• Title/Summary/Keyword: milk protein

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Rumen bacteria influence milk protein yield of yak grazing on the Qinghai-Tibet plateau

  • Fan, Qingshan;Wanapat, Metha;Hou, Fujiang
    • Animal Bioscience
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    • v.34 no.9
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    • pp.1466-1478
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    • 2021
  • Objective: Ruminants are completely dependent on their microbiota for rumen fermentation, feed digestion, and consequently, their metabolism for productivity. This study aimed to evaluate the rumen bacteria of lactating yaks with different milk protein yields, using high-throughput sequencing technology, in order to understand the influence of these bacteria on milk production. Methods: Yaks with similar high milk protein yield (high milk yield and high milk protein content, HH; n = 12) and low milk protein yield (low milk yield and low milk protein content, LL; n = 12) were randomly selected from 57 mid-lactation yaks. Ruminal contents were collected using an oral stomach tube from the 24 yaks selected. High-throughput sequencing of bacterial 16S rRNA gene was used. Results: Ruminal ammonia N, total volatile fatty acids, acetate, propionate, and isobutyrate concentrations were found to be higher in HH than LL yaks. Community richness (Chao 1 index) and diversity indices (Shannon index) of rumen microbiota were higher in LL than HH yaks. Relative abundances of the Bacteroidetes and Tenericutes phyla in the rumen fluid were significantly increased in HH than LL yaks, but significantly decreased for Firmicutes. Relative abundances of the Succiniclasticum, Butyrivibrio 2, Prevotella 1, and Prevotellaceae UCG-001 genera in the rumen fluid of HH yaks was significantly increased, but significantly decreased for Christensenellaceae R-7 group and Coprococcus 1. Principal coordinates analysis on unweighted UniFrac distances revealed that the bacterial community structure of rumen differed between yaks with high and low milk protein yields. Furthermore, rumen microbiota were functionally enriched in relation to transporters, ABC transporters, ribosome, and urine metabolism, and also significantly altered in HH and LL yaks. Conclusion: We observed significant differences in the composition, diversity, fermentation product concentrations, and function of ruminal microorganisms between yaks with high and low milk protein yields, suggesting the potential influence of rumen microbiota on milk protein yield in yaks. A deeper understanding of this process may allow future modulation of the rumen microbiome for improved agricultural yield through bacterial community design.

Monitoring Nutritional Status of Dairy Cows in Taiwan Using Milk Protein and Milk Urea Nitrogen

  • Hwang, Sen-Yuan;Lee, Mei-Ju;Chiou, Peter Wen-Shyg
    • Asian-Australasian Journal of Animal Sciences
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    • v.13 no.12
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    • pp.1667-1673
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    • 2000
  • The climate and marketing system of raw milk in Taiwan create problems in balance feeding of protein and energy in lactating cows in Taiwan. Level of urea nitrogen both in bulk milk and serum reflects ruminal protein degradation and post-ruminal protein provision, whereas milk protein concentration responds to dietary energy intake and bacterial protein production in the rumen. Establishment of a range of reference standards in milk protein and urea nitrogen levels can be applied as a noninvasive economical feeding guide to monitor the balance of protein and energy intake. Standard reference levels of 3.0% milk protein and 11-17 mg/dL milk urea nitrogen (MUN) were established. Level of milk protein below 3.0% is regarded as indicating inadequate dietary energy whereas MUN below or above the range is regarded as a deficiency or surplus in dietary protein. Results from analysis of bulk a milk samples collected from 174 dairy herds over Taiwan showed that only one quarter (25.29%) of the herds received a balanced intake of protein and energy, 33.33% adequate protein with energy inadequate, 22.99% herds in protein surplus with energy inadequate, 10.35% herds in protein surplus with energy adequate, 4.6% protein deficiency with energy adequate, and 3.45% herds with both protein and energy inadequate. Energy inadequate herds accounted for 60% of the total dairy herds in Taiwan with 56% adequate, 38% surplus and 6% inadequate in protein. In comparing milk sampled from bulk milk on different seasons from Lee-Kang area in the southern Taiwan, the concentrations of milk fat and milk protein were significantly higher in the cool season (February) than in the warm season (August) (p<0.05), whereas the urea nitrogen in the milk was significantly lower in the cool season than in the warm season (p<0.05). This indicated that lactating cows had excess protein and/or inadequate energy intake in the warm season in this area. It appears that the major problem feeding in lactating cows is energy intake shortage, especially during the warm season in Taiwan.

