Studies of composition and major protein level in milk and colostrum of mares

Biochemical properties of sheep colostrum and its potential benefits for lamb survival: a review

Colostrum is the initial secretion of the mammary glands following parturition, which offers main food, protection, and biological active substances for the new born. The most threatening episode of neonate's life is the initial two weeks after birth. This period is associated with high neonatal mortality and morbidity. These worthwhile losses lead to a poor prolificacy rate, low profitability, and ultimately poor performance in animal production. Hence, both diseases and mortality cause valuable losses in terms of production and economic losses. The survival of neonate is correlated with their immune status and passive immune transfer (PIT). Colostrum provides the primary source of nutrition and immunity (PIT) that protects neonates against infections. It must be given as soon as possible after birth since its immunoglobulins are absorbed within the first 16-27 hours after birth, ideally within 2-4 hours. As a result, immunoglobulin (PIT) is the most important component of distressing infectious immunity, and a passable concentration of immunoglobulin in the blood of newborn lambs is linked to their health and survival rate. In this review, we summarized the importance of colostrum in early life and its association with neonatal lamb's survival, profitability and productivity of sheep farming.

A Comparative Analysis of the Gene Expression Profiles in the Mammary Glands of Lactating and Nonlactating Mares at the Second Month of Gestation

To investigate molecular regulation involved in lactation during pregnancy, this study focused on the transcriptomic profiles of mammary tissue from lactating and non-lactating Mongolian mares at the second month of gestation. A total of 4197 differentially expressed genes were identified by comparing mammary tissues from pregnant mares at two different states, including 1974 differentially expressed genes such as the milk protein-related genes a-s1-casein (CSN1S1), k-casein (CSN3), lactalbumin (LALBA), and lactoferrin (LTF), which were highly expressed in the lactating mares group, and overall, these differentially expressed genes were mainly associated with biological processes such as endoplasmic reticulum protein processing, the Toll-like receptor signaling pathway, steroid biosynthesis, cytokine-cytokine receptor interactions, and amino sugar and nucleotide glycolysis. These findings serve as a foundation for investigating the molecular underpinnings of lactation in pregnant equids.

Identification and comparison of milk fat globule membrane and whey proteins from Selle Français, Welsh pony, and Tieling Draft horse mare's milk

Horse's milk, with a high nutritional value and few allergenic proteins, could substitute cow's milk for infant consumption. Herein, a label-free, proteomic method was used to identify and compare milk fat globule membrane (MFGM) and whey proteins from three different horse breeds: Selle Français (SF), Welsh pony (WP), and Tieling Draft Horse (TDH). In MFGMs, 16 (SF), 66 (WP), and 45 (TDH) unique proteins were identified, which are involved in the endocytosis, ribosome, and staphylococcus aureus infection pathways, respectively. In whey, 31 (SF), 75 (WP), and 23 (TDH) unique proteins were identified, which are involved in the autophagy-animal, phenylalanine metabolism, and Vasopressin-regulated water reabsorption pathways, respectively. SF contained the lowest concentration of β-lactoglobulin, which can cause allergic reactions in humans. Our findings describe the nutritional differences and functional diversities of MFGM and whey proteins in different horse breeds, which could support developing formula more suitable for human infants.

