Changes in milk fat globule membrane proteins along lactation stage of Laoshan dairy goat

The milk fat globule membrane(MFGM)is a complex structure with numerous functions,and its composition is affected by many factors.There have been few systematic investigations on goat MFGM proteome profiling during lactation.Individual milk samples from 15 healthy dairy goats were obtained at six lactation time points for investigation of the MFGM proteome using both data-independent acquisition(DIA)and data-dependent acquisition(DDA)proteomics techniques combined with multivariate statistical analysis.Using the DIA method,890 variably abundant MFGM proteins were discovered throughout the lactation cycle.From 1 to 240 d,butyrophilin subfamily 1 member A1,lipoprotein lipase,perilipin-2,and adipose triglyceride lipase were upregulated,while APOE,complement C3,clusterin,and IgG were downregulated.Furthermore,from 1 to 90 d,annexin A1,annexin A2,and antithrombin-ll were downregulated,then upregulated by d 240.Albumin had a high degree of connectedness,indicating that it was a key protein,according to protein-protein interaction research.Overall,our findings gave new insights into the biological features of MFGM protein in goat milk throughout lactation,which may aid in the creation of specialized MFGM products and infant formula.

Efficacy of fermented milk and whey proteins in Helicobacter pylori eradication:A review

Helicobacter pylori (H. pylori) eradication is considered a necessary step in the management of peptic ulcer disease, chronic gastritis, gastric adenocarcinoma and mucosa associated lymphoid tissue lymphoma. Standard triple therapy eradication regimens are inconvenient and achieve unpredictable and often poor results. Eradication rates are decreasing over time with increase in antibiotic resistance. Fermented milk and several of its component whey proteins have emerged as candidates for complementary therapy. In this context the current review seeks to summarize the current evidence available on their role in H. pylori eradication. Pertinent narrative/systematic reviews, clinical trials and laboratory studies on individual components including fermented milk, yogurt, whey proteins, lactoferrin, α-lactalbumin (α-LA), glycomacropeptide and immunoglobulin were comprehensively searched and retrieved from Medline, Embase, Scopus, Cochrane Controlled Trials Register and abstracts/proceedings of conferences up to May 2013. A preponderance of the evidence available on fermented milk-based probiotic preparations and bovine lactoferrin suggests a beneficial effect in Helicobacter eradication. Evidence for α-LA and immunoglobulins is promising while that for glycomacropeptide is preliminary and requires substantiation. The magnitude of the potential benefit documented so far is small and the precise clinical settings are ill defined. This restricts the potential use of this group as a complementary therapy in a nutraceutical setting hinging on better patient acceptability/compliance. Further work is necessary to identify the optimal substrate, fermentation process, dose and the ideal clinical setting (prevention/treatment, first line therapy/recurrence, symptomatic/asymptomatic, gastritis/ulcer diseases etc.). The potential of this group in high antibiotic resistance or treatment failure settings presents interesting possibilities and deserves further exploration.

Genetic Polymorphism of Milk Protein and Their Relationships with Milking Performances in Chinese Yak

The milk protein polymorphisms were typed by polyacrylamide gel electrophoresis (PAGE)from 109 Maiwa and 100 Jiulong yaks, and the relationships among milk protein polymorphisms,milking traits and milk protein compositions were studied. The results showed thatβ-CN,κ-CN andα-La were monomorphic,αs1-CN andβ-Lg were polymorphic, the dominantgenes were αs1-CN D and β-Lg E,respectively. The frequencies of αs1-CN D were 0.8073and 0.6000 and β-Lg E were 0.9770 and 0.9700 in two populations respectively.The meanheterozygosities were 0.1021 and 0.1867 in two populations. No significant effects onmilking traits and milk protein compositions were observed except for αs1-CN locus onfat percentage in Jiulong yak.

