Milk Protein Composition Research Articles

EFFECT OF NUTRIENTS OF FEED PREPARED WITH PROBIOTIC ON MILK QUALITY AND COW PRODUCTIVITY IN THE FOREST-STEPPE ZONE OF THE CARPATIAN REGION

The purpose of the research was to determine the effect of feed nutrients, in particular, silage prepared from a wheat-oat mixture with the use of the probiotic preparation kt-l 18/1 (selection of the probiotics laboratory of the institute of agricultural microbiology and apv) in a dose of 8.0 ml of suspension per 1 ton of green mass on the fractional composition of milk proteins and its qualityand on the productivity of cows in the forest-steppe zone of the Carpathian region.
 The research was carried out on two groups of lactating cows of the Ukrainian black-spotted breed, similar in age, live weight and milk yield for the previous lactation, 10 cows each. In each the animals of both groups received the basic diet, in addition to which the cows of the control group were fed 20 kg of wheat-oat silage prepared on the farm according to traditional technology, and the experimental group - 19 kg of silage preserved with the use of the probiotic KT-l 18/1.
 It was established that the use of probiotics for harvesting silage contributed to obtaining a high-quality product, the introduction of which into the rations of cows in the transition period made it possible to minimize the deficit of dry matter (from 19.8 to 9.1%) and protein (from 4.2% to2.1%), and in winter – from 28.0 to 8.5% in terms of dry matter and from 10.1 to 0% in terms of protein, respectively.
 The study of the chemical composition showed an increase in the content of dry matter, mainly due to the total protein, fat and casein in the milk of experimental cows both in the transitional and stable periods of retention
 The milk of the cows of the research group during the stable period of storage contained more dry matter, fat, total protein and casein, respectively, by 4.8; 3,4; 5.2 and 5.6% than the control, which led to an increase in its density by 0.7 оА.
 In the milk of experimental cows, the improvement of parameters affecting its syrupiness was noted: casein content, density. According to both the reductase test and the fermentation test, which indicates the presence of gas-forming microflora in the milk and its syrupy quality, the milk of the control cows was assigned to the ІІ, and the experimental cows to the І quality class.
 The average daily yield of natural milk for 45 days of the accounting period in the experimental group was 16.7 kg and was 5.7% higher than in the control group (15.8 kg).

Host genetic control on rumen microbiota and its impact on dairy traits in sheep

BackgroundMilk yield and fine composition in sheep depend on the volatile and long-chain fatty acids, microbial proteins, vitamins produced through feedstuff digestion by the rumen microbiota. In cattle, the host genome has been shown to have a low to moderate genetic control on rumen microbiota abundance but a high control on dairy traits with heritabilities higher than 0.30. There is little information on the genetic correlations and quantitative trait loci (QTL) that simultaneously affect rumen microbiota abundance and dairy traits in ruminants, especially in sheep. Thus, our aim was to quantify the effect of the host genetics on rumen bacterial abundance and the genetic correlations between rumen bacterial abundance and several dairy traits, and to identify QTL that are associated with both rumen bacterial abundance and milk traits.ResultsOur results in Lacaune sheep show that the heritability of rumen bacterial abundance ranges from 0 to 0.29 and that the heritability of 306 operational taxonomic units (OTU) is significantly different from 0. Of these 306 OTU, 96 that belong mainly to the Prevotellaceae, Lachnospiraceae and Ruminococcaceae bacterial families show strong genetic correlations with milk fatty acids and proteins (absolute values ranging from 0.33 to 0.99). Genome-wide association studies revealed a QTL for alpha-lactalbumin concentration in milk on Ovis aries chromosome (OAR) 11, and six QTL for rumen bacterial abundances i.e., for two OTU belonging to the genera Prevotella (OAR3 and 5), Rikeneleaceae_RC9_gut_group (OAR5), Ruminococcus (OAR5), an unknown genus of order Clostridia UCG-014 (OAR10), and CAG-352 (OAR11). None of these detected regions are simultaneously associated with rumen bacterial abundance and dairy traits, but the bacterial families Prevotellaceae, Lachnospiraceae and F082 show colocalized signals on OAR3, 5, 15 and 26.ConclusionsIn Lacaune dairy sheep, rumen microbiota abundance is partially controlled by the host genetics and is poorly genetically linked with milk protein and fatty acid compositions, and three main bacterial families, Prevotellaceae, Lachnospiraceae and F082, show specific associations with OAR3, 5, 15 and 26.

