IntroductionDairy production depends on the dairy cattlereproduction, while effective calf management dependson the structure and quality of feeds early in life. Ideally,good-quality colostrum, milk, or its replacers shouldprovide 9–12 g of daily liveweight gain per 1 kg. Poorweight gain is associated with poor immunity. However,if daily liveweight gain exceeds 15 g, it often causesobesity and affects the development of the mammarygland, which reduces milk production in adulthood.Good-quality calf starters prolong dairy cow’sproductive lifetime and increase its fertility. Second,third, and fourth calves are known to grow into morevaluable cows capable of higher milk yields and fertility.The determining factors for effective calf rearing are theirhealth, weight, and first calving age, which depend on thequality of colostrum and feeds in the first three months oflife [1].During this time, one calf consumes 300–350 Lof milk. However, feeding whole milk to dairy calvesreduces the marketability of dairy production andincreases the cost of herd management.Calf milk replacers (CMR) can increase themarketability and reduce these costs [2]. In Russia, CMRmarket volume is 120,000 tons per year. The marketdemands are satisfied by 30%, of which import accountsfor 20%.Russia possesses sufficient resources of milk wheyto produce CMRs. The rapidly increasing pork andsoybeans production can provide animal fat and highqualityvegetable protein for CMR formulations.A good CMR fulfills the following functions:– providing controlled weight gain;– replacing as much milk in calves’ diet as possible;– offering opportunities for using any whey, except forsalted one;– introducing fat in sufficient quantity;– ensuring high microbiological indicators;– increasing productivity while demanding littleinvestment.CMRs for young farm animals can be classifiedaccording to the main components:– skim milk and vegetable/animal fats;– whey protein concentrates and vegetable/animal fats;and– whey, vegetable protein concentrates, and vegetable/animal fats.These three CMRs have the same feeding efficiency,but the plant-based CMRs are more economical. Theyinclude protein concentrates that need special qualitystandards. For instance, they should contain a particularset of available amino acids but no such antialimentationfactors as oligosaccharides, allergenic proteins, variousinhibitors that might affect feed digestion, etc. Thesefactors can be eliminated by using special technologies,e.g. protein purification or molecular weight change.To ensure proper development of skeletal system,качественными кормами, направлено на обеспечение воспроизводства и поддержание молочного стада. Цель работы –комплексная оценка качественных характеристик молозива и заменителей молока, а также технологических подходов в этойобласти.Объекты и методы исследования. Молозиво и заменители цельного молока (ЗЦМ), методы их обработки; анализ процессовполучения новых видов ЗЦМ, направленных на ресурсо- и энергосбережение.Результаты и их обсуждение. Приведены потребности телят в молозиве, обсуждены качественные характеристикипервичного молока и подходы к их регулированию. Особое внимание уделено микробиологическим показателям первичногомолока, значению молозива в формировании иммунитета молодняка. Охарактеризованы возможности ферментативногорегулирования функциональных свойств молозива в результате гидролиза белков с применением высокоактивнойэндопептидазы (алкалаза). Рассмотрены варианты использования различных ферментных препаратов и бактериальныхзаквасок для получения гидролизованного и ферментированного молозива. Проведен анализ основных процессовыхпоказателей ЗЦМ с промежуточной влажностью. Обоснована целесообразность применения ряда методик для определенияжирнокислотного и белкового состава концентрированных ЗЦМ. Отмечено, что способы получения ЗЦМ оказываютсущественное влияние на значения анализируемых показателей.Выводы. Воспроизводство и реализация генетического потенциала молочного стада, а также экономикасельскохозяйственного производства определяются факторами, связанными с питанием молодняка сельскохозяйственныхживотных. Ферментативная обработка сырья является перспективным подходом для получения продуктов с улучшеннымифункциональными свойствами. Практическое применение глубоких гидролизатов молозива представляется целесообразным,в том числе в составе специализированных продуктов детского, спортивного и диетического питания.