Study on screening potential allergenic proteins from infant milk powders based on human mast cell membrane chromatography and histamine release assays

Cow's milk allergy is mainly observed in infants and young children. Most allergic reactions affect the skin, followed by the gastrointestinal and respiratory systems. Conventional diagnosis is based on positive allergy studies and evaluation of parameters including IgE and IgG1 levels, acute allergic skin response and anaphylactic shock reactions. We developed a cell membrane chromatographic(CMC)method based on human mast cells(HMC-1) for screening potential allergens in infant formula milk powders(IFMP). HMC-1 cell membranes were extracted and mixed with silica to prepare cell membrane chromatography columns(10 mm ? 2 mm i.d., 5 mm). Under the conditions of 0.2 mL/min flow rate and214 nm detection wavelength, human breast milk showed no retention. However, IFMP showed clear retention. The retained fractions were collected and analyzed through matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF-MS). Four major milk proteins, i.e., α-casein, β-casein, α-lactalbumin, and β-lactoglobulin A, were identified. Furthermore, these proteins and β-lactoglobulin B showed clear retention on HMC-1/CMC columns. To test the degranulation effects of the five proteins, histamine and β-hexosaminidase release assays were carried out. All five proteins induced HMC-1 cells to release histamine and β-hexosaminidase. Also, we established a reversed phase liquid chromatographic(RPLC) method for the determination of the five proteins in IFMP and the results showed that 90% proteins in IFMP were α-casein and β-casein. We concluded that cow's milk proteins may be potential allergens and caseins cause more β-casein allergic risk than other proteins. This conclusion was consistent with other studies.

Comparison Between MIR and NIR Spectroscopic Techniques for the Determination of Fat and Protein Contents in Milk

To compare mid-infrared(MIR)and near-infrared(NIR)spectroscopies for the determination of the fat and protein contents in milk,the same sample sets with varying concentrations of fat and protein were measured in the MIR range of 3 200-700 cm-1 and NIR range of 9 000-4 000 cm-1.The spectral features in the two regions were analyzed.The MIR spectra of milk were characteristic due to the MIR inherent molecular specificity,whereas the NIR spectra were relatively characterless due to the NIR low selectivity.Partial least squares(PLS)regression models for fat and protein were developed by using both MIR and NIR spectra.MIR data with no pretreatment gave better results than NIR data.The square correlation coefficient(R2)and the root mean square error of prediction(RMSEP)were 0.98 and 0.10 g/dL for fat and 0.97 and 0.11 g/dL for protein.With NIR techniques,satisfactory results were not obtained with raw data.However,NIR data after pretreatment gave similarly good results to the ones using MIR method.This paper indicates that either of the MIR and NIR spectral methods is reliable for the determination of the fat and protein contents.

The market for amino acids: understanding supply and demand of substrate for more efficient milk protein synthesis

For dairy production systems, nitrogen is an expensive nutrient and potentially harmful waste product. With three quarters of fed nitrogen ending up in the manure, significant research efforts have focused on understanding and mitigating lactating dairy cows' nitrogen losses. Recent changes proposed to the Nutrient Requirement System for Dairy Cattle in the US include variable efficiencies of absorbed essential AA for milk protein production. This first separation from a purely substrate-based system, standing on the old limiting AA theory, recognizes the ability of the cow to alter the metabolism of AA. In this review we summarize a compelling amount of evidence suggesting that AA requirements for milk protein synthesis are based on a demand-driven system. Milk protein synthesis is governed at mammary level by a set of transduction pathways, including the mechanistic target of rapamycin complex 1(mTORC1), the integrated stress response(ISR), and the unfolded protein response(UPR). In tight coordination, these pathways not only control the rate of milk protein synthesis, setting the demand for AA, but also manipulate cellular AA transport and even blood flow to the mammary glands, securing the supply of those needed nutrients. These transduction pathways, specifically mTORC1, sense specific AA, as well as other physiological signals, including insulin, the canonical indicator of energy status. Insulin plays a key role on mTORC1 signaling, controlling its activation, once AA have determined mTORC1 localization to the lysosomal membrane.Based on this molecular model, AA and insulin signals need to be tightly coordinated to maximize milk protein synthesis rate. The evidence in lactating dairy cows supports this model, in which insulin and glucogenic energy potentiate the effect of AA on milk protein synthesis. Incorporating the effect of specific signaling AA and the differential role of energy sources on utilization of absorbed AA for milk protein synthesis seems like the evident following step in nutrient requirement systems to further improve N efficiency in lactating dairy cow rations.