Milk proteins as a feed restriction signature indicating the metabolic adaptation of dairy cows

Milk production in dairy cows is affected by numerous factors, including diet. Feed restriction is known to have little impact on milk total protein content but its effect on the fine protein composition is still poorly documented. The objective of this study was to describe the effects of two feed restriction trials of different intensities on the milk protein composition of Holstein cows. One restriction trial was of high intensity (H: 8 mid-lactation Holstein cows) and the second of moderate intensity (M: 19 peak lactation Holstein cows). Feed restriction decreased the milk protein yield for caseins under the M trial and of all six major milk proteins under the H trial. These decreased yields lead to lower concentrations of αs1-, αs2- and β-caseins during the H trial. The milk proteome, analyzed on 32 milk samples, was affected as a function of restriction intensity. Among the 345 proteins identified eight varied under the M trial and 160 under the H trial. Ontology analyses revealed their implication in carbohydrate, lipid and protein metabolisms as well as in the immune system. These proteins reflected adaptations of the animal and mammary gland physiology to feed restriction and constituted a signature of this change.

Feeding of palm oil fatty acids or rapeseed oil throughout lactation: Effects on mammary gene expression and milk production in Norwegian dairy goats.

Lipid added as rapeseed or palm oil to the diet of dairy goats over 8 mo of one lactation alters fat secretion and milk fatty acid (FA) and protein composition. In this study, we examined the contribution of mammary gene expression to these changes and included 30 multiparous goats of Norwegian dairy goat breed for a 230-d experimental period, with indoor feeding from 1 to 120 d in milk (DIM), mountain grazing from 120 to 200 DIM, and indoor feeding from 200 to 230 DIM. After an initial period (1-60 DIM) when the control diet was given to all goats, the animals were subdivided into 3 groups of 10 goats. Treatments (60-230 DIM) were basal concentrate (control) alone or supplemented with either 8% (by weight) hydrogenated palm oil enriched with palmitic acid (POFA) or 8% (by weight) rapeseed oil (RSO). Milk was sampled individually from all animals throughout lactation, at 60, 120, 190, and 230 DIM for milk yield and composition. On d 60, 120, 190, and 230, mammary tissue was collected by biopsy to measure mRNA abundance of 19 key genes. None of the 19 genes involved in milk protein, apoptosis, lipid metabolism, transcription factors, and protein of the milk fat globule membrane, as measured by mRNA abundance, were affected by the lipid supplements, although POFA increased milk fat content, and POFA and RSO affected milk FA composition. Over the experimental period (120-230 DIM), the mRNA abundance of 13 of the 19 studied genes was affected by lactation stage. For some genes, expression either gradually increased from 120 to 230 DIM (CSN2, CASP8, CD36, GLUT4) or increased from 120 to 200 and then remained stable (XDH), or decreased (CSN3, G6PD, SREBF1, PPARG1) or increased only at 230 DIM (SCD1, SCD5, ELF3). For a second group of genes (CSN1, LALBA, FABP3, FASN, LPL, MFGE8), expression was stable over the lactation period. Our results suggest that factors other than gene expression, such as substrate availability or posttranscriptional regulation of these genes, could play an important role in the milk fat and FA responses to dietary fat composition in the goat. In conclusion, mammary gene expression in goats was more regulated by stage of lactation than by the dietary treatments applied.