Ключевые слова. Молозиво, заменители цельного молока, гидролиз, антигенность, иммуноглобулины, ферменты,жирнокислотный составФинансирование. Работа выполнена в рамках государственного задания Министерства науки и высшего образованияРоссийской Федерации (Минобрнауки России) (тема № АААА-А20-120011500098-1).Для цитирования: Quality Control of Colostrum and Protein Calf Milk Replacers / V. D. Kharitonov, V. A. Asafov,E. L. Iskakova [et al.] // Food Processing: Techniques and Technology. – 2021. – Т. 51, № 1. – С. 188–195. https://doi.org/10.21603/2074-9414-2021-1-188-195.190KharitonovV.D. et al. Food Processing: Techniques and Technology, 2021, vol. 51, no. 1, pp. 188–195a good CMR should contain available macro- andmicroelements, which need to be introduced in such away as to ensure effective utilization.Acid whey poses a certain challenge: it needs acidityregulators that provide the required osmotic pressure inthe intestinal tract of animals.If all the above factors are taken into account, newtechnologies and formulations of plant-based CMRs canensure necessary weight gain and productivity.As for soy-based CMRs, which are based on soy flour,milk, and cereal flour, they have a lot of disadvantages asthey cannot be applied to very young animals and mayreduce their productivity in the future [1, 2]. The researchobjective was to provide comprehensive assessmentof the qualitative indicators of colostrum and milksubstitutes, as well as to define possible technologicaloptions in this area.Study objects and methodsThe studies were carried out on the premises of twoorganizations: Laboratory of Resource-Saving Processesand Functional Products at the All-Russian ScientificResearch Institute of the Dairy Industry (Moscow,Russia) and the Research Laboratory of AppliedBiological Issues at Belarusian State University (Minsk,Belarus).The research featured colostrum, and calf milkreplacers (CMR) produced by the All-Russian ResearchInstitute of Dairy Industry. The assessment methodologywas based on physicochemical, biochemical, andsanitary-hygienic indicators, as well as on the criteria forthe optimal weight gain of baby calves. The study madeit possible to define the efficiency factors, to developcontrol methods for quality indicators and composition,and to analyze the processes of obtaining new resourcesavingand energy-efficient CMRs [3].The study involved contemporary approachesto defining the biologically active properties ofnative, fermented, and hydrolyzed colostrum, i.e.the fluorometric method for antioxidant activity, theimpedimetric method for antimicrobial effect, and theAmes test for antimutagenic effect [4, 5].Results and discussionColostrum quality assessment. Colostrum is avaluable source of highly-concentrated biologicallyactive substances of protein nature:– lysozyme, lactoperoxidase, and lactoferrin that performthe functions of nonspecific immunity;– immunoglobulins responsible for specific protection inthe first hours after birth; and– transfer factors that serve as a signaling environmentfor triggering the mechanism of specific body defense.The quality of colostrum defines health status, weightgain, and calf raising economy. The list of importantfactors includes the IgG content, bacterial contamination,and storage conditions.High-quality colostrum for calf feeds should meetthe following requirements: IgG content ≥ 50 g/L ofimmunoglobulins; amount of colostrum = 10% of thebody weight (≈ 4 L); feeding time after calving ≤ 6 h;microbiological purity ≤ 100,000 CFU/mL [6, 7].Bacterial contamination of colostrum can causevarious diseases. Moreover, bacteria prevent immunoglobulinabsorption. In this regard, microbiologicalcontrol methods for colostrum microflora are priorityscientific issues because colostrum quality on dairyfarms needs to be improved. Heinrichs et al. studiedheat treatment of colostrum in order to reducebacterial and pathogenic growth while increasing IgGabsorption. The scientists also established the upperlimit of immunoglobulin absorption from colostrumand its substitutes, as well as assessed the possibilityof introducing lactoferrin and sodium bicarbonate intomaternal colostrum [8].The IgG concentration in the blood was found toaffect calves’ resistance to diseases. The amount ofabsorbed immunoglobulins depends on their consumptionwith colostrum, as well as on the efficiency of absorptionfrom the intestinal tract [9–11].The calf should receive the first portion of colostrumwithin the first hour after birth, and it should be atleast 70 mL/kg of body weight. The rate of feedingcolostrum during the first day depends on the IgG content(Table 1) [12].Colostrum immunoglobulins that