Multi‑omics reveals that the host‑microbiome metabolism crosstalk of differential rumen bacterial enterotypes can regulate the milk protein synthesis of dairy cows

Background Dairy cows’lactation performance is the outcome of the crosstalk between ruminal microbial metabo-lism and host metabolism.However,it is still unclear to what extent the rumen microbiome and its metabolites,as well as the host metabolism,contribute to regulating the milk protein yield(MPY).Methods The rumen fluid,serum and milk of 12 Holstein cows with the same diet(45%coarseness ratio),parity(2–3 fetuses)and lactation days(120–150 d)were used for the microbiome and metabolome analysis.Rumen metabolism(rumen metabolome)and host metabolism(blood and milk metabolome)were connected using a weighted gene co-expression network(WGCNA)and the structural equation model(SEM)analyses.Results Two different ruminal enterotypes,with abundant Prevotella and Ruminococcus,were identified as type1 and type2.Of these,a higher MPY was found in cows with ruminal type2.Interestingly,[Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae(the differential bacteria)were the hub genera of the network.In addition,differential ruminal,serum and milk metabolome between enterotypes were identified,where the cows with type2 had higher L-tyrosine of rumen,ornithine and L-tryptophan of serum,and tetrahydroneopterin,palmitoyl-L-carnitine,S-lactoylglutathione of milk,which could provide more energy and substrate for MPY.Further,based on the identi-fied modules of ruminal microbiome,as well as ruminal serum and milk metabolome using WGCNA,the SEM analysis indicated that the key ruminal microbial module1,which contains the hub genera of the network([Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae)and high abundance of bacteria(Prevotella and Ruminococcus),could regulate the MPY by module7 of rumen,module2 of blood,and module7 of milk,which contained L-tyrosine and L-tryptophan.Therefore,in order to more clearly reveal the process of rumen bacterial regulation of MPY,we established the path of SEM based on the L-tyrosine,L-tryptophan and related components.The SEM based on the metabolites suggested that[Ruminococcus]gauvreauii group could inhibit the energy supply of serum tryptophan to MPY by milk S-lactoylglutathione,which could enhance pyruvate metabolism.Norank_f_Ruminococcaceae could increase the ruminal L-tyrosine,which could provide the substrate for MPY.Conclusion Our results indicated that the represented enterotype genera of Prevotella and Ruminococcus,and the hub genera of[Ruminococcus]gauvreauii group and norank_f_Ruminococcaceae could regulate milk protein synthesis by affecting the ruminal L-tyrosine and L-tryptophan.Moreover,the combined analysis of enterotype,WGCNA and SEM could be used to connect rumen microbial metabolism with host metabolism,which provides a fundamental understanding of the crosstalk between host and microorganisms in regulating the synthesis of milk composition.

The Influence of Heat Treatment on Interaction of Green Tea Flavonoids with Milk Proteins

Several heat treatment norms are applied in the dairy industry during the manufacture of various products. The knowledge on the influence of temperature on the proteins-flavonoid binding is critical for optimization of process conditions. The aim of this study was to establish the effect of heat treatment on the interaction between milk proteins and flavonoids and also determine when to apply heat treatment. Reverse-phase high-performance liquid chromatography (RP-HPLC) analysis revealed that free flavonoids decreased in the presence of milk proteins and a binding ratio (%) was calculated based on this decrease. Three different heat treatment norms were selected (80, 85 and 90℃×10 min). Analyses were carried out in both sodium caseinate and skimmed milk samples to observe the possible effect of milk serum proteins on the interaction. The binding ratio between flavonoids and proteins was found to be higher in the samples where green tea extract (GTE) was added before heat treatment than in the samples where GTE was added after heat treatment in both the skimmed milk and sodium caseinate systems. Results of protein surface hydrophobicity (PSH) index and protein partition also demonstrated that heat treatment must be applied after the addition of GTE to improve the amount of GTE binding to milk proteins.