Milk Coagulation Properties: A Study on Milk Protein Profile of Native and Improved Cattle Breeds/Types in Sri Lanka

This study was conducted to assess the variations of milk coagulation properties (MCP) among two native cattle types, e.g., Thamankaduwa White (TW), Lankan cattle (LC) and two improved cattle breeds, e.g., Friesian (FR) and Jersey (JS), in relation to distinctive milk protein compositions. MCP traits, including rennet coagulation time (RCT), curd firmness, meltability and yield, were measured. The milk protein profile of each breed/type was analyzed using capillary zone electrophoresis. Significant differences (p < 0.05) were observed among two native and improved cattle breeds/types in relation to RCT. Friesian and TW milk had the longest and shortest (p < 0.05) RCT, respectively. There was no significant difference in firmness among the four breeds/types. The highest (p < 0.05) coagulum yield was recorded for TW milk, followed by LC, JS and FR. TW milk had the highest (p < 0.05) meltability values. As revealed by the protein profiles, κ-casein concentration was significantly higher in TW milk compared to the other three breeds/types. None of the other milk protein fractions showed significant differences among the four breeds/types. The overall results indicate the superior MCP of TW milk, emphasizing the value of native breeds which could be exploited in the development of niche dairy products while supporting the conservation effort of the native cattle gene pool.

Характеристика сезонных изменений белкового состава молока хайнака

The qualitative composition of commercial milk is a relevant issue of the food industry. The khainak, or yattle, is a hybrid between the yak and domestic cattle. The research objective was to study the seasonal protein composition of khainak milk from the Northern Kyrgyzstan highlands.
 The study featured samples of khainak milk obtained from farms located in the Issyk-Kul region at an altitude of 2840 m above sea level. Standard research methods included high pressure liq uid chromatography and capillary electrophoresis. Khainak milk has more protein than cow milk, and the mass fraction of protein in it is 3.91–4.39%. In this research, the mass fraction of protein in khainak milk obtained in spring, summer, and autumn exceeded that of cow milk by 0.54, 1.02, and 0.84%, respectively. The total nitrogen content correlated with the mass fraction of protein, i.e., it was at its highest in summer (0.689 ± 0.004%). The content of non-protein nitrogen remained almost the same (0.0489–0.0496%). Spring milk contained by 0.2% more whey protein than summer milk (0.94 ± 0.05%) and autumn milk (0.97 ± 0.05%). Summer milk demonstrated a 1% increase in casein proteins, compared to spring and autumn samples. The average β-lactoglobulin content was 2.35 mg·mL–1, while α-lactoalbumin was 2.12 mg·mL–1 of the total albumin fraction. In terms of amino acid composition, khainak milk was balanced except for tryptophan. In the warm season, the content of essential amino acids was higher than in the cold season ( P < 0.05), which corresponded to the changes in total protein co ntent.
 Khainak milk is richer in protein and some other components than cow milk, which makes it a valuable non-traditional dairy raw material for such protein products as cheese or cottage che ese, including their functional variants.

Особенности получения и применения мицеллярного казеина в технологии молокоемких белковых продуктов

The modern food industry sees raw milk as a source of functional ingredients. Technologies of protein ingredients have a great scientific and practical importance because membrane fractionation methods preserve the native structure and properties of protein components. The resulting proteins have good fat profile, moisture retention, and emulsification characteristics, as well as perform some useful technological functions in food systems. They have no status of food additives and can be applied in various branches of food production. Unfortunately, the Russian food industry has no such technologies of its own. This article introduces some technological recommendations for the p roduction of domestic micellar casein concentrate.
 The research involved skim milk, commercial micellar casein concentrates from various manufacturers, curd samples with 9.0% of fat in dry matter, and Rossiysky cheese produced according to traditional formulation and technology. The experiment relied on standard research methods of physical and chemical analysis to establish the chemical composition of the samples, e.g., fractional composition of skim milk proteins, grain-size distribution, amino acid profile, etc.
 The study involved a comparative analysis of the chemical composition, as well as functional and technological properties of commercial micellar casein concentrates from various manufacturers. A set of experiments made it possible to define the thermal effect on raw material and to predict the prospects for usage of the new technology. Samples with a high ratio of casein:whey proteins and a moderately high heat treatment increased the curd and cheese yield by 10–12% in comparison with the traditional formulation. Samples with the maximal concentration of undenatured milk-serum protein nitrogen increased the yield of protein dairy products by 2–3% in comparison with other samples of micellar casein concentrates. The ratio of casein:whey proteins was 80:20 in skim milk obtained at PJSC Dairy “Voronezhsky”. The optimal pore diameter was ≥ 15 nm. As for the microbiological properties, QMA&OAMO was 6×104 CFU/dm3, and no pathogenic microorganisms were detected.
 Therefore, low-temperature pasteurization proved feasible at ≤ 76 ± 2°C and 10–15 s of hold time. The micellar casein concentrate added certain functional and technological properties to the finished product, depending on the specific application scope. 
 The new technology will enable the domestic food industry to ov ercome the existing import dependence.