a calf receives inthe first hours after birth lengthen the period of passiveimmunity. Endogenous antibody synthesis sufficient toprotect calves from infectious diseases usually developsat 1–3 months [9, 10].A sufficient amount of high-quality colostrum allowslacto- and bifidobacteria to colonize the intestines. Thenormal intestinal microflora of calves consists of equalnumbers of lactobacilli, bifidobacteria, and Escherichia,while the staphylococcus population is half as low [13].Colostrum contamination occurs in the udderor teat canal. It can also be caused by poor sanitaryconditions. Bacterial contamination of colostrum starts at100,000 CFU/mL, but experts notice negative effectsalready at 50,000 CFU/mL [14].Table 1. Amount of colostrum in calves’ diet,depending on the age and IgG concentrationTime afterbirth, hColostrum feeding rate at a particular IgGconcentration, L25 g/L 50 g/L 75 g/L 100 g/L1 4.0 2.0 1.3 1.03 — 2.5 1.6 1.36 — 2.9 1.9 1.59 — — 2.2 1.712 — — 2.5 1.915 — — 2.8 2.218 — — — 2.4191Харитонов В. Д. [и др.] Техника и технология пищевых производств. 2021. Т. 51. № 1 С. 188–195Low-temperature treatment at 63–66°С decreasesthe level of microbiological contamination of colostrumwithout affecting its immunomodulatory properties [15].These methods reduce colostrum deficiency byreserving it from healthy cows starting with the thirdlactation. Mature cows produce better colostrumcompared to heifers. The density of their milk is higherby 0.02 g/cm3, IgG content – by 73.4–122.2 mg/mL, IgAand IgM – by 8 mg/mL and 6 mg/mL, respectively, andthe mass fraction of dry matter – by 2.4% [12].One of our previous research showed that rawcolostrum obtained from farms in the Moscow Regiondid not meet the above requirements for microbiologicalparameters [3]. One of our previous studies featuredthe possibility of reducing the bacterial contaminationof colostrum by its fermentation with Lactobacillusacidophilus (strain No. 630, not viscous). The methodimproved microbiological indicators, increased theamount of lactic acid cultures, and raised the antioxidantactivity of fermented colostrum because the bacterialproteolytic system was broken down by proteins [4].Colostrum surpasses whole milk in nutritionalvalue and composition of biologically active components[16–19], which makes it a promising raw materialfor functional and diet foods for children, athletes,etc. One of our previous studies also featured thephysicochemical and biologically active properties ofcolostrum fermented with L. acidophilus and treated withproteolytic enzyme (alkalase) [4].The research defined the peptide composition,antioxidant activity, antimutagenic properties, andantimicrobial action of skim colostrum samples subjectedto hydrolysis and fermentation. Enzymatic hydrolysisappeared to provide better proteolysis (17.4%) thanfermentation with L. acidophilus (7.5%). The antioxidantactivity of the peptide fractions of hydrolyzed andfermented colostrum increased by 4.1 and 2.0 times ascompared to the original colostrum (dry solids content).As the proportion of the peptide fraction and the degreeof colostrum proteolysis increased, the antiradical activityincreased and the level of induced mutation (in the Amestest) decreased. Low molecular weight fractions ofhydrolyzed colostrum developed specific peptides withantimicrobial activity.As a result, they were found to be more effectiveagainst Escherichia coli, test strain ATCC 8739, thanagainst Staphylococcus aureus, ATCC 6538 grampositivestrain [4]. Complexation of hydrolysates withcyclic oligosaccharide (β-cyclodextrin) made it possibleto preserve the antimutagenic effect, increase theantibacterial effect of colostrum peptides, and improvetheir organoleptic properties [5]. The research resultsproved relevant when introducing inclusion complexesinto functional products.The abovementioned studies allowed us to obtainsamples of hydrolyzed and fermented colostrum withconfirmed biologically active properties [4, 5]. Therefore,fermentation and hydrolysis proved able to regulate thefunctional properties of products, which can be used indeveloping new feeds for young farm animals.Analysis of approaches to assessing the qualityindicators of new types of milk replacers. Various CMRscan increase marketability and reduce costs in dairyfarming [3, 20].The types of CMRs that are popular in contemporarydairy farming are based on:– skim milk and non-dairy fats;– whey protein concentrate and non-dairy fats;– whey and specialized concentrates and isolates of soyprotein and non-dairy