Correlation between the Insertion/Deletion Mutations of Prion Protein Gene and BSE Susceptibility and Milk Performance in Dairy Cows

Objective To investigate the 23 bp and 12 bp insertion/deletion(indel)mutations within the bovine prion protein(PRNP)gene in Chinese dairy cows,and to detect the associations of two indel mutations with BSE susceptibility and milk performance.Methods Based on bovine PRNP gene sequence,two pairs of primers for testing the 23 bp and 12 bp indel mutations were designed.The PCR amplification and agarose electrophoresis were carried out to distinguish the different genotypes within the mutations.Moreover,based on previous data from other cattle breeds and present genotypic and allelic frequencies of two indels mutations in this study,the corrections between the two indel mutations and BSE susceptibility were tested,as well as the relationships between the mutations and milk performance traits were analyzed in this study based on the statistical analyses.Results In the analyzed Chinese Holstein population,the frequencies of two"del"alleles in 23 bp and 12 bp indel muations were more frequent.The frequency of haplotype of 23del-12del was higher than those of 23del-12ins and 23ins-12del.From the estimated r2and D’values,two indel polymorphisms were linked strongly in the Holstein population(D’=57.5%,r2=0.257).Compared with the BSE-affected cattle populations from the reported data,the significant differences of genotypic and allelic frequencies were found among present Holstein and some BSE-affected populations(P<0.05 or P<0.01).Similarly,there were significant frequency distribution differences of genotypes and alleles among Chinese Holstein and several previous reported healthy dairy cattle(P<0.05 or P<0.01).Moreover,association of genotype and combined genotypes of two indel polymorphisms with milk performance and resistant mastitis traits were analyzed in Holstein population,but no significant differences were found(P>0.05).Conclusions These observations revealed that the influence of two indel mutations within the bovine PRNP gene on BSE depended on the breed and they did not affect the milk production traits,which layed the foundation for future selection of resistant animals,and for improving health conditions for dairy breeding against BSE in China.

Bacillus subtilis Co-transfected with a Lysine-rich and a Methionine-rich Protein Gene and Its Effect on Cow Milk Production

The probiotic Bacillus subtilis （B. subtilis） was widely applied in animal production as feed additive. Lysine （Lys） and methionine （Met） were the two most important limiting amino acids in livestock animal feed. Raising Lys and Met contents in B. subtilis would provide better effects for animal production and save Lys and Met supplements. We still didn＇t know whether Lys- rich and Met-rich protein genes from plants could be transfected into B. subtilis and expressed at a high level so as to improve animal production, such as milk production as an additional diet. The Lys-rich protein gene （Cflr） and Met-rich 10 ku-δ Zein were cloned from pepper anther and maize endosperm, respectively. Then they were constructed into plasmids individually and successfully cotransfected into B. subtilis. Upon IPTG induction, mRNAs and protein expressions could be observed. Lys and Met contents in the fermentation broth were raised by 65.92% and 46.39%, respectively. After feeding 200 g and 400 g· cow^-1· d^-1, transgenic B. subtilis fermentation broth, the milk yield, milk protein and milk fat contents all significantly increased. The Lys-rich protein gene （Cflr） and Met-rich 10 ku-δ Zein were successfully transfected into B. subtilis. Contents of Lys and Met in the transgenic B. subalis obviously raised and the fermentation broth of the transgenic bacteria could effectively improve milk yield and quality.

Dietetic Valorization of Cow＇s Milk Proteins Fermented at 45 ℃ by Lactobacillus acidophilus Associated with Bifidobacteria