The effect of nanoemulsified methionine and cysteine on the in vitro expression of casein in bovine mammary epithelial cells

  • Kim, Tae-Il;Kim, Tae-Gyun;Lim, Dong-Hyun;Kim, Sang-Bum;Park, Seong-Min;Lim, Hyun-Joo;Kim, Hyun-Jong;Ki, Kwang-Seok;Kwon, Eung-Gi;Kim, Young-Jun;Mayakrishnan, Vijayakumar
    • Asian-Australasian Journal of Animal Sciences
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    • v.32 no.2
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    • pp.257-264
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    • 2019
  • Objective: Dairy cattle nutrient requirement systems acknowledge amino acid (AAs) requirements in aggregate as metabolizable protein (MP) and assume fixed efficiencies of MP used for milk protein. Regulation of mammary protein synthesis may be associated with AA input and milk protein output. The aim of this study was to evaluate the effect of nanoemulsified methionine and cysteine on the in-vitro expression of milk protein (casein) in bovine mammary epithelial cells (MAC-T cells). Methods: Methionine and cysteine were nonionized using Lipoid S 75 by high-speed homogenizer. The nanoemulsified AA particle size and polydispersity index were determined by dynamic light scattering correlation spectroscopy using a high-performance particle sizer instrument. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was performed to determine the cytotoxicity effect of AAs with and without nanoionization at various concentrations (100 to $500{\mu}g/mL$) in mammary epithelial cells. MAC-T cells were subjected to 100% of free AA and nanoemulsified AA concentration in Dulbecco's modified Eagle medium/nutrient mixture F-12 (DMEM/F12) for the analysis of milk protein (casein) expression by the quantitative reverse transcription polymerase chain reaction method. Results: The AA-treated cells showed that cell viability tended to decrease (80%) in proportion to the concentration before nanogenesis, but cell viability increased as much as 90% after nanogenesis. The analysis of the expression of genetic markers related to milk protein indicated that; ${\alpha}_{s2}$-casein increased 2-fold, ${\kappa}$-casein increased 5-fold, and the amount of unchanged ${\beta}$-casein expression was nearly doubled in the nanoemulsified methionine-treated group when compared with the free-nanoemulsified methionine-supplemented group. On the contrary, the non-emulsified cysteine-administered group showed higher expression of genetic markers related to milk protein ${\alpha}_{s2}$-casein, ${\kappa}$-casein, and ${\beta}$-casein, but all the genetic markers related to milk protein decreased significantly after nanoemulsification. Conclusion: Detailed knowledge of factors, such nanogenesis of methionine, associated with increasing cysteine and decreasing production of genetic markers related to milk protein (casein) will help guide future recommendations to producers for maximizing milk yield with a high level of milk protein casein.

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

  • Mao, Y.J.;Zhong, G.H.;Zheng, Y.C.;Pen, X.W.;Yang, Z.P.;Wang, Y.;Jiang, M.F.
    • Asian-Australasian Journal of Animal Sciences
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    • v.17 no.11
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    • pp.1479-1483
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    • 2004
  • Milk protein polymorphisms were genotyped by polyacrylamide gel electrophoresis (PAGE) from 109 Maiwa and 100 Jiulong yaks. The relationships between milk protein polymorphisms and 3 milking traits were studied. The results showed that $\beta$-CN, $\kappa$-CN and $\alpha$-La were monomorphic, and ${\alpha}_{s1}$-CN and $\beta$-Lg were polymorphic, with ${\alpha}_{s1}$-CN D and $\beta$-Lg E as dominant genes, respectively. The frequencies of ${\alpha}_{s1}$-CN D were 0.8073 and 0.6000 in two populations and $\beta$-Lg E were 0.9770 and 0.9700. The mean heterozygosities were 0.1021 and 0.1867 in the two populations. No significant effects on milking traits and milk protein compositions were observed except for ${\alpha}_{s1}$-CN locus on fat percentage in Jiulong yak.