fats; and– whey, soy flour, and non-dairy fats.The first three types are complete balanced feedsadapted to the needs of calves. They provide an averagedaily weight gain of 650–900 g. The fourth is intendedfor older calves. For an adapted feed, it contains toomuch lectins, oligosaccharides, and allergens.According to the production method, CMRs aredivided into whole milk replacer, which is a liquidproduct dried on a spray dryer, and regenerated milkprepared by dry mixing of ingredients, including fat.Each method has its own advantages anddisadvantages. Regenerated milk is more technologicallyadvanced in terms of production. However, fats have tobe introduced since calf feeds should not contain freefats. If free facts are present in the feed, calves absorbit poorly and develop slowly. As a result, regeneratedmilk has a low fat percentage (12%). The fat:proteinratio is 0.5:1, while in milk it is 1.2:1. Thus, calves maynot receive the energy necessary for growth and have toconsume more feed to replenish it.The main condition for the CMR production is thatreplacers should be cheaper than whole milk and providea required growth rate.The correct economic assessment of CMR cost is thecost of feed per 1 kg of weight gain. It justifies the useof whey-based replacers, specialized concentrates, andisolates of soy proteins and non-dairy fats. These CMRsare as effective as CMRs based on skim milk, but theirraw material composition is significantly cheaper. Lowenergy consumption and specific capital investments areimportant factors in CMR production.CMRs with intermediate moisture are quiteadvantageous as they make it possible to:– reduce spray drying costs;– use any kind of whey, except for salted one;– add fat in any required amount;– start a low investment production;– use methods of fermentation of protein fractions;– obtain products with specified probiotic properties; and– achieve good recombination before use;– obtain a product with a high degree of fat emulsificationand a minimum content of free fat.192KharitonovV.D. et al. Food Processing: Techniques and Technology, 2021, vol. 51, no. 1, pp. 188–195CMR production for young farm animals has acquiredindustrial scales in most developed countries. In Russia,it started in the 1970s [20, 21].Specialists dealing with CMR technologies focus onregulating their composition and functional propertiesand calculating the rational content of the mass fractionof solids. One of the topical areas of research is thedevelopment of new methodological approaches to theCMR technology, e.g., how to avoid drying stage andproduce concentrated CMR. The production methodologyand quality assessment of concentrated CMRs include thefollowing stages:1. Technological and processing options andparameters for obtaining various products based on dryand concentrated CMRs. Parameters that provide therequired levels of optimization, composition, quality, andphysicochemical properties involve technological modesat all production stages, including biotechnologicaltransformation of raw materials components duringprocessing.2. Parameters that ensure increased ecological safety,as well as low energy and resource consumption.3. Interconnection between quality indicators andproperties of dry and concentrated products, productionmodes, and energy consumption.4. Parameters that assess the end use based onobjective testing, including zootechnical research.5. Indicators of economic efficiency.This methodology requires the basic technologicalregimes that determine the optimal ranges of the massfraction of dry substances at various stages of dehydrationand in the final product. These technological modesdepend on the physicochemical and thermophysicalproperties of the product during production [22].These specific features mean that the methodologyfor concentrated CMR production must observe somespecific approaches. For instance, the efficiency ofdehydration decreases during the first stage followingthe increase in the concentration of the mass fraction ofdry substances. During vacuum evaporation, the heattransfer coefficient decreases as the mass fraction ofdry substances increases during thickening. Anotherlimiting factor is that viscosity increases togetherwith the concentration of the mix, which increasesenergy consumption and can terminate the dehydrationprocess [20].Dehydration usually presupposes a two-stagescheme of sequentially mounted reverse osmosis units.As a result, it is possible to estimate the approximatepermissible concentrations of the condensed product.For example, the limiting