Cow＇s milk constitutes a significant food for babies when mother＇s milk is insufficient. The purpose of this work is to offer a fermented milk, potentially hypoallergenic, using selected Lactobaeillus acidophilus and Bifidobacteria sp. for their proteolytic activities. The fermentation is evaluated by the rate of lactic acid production and by the bacterial enumeration at 45 ℃. The rate of acidification obtained by mixed cultures （La ＋ B. longum, 63.8 ± 3.5 °D） and （La ＋ B. breve, 43.4 ± 1.67 °D） compared with the control （milk） （18.6 ± 1.31 °D）. The result of the best hydrolysis was obtained by （La＋ B. longum） （154.88 ± 30.33 ug/mg） which corresponded to a better release of the a-NH2 functions （103.32 ± 12.81 umoles/mg） compared with control （307.2 ± 11.54 ug/mg and 10.25 ± 0.44 umoles/mg ）. The best synergy was obtained by （La ＋ B. bifidum） （13 × 10^6 cfu/mL and 60 × 10^6 cfu/mL） and reached 95 × 10^10 cfu/mL and 119 × 10^10 cfu/mg at the end. The electrophoresis of fermented milk revealed the presence of soluble proteins （a-Lactalbumin and β-Lactoglobulin）. The Enzyme Linked Immtmo Sorbent Assay showed the results of residual antigenic activities of β-Lg （1.4 ± 0.23 ug/mg）, a-La （0.012 ± 0.004 ug/mg） and bovin serum albumin （0.014 ± 0.005 ug/mg）by the associations （La ＋ B. longum）, （La ＋ B. bifidum） and （La ＋ B. bifidum） compared with the control （14.43 ± 5.91 ug/mg, 0.183 ± 0.062 gg/mg, 0.05 ± 0.008 ug/mg） respectively. Lactic fermentation reduced to a significant antigenic reactivity of principal whey milk proteins.

Physico-Chemical Properties of Milk Whey Protein Agglomerates for Use in Oral Nutritional Therapy

Agglomerates based on milk whey proteins and modified starch (MS) were developed for patients with dysphagia. Calcium caseinate (CaCas), whey protein isolate (WPI), concentrate (WPC) and hydrolysate (WPH) were used. The sources were agglomerated with the MS and an increase in the porosity and viscosity of the agglomerates were observed. In all the systems evaluated, the WPI agglomerate at a concentration of 112 g/L showed a viscosity between 2122 and 5110 cP, and the agglomerates of WPC and WPH between 1115?-?2880 cP and 2600 - 6651 cP, respectively. CaCas exhibited high values in water and milk of 3200 cP and 6651 cP, respectively, and low values of 640 cP in juice. In sensory tests, the 70% WPI: 30% MS juice obtained a score 6.97, an improvement in relation to the other agglomerates, but not differing (p = 0.681) from the commercial thickener, 6.91 (p = 0.380). Based on these results, the 70% WPI: 30% MS was suggested for use in the nutritional therapy of patients with dysphagia.

Whey Protein-Carboxymethylcellulose Obtained by Complex Coacervation as an Ingredient in Probiotic Fermented Milk

Discharge of whey proteins is still a current practice by small cheese producers. The development of low-cost alternatives for recovery of these proteins is fundamental for small producers who cannot apply expensive techniques. The present study investigated the complex coacervation technique as a cheap technology to recover proteins from sweet whey using carboxymethylcellulose, and the coacervate used as an ingredient in the formulation of probiotic fermented milk. The nutritional properties of whey-carboxymethylcellulose coacervates (WP-CMC) were evaluated in trials with animals (rats) using casein as a reference. All these parameters—the coefficient of feed efficiency (CEA), protein digestibility-corrected amino acid score (PDCAAS), and net protein ratio (NPR), as well as weight gain—were determined to evaluate protein quality. A sensory acceptance test was applied to evaluate the sensory characteristics of the product. The complex coacervation technique recovered 86% of the protein from sweet whey. No significant (p > 0.05) differences were observed in the biological tests for both groups (WP-CMC and Casein groups) when NPR (4.98 to 5.04), digestibility (92.35 to 90.64), and CEA (0.40 to 0.42) were evaluated. Probiotic fermented milk beverage containing WP-CMC (0.78%) and guar gum (0.68%) presented good acceptability as determined by sensory evaluation. WP-CMC can be considered an ingredient with high nutritional and biological value that could be applied in probiotic fermented milk as an alternative to small producers to allocate the residual whey from cheese manufacture.

