus SM. The Met supplements were adjusted daily and top-dressed over the total mixed ration at a rate of 0.19 or 0.07% (DM) of feed for MS or SM. Liver tissue was collected on −10, 7, and 21 d, and blood samples more frequently, from −21 through 21 d. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) with the preplanned contrasts CON versus SM + MS and SM versus MS. No differences in prepartal DM intake (DMI) or body condition score were observed. After calving, body condition score was lower (2.6 vs. 2.8), whereas DMI was greater (15.4 vs. 13.3 kg/d) for Met-supplemented cows. Postpartal diet × time interactions were observed for milk fat percentage, milk fat yield, energy-corrected milk:DMI ratio, and energy balance. These were mainly due to changes among time points across all treatments. Cows supplemented with either Met source increased milk yield, milk protein percentage, energy-corrected milk, and milk fat yield by 3.4 kg/d, 0.18% units, 3.9 kg/d, and 0.18 kg/d, respectively. Those responses were associated with greater postpartum concentration of growth hormone but not insulin-like growth factor 1. There was a diet × time effect for nonesterified fatty acid concentration due to greater values on d 7 for MS; however, liver concentration of triacylglycerol was not affected by diet or diet × time but increased postpartum. Blood neutrophil phagocytosis at 21 d was greater with Met supplementation, suggesting better immune function. Supplemental MS or SM resulted in a tendency for lower incidence of ketosis postpartum. Although supplemental MS or SM did not decrease liver triacylglycerol, it improved milk production-related traits by enhancing voluntary DMI.