Prediction of Indirect Indicators of a Grass-Based Diet by Milk Fourier Transform Mid-Infrared Spectroscopy to Assess the Feeding Typologies of Dairy Farms.

Simple SummaryThe dairy industry is interested in developing a detection tool for milk produced from pasture to certify the protected designation of origin of certain dairy products. As the cattle’s grazing influences the milk composition, the milk mid-infrared (MIR) spectra will be modified. Therefore, this study aims to develop a predictive model allowing one to use milk MIR spectrometry to classify milk as produced from a cattle diet either based on grass or not. To achieve this objective, the collection of grazing calendars from farms is needed. Unfortunately, this is hardly possible, as this information is rarely recorded. Therefore, the innovation of this research consists of using the usual farming practices developed in the southern part of Belgium combined with a large-scale milk database containing 48 milk composition-related traits. Indeed, in this geographical area, the cows are mainly on pasture between April and September. Therefore, the month of testing can be considered indirect information about their feeding. The developed models were able to distinguish with a precision of around 90% the supposed grass-based diet. Therefore, the probability of belonging to the GRASS class could be used in a tool counting the number of grazing days to confirm the labeling of dairy products.This research aims to develop a predictive model to discriminate milk produced from a cattle diet either based on grass or not using milk mid-infrared spectrometry and the month of testing (an indirect indicator of the feeding ration). The dataset contained 3,377,715 spectra collected between 2011 and 2021 from 2449 farms and 3 grazing traits defined following the month of testing. Records from 30% of the randomly selected farms were kept in the calibration set, and the remaining records were used to validate the models. Around 90% of the records were correctly discriminated. This accuracy is very good, as some records could be erroneously assigned. The probability of belonging to the GRASS modality allowed confirmation of the model’s ability to detect the transition period even if the model was not trained on this data. Indeed, the probability increased from the spring to the summer and then decreased. The discrimination was mainly explained by the changes in the milk fat, mineral, and protein compositions. A hierarchical clustering from the averaged probability per farm and year highlighted 12 groups illustrating different management practices. The probability of belonging to the GRASS class could be used in a tool counting the number of grazing days.

Effects of preservative, storage time, and temperature of analysis on detailed milk protein composition determined by reversed-phase high-performance liquid chromatography.

Milk preservative and freezing are used as strategies to prevent microbial growth and milk degradation, especially when immediate analytical processing is not feasible. The effects of the addition of preservative and freezing procedures have been investigated mainly in relation to milk gross chemical composition predicted through mid-infrared spectroscopy. This study aimed to determine whether different preservatives (i.e., no preservative, hydrogen peroxide, Bronopol, and Azidiol), freezing times (i.e., 0, 7, and 30 d), and temperatures of analysis (i.e., 5 and 21°C) influence the composition of milk protein fractions determined through reversed-phase HPLC. Bulk milk samples for the analysis of protein profile were collected from 5 commercial dairy farms. Data were analyzed with a linear mixed model, which included type of preservative, time of storage, temperature of analysis, and the interaction between type of preservative and time of storage as fixed effects, with the farm and the residual as random effects. Samples with no preservative had the greatest amount of all protein fractions, whereas Bronopol-preserved milk had the lowest amount. Increasing storage time under freezing conditions had a nonlinear detrimental effect on milk protein fractions. The temperature of analysis significantly contributed to the variation of κ-casein, β-casein, αS1-casein, β-lactoglobulin, and α-lactalbumin fractions. The z-scores were calculated to evaluate the similarity between detailed protein profile of fresh milk without preservative analyzed at 5°C and detailed protein profile of milk treated according to the tested conditions. Overall results suggested a good agreement between different analytical conditions. Still, short storage time under freezing conditions is recommended to avoid degradation of milk protein fractions and consequent analytical underestimation.