Water-dispersed bone morphogenetic protein nanospheres prepared by co-precipitation method

A modified complex coacervation-co-precipitation method was used to prepare bone morphogenetic protein (BMP)-loaded nanospheres. Three natural polymers were used as packing materials to obtain nanoscale delivery device for BMP,in the presence of phosphatidylcholine functioning as stabilizer. Positively charged polysaccharide, N,N-diethylaminoethyl dex-tran (DEAE-dextran) tended to form stable, uniform and smaller size particles carrying BMP. Negatively charged bovine serum albumin (BSA) induced precipitation of the produced BMP particles due to its weak interaction with BMP molecules, although it produced nanosized BMP spheres. While collagen, a weakly positively charged protein shaped larger particles due to the strong interaction among themselves. A mechanism of co-precipitation process was also deduced to depict the formation of stable nanospheres.

Feeding Protected Lysine and Methionine Modifies Milk Protein Profile in Grazing Dairy Cows

The experiment was designed to determine the effect of protected lysine (Lys) and methionine (Met) supply on milk protein profile in grazing dairy cows specifically in the caseins (CNs) and α-lactalbumin fractions. Twelve multiparous mid lactation Holstein cows producing 24 (±4.76) kg of milk were assigned to one of two treatments (six cows per treatment) during an experimental period of 21 days. In the control (C) group, cows grazed a Pennisetum clandestinum pasture and were supplemented with a commercial concentrate according to milk production. In the Met-Lys treatment, cows received the same ration supplemented with protected Lys and Met. Milk yield and composition and milk protein profile were measured at the start and the end (21st day) of the experimental period. The Tricine-SDS-PAGE and the Gel-Quant Express Analysis (Invitrogen) software were used to determine milk protein composition. Statistical analysis was performed using the SAS’s PROC MIXED procedure through a mixed model that included the animal as a random effect and the treatments as a fixed effect adjusted by covariables. Milk production averaged 23.7 (±2.0) kg cow-1 day-1 without differences between treatments (P P -1 day-1) compared to C (24.2 kg cow-1 day-1). Milk protein content (g/kg) did not differ (C = 30.4;Met-Lys = 31.1) and lactose content tended (P P β-CN also increased (P < 0.05) after protected aminoacid supply (C = 9.58;Met-Lys = 10.35). It can be concluded that milk protein composition was improved by protected Lys-Met supply without altering other compositional parameters of milk composition. Milk nutritional quality and its potential yield for cheese-making were positively enhanced.

Very early onset perinatal constipation:Can it be cow’s milk protein allergy?

Delayed passage of meconium or constipation during the perinatal period is traditionally regarded as a signal to initiate further work up to evaluate for serious diagnoses such as Hirschsprung’s disease(HD),meconium ileus due to Cystic Fibrosis,etc.The diagnosis of HD particularly warrants invasive testing to confirm the diagnosis,such as anorectal manometry or rectal suction biopsy.What if there was another etiology of perinatal constipation,that is far lesser known?Cow’s milk protein allergy(CMPA)is often diagnosed in infants within the first few weeks of life,however,there are studies that show that the CMPA allergen can be passed from mother to an infant in-utero,therefore allowing symptoms to show as early as day one of life.The presentation is more atypical,with perinatal constipation rather than with bloody stools,diarrhea,and vomiting.The diagnosis and management would be avoidance of cow's milk protein within the diet,with results and symptom improvement in patients immediately.Therefore,we discuss whether an alternative pathway to address perinatal constipation should be further discussed and implemented to potentially avoid invasive techniques in patients.This entails first ruling out CMPA with safe,noninvasive techniques with diet modification,and if unsuccessful,then moving forward with further diagnostic modalities.

Analysis of influence of water temperature on milk powder proteins using MALDI-TOF MS

The influence of water temperature on protein composition in the reconstitution of milk powder was evaluated using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF MS）. 11 ion peaks in the matrix-assisted laser desorption/ionization （MALDI） spectra were examined to study the alteration of relative quantities of milk proteins when water at different temperature was employed in the reconstitution of milk powder. A discrepancy factor Dij was implemented to represent the degree of milk proteins＇ denaturation. Data obtained indicated that Dij value increased with rising water temperature, and thermal damage to milk proteins became evidently when the water temperature exceeded 60℃. The results confirmed that nutrient loss occurred when milk proteins denatured in water at high temperatures.

