Milk Fat Content Research Articles

The serine protease 2 gene regulates lipid metabolism through the LEP/ampkα1/SREBP1 pathway in bovine mammary epithelial cells

Molecular breeding has brought about significant transformations in the milk market and production system during the twenty-first century. The primary economic characteristic of dairy production pertains to milk fat content. Our previous transcriptome analyses revealed that serine protease 2 (PRSS2) is a candidate gene that could impact milk fat synthesis in bovine mammary epithelial cells (BMECs) of Chinese Holstein dairy cows. To elucidate the function of the PRSS2 gene in milk fat synthesis, we constructed vectors for PRSS2 overexpression and interference and assessed intracellular triglycerides (TGs), cholesterol (CHOL), and nonesterified fatty acid (NEFA) contents in BMECs. Fatty acid varieties and components were also quantified using gas chromatography‒mass spectrometry (GC‒MS) technology. The regulatory pathway mediated by PRSS2 was validated through qPCR, ELISA, and WB techniques. Based on our research findings, PRSS2 emerges as a pivotal gene that regulates the expression of associated genes, thereby making a substantial contribution to lipid metabolism via the leptin (LEP)/Adenylate-activated protein kinase, alpha 1 catalytic subunit (AMPKα1)/sterol regulatory element binding protein 1(SREBP1) pathway by inhibiting TGs and CHOL accumulation while potentially promoting NEFA synthesis in BMECs. Furthermore, the PRSS2 gene enhances intracellular medium- and long-chain fatty acid metabolism by modulating genes related to the LEP/AMPKα1/SREBP1 pathway, leading to increased contents of unsaturated fatty acids C17:1N7 and C22:4N6. This study provides a robust theoretical framework for further investigation into the underlying molecular mechanisms through which PRSS2 influences lipid metabolism in dairy cows.

Application of a short-wave pocket-sized near-infrared spectrophotometer to predict milk quality traits

Portable-hand-held devices based on near-infrared (NIR) technology have improved and are gaining popularity, even if their implementation in milk has been barely evaluated. Thus, the aim of the present study was to assess short-wave pocket-sized NIR devices' feasibility to predict milk quality. A total of 331 individual milk samples from different cow breeds and herds were collected in 2 consecutive days for chemical determination and spectral collection by using 2 pocket-sized NIR spectrophotometers working in the range of 740-1070 nm. The reference data was matched with the corresponding spectrum and modified-partial least-squares regression models were developed. A 5-fold cross-validation was applied to evaluate individual devices' performance and an external-validation with 25% of the data set as the validation set was applied for the final models. Results revealed that both devices' absorbance was highly correlated but greater for instrument A than B. Thus, the final models were built by averaging the spectra from both devices for each sample. The fat content prediction model was adequate for quality control with a coefficient of determination (R2ExV) and a residual predictive deviation (RPDExV) in external validation of 0.93 and 3.73, respectively. Protein and casein content as well as fat-to-protein ratio prediction models might be used for a rough screening (R2ExV > 0.70; RPDExV > 1.73). However, poor prediction models were obtained for all the other traits with an R2ExV between 0.43 (urea) and 0.03 (somatic cell count), and a RPDExV between 1.18 (urea) and 0.22 (somatic cell count). In conclusion, short-wave portable-hand-held NIR devices accurately predicted milk fat content, and protein, casein, and fat-to-protein ratio might be applied for rough screening. It seems that there is not enough information in this NIR region to develop adequate prediction models for lactose, somatic cell count, urea, and freezing point.

Grapefruit (Citrus paradisi Mcfad.) and its phytochemical inhibits pancreatic lipase enzyme and modulates the saturated fat-induced obesity model

The prevalence of obesity has reached epidemic proportions and warrants numerous interventions, mostly using functional foods or medicinal plants to combating obesity. This review focuses on medicinal plants that elicit anti-obesity effect targeting pancreatic lipase enzyme (PLE). However, the putative processes of the plants targeting PLE and its consequential effects on triglyceride breakdown remains elusive. The effect of aqueous methanolic extracts, fractions and isolates of selected plants on PLE was tested in-vitro. The potent plant extract was examined for its effect on triglyceride levels in rats administered using saturated fat-rich coconut milk versus non-fat milk model in-vivo. Our observations illustrates that the Citrus paradisi aqueous methanolic extract (CPAME) inhibits PLE and modulate the saturated fat-induced weight gain and triglyceride levels. Whilst, the hesperidin isolated from CPAME has shown potential to inhibit PLE, the observations warrant further investigations on flavonoid and other compounds in grape fruit. Therefore, CPAME could be a promising target in combating obesity by inhibiting PLE.