Correlation of maternal dietary intake with breast milk composition and infant growth.

Background: Maternal dietary intake during the period of lactation has an impact on infants growth. Macronutrients in breast milk are affected by several factors such as maternal dietary intake and maternal nutritional status. This study aims to prove the association between maternal protein and fat intake with the composition of breast milk and growth of infants (age 0-6 months). Methods: Prospective study was conducted for 6 months in 41 mother-infant pairs who were exclusively breastfed, and visited to hospitals or health centres. The mothers age is <40 years old with normal and single pregnancy. The breast milk was collected and analyzed using Human Milk Analyzer. Results: There was a negative correlation between maternal protein intake and breast milk composition at 3 months old infants (p = 0.042), between fat intake with HAZ score at 2 weeks (p = 0.048), and between protein intake with HAZ score at 3 months (p = 0.049). Finally, there was a significant increase in WAZ and HAZ score in all sample groups. Although the maternal protein intake of our subjects were only at 83% of Indonesian's RDA average, the protein composition of breast milk and the growth of the infants was sufficient. Conclusion: There is correlation between maternal dietary intake with the composition of breastmilk and infant growth. Even though the calories and protein intake of the mother is lower than the RDA, the breast milk is still sufficient for the growth of infants aged 0-6 months who are exclusively breastfed.

Comparative Proteomic Analysis of Proteins in Breast Milk during Different Lactation Periods.

Breast milk is an unparalleled food for infants, as it can meet almost all of their nutritional needs. Breast milk in the first month is an important source of acquired immunity. However, breast milk protein may vary with the stage of lactation. Therefore, the aim of this study was to use a data-independent acquisition approach to determine the differences in the proteins of breast milk during different lactation periods. The study samples were colostrum (3–6 days), transitional milk (7–14 days), and mature milk (15–29 days). The results identified a total of 2085 different proteins, and colostrum contained the most characteristic proteins. Protein expression was affected by the lactation stage. The proteins expressed in breast milk changed greatly between day 3 and day 14 and gradually stabilized after 14 days. The expression levels of lactoferrin, immunoglobulin, and clusterin were the highest in colostrum. CTP synthase 1, C-type lectin domain family 19 member A, secretoglobin family 3A member 2, trefoil factor 3 (TFF3), and tenascin were also the highest in colostrum. This study provides further insights into the protein composition of breast milk and the necessary support for the design and production of infant formula.

Comparative Analysis of the Protein Composition of Goat Milk from French Alpine, Nubian, and Creole Breeds and Holstein Friesian Cow Milk: Implications for Early Infant Nutrition.

Simple SummaryGoat’s milk is a food that contains proteins of value for nutrition. The protein profile in the milk of goat breeds is different from that of cow milk, with a lower relative abundance of allergenic proteins. In addition, regardless of the breed, goat milk has beta-casein of type A2 in a more significant proportion than cow milk, which impacts different bioactive peptides hydrolyzed in the milk of the species.Of the diversity of proteins and high digestibility, goat milk will be a food of significant value for infant nutrition. The genetic polymorphisms of milk proteins play an essential role in the different degrees of allergic reactions. This work aimed to identify the proteins and peptides in the composition of goat milk and compare them to those in cow’s milk. The work was performed with goats French Alpine, Nubian, and Creole breeds and Holstein Friesian milking cows at the Universidad Autónoma de Querétaro, Amazcala. We investigated the relative abundance of goat and cow milk protein fractions by SDS-PAGE resolution and the densitometric analysis of gels. The protein alfa-casein was (17.67 ± 0.46) for Creole, (19.18 ± 0.88) French Alpine, (17.35 ± 0.49) Nubian, and (35.92 ± 1.96) Holstein cows. The relative abundance obtained from alfa-casein was statistically different between goats and cows, and this protein was vital because it is a protein related to allergies. On the other hand, the amino acid in position 67 of the beta-casein from three goat breeds is a Proline, so it is assumed that the beta-casein variant of goat milk is an A2-type. The latter has excellent relevance for infant nutrition and differs from cow milk.