Characterization of lyophilized equine colostrum

Foals require maternal colostrum in the first hours of life to prevent failure of transfer of passive immunity (FTIP). Innovative storage methods such as lyophilization may enable conservation of colostrum immunoglobulins by a differentiated process of dehydration. The current study aimed to compare the quality of equine colostrum after freezing and after the lyophilization process. Thirty-one pregnant Quarter Horse mares were used. The IgG concentration of frozen and lyophilized colostrum was determined by simple radial immunodiffusion (SRID) and Brix refractometry. The physical-chemical composition (pH, total protein (TP), fat, lactose, salts, total solids (TS), and density) of the samples was evaluated and the lyophilized colostrum reconstitution test was performed. There were no significant differences (P > 0.05) in the variables IgG, fat, lactose, salts, TS, density, and pH between samples measured before and after lyophilization. There was a significant difference (P < 0.05) between the Brix average and the TP of the frozen and lyophilized colostrum samples. Lyophilization resulted in a small reduction (6.55%) in the IgG concentration measured by SRID. A strong positive correlation was observed between colostrum density and IgG concentration by SRID (r = 0.76) and between Brix and IgG concentration by SRID (r = 0.77). In the reconstitution test, the lyophilized colostrum was easily rehydrated in water, with full dilution, and remained stable. Lyophilization could be an alternative for the conservation of mare colostrum, since it is a very efficient process for retaining the physicochemical characteristics of the product, with minimal loss, particularly of IgG.

The Influence of Selected Factors on the Nutritional Value of the Milk of Cold-Blooded Mares: The Example of the Sokólski Breed

This study assessed the effect of access to pasture, lactation number, and foals’ sex on the nutritional value of milk (79 samples) from nine mares. The following were analysed: content of dry matter, protein, fat, lactose, and ash; percentages of α-lactalbumin (α-La), β-lactoglobulin (β-Lg), serum albumin (SA), immunoglobulins (Ig), lactoferrin (Lf), and lysozyme (Lz) in the total protein; and the fatty acid profile. Mares without access to pastures were shown to produce milk with a higher dry matter content, including fat, lactose, and ash; higher percentages of β-Lg, α-La, Ig, and Lf; and a better fatty acid profile. The milk from mares with access to pasture contained more protein, including higher percentages of SA and Lz. Milk from mares in lactations 4–6 had the highest fat and protein concentrations and the lowest lactose concentration. The α-La level was highest in lactation 1, Lf in lactations 2–3, and Lz in lactations 4–6. Milk from mares in lactations 4–6 had the best fatty acid profile (the lowest concentration of saturated fatty acids (SFAs) and the highest concentration of monounsaturated fatty acids(MUFA) and polyunsaturated fatty acids (PUFA)). Milk from mothers of female offspring had higher dry matter, fat, and protein concentrations, a higher share of lysozyme, and a better fatty acid profile.

Implications of placentation type on species-specific colostrum properties in mammals

Maternal care is essential to optimally support survival of the offspring. During evolution of mammalian species, different phenotypes have evolved in relation to gestation length, number, size, and maturation stage of the offspring at parturition, as well as colostrum and milk composition. The aim of the present review is to describe relationships between placental function and colostrum and milk composition in different mammalian species. Species covered in this article include humans, rabbits, rodents (rat and mouse), carnivores (cats and dogs), and a variety of ungulate species (cattle, sheep, goats, pigs, and horses). Species-specific aspects are elucidated with a special focus on the transfer of passive immunity. In this regard, the structure and thus the capability of the placenta to transport immunoglobulins from maternal to fetal circulation in utero dictates the necessity of the passive transfer of immunity via colostrum. Consequently, species with exclusive postpartal transfer of immunity such as in all ungulate species have greater immunoglobulin G concentrations in colostrum than species with a prepartal transfer in utero, where especially immunoglobulin A with its local immune function in the gastrointestinal tract is present in colostrum (e.g., rabbit and human). In terms of the nutritional purpose, suckling frequency is an important factor determining the gross composition of colostrum as well as in the mature milk of these species. Milk of nidicolous animals with long intervals in-between suckling events contains more fat than milk of nidifugous animals with constant access to their mother. However, the importance of colostrum and milk consumption for newborn animals and human babies goes beyond nutrition and the transfer of immunity. Numerous bioactive components such as growth factors, hormones, and oligosaccharides are enriched in colostrum and transition milk, which support the development of the intestinal tract and local immune system.