Particle Size Distribution and Feed Sorting of Hay-Based and Silage-Based Total Mixed Ration of Calabrian Dairy Herds

Dietary particle size is one of the most relevant factors influencing rumen function and the selection of the most palatable components of the total mixed ration (TMR) by cows. The aim of this study was to evaluate the particle size distribution (PSD), homogeneity, sorting level, physically effective NDF (peNDF) content of TMRs, and production performances in Calabrian commercial dairy herds in southern Italy. The research was conducted in 13 farms, including 8 with hay-based TMR and 5 with silage-based TMR. All herds delivered fresh feed once a day. At each farm, the TMRs were examined with the Penn State Particle Separator (PSPS) to determine PSD, homogeneity, and feed sorting at two time points (i.e., at fresh feed delivery = T0 and 24 h after feed delivery = Tf). None of the diets that were evaluated met the recommended PSD, showing an excess of long fraction, very short fraction, or both. The homogeneity was good except for three diets, but particle selection raised some concerns in 85% of the farms due to the preferential consumption of the very short fraction by the cows, with rejection of the long fractions. All the diets analyzed met the Penn State University recommended neutral detergent fiber (NDF) values (>28%) except for one farm’s diet. In three of the TMRs observed, however, the content of peNDF > 8 mm was less than 15%. NDF and peNDF > 8 mm values of TMRs showed statistically significant correlations with milk fat content. Therefore, it is important to evaluate the chemical and physical properties of TMR to provide a consistent diet and prevent feed sorting.

Microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for the elemental analysis of complex matrix samples

Microwave induced plasma optical emission spectrometry (MIP-OES) has gained widespread attention in the last few years for trace elemental analysis. Among the new generation of MIPs it is worth to mention the microwave-sustained inductively coupled atmospheric-pressure plasma (MICAP) for which previous works have shown similar detection capabilities to those afforded by ICP-OES. Nevertheless, this instrument has not been applied yet to complex matrix sample analysis. Therefore, the goal of this work is to evaluate MICAP-OES performance (e.g., analytical figures of merit, matrix effects, etc.) for elemental analysis of samples of different nature (e.g., environmental, food and polymers). To this end, both spectral and non-spectral interferences were investigated for 19 elements (Ag, Al, As, B, Ca, Cd, Co, Cr, Cu, Fe, Ga, In, Mg, Mn, Ni, Pb, Sr, Tl, Zn) in the presence of inorganic acid, organic and saline solutions and compared to a 5 % w w−1 HNO3 solution. Unlike previous MIPs, experimental data showed that the optimum nebulizer gas flow rate for a given emission wavelength was mostly independent of matrix characteristics. Regarding matrix effects, this device was highly robust operating both inorganic acid and organic matrices. Interestingly, when operating saline matrices, changes on emission signal by easily ionizable elements were less significant than those early reported by alternative MIP cavities. Moreover, due to MICAP spectrometer design employed allows real-time simultaneous analysis, Rh, Pd, Sc and Y were suitable internal standards to minimize non-spectral interferences. Finally, MICAP-OES can be successfully applied to the elemental analysis of different complex matrix samples (i.e., CRM-DW1 Drinking water; BCR-146 Sewage sludge industrial; BCR-185 Bovine liver; BCR-278R Mussel tissue; NIST-1549 Non-fat milk powder; ERM-EC681k Polyethylene (high level) and BCR-483 Sewage sludge amended soil).