Effect of Different Protein Levels on Nutrient Digestion Metabolism and Serum Biochemical Parameters in Calves

The current study has been performed to examine the effects of different dietary protein levels on the growth, nutrient digestion and absorption, as well as biochemical parameters in calves. Nine healthy newborn calves were selected, randomly divided into 3 groups and fed 3 milk replacers with different protein levels （18, 22, and 26%）, respectively. Five period-digestion-metabolism trials were taken between 12-20, 22-30, 32-40, 42-50, and 52-60 days after birth. All 3 groups showed a similar growth curve during 11 to 61 experimental days, however, the growth rate of the 22% crude protein （CP） group was 8.89% higher than that of the 18% CP group and 19.48% higher than that of the 26% CP group, respectively. The apparent digestibility of dry material （DM） declined gradually with age, whereas, the apparent digestibility of N, extract ether （EE） rose slightly. Compared to the 22% CP and 26% CP group, calves fed with 18% CP apparently had a lower digestibility than DM, EE, and nitrogen （N）. The average apparent digestibilities of N were 69.39, 75.36, and 74.55%, respectively. Both the apparent digestibility and retention of calcium （Ca） and phosphorus （P） were steady throughout the experiment, but the average apparent digestibility of P in the 26% CP group was only 63.83%, which was markedly lower than that of the 18% CP group （70.40%） and 22% CP group （69.73%）. In addition, the serum concentrations of total protein （TP）, albumin （ALB）, and globulin （GLOB） of the 22% CP group were higher than those in the 18% CP and 26% CP groups. The urea N （BUN） content in the 18% CP group, on the other hand, was significantly lower than that of the other two groups. The highest glucose （GLU） concentration was found in the 22% CP group （5.38 mmol L^-1）, at the end of the trials. The protein levels in the milk replacer affected the digestion metabolism of nutrition and the serum biochemical parameters of calves at different physiological phases. Calves fed with 22% CP milk replacer had a better growth performance than the other groups.

Development of a Rapid Multi-residue Assay for Detecting β-lactams Using Penicillin Binding Protein 2x

Objective To develop a rapid multi-residue assay for detecting 16 demanded by the European Union （EU）. Methods A recombinant penicillin-binding protein （PBP） 2x＊ from Streptococcus pneumoniae R6 was expressed in vitro and six β-1actams were conjugated to HRP by four methods. A rapid multi-residue assay for β-1actams was established with PBP2x＊ and HRP-conjugate. Results PBP2x＊ was expressed and purified successfully and the ideal HRP-conjugate was identified. The multi-residue assay was developed. After optimization, penicillin G, ampicillin, amoxicillin, cloxacillin, dicloxacillin, oxacillin, nafcillin, cephalexin, ceftiofur, cefalonium, cefquinome, cefazolin, cefoperazone, cephacetrile, and cephapirin can be detected at levels below MRL in milk with simple pretreatment. Conclusion This assay developed can detect all 16 β-1actams demanded by the European Union （EU）. The whole procedure takes only 45 min and can detect 42 samples and the standards with duplicate analysis.

Recent progress of porcine milk components and mammary gland function

As the only nutritional source for newborn piglets,porcine colostrum and milk contain critical nutritional and immunological components including carbohydrates,lipids,and proteins(immunoglobulins).However,porcine milk composition is more complex than these three components.Recently,scientists identified additional and novel components of sow colostrum and milk,including exosomes,oligosaccharides,and bacteria,which possibly act as biological signals and modulate the intestinal environment and immune status in piglets and later in life.Evaluation of these nutritional and non-nutritional components in porcine milk will help better understand the nutritional and biological function of porcine colostrum and milk.Furthermore,some important functions of the porcine mammary gland have been reported in recent published literature.These preliminary studies hypothesized how glucose,amino acids,and fatty acids are transported from maternal blood to the porcine mammary gland for milk synthesis.Therefore,we summarized recent reports on sow milk composition and porcine mammary gland function in this review,with particular emphasis on macronutrient transfer and synthesis mechanisms,which might offer a possible approach for regulation of milk synthesis in the future.