concentration of milk whey is25% when using reverse osmosis plants and 57% whenusing vacuum evaporators. These values depend on theproperties of the mix before concentration and requireexperimental testing.The mass fraction of the dry matter of concentratedCMRs can be controlled by adding additional componentsto the mix – dry or texturized. These processes incombination with direct methods of concentration makeit possible to control the mass fraction of dry substancesin a rather wide range. The upper values are affected byviscosity, gelling properties, and stratification, whichdepend on temperature and some other factors.Another important task of concentrated CMRproduction is to achieve maximal storage stability.This indicator can be improved using severaleffective techniques, e.g. pasteurization or cold storage,which inhibits bad microflora. Other methods ofinhibiting pathogenic microflora include fermentation,preservatives, heat sterilization, and ultraviolettreatment [20].From the point of view of production economy, longshelf life is not important since it increases additionalcosts for intermediate storage and related equipment.The optimal storage temperature for milk replacer isdetermined by its delivery radius and the technicalcapabilities of each customer.The approximate storage time for concentrated CMRsis based on some assumptions.The first assumption is that the production time anduse in practical conditions do not fluctuate. For example,the production time does not exceed two days, eventaking into account its storage at the plant and a 20%time cushion. The time the CMR spends on the farm isapproximately the same. Thus, the rational value of thestorage stability of concentrated CMRs depends onlyon the delivery radius and time. The delivery time takesno more than one day within a radius of up to 400 km.Therefore, delivery time hardly affects the need toincrease the storage stability of concentrated CMRs.What is more important is customer’s interest increating a stable, long-term supply of a concentratedCMR on the farm. As a result, producers may want tostock the CMR for the subsequent targeted delivery to thecustomer in particular amounts.Like many other multicomponent products withintermediate moisture content, CMRs require acomplex multifactorial production process that can beimplemented in various ways using various technologicaland technical methods of raw material processing(Fig. 1).Figure 1 shows that the basic principles of processingmulticomponent products remain the same, whilespecific technological methods are constantly beingimproved. Recent studies in the field of animal and plantbiotransformation revealed some new plant raw materialsand more effective means that facilitate and controlemulsification of vegetable fats and protein hydrolysis [4,5, 23–31].Such innovations help to achieve these goals (Fig. 1)if based on the analysis of a set of interrelated processparameters at all production stages.193Харитонов В. Д. [и др.] Техника и технология пищевых производств. 2021. Т. 51. № 1 С. 188–195New types of raw materials and processing methodsrequire new methods for assessing properties, quality,and physicochemical parameters of the product, e.g.the degree of emulsification of fats and changes in theantigenicity of plant proteins at particular productionstages. For instance, the main indicators of high-fatCMRs include the dispersed composition of vegetablefats, assessed by the average diameter of the fat globulesand their level of monodispersity in the CMR.Another indicator is the protein coating of thefat globules. However, no official indicator has beendeveloped so far for assessing protein globule membranesin concentrated CMRs. Qualitative assessment of thisindicator and change patterns in fat stability in variousprocessing modes are associated with dairy fat withoutprotein membranes. In liquid dairy products, such fatis usually called destabilized, whereas in dry dairyproducts, it is called free fat with surface free fat [26].However, these indicators are not decisive for assessingthe properties of concentrated CMRs, for the reasonsmentioned below.Free fat without globule membranes producealmost no oxidative taste in dry whole milk during sixmonths of storage, even at 30°C. In dairy fats, the rateof oxidative spoilage is highly inertial and depends onthe state of fatty acids, antioxidants, oxygen contactsurface, processing conditions, and storage conditions.In concentrated CMRs based on milk fats, their oxidationdegree is always relatively low because they