Продуктивность коров при разной комбинации линий

The purpose of the study was to study the milk productivity of cows with different combinations of lines. The object of the study were first-calf cows of the black-and-white breed of the line Vis Back Aidiala 101341, Reflection Soveringa 198998, Montvik Chiefteina 95679. Cows obtained by intraline selection of the Aidial line have a high level of milk productivity, with milk yield of 5571 kg of milk, milk fat yield of 226 kg and protein yield of 171 kg, while significantly (P<0.05-0.01) superior to first-calf heifers, belonging to the Sovering line for 102 kg, 4 kg of fat and 4 kg of protein, and to the Chieftain line - for 259 kg of milk, 16 kg of fat and 11 kg of protein, respectively. When crossing the Ideal-Sovering lines, the highest milk yield is observed (5667 kg), with good milk fat content (4.01 %), high yield of milk fat (227 kg) and milk protein (172 kg). With the reverse cross Sovering-Idial, slightly lower milk productivity rates were obtained. When using bulls of the Aidial line on cows of the Governer line, high milk fat content (4.07 %) and milk fat yield (228 kg) were obtained, with average values of milk yield (5596 kg), protein mass fraction (3.01 %) and its yield (168 kg). Unsuccessful combinations of lines in both forward and reverse directions are crosses of the Idial and Chieftain lines. The descendants of such combinations have the lowest milk productivity. Thus, the use of line manufacturers R. Sovering and V.B. Idiala, both with intraline selection and interline combination, gives the best milk productivity indicators. Consequently, it is necessary to evaluate bulls according to the compatibility of lines; this has a great influence on the productivity of the offspring, since sires of the same line, when inseminating cows of the same lines, produce offspring of different productivity.

2-Hydroxy-4-(Methylthio)-Mutanoate Supplementation Affects Production, Milk Fatty Acid Profile, and Blood Metabolites of High-Producing Holstein Cows

The objectives of this study were to evaluate the effects of supplementing the diet of high-producing Holstein cows with 2-hydroxy-4-(methylthio)-butanoate (HMTBa) on their milk production and composition, milk fatty acid profile, blood metabolites, and body parameters. The study was conducted in a commercial dairy herd in Paraná State, Southern Brazil. One hundred and fifty-eight multiparous cows were used in a randomized block design during 42 experimental days. Cows were distributed into two treatments: the control treatment cows received 100 g/cow/day of corn meal, while the HMTBa-supplemented cows received 35 g of HMTBa + 65 g/cow/day of corn meal. HMTBa supplementation did not alter milk production but improved milk fat content. Cows receiving HMTBa supplementation showed an increase in the concentration of milk medium-chain fatty acids. Serum levels of blood urea and aspartate aminotransferase were lower in HMTBa-supplemented cows. Cows supplemented with HMTBa increased their body condition score. In summary, HMTB supplementation in high-producing Holstein cows improved productive performance, particularly increased milk fat content, altered milk fatty acid profile, and changed some blood metabolites. Our findings contribute to our understanding of using a methionine analogue as a dietary strategy for optimizing milk quality in high-producing Holstein cows.

Reducing dietary protein and supplementation with starch or rumen-protected methionine and its effect on performance and nitrogen efficiency in dairy cows fed a red clover and grass silage–based diet

The increasing cost of milk production, in association with tighter manure N application regulations and challenges associated with ammonia emissions in many countries, has increased interest in feeding lower crude protein (CP) diets based on legume silages. Most studies have focused on alfalfa silage, and little information is available on low-CP diets based on red clover silage. Our objectives were to examine the effects of dietary CP content and supplementing a low-CP diet with dietary starch or rumen-protected Met (RPMet) on the performance, metabolism, and nitrogen use efficiency (NUE; milk N output/N intake) in dairy cows fed a red clover and grass silage-based diet. A total of 56 Holstein-Friesian dairy cows were blocked and randomly allocated to 1 of 4 diets over a 14-wk feeding period. Diets were based on red clover and grass silages at a ratio of 50:50 on a dry matter (DM) basis and were fed as a total mixed ration, with a 53:47 ratio of forage to concentrate (DM basis). The diets were formulated to supply a similar metabolizable protein (MP) content, and had a CP concentration of either 175 g/kg DM (control [CON]) or 150 g/kg DM (low-protein [LP]), or LP supplemented with either additional barley as a source of starch (LPSt; +64 g/kg DM) or RPMet (LPM; +0.3 g/100 g MP). At the end of the 14-wk feeding period, 20 cows (5 per treatment) continued to be fed the same diets for a further 6 d, and total urine output and fecal samples were collected. We observed that dietary treatment did not affect DM intake, with a mean of 21.5 kg/d; however, we also observed an interaction between diet and week with intake being highest in cows fed LPSt in wk 4 and CON in wk 9 and 14. Mean milk yield, 4% fat-corrected milk, and energy-corrected milk were not altered by treatment. Similarly, we found no effect of dietary treatment on milk fat, protein, or lactose content. In contrast, milk and plasma urea concentrations were highest in cows fed CON. The concentration of blood plasma β-hydroxybutyrate was highest in cows receiving LPM and lowest in LPSt. Apparent NUE was 28.6% in cows fed CON and was higher in cows fed any of the low-protein diets (LP, LPSt, or LPM), with a mean value of 34.2%. The sum of milk fatty acids with a chain length below C16:0 was also highest in cows fed CON. We observed that dietary treatment did not affect the apparent whole-tract nutrient digestibility of organic matter, N, neutral detergent fiber, and acid detergent fiber, with mean values of 0.785, 0.659, 0.660, and 0.651 kg/kg respectively, but urinary N excretion was approximately 60 g/d lower in cows fed the low-CP diets compared with CON. We conclude that reducing the CP content of red clover and grass silage-based diets from 175 to 150 g/kg DM while maintaining MP supply did not affect performance, but reduced the urinary N excretion and improved NUE, and that supplementing additional starch or RPMet had little further effect.