Arabian mare's milk characterisation and clotting ability

The objective of this study is to characterize purebred Arab mares' milk through monitoring its physicochemical and microbiological composition during different lactation stages and to test its ability to coagulate. Sixteen purebred Arabian mares were selected among 45 mares with approximately the same foaling dates. Milk samples were collected once a week for each mare during 4 months of lactation and analysed in three replicates for physicochemical composition, nitrogen fractions, somatic cell count and total bacterial count. Coagulation assays were carried out in triplicates on fresh mare's milk using increasing doses of calf rennet, starter (Streptococcus thermophilus) and CaCl₂. Arab mare's milk is characterized by an alkaline pH, low-fat and protein contents and high lactose content. The somatic cell and bacterial counts are very low, indicating good health status of mares. Fat and protein contents decreased as the stage of lactation progressed. However, as lactation number increased, fat level tended to increase while protein level tended to decrease. Clotting assays proved that it is possible to coagulate Arabian mare's milk using appropriate doses of calf rennet and starter, while respecting the coagulation procedures and parameters.

The Indicators of Clinical and Subclinical Mastitis in Equine Milk

Simple Summary

Mastitis, the inflammation of the mammary gland, is a major problem in a mare’s perinatal period, negatively affecting both the health of the mare and newborn foal and the quality of milk produced on dairy equine farms. The detection of mastitis is therefore one of the important goals in the equine breeding and dairy industry. This study aimed to determine the somatic cell count (SCC), the percentage of the immune cells, the electrical conductivity (ECM), and bacteriological index (BII) in milk collected from mares with (CM) and without (NCM) clinical symptoms of mastitis. The increase in examined indicators is suspected to be a subclinical mastitis indicator, therefore the study aimed to separate two subgroups, mares with (SM) and without (NSM) subclinical symptoms of mastitis. In milk from NCM mares the values of SCC, immune cells, and ECM increased immediately after birth and weaning, whereas during the rest of the lactation period their values were at a low level. Similarly, in milk from CM mares, the values of examined indicators were high and comparable to the weaning time. An increase in the level of examined indicators may become an early indication of subclinical mastitis.

Abstract

The somatic cell count in milk (SCC) and electrical conductivity of milk (ECM) are indicators of the health status of the mammary gland. Among somatic cells, mainly polymorphonuclear neutrophils (PMN), macrophages (MAC), and lymphocytes (LYM) are rated. This study aimed to determine the SCC, PMN, MAC, LYM, ECM, and bacteriological index (BII) in milk collected from mares with (CM) and without (NCM) clinical symptoms of mastitis concerning mares with (SM) and without (NSM) subclinical mastitis. Milk samples were collected from 27 mares divided into NCM (n = 12) and CM (n = 15) groups. In samples, SCC quantification, cytological examinations, ECM measurement, and bacteriological examination were performed. In NCM mares, the values of SCC, PMN, MAC, LYM, and ECM were higher in initial than in consecutive examined days after birth until weaning. After weaning the proportion of SCC, PMN, MAC, LYM, ECM, and BII increased and did not differ with the average values in CM mares. These equine milk indicators may reflect an early symptom of subclinical mastitis and in the future may be used in the early detection of mastitis or as a tool of assessment of the health status of the mammary gland in the dairy equine farm.

Concentrations of Fat, Protein, Lactose, Macro and Trace Minerals in Alpaca Colostrum and Milk at Different Lactation Stages

Although alpacas are not used for milk production a detailed knowledge on the composition of the colostrum and milk is needed for development of colostrum and milk replacers. The aim of the present study was to measure the concentration of fat, protein, lactose, and minerals in alpaca colostrum and milk. Colostrum samples were taken daily over four days after parturition from 20 multiparous alpaca mares. Milk samples were obtained monthly, during the first four months of lactation from 17 alpacas. Composition of colostrum and milk differed in numerous indicators. The concentrations of fat and lactose increased from day 1 (0.5%, 4.0%) to day 4 (5.3%, 5.0%), protein decreased from 20.4% on day 1 to 8.3% on day 4. In milk these three indicators did not change during the lactation. Minerals have been little studied in alpaca colostrum and milk in the past, many of which had the highest concentrations in colostrum immediately after birth. The results of the present study do not support that goat's milk is the preferred substitute for feeding crias. This study contributes to the knowledge of the composition of alpaca colostrum and milk which can be of particular use in developing replacers.