Ceramic membrane filtration of skim milk for the production of a casein-enriched permeate

The protein composition of skim milk was adjusted using a pilot-scale membrane microfiltration system to produce a casein-enriched permeate with a ratio of casein to serum protein close to 1:1. Microfiltration was performed at 50 °C to a volume concentration factor of 3 followed by 2 diafiltration steps. Three different membrane pore sizes (0.10, 0.14 and 0.20 μm) were used to compare the separation effect, then the effect of three different transmembrane pressures (100, 120 and 150 kPa) on protein composition in the permeate was studied. Membranes of 0.10 and 0.14 μm retained most of the casein. The 0.20 μm membrane allowed casein to pass through and made the ratio of casein to serum protein in the permeate close to 50:50 with a mean flux of 128.3 kg m−2 h−1 at 120 kPa, demonstrating the potential application of a 0.20 μm membrane to produce a new dairy ingredient.

Obesogenic diet in mice compromises maternal metabolic physiology and lactation ability leading to reductions in neonatal viability.

Diets containing high-fat and high sugar (HFHS) lead to overweight/obesity. Overweight/obesity increases the risk of infertility, and of the pregnant mother and her child for developing metabolic conditions. Overweight/obesity has been recreated in mice, but most studies focus on the effects of chronic, long-term HFHS diet exposure. Here, we exposed mice to HFHS from 3 weeks prior to pregnancy with the aim of determining impacts on fertility, and gestational and neonatal outcomes. Time-domain NMR scanning was used to assess adiposity, glucose, and insulin tolerance tests were employed to examine metabolic physiology, and morphological and proteomic analyses conducted to assess structure and nutrient levels of maternal organs and placenta. Fertility measures of HFHS dams were largely the same as controls. HFHS dams had increased adiposity pre-pregnancy, however, exhibited exacerbated lipolysis/hyper-mobilization of adipose stores in late pregnancy. While there were no differences in glucose or insulin tolerance, HFHS dams were hyperglycemic and hyperinsulinemic in pregnancy. HFHS dams had fatty livers and altered pancreatic islet morphology. Although fetuses were hyperglycemic and hyperinsulinemic, there was no change in fetal growth in HFHS dams. There were also reductions in placenta formation. Moreover, there was increased offspring loss during lactation, which was related to aberrant mammary gland development and milk protein composition in HFHS dams. These findings are relevant given current dietary habits and the development of maternal and offspring alterations in the absence of an increase in maternal weight and adiposity during pregnancy, which are the current clinical markers to determine risk across gestation.

Features of the functional composition of goat's milk and its importance as the basis for infant formula

Goat milk has a long history of use in human nutrition. There are currently many studies examining the functional characteristics and nutritional value of goat milk and its importance in the production of various dairy products. Before, native goat milk was widely used for feeding young children if the breastfeeding was impossible. To date, however, the practice of feeding unmodified goat milk, as well as cow milk, to infants under 12 months of age is strongly discouraged, as this leaves them exposed to the risk of electrolyte imbalance, as well as iron, folic acid, and vitamin B12 deficiencies. Commercial production of formulas based on goat milk began in the 1980s, and since then there have been many studies which show the safety and effectiveness of these formulas. The review provides the latest evidenced-based information on the composition and functional properties of individual components of the goat milk and goat milk formulas. The protein and amino acid composition of goat milk, as well as the features of its effects on the formation of the infant's intestinal microbiota, are described in detail. The studies investigating goat milk oligosaccharides and their similarity to human milk oligosaccharides are presented. The characteristics of the goat milk fat profile have been demonstrated. As an example of an adapted goat milk formula, a formula designed to meet all standards is presented. The fat profile of the presented formula is modified by introducing a patented lipid complex consisting of β-palmitate in its composition. In addition, the presented formula composition includes such oligosaccharides as galacto- and fructo-oligosaccharides, which availability ensure the formation of an optimal intestinal microbiota.