are based onfresh milk [27].Taking into account these factors and the relativelyshort shelf life of concentrated CMRs, which does notexceed several weeks, the oxidation degree of the fatphase can be considered a limiting factor only for theinitial value immediately after production. However,increased oxidation is an important factor whenproducing concentrated CMRs with non-dairy animal andvegetable fats.As a result, the oxidation degree of non-dairy fats isa limiting factor: the values of this indicator should beequal to the dairy fat of pasteurized milk. Thus, whenproducing a concentrated CMR, the oxidation degree offat phase should be determined before adding it to themix, not before feeding it to baby calves. Based on thedata mentioned above, the analysis of the total contentof unprotected fat, destabilized or free, should takeplace after the methodology is improved and samplepreparation is thoroughly studied.Additional tests required for fat phase assessmentinclude the assessment of its fatty and amino acids, aswell as the dispersion of fat globules, which shouldcorrespond to the average size of fat globules in raw milk.The assessment methodology for protein properties ofa concentrated CMR also has its peculiarities because ofits plant origin and different initial composition. In thisregard, reducing the level of anti-nutritional substancesin the protein composition is of great importance. As aresult, assessing the antigenic properties of the proteinand its polypeptide profile is also extremely important.These indicators affect the zootechnical indicatorswhen feeding milk replacers to young farm animals.Therefore, they should be controlled at variousproduction stages, using traditional or novel techniquesof biotransformation of the original protein raw material.ConclusionThe main factor that determines the efficiencyand economy of feed for young farm animals is thebioavailability of its protein and fat components.The present research analyzed the qualitativeindicators of colostrum and milk replacers. The analysisrevealed that some of their physicochemical propertiesneed additional control, i.e. the concentration ofimmunoglobulins, the polypeptide and amino acid profileof the protein component. The sanitary and hygienicindicators of primary milk can be controlled using variousapproaches, e.g. thermal inactivation or fermentation ofcolostrum with acidophilus bacillus, which reduces thenumber of pathogens.The animal and vegetable fats that are part of milkreplacers have some specific properties. Therefore,Figure 1. Basic processing procedures and required indicators of concentrated milk replacersDecreasingresourceand energy costsIncreasingstoragestabilityIncreasingusefulpropertiesIncreasingeconomic efficiencyand competitivenessMixingand dosingBiotransformationof proteinEmulsification(homogenization)of fatConcentrating raw materialsto the required mass fractionof dry substances in the mixAjusting production modes to the required indicators of the finished producttheir assessment should be based on the methods fordetermining the average diameter of fat globules, fattyacid composition, and the initial oxidation state of fats.A complex study of the fat phase requires methods thatmake it possible to establish the peptide and amino acidprofile, as well as to assess the level of anti-nutritionaland antigenic properties. In concentrated milk replacers,the qualitative and quantitative indicators of theprotein and fat components depend on the methods andparameters their production.Only by controlling the quality of colostrum and usinghigh-quality whole milk replacers, farmers can providerapid weight gain, earlier calving, high productivity, andprolonged lactation.ContributonV.D. Kharitonov supervised the project and wrotethe paragraph about concentrated milk replacers.V.A. Asafov collected the material on colostrum andwrote the respective paragraph. E.L. Iskakova performedthe experimental research on the hydrolysis of plantproteins, processed the obtained data, and describedthe results. N.L. Tankova performed the experimentalstudies of colostrum fermentation, processed thedata, and described them. T.M. Halavach conductedthe experimental research on enzymatic colostrumhydrolysis, described the properties of the obtainedpeptides, processed the data, and described the results.V.P. Kurchenko supervised the project, collected researchmaterial, and performed its synthesis.Conflict of interestThe authors declare that there is no conflict ofinterests regarding the publication of this article.