Effects of the Inclusion of Different Levels of Dietary Sunflower Hulls on the Colostrum Compositions of Ewes

Simple Summary

Increasing the cost of roughages, as a result of high demand by livestock producers, leads to a search for alternative sources. Plant by-products such as sunflower hulls can be used as an alternative source of fiber. This manuscript is a part of ongoing research to identify the best levels to be used without negative effects on ruminant animals’ performances.

Abstract

This study investigated the effects of supplementing different levels of sunflower hulls (SFH) to the complete feed of late-gestation pregnant ewes on the nutritive and fatty acids profile of colostrum at three and 48 h postpartum. In this study, 24 primiparous lactating Naemi ewes were randomly selected at parturition from four dietary groups as follows: (1) C (control), total mixed ration (TMR; 0% SFH), (2) S12, TMR1 with 12% SFH (level 1), (3) S20, TMR2 with 20% SFH (level 2), and (4) S28, TMR3 with 28% SFH (level 3). The body condition scores were estimated 30 days prepartum. Colostrum samples were collected at three and 48 h postpartum to measure the nutritive values and fatty acids profiles. Data were analyzed as a complete randomized design with repeated measures and via Pearson’s correlation and regression analyses. The results indicated a numerical correlation (R² = 0.42; p < 0.09) between the body condition score and both colostrum fat and total solids. SFH increased the colostrum fat % (p < 0.05), especially for S12 and S20, following a cubic trend. Additionally, the colostrum from S12 and S20 ewes had a higher proportion of unsaturated fatty acids (USFAs), omega3 and lower levels of saturated fatty acids (SFAs), other than margaric acid (C17) and stearic acid (C18), SFA/USFA, and omega 6/omega 3. Furthermore, the regression analysis of the fatty acid classes and indices indicated a quadratic relationship between the parameters and SFH levels. The results confirm that the inclusion of SFH at levels greater than 20% may have a negative effect on some fatty acid parameters as a result of the high lignin intake. In conclusion, up to 20% SFH can be used in a complete feed for pregnant ewes without negative effects on the colostrum fat content and fatty acids profiles.

Chemical composition and lipid profile of mare colostrum and milk of the quarter horse breed

The objective of this study was to characterize the chemical composition and lipid profile of colostrum and milk of purebred Quarter Horse mares. Thirty-four (34) purebred mares were selected, which were then separated into groups according to age, birth order and lactation stage. Colostrum samples were collected in the first six hours after delivery and milk samples from the 7^th postpartum day, with intervals of 14 days until the end of lactation. The samples were refrigerated and sent to the Milk Laboratory of the University (Laboleite—UFRN), where they were analyzed for chemical composition. Colostrum was assessed by refractometry. The lipid profile was determined by gas chromatography through a separation of methyl esters. The data were tabulated and subjected to descriptive statistics and analysis of variance by the F-Test, and the groups were compared by the Tukey test using a significance level of 5%. There was high protein content and reduced lactose content for the colostrum of the Quarter Horse mares, differing from other breeds. The milk composition was not influenced by the mares’ age. However, variations in the lactation stage and in the birth order of the Quarter Horse mares altered the milk’s chemical composition. There is variation in the lipid composition of milk according to the lactation stage, without changing the characteristic profile of the mares’ milk or diminishing the nutritional quality of the lipid fraction.