Farmers' Perceptions on Implementing Automatic Milking Systems in Large USA Dairies: Decision-Making Process, Management Practices, Labor, and Herd Performance.

Automatic Milking System (AMS) installations are increasing in the USA despite the higher investment cost than conventional systems. Surveys on AMSs conducted outside the USA focused on small-medium herds, specific regions, or aspects of AMS milking. This study described farmers' perceptions about the decision-making process of adopting an AMS in the USA's large dairies (≥7 AMS boxes) regarding changes in technology, housing, management practices, labor, herd performance, and health. After being contacted, 27 of 55 farmers from large AMS herds completed the survey. The main reasons for adopting an AMS were labor costs, cows' welfare, and herd performance. Most farms constructed new barns, used a free-flow traffic system, and changed their feed management. Increases in water and energy use were perceived by 42% and 62% of farmers, respectively. Farmers estimated decreases in labor costs of over 21%, and AMS employees worked 40-60 h/week. Milk production increases were reported by 58%, with 32% observing higher milk fat and protein content. Easier sick cow detection, better mastitis management, and improvements in pregnancy rates were reported. Thus, farmers transitioning to AMSs perceived altered resource utilization, labor cost savings, and improvements in employee quality of life, animal welfare, and farm management. While 54% of respondents would recommend an AMS to other farms, 38% suggested considering additional aspects prior to adoption.

Research Progress on the Mechanism of Milk Fat Synthesis in Cows and the Effect of Conjugated Linoleic Acid on Milk Fat Metabolism and Its Underlying Mechanism: A Review.

Milk fat synthesis in cows mainly includes the synthesis of short- and medium-chain fatty acids, the uptake, transport, and activation of long-chain fatty acids (LCFAs), the synthesis of triglycerides, and the synthesis of the genes, transcription factors, and signaling pathways involved. Although the various stages of milk fat synthesis have been outlined in previous research, only partial processes have been revealed. CLA consists of an aggregation of positional and geometric isomers of linoleic fatty acid, and the accumulated evidence suggests that the two isomers of the active forms of CLA (cis-9, trans-11 conjugated linoleic acid and trans-10, cis-12 conjugated linoleic acid, abbreviated as c9, t11-CLA and t10, c12-CLA) can reduce the fat content in milk by regulating lipogenesis, fatty acid (FA) uptake, oxidation, and fat synthesis. However, the mechanism through which CLA inhibits milk fat synthesis is unique, with most studies focusing only on the effects of CLA on one of the genes, transcription factors, or signaling pathways involved. In this study, we summarized the structure and function of classic genes and pathways (mTOR, SREBP, AMPK, and PPARG) and new genes or pathways (THRSP, METTL3, ELOVL, and LPIN1) involved in each stage of milk fat synthesis and demonstrated the interactions between genes and pathways. We also examined the effects of other substances (melanin, nicotinic acid, SA, etc.). Furthermore, we evaluated the influence of β-sitosterol, sodium butyrate, Met arginine, and Camellia oleifera Abel on milk fat synthesis to improve the mechanism of milk fat synthesis in cows and provide a mechanistic reference for the use of CLA in inhibiting milk fat biosynthesis.