Allergenicity Reduction of Milk (우유에서의 알레르겐 저감화 방법)

  • Ha, Woel-Kyu
    • Journal of Dairy Science and Biotechnology
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    • v.26 no.1
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    • pp.27-36
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    • 2008
  • This review was written to introduce updated data on the structure and function of the major milk proteins identified as allergens, the characterization of their epitopes in each allergenic milk proteins, and the reduction of milk protein allergenicity. Most mammalian milk protein, even protein present at low concentration, are potential allergens. Epitopes identified in milk proteins are both conformational(structured epitope) and sequential epitopes(linear epitope), throughout the protein molecules. Epitopes on casein and whey proteins are reported to be sequential epitope and conformational epitopes, respectively. Conformational epitopes on whey protein are changed into sequential epitope by heat denaturation during heat treatment. Several methods have been proposed to reduce allergenicity of milk proteins. Most ideal and acceptable method to make hypoallergenic milk or formula, so far, is the hydrolysis of allergenic milk proteins by enzymes that has substrate specificity, such as pepsin, trypsin, or chymotrypsin. Commercial formulas based on milk protein hydrolysate are available for therapeutic purpose, hypoantigenic formula for infants from families with a history of milk allergy and hypoallergenic formula for infants with existing allergic symptoms.

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A Study on the Allergenicity of Milk Protein (우유 단백질의 Allergenicity에 관한 연구)

  • 정은자
    • The Korean Journal of Food And Nutrition
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    • v.8 no.2
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    • pp.79-87
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    • 1995
  • It is generally known that the protein of talk has allergenicity and the allerenicity Induces allergic diseases. Finding methods to reduce the allergenicity of the food and develop methods to make low allergic food is the purpose of this study. For this study, 1 tried various experimental methods : heat treatment, irradation with ultraviolet and microwaves treatment with polyphosphate, enzyme hydrolysis and PCA inhibition test using guinea pigs and degrees of hydrolysis. The results obtained are as follows. Heat treatment reduced allergenicity of milk protein. The higher the heat, the better the effect. Irradiating with ultraviolet and microwave increased both the degree of protein hydrolysis and PCA inhibition reduced the allergenicity. Ultraviolet was more effective than microwaves on milk protein. Enzyme treatment increased the degree of hydrolysis and PCA inhibition, and reduced allergenicity considerably. Neutrase was more effective than alcalase on milk protein. Adding Polyphosphate did not induced protein hydrolysis, but increased PCA inhibition and reduced allergenicity.

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Milk Protein-Stabilized Emulsion Delivery System and Its Application to Foods

  • Ha, Ho-Kyung;Lee, Won-Jae
    • Journal of Dairy Science and Biotechnology
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    • v.38 no.4
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    • pp.189-196
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    • 2020
  • Milk proteins, such as casein and whey protein, exhibit significant potential as natural emulsifiers for the preparation and stabilization of emulsion-based delivery systems. This can be attributed to their unique functional properties, such as the amphiphilic nature, GRAS (generally recognized as safe) status, high nutritional value, and viscoelastic film-forming ability around oil droplets. In addition, milk protein has been used as a coating material in emulsion-based delivery systems to protect bioactive compounds during food processing and storage owing to its unique functional properties. These properties include the ability to bind lipophilic bioactive compounds and antioxidant activity. In this review, we present the use of milk proteins as emulsifiers for the formation of emulsions and food applications of milk protein-stabilized emulsion delivery systems.

Compensatory nutrition-Mediated Lactation Potential and Milk Protein Gene Expression in Rats (보상성장에 의한 에너지 섭취량 조절이 흰쥐의 유생산능력과 유단백질 유전자 발현에 미치는 영향)

  • 김상훈
    • Journal of Nutrition and Health
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    • v.33 no.7
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    • pp.697-702
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    • 2000
  • The objective of this study was to determine the extent to which the compensatory nutrition regimen modulates lactation performance and milk protein gene expression in the first and second lactation cycles. Female rats(28 days of age) were assigned to 1)control ad libitum ; 2) stari-step compensatory nutrition(SSCN) regimen an alternating 3-2-3-4-week schedule beginning with an energy restriction diet(40% restriction) for 3 weeks followed by the control diet(ad libitum) for 2 weeks and then alternating another 3-4 week feeding regimen. The SSCN rats were received an overall 20% energy restriction(average from all stair-step periods) compared with the conventionally fed control group. Rats were bred during the first week of the second realimentation. All pups were weaned on day 21 of lactation. About 1 week after weaning all dams were mated for the second pregnancy. Mammary tissues were obtained from pregnant and lactating rats during the first and second lactation cycles. During these lactation cycles the SSCN group had a 11% increase in average lactation performance over that of control. The SSCN group had significantly increased levels of milk protein gene($\alpha$- and $\beta$-casein) expression in mammary tissues during the first lactation cycle compared with those of the control group. During the second lactation period the levels of milk protein gene expression in lactating mammary tissues of the SSCN group were also higher than those of the control group. These results suggest that the effects of compensatory growth imposed at an early age extend to the second lactation cycle with regard to increased lactation performance and milk protein gene expression.