Milk Products from Minor Dairy Species: A Review

Milk processing is one of the most ancient food technologies, dating back around 6000 BC. The majority of dairy products are manufactured from cows, buffaloes, goats, and sheep; their production technologies are mostly standardized and have been widely investigated. Milk and dairy products from minor species are less important under the economic point of view, but they play a fundamental social role in many marginal and poor areas. Due to scarce interest of the dairy industry, their technological characteristics and related issues have been investigated less. Recently, the increasing interest toward ethnic foods and food biodiversity is helping these minor products to emerge from the "darkness" in which they have remained for long time. Some of them are increasingly seen as useful for the valorization of marginal areas, while others are recognized as innovative or healthy foods. The present review aims to resume the most recent knowledge about these less-known dairy products. The first part summarizes the main technological properties of equine, camel, and yak milk with a view to processing. The second is a survey on the related dairy products, both the traditional ones that have been manufactured for a long time and those that have been newly developed by food researchers.

Impact of humic acid as an organic additive on the milk parameters and occurrence of mastitis in dairy cows

Given growing concerns about the use of antibiotics in the treatment of animals, identifying organic alternatives as feed additives to improve animal health and the development of immune responses has become of interest in dairy farming. Humic acids (HA) seem to be a suitable alternative with a favorable impact on the health and production parameters of animals. This study aimed to determine the effects of an HA supplemented diet on milk parameters as well as the effects on somatic cell count (SCC) and the occurrence of mastitis in dairy cows during the peripartum period. Twenty dairy cows in the last stage of pregnancy were selected from a herd of 140 cows. The selected cows were randomly divided into two groups: control (C) and experimental (E). The two groups were fed the same feed mixture and group E was additionally supplemented with HA at a total dose of 100 g per cow per day during the last 50 days of pregnancy. The milk parameters (dry matter, lactose, fat, crude protein, casein and milk urea) and SCC of every cow, and the presence of mastitis, were checked on days 10 and 30 during the first month of lactation. The results of the study show that dietary supplementation with HA significantly reduced the milk urea (MU) content and SCC on the 10th day after calving but did not affect the other milk compositions. In addition to the decreased MU and SCC, the number of positive quarters detected by the California Mastitis Test was reduced by 20.0% and the occurrence of mastitis caused by coagulase-negative staphylococci (CNS). Based on the obtained results we can conclude that the addition of HA stabilizes the nutrient digestion, as was confirmed by a reduced MU content in the supplemented group. Their indirect beneficial effects improved the development of immune responses, resulting in decreased SCC and the occurrence of mastitis caused by CNS.

Effect of Soy Lecithin Supplementation in Beef Cows before Calving on Colostrum Composition and Serum Total Protein and Immunoglobulin G Concentrations in Calves

Simple Summary

Until recently, fat supplements were considered merely as a source of energy for cows during transition. However, individual fatty acids included in fat supplements may clearly induce different production and metabolic responses, which in consequence change the nutritional value of bovine colostrum. Therefore, it is necessary to consider the type of fat additive to use in feed ration. This study aimed to determine an effect of soy lecithin supplementation on beef cow’s colostrum composition and selected blood parameters in their calves. Obtained results suggest that soy lecithin addition in cows before calving has a beneficial impact on colostrum composition. This concerns mainly an increase of linoleic acid in colostrum, which may influence IgG activity in calf serum. In turn, higher content of these components in colostrum may contribute to improve calves’ survival rate during the first weeks of their life.

Abstract

The aim of this study was to investigate the impact of soy lecithin supplementation in beef cow’s nutrition on colostrum composition and serum concentrations of immunoglobulin G (IgG) and serum total protein (STP) in calves. Twenty pregnant Charolaise cows were assigned to two groups. In the supplementation group (n = 10) during the last four weeks of pregnancy, soy lecithin was administrated in an amount of 20 g/cow/day. In both groups, basic composition (protein, fat, lactose, dry matter), somatic cell count (SCC), total bacteria count (TBC), IgG concentration, and fatty acids profile were determined in colostrum samples. Moreover, STP and IgG concentration were measured in calves’ blood samples on the 3rd, 7th, 14th, and 21st days of life, mothered by supplementation and control cows. Animals fed with soy lecithin before calving produced colostrum with a higher (p = 0.049) level of linoleic acid (C18:2 n-6). In addition, these results showed that soy lecithin supplementation has contributed to an increase (p = 0.029) of serum IgG in calves on the 14th day of life. The impact of such change in colostrum on IgG levels on calves serum and their half-life need further analysis.