Lactose hydrolyzing activity of the lactase immobilized polycaprolactone and silk fibroin-based nanofiber and nitrocellulose membrane

This study aimed to investigate the activity of lactase immobilized polycaprolactone and silk fibroin (PCL/SF)-based nanofiber and nitrocellulose membrane for the preparation of lactose-reduced milk. PCL/SF -based nanofiber was prepared by using the electrospinning method. The lactase enzyme was immobilized using the physical adsorption method on both surfaces, and then the optimum operating temperature and pH of the immobilized enzymes were determined. The efficiency of the immobilized lactase enzyme was determined in both goat and cow milk. The nutrient content of milk was also analyzed before and after the incubation of nanofiber and membrane with milk. The lactose hydrolysis efficiency of the lactase immobilized nitrocellulose membrane was found to be higher than the lactase immobilized PCL/SF -based nanofiber. Lactose was hydrolyzed 59% in cow milk and 87% in goat milk by using lactase immobilized nitrocellulose membrane. 42% of lactose was also hydrolyzed in cow milk and 21% was hydrolyzed in goat milk by using lactase immobilized PCL/SF-based nanofiber. However, the use of these two bioactive surfaces did not change the fat and protein composition of both cow and goat milk. In conclusion, lactase immobilized nitrocellulose membrane was found to be more advantageous in the production of lactose-reduced milk than the lactase immobilized polycaprolactone/silk fibroin nanofiber.

Effect of feed on the milk protein and fat composition

Abstract. Feed is considered the most important factor affecting the composition of cow's milk of which the quality can be evaluated, essentially, through two parameters, the fat and protein content, because of their industrial interest. This study aims to evaluate the impact of seven different rations (R1-R7) on the protein and fat content of Prim’holstein cow milk in a cattle farm in Algiers. The results showed that the dry matter (DM) content of forages and concentrate was 72.74% (62.94% - 81.49%) and 27.25% (18.51% - 37.06%), respectively. The forage unit milk (FUM) and the digestible nitrogen matter (DNM) contents of forage were 60.50% (51.37% - 72.08%) and 61.15% (46.73% - 74.63%), respectively. In concentrate, the FUM and DNM contents were 39.50% (24.85 - 51.5%) and 38.85% (25.37 - 52.39%), respectively (Table 3). The forages showed significantly higher DM, FUM and DNM contents than the concentrate (p&lt;0.0001). The type of ration showed a highly significant effect on the quantity of milk produced per day, protein content and defatted dry matter. However, no significant influence was observed for the fat content. The highest milk production (ranging from 17.31 to 19.64 liters/day) and the highest defatted dry matter (87.03 and 87.92 g/l) were recorded in cows which received rations R2, R3, R4 and R5 (p&lt;0.0001). The highest protein content values (32.87 and 33.20 g/l) were observed in the milk of cows that were fed with rations R2, R3 and R4. The lowest levels were observed for rations R6 (31.80 g/l) and R7 (31.22 g/l) (p&lt;0.0001). Protein to fat content ratio ranged from 0.79 to 0.84 and fat to protein content ratio ranged from 1.19 to 1.27. Good management of the diet and feeding practices of the dairy cows allow having an adequate protein and fat content in the milk. A diet composed of forages with an adequate supplementation in concentrate leads to the optimal results. Further studies are important to evaluate the effect of the physical form of the diet on the physicochemical quality of the milk.