Non-targeted metabolomics identifies biomarkers in milk with high and low milk fat percentage

Milk is widely recognized as an important food source with health benefits. Different consumer groups have different requirements for the content and proportion of milk fat; therefore, it is necessary to investigate the differential metabolites and their regulatory mechanisms in milk with high and low milk fat percentages (MFP). In this study, untargeted metabolomics was performed on milk samples from 13 cows with high milk fat percentage (HF) and 13 cows with low milk fat percentage (LF) using ultra-high performance liquid chromatography coupled with mass spectrometry (UHPLC-MS/MS). Forty-eight potential differentially labeled compounds were screened using the orthogonal partial least squares-discriminant analysis (OPLS-DA) combined with the weighted gene co-expression network analysis (WGCNA) method. Amino acid metabolism was the key metabolic pathway with significant enrichment of L-histidine, 5-oxoproline, L-aspartic acid, and L-glutamic acid. The negative correlation with MFP differentiated the HF and LF groups. To further determine the potential regulatory role of these amino acids on milk fat metabolism, the expression levels of marker genes in the milk fat synthesis pathway were explored. It was noticed that L-histidine reduced milk fat concentration primarily by inhibiting the triglycerides (TAG) synthesis pathway. L-aspartic acid and L-glutamic acid inhibited milk fat synthesis through the fatty acid de novo and TAG synthesis pathways. This study provides new insights into the mechanism underlying milk fat synthesis and milk quality improvement.

A Preliminary Study on the Effect of Different Feeding Regimes on the Milk Chemical Composition of the Maltese Goat Breed During the Early Stage of Lactation

The Maltese goat is a breed of goats which is sparsely found in a few countries and also progressively being eradicated due to the Maltese goat being bred with other goat breeds, thus reducing the breed population. This research sets to understand how the effect of different feeding regimes affects the physiochemical characteristics of the Maltese goats’ milk. The researcher collected 112 milk samples from 112 Maltese goats, kept on 17 farms. The milk samples were categorised into four different feeding regimes. After collection, milk was stored and tested in the lab utilising an ultrasonic milkanalyser and a pH meter. Values for the content of fat, protein, salts, lactose, solid-not-fats, freezing point, density, and pH were recorded and tabulated. The results show that feeding regime three, consisting of high levels of protein (11% to 13%) and low levels of rich-quality fibre (12% to 20%), yield milk rich in protein (4.23%), fat (3.86%), lactose (4.09%), and salts (0.66%). The results also conclude that feeding regime one, consisting of low protein (7% to 10%) and low content of rich-quality fibre (12% to 20%), yields the highest milk fat content (4.23%), but the lowest levels of protein (3.82%), salts (0.59%), and lactose (3.62%). Consequently, feeding regime three results as being the ideal feed to obtain a high content of the indicated physio-chemical characteristics.

Quality of yogurt produced from various types of milk as raw materials

Different types of milk are used to make yogurt, which gives it different qualities. Fresh milk, powdered milk, low-fat milk, non-fat milk, and Ultra High Temperature (UHT) milk all have different qualities. The goal of the study was to look at the chemical, physical, and sensory properties of yogurt made from different ingredients. The treatment’s base materials were P1: yogurt made with fresh milk, P2: yogurt made with milk powder, P3: yogurt made with ultra-high-temperature milk, P4: yogurt made with low-fat milk, and P5: yogurt made with non-fat milk. Commercial yogurt starters were used to make yogurt, and each treatment was done four times. Other tests were done with Duncan. The factors for the study are the amount of moisture, total solids, pH, total titratable acidity, and how it tastes. The results showed that the moisture content, total solids, pH, and total titratable acidity were all significantly different (P<0.05), as were the taste and preferences. The results of the study show that yogurt with different ingredients has different qualities.

Cow productivity depending on the energy level of their feeding

This article presents the results of a scientific and economic experiment conducted on lactating cows of Holstein black-and-white breed during the second lactation period, in which the effect of increased energy levels of feeding dairy cows on their productivity was studied. Based on the conducted studies, it was revealed that an increase in the energy level of feeding lactating cows of the experimental group in the second lactation period by 33.3 MJ of metabolic energy due to a decrease in the yield of corn silage and concentrated feed, the replacement of mixed hay with alfalfa hay and the introduction of long-term grass haylage into the feeding diet contributed to a better consumption of metabolic energy by 31.3 MJ, dry matter – by 5.2 kg, crude protein – by 997 g, including digestible protein – by 613 g, crude fiber – by 1594 g, crude fat – by 237 g, sugar – by 553 g, compared with lactating cows of the control group. This led to an increase in gross milk production during the second lactation period in lactating cows of the experimental group by 275 kg, an increase in the fat content in milk by 0.02% and protein by 0.03%, respectively, then in lactating cows of the control group. One energy feed unit in the feeding diet of lactating cows of the control group accounted for 12.3 g less digestible protein than in the experimental group. The consumption of concentrates per 1 kg of milk in the control group was 25% higher than in the experimental group.