Effects of Single Nucleotide Polymorphisms in the SLC27A3 Gene on the Nutritional Value of Sheep Milk

The current research was undertaken to use the genetic potential of animals to obtain high-quality dairy products. Single nucleotide polymorphisms (SNPs) in SLC27A3 gene were identified in Zošľachtená valaška sheep using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Correlations between genotypes and milk composition and nutritional value were analysed This study showed that milk from sheep with TT genotype in the SNP4 locus was characterised by higher (p < 0.01) fat and dry matter content and lower lactose concentration, compared to sheep with AA and TA genotypes, respectively. Moreover, it was found that animals with GG genotype in SNP1 produced milk with higher C18:1n9c, C18:1n7t, CLA, and other unsaturated fatty acids (UFAs) content than sheep with TT. Additionally, milk from animals with CC at the SNP3 locus had significantly higher (p < 0.01) levels of UFAs than milk from sheep with other genotypes in the SNP3. In summary, it may be concluded that milk from animals with TT genotype of SNP4 is characterised by higher fat and dry matter content. Whereas, milk from sheep with GG in SNP1 and with CC in SNP3 is characterised by higher content of UFAs, which increases milk value as material for functional food production.

Alternatives in Donkey semen cryopreservation: Mare vs. Jenny Colostrum

The aim of this study was to test and compare two new components in extenders for freezing donkey semen: mare colostrum and jenny colostrum. Colostrum was obtained from four mares and four jennies right after the foal's birth. Ejaculates were collected from five fertile donkeys. Sperm samples were pooled, diluted and cryopreserved in three different experimental extender groups: lactose supplemented with egg yolk extender (20%) as the control group, lactose supplemented with jenny colostrum extender (20%), and lactose supplemented with mare colostrum extender (20%). After thawing, we evaluated the sperm motility by means of computer-assisted analysis, viability by SYBR-14 and propidium iodide (PI), membrane functional by HOS test and acrosome integrity by isothiocyanate conjugated with peanut agglutinin (FITC-PNA) and PI. The results demonstrated that lactose-jenny colostrum extender displayed significantly higher values (p < .05) in nearly all parameters evaluated - Total Motility, Viability, HOS test, VCL, VSL, VAP, LIN, STR and WOB -, compared with mare colostrum and egg yolk extenders after thawing. In conclusion, the extender containing jenny colostrum used for donkey semen cryopreservation improved the donkey sperm quality after the freezing-thawing process.

Effect of Mare Colostrum in Extenders for Freezing Stallion Semen

This study aimed to evaluate the addition of mare colostrum in stallion freezing extenders to improve sperm quality. First, colostrum samples were collected from four mares after the foal's birth and their composition was determined. Ejaculates were collected from nine fertile stallions. Sperm samples were pooled, diluted, and cryopreserved into three experimental extender groups: Lactose-based extender supplemented with mare colostrum (20%), lactose-based extender supplemented with egg yolk (20%), and BotuCrio. The quality of the post-thaw semen samples were evaluated assessing sperm motility by means of computer-assisted analysis, viability by SYBR-14 and propidium iodine (PI) stain, acrosome integrity by fluorescein isothiocyanate and peanut agglutinine (FITC-PNA) and PI stain, plasma membrane functionality by hypo-osmotic swelling (HOS) test, and DNA denaturation by acridine orange (AO) test. There were no significant differences in the percentages of total motility, acrosome integrity, and DNA fragmentation among the extenders after thawing. Kinematics parameters showed significantly higher values in BotuCrio than in lactose extenders (P < .05). BotuCrio and lactose colostrum extender yielded significantly better rates for HOS-test, linearity, straightness, and wobble than egg-yolk extender (P < .05). However, in relation to sperm viability, lactose egg yolk extender showed significantly better results in comparison to the others seminal experimental media (P < .05). In conclusion, the incorporation of mare colostrum into cryopreservation media protected the sperm against cold-shock; therefore, it may be a good cryoprotectant agent alternative in extenders for freezing stallion semen.