Comparative analysis of caseins in Saanen goat milk from 3 different regions of China using quantitative proteomics

A quantitative proteomic technique based on data-independent acquisition (DIA) was used to analyze differentially expressed caseins of Saanen goat milk samples collected from 3 regions in China (Guangdong, GD; Inner Mongolia, IM; Shaanxi, SX). A total of 345 proteins were quantified in each sample. Gene Ontology (GO) analysis showed that proteins were mainly involved in cellular process and cell and binding functions. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated that proteins were mainly involved in metabolic pathways. Differentially expressed proteins (DEP) between goat milk from 3 comparison groups composed of paired regions were compared and analyzed. The number of DEP was 114, 69, and 79 for GD versus IM, GD versus SX, and IM versus SX, respectively. The GO enrichment analysis of the 3 comparison groups showed that differences were mainly related to the regulation of biological quality, biological regulation, and response to stimulus in terms of biological process; extracellular region for cellular component; and binding function for molecular function. Pathways in which DEP of GD versus IM, GD versus SX, and IM versus SX were mostly protein processing in endoplasmic reticulum for the first 2 groups and metabolic pathways for the last. Protein-protein interaction network analysis demonstrated that the most prominent DEP was heat shock protein 90 β family member 1 for both the GD versus IM and the GD versus SX groups, and haptoglobin for the IM versus SX group. Data from this study may offer useful information for further investigation of the protein composition of Saanen goat milk and its application in the dairy industry.

Breeding for improved protein fractions and free amino acids concentration in bovine milk.

Considerable resources are required to routinely measure detailed milk compositional traits. Hence, an insufficient volume of phenotypic data can hinder genetic progress in these traits within dairy cow breeding programmes. The objective of the present study was to quantify the opportunities for breeding for improved milk protein and free amino acid (FAA) composition by exploiting mid‐infrared spectroscopy (MIRS) predictions routinely recorded from milk samples. Genetic parameters for protein fractions and FAA composition were estimated using 134,546 test‐day records from 16,166 lactations on 9,572 cows using linear mixed models. Heritability of MIRS‐predicted protein fractions ranged from 0.19 (α‐lactalbumin) to 0.55 (β‐lactoglobulin A), while heritability of MIRS‐predicted FAA ranged from 0.08 for glycine to 0.29 for glutamic acid. Genetic correlations among the MIRS‐predicted FAA were moderate to strong ranging from −0.44 (aspartic acid and lysine) to 0.97 (glutamic acid and total FAA). Adjustment of the genetic correlations for the genetic merit of 24‐h milk yield did not greatly affect the correlations. Results from the current study highlight the presence of exploitable genetic variation for both protein fractions and FAA in dairy cow milk. Besides, the direction of genetic correlations reveals that breeding programmes directly selecting for greater milk protein concentration carry with them favourable improvement in casein and whey fractions.

The Texture of Camel Milk Cheese: Effects of Milk Composition, Coagulants, and Processing Conditions.

Numerous people in African, Middle Asian, Middle Eastern, and Gulf Cooperation Council (GCC) countries highly value camel milk (CM) as it plays a vital role in their diet. The protein composition of CM as well as the structure of its casein micelles differs significantly from bovine milk (BM). Cheeses made from CM have a weak curd and soft texture compared to those made from BM. This review article presents and discusses the effect of milk protein composition, processing conditions (pasteurization and high-pressure treatment), and coagulants (camel chymosin, organic acids, plant proteases) on the quality of CM cheeses. CM cheese's weak texture is due to compositional characteristics of the milk, including low κ-casein-to-β-casein ratio (≈0.05 in CM vs. ≈0.33 in BM), large micelle size, different whey protein components, and higher proteolytic activity than BM. CM cheese texture can be improved by preheating the milk at low temperatures or by high pressure. Supplementing CM with calcium has shown inconsistent results on cheese texture, which may be due to interactions with other processing conditions. Despite their structure, CM cheeses are generally well liked in sensory studies.