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Blood amino acids profile responding to heat stress in dairy cows

  • Guo, Jiang;Gao, Shengtao;Quan, Suyu;Zhang, Yangdong;Bu, Dengpan;Wang, Jiaqi
    • Asian-Australasian Journal of Animal Sciences
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    • v.31 no.1
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    • pp.47-53
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    • 2018
  • Objective: The objective of this experiment was to investigate the effects of heat stress on milk protein and blood amino acid profile in dairy cows. Methods: Twelve dairy cows with the similar parity, days in milk and milk yield were randomly divided into two groups with six cows raised in summer and others in autumn, respectively. Constant managerial conditions and diets were maintained during the experiment. Measurements and samples for heat stress and no heat stress were obtained according to the physical alterations of the temperature-humidity index. Results: Results showed that heat stress significantly reduced the milk protein content (p<0.05). Heat stress tended to decrease milk yield (p = 0.09). Furthermore, heat stress decreased dry matter intake, the concentration of blood glucose and insulin, and glutathione peroxidase activity, while increased levels of non-esterified fatty acid and malondialdehyde (p<0.05). Additionally, the concentrations of blood Thr involved in immune response were increased under heat stress (p<0.05). The concentration of blood Ala, Glu, Asp, and Gly, associated with gluconeogenesis, were also increased under heat stress (p<0.05). However, the concentration of blood Lys that promotes milk protein synthesis was decreased under heat stress (p<0.05). Conclusion: In conclusion, this study revealed that more amino acids were required for maintenance but not for milk protein synthesis under heat stress, and the decreased availability of amino acids for milk protein synthesis may be attributed to competition of immune response and gluconeogenesis.

Development and evaluation of probiotic delivery systems using the rennet-induced gelation of milk proteins

  • Ha, Ho-Kyung;Hong, Ji-Young;Ayu, Istifiani Lola;Lee, Mee-Ryung;Lee, Won-Jae
    • Journal of Animal Science and Technology
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    • v.63 no.5
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    • pp.1182-1193
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    • 2021
  • The aims of this study were to develop a milk protein-based probiotic delivery system using a modified rennet-induced gelation method and to determine how the skim milk powder concentration level and pH, which can affect the rennet-induced intra- and inter-molecular association of milk proteins, affect the physicochemical properties of the probiotic delivery systems, such as the particle size, size distribution, encapsulation efficiency, and viability of probiotics in simulated gastrointestinal tract. To prepare a milk protein-based delivery system, skim milk powder was used as a source of milk proteins with various concentration levels from 3 to 10% (w/w) and rennet was added to skim milk solutions followed by adjustment of pH from 5.4 or 6.2. Lactobacillus rhamnosus GG was used as a probiotic culture. In confocal laser scanning microscopic images, globular particles with a size ranging from 10 ㎛ to 20 ㎛ were observed, indicating that milk protein-based probiotic delivery systems were successfully created. When the skim milk powder concentration was increased from 3 to 10% (w/w), the size of the delivery system was significantly (p < 0.05) increased from 27.5 to 44.4 ㎛, while a significant (p < 0.05) increase in size from 26.3 to 34.5 ㎛ was observed as the pH was increased from 5.4 to 6.4. An increase in skim milk powder concentration level and a decrease in pH led to a significant (p < 0.05) increase in the encapsulation efficiency of probiotics. The viability of probiotics in a simulated stomach condition was increased when probiotics were encapsulated in milk protein-based delivery systems. An increase in the skim milk powder concentration and a decrease in pH resulted in an increase in the viability of probiotics in simulated stomach conditions. It was concluded that the protein content by modulating skim milk powder concentration level and pH were the key manufacturing variables affecting the physicochemical properties of milk protein-based probiotic delivery systems.