Polymorphism in ovine ANXA9 gene and the physio-chemical properties and the fraction of protein in milk

BACKGROUND

Annexin A9 (ANXA9) is a specific fatty acid transport protein. The ANXA9 gene is expressed in various tissues, including secretory tissue and the mammary glands. The association between the three single nucleotide polymorphisms (SNPs) of the ANXA9 gene and sheep's milk composition was assessed.

RESULTS

Genotype analysis was performed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The ANXA9 polymorphisms that were studied had the following major allele frequencies (MAFs): SNP1: allele G 0,66; SNP2: allele G 0,54; SNP3: allele C 0,57. The study found the most favorable profile of protein fractions, namely increased kappa-casein fractions and a decreased level of whey protein in sheep's milk for the SNP1 and SNP3 polymorphisms. Sheep with the SNP1 GA genotype had the highest (P < 0.05) content of fat and dry matter in milk. AXNA9 gene polymorphism did not influence the levels of protein, lactose, or urea in sheep's milk.

CONCLUSION

The information contained in this study may be useful for determining the impact of the ANXA9 gene on sheep's milk. The ANXA9 SNP1 and SNP3 polymorphism results could be included in breeding programs to select sheep with the genotypes ensuring the highest kappa-casein levels in milk. However, it is worth conducting further research on ANXA9 and milk composition in larger herds of animals and various breeds of sheep. © 2018 Society of Chemical Industry.

Effects of udder infections with Staphylococcus xylosus and Staphylococcus warneri on the composition and physicochemical changes in cows milk

The aim of this study was an evaluation of the effects of two species of coagulase negative staphylococci (CNS), Staphylococcus xylosus and Staphylococcus warneri, on the changes in technological parameters of cows' milk. The study was conducted in a herd of Slovak Pied cattle breed (with share of HF blood). Based on the performance results from three subsequent months, cows in the 2nd and 3rd lactation with SCC up to 200 thousand/ml (8 heads, 32 quarters), and above 800 thousand/ml (8 heads, 32 quarters), after the 4th month of lactation, were selected. The samples were subjected to microbiological analysis, total bacteria count, somatic cell count; basic milk composition and physicochemical properties were also examined. The research has found the impact of bacterial infection on the increasing (p<0.05) of the number of somatic cells and a decrease (p<0.01) in protein levels in milk due to both types of staphylococci. There was a significant (p<0.05) reduction in C8: 0, C10: 0 and the total amount of saturated fatty acids in the milk of the infected cows in comparison to the healthy ones. The research also revealed higher (p<0.01) levels of C14: 0 and C20: 1 in milk from the healthy cows.

An effect of mammary gland infection caused by Streptococcus uberis on composition and physicochemical changes of cows' milk

An effect of mammary gland infection caused by Streptococcus uberis on the changes in cows' milk composition and its physicochemical properties was examined. The study was conducted in the herd of Slovak Pied breed cattle (with a share of HF blood), in 2nd and 3rd lactation, after 4th month of milking. Milk samples were collected from a quarter milking. The samples were subjected to microbiological analysis, basic milk composition, total bacteria count, somatic cell count and physicochemical properties were examined. Also analyses of protein fractions share and fatty acids profile were conducted. An effect of bacterial infection of the mammary gland bring an increase (P<0.01) in somatic cell count was observed in this study. Milk samples contaminated with S. uberis were characterized by higher (P<0.05) total bacteria count and total protein compared to milk samples collected from non-infected mammary gland. The level of κ-casein was significantly (P<0.05) decreased in cows with subclinical mastitis caused by S. uberis. Significant (P<0.05) reduction in the share of C13:0 acid, and an increased level of C18:0, C18:1n7t and CLA were observed in milk contaminated with S. uberis compared to healthy cows' milk. It should be concluded that S. uberis causes the increase in total bacteria count, SCC and the decrease in κ-casein level, which significantly affects deterioration of technological quality of cows' milk.