Evaluation of milk yield of Three-breed (1/4 Caucasian grey x 1/4 Jersey x 1/2 Holstein) genotype cows under conditions of manger-pasture keeping

The F6 generation cows, which were made from “itself” breeding of three-breed cows (1/4 Caucasian Gray x 1/4 Jersey x 1/2 Holstein) (1/4 CG x 1/4 J x 1/2 H), the 305 days of first lactation exceed the Holstein breed to the standard by 175 kg or 4.2 %, milk fat content by 0.65 %, protein by 1 %, milk fat by 33.5 kg or 22.2 %. During pasture period from each cow was obtained 2540 kg of milk conforming to sanitary and hygienic standards. In the third calving, 170 days of pasture period and 195 days of manger keeping, the amount of milk in 305 days of lactation was 5337 kg, the amount of milk fat + milk protein was 407.7 kg, the reproductive ability was 100%. During manger period 0.77 FU (feed unit) or 0.90 EFU (energetic feed unit) and 80 g of digestible protein were spent to produce 1 kg of milk. The realization of pasture promotes to the increase generation, high vitality, proportionated exterior, strong limbs and a dense composition.

Breeding and productive qualities of Ayrshire cattle

In the current conditions of livestock development in the country, dairy cattle breeding requires animals having not only high genetic potential, but also characterized by a high level of milk production. The purpose is to study the breeding and productive qualities of Ayrshire cattle bred in the conditions of the Republic of Mari El. The research was carried out at CJSC Mariiskoye in the Republic of Mari El. The test subject is Ayrshire dairy cattle. Currently, Ayrshire cattle bred on the farm are purebred and have an elite-record class. The herd is young, the average age of the cows is 3.4 calvings. On average, one cow produces 6,876 kg of milk per lactation with a milk fat content (MFC) of 4.5% and a milk protein content (MPC) of 3.34%. The level of cow's milk production exceeds the requirements of the class 1 standard for milk yield by 76.5%, for MFC by 3.4%, and for the amount of milk fat by 26.2%. The cows significantly exceed the established standard for live weight by 12–20% and have an excellent exterior for dairy cattle. Currently, in the herd, there are animals belonging to 5 lines. The cows of the Urho Errant and O.R. Lichting lines yielded more than the average for the herd (7,017 kg and 6,930 kg, respectively). The cows of the S.B. Commander line were giving milk with high fat content and the cows of the Sniperum SRB line were giving milk with high protein content. In the herd, the production is ensured by daughters from 19 bulls.

ХИМИЧЕСКИЙ СОСТАВ И ТЕХНОЛОГИЧЕСКИЕ СВОЙСТВА МОЛОКА КОРОВ-ПЕРВОТЕЛОК ПРИ РАЗНЫХ СПОСОБАХ СОДЕРЖАНИЯ И ТЕХНОЛОГИЯХ ДОЕНИЯ

Industrial milk production is based on high-tech processes at the current stage. Strong requirements imposed on milk quality are due to the quality of raw materials for producing a wide range of dairy products. The production of milk that meets sanitary and hygienic standards and the requirements of regulatory and technical documents (regulations and standards) is a priority in dairy cattle breeding. Analysis of the chemical composition of milk obtained from the control and experimental groups showed that the milk fat content was the highest (4.06 %) in the 1st experimental group and exceeded the control (3.93 %) and the 2nd experimental (3.94 %) groups. Under the loose housing system the mass fraction of protein was 3.15 %; the value was 0.02 points larger compared with the tie housing system. The milk density in the animal groups ranged from 1027.0 to 1029.0 kg/m3 , which meets the requirements of GOST 31449-2013. The largest mass fraction of dry solids in milk was found in the 2nd experimental group (12.58 %). The data analysis indicates that the housing system type and the milking technology of first-calf heifers have an effect on the number of milk fat globules per 1 cm3 and their diameter. The analysis of the quantitative and qualitative composition of fat globules has provided more complete data about the milk fat fraction, which is a crucial index in milk production. The milk obtained from the Holstein breed heifers in the studied groups can be used for cheese making. The third yogurt sample had a milky white colour, homogeneous throughout the mass; the consistency was homogeneous, with good curd tension and low viscosity; the sample had a pure, fermented milk flavour, without foreign traces.