Screening for the Most Suitable Reference Genes for Gene Expression Studies in Equine Milk Somatic Cells

Apart from the well-known role of somatic cell count as a parameter reflecting the inflammatory status of the mammary gland, the composition of cells isolated from milk is considered as a valuable material for gene expression studies in mammals. Due to its unique composition, in recent years an increasing interest in mare's milk consumption has been observed. Thus, investigating the genetic background of horse's milk variability presents and interesting study model. Relying on 39 milk samples collected from mares representing three breeds (Polish Primitive Horse, Polish Cold-blooded Horse, Polish Warmblood Horse) we aimed to investigate the utility of equine milk somatic cells as a source of mRNA and to screen the best reference genes for RT-qPCR using geNorm and NormFinder algorithms. The results showed that despite relatively low somatic cell counts in mare's milk, the amount and the quality of the extracted RNA are sufficient for gene expression studies. The analysis of the utility of 7 potential reference genes for RT-qPCR experiments for the normalization of equine milk somatic cells revealed some differences between the outcomes of the applied algorithms, although in both cases the KRT8 and TOP2B genes were pointed as the most stable. Analysis by geNorm showed that the combination of 4 reference genes (ACTB, GAPDH, TOP2B and KRT8) is required for apropriate RT-qPCR experiments normalization, whereas NormFinder algorithm pointed the combination of KRT8 and RPS9 genes as the most suitable. The trial study of the relative transcript abundance of the beta-casein gene with the use of various types and numbers of internal control genes confirmed once again that the selection of proper reference gene combinations is crucial for the final results of each real-time PCR experiment.

Influence of stage of lactation and year season on composition of mares' colostrum and milk and method and time of storage on vitamin C content in mares' milk

BACKGROUND

Mares' milk is becoming increasingly popular in Western Europe. This study was thus aimed at investigating the impact of stage of lactation and season on chemical composition, somatic cell count and some physicochemical parameters of mares' colostrum and milk, and at developing a method for the determination of vitamin C (ascorbic acid) in mares' milk and to determine its content in fresh and stored milk.

RESULTS

The analysis conducted showed an effect of the stage of lactation on contents of selected chemical components and physicochemical parameters of mares' milk. In successive lactation periods levels of fat, cholesterol, energy value, citric acid and titratable acidity decreased, whereas levels of lactose and vitamin C, as well as the freezing point, increased. Analysis showed that milk produced in autumn (September, October, November) had a higher freezing point and lower concentrations of total solids, protein, fat, cholesterol, citric acid and energy value in comparison to milk produced in summer (June, July, August). Mares' milk was characterised by low somatic cell count throughout lactation. In terms of vitamin C stability the most advantageous method of milk storage was 6-month storage of lyophilised milk.

CONCLUSION

In general, the results confirmed that mares' milk is a raw material with a unique chemical composition different from that produced by other farm animals.

Proteomics-driven analysis of ovine whey colostrum

The aim of this study was to shed light in to the complexity of the ovine colostrum proteome, with a specific focus on the low abundance proteins. The ovine colostrum is characterized by a few dominating proteins, as the immunoglobulins, but it also contains less represented protein species, equally important for the correct development of neonates. Ovine colostrum, collected immediately after lambing, was separated by 1D SDS-PAGE. Proteins bands were digested with trypsin and the resulting peptides were analyzed by LC-MS/MS. On the basis of the Swiss-Prot database, a total of 343 unique proteins were identified. To our knowledge, this study represents the most comprehensive analysis of ovine colostrum proteome.