Influence of feed mixtures on the productivity of cows and chemical composition of milk during the period of increasing the milk yield

There is a wide variety of climatic zones in the huge territories of our country, which require special approaches to feeding and housing of animals. Providing animals with adequate and rationed feeding under the conditions of the Northern Trans-Urals and Siberia is a difficult task due to the long stall period. The purpose of the work was to determine the infl uence of diff erent methods of feed distribution such as separate and feed mixture on milk productivity of cows and the chemical composition of milk during the period of increasing the milk yield. It was found that the milk yield of natural fat content during the fi rst 100 days of lactation in the experimental group of cows was 325 kg or 10,21 % higher than in the control group. Milk fat yield was obtained from the cows of the experimental group by 16,5 kg or 13,80 % more compared to the animals of the control group. The mass fraction of fat in the milk of cows in the experimental group was higher by 0,12 abs.%. However, the difference between groups in milk yield, milk fat content and milk fat yield was statistically insignificant. The difference in the content of protein, ash, calcium and phosphorus in the milk of the experimental animals was also insignificant, although there was some advantage in the content of these indicators in the experimental group, where the feed was fed in the form of the feed mixture. It was found when analyzing economic indicators that for cows in the control group the prime-cost of 1 kg of milk was 16,49 rubles, which was by 1,53 rubles or 3,91 % more than in the experimental group. At the same time, the level of profitability of milk production in the experimental group was higher than 12,66 abs.% compared to the control group.

Hybrid de novo and haplotype-resolved genome assembly of Vechur cattle - elucidating genetic variation.

Cattle contribute to the nutritional needs and economy of a place. The performance and fitness of cattle depend on the response and adaptation to local climatic conditions. Genomic and genetic studies are important for advancing cattle breeding, and availability of relevant reference genomes is essential. In the present study, the genome of a Vechur calf was sequenced on both short-read Illumina and long-read Nanopore sequencing platforms. The hybrid de novo assembly approach was deployed to obtain an average contig length of 1.97 Mbp and an N50 of 4.94 Mbp. By using a short-read genome sequence of the corresponding sire and dam, a haplotype-resolved genome was also assembled. In comparison to the taurine reference genome, we found 28,982 autosomal structural variants and 16,926,990 SNVs, with 883,544 SNVs homozygous in the trio samples. Many of these SNPs have been reported to be associated with various QTLs including growth, milk yield, and milk fat content, which are crucial determinants of cattle production. Furthermore, population genotype data analysis indicated that the present sample belongs to an Indian cattle breed forming a unique cluster of Bos indicus. Subsequent FST analysis revealed differentiation of the Vechur cattle genome at multiple loci, especially those regions related to whole body growth and cell division, especially IGF1, HMGA2, RRM2, and CD68 loci, suggesting a possible role of these genes in its small stature and better disease resistance capabilities in comparison with the local crossbreeds. This provides an opportunity to select and engineer cattle breeds optimized for local conditions.

Exploring the presence of genotype-by-environment interactions between dairy cow herds milking once-a-day or twice-a-day for the entire lactation

The objective was to explore if the regression of phenotypic performance for six milk production traits on the respective estimate of genetic merit for that trait differed by herd milking frequency; variance components for each trait in the two milking frequency environments were also estimated as well as the genetic correlation between the same trait in both environments. The data used included 12,581 lactations from 5,456 cows in 32 spring-calving once-a-day (OAD) milking herds. Each OAD herd was matched with three contemporary twice-a-day (TAD)-milking herds; 35,823 lactations from 15,188 cows in 96 TAD herds were used. Mean yield was 20% (fat yield) to 31% (milk yield) lower in OAD herds. Milk protein concentration was 11% higher in OAD herds, while milk fat concentration was 16% higher in OAD herds. The mean back-transformed somatic cell score (SCS) was 100,390 cells/mL in OAD herds and 72,493 cells/mL in TAD herds. The association between each milk production trait and its respective estimate of genetic merit differed by herd milking frequency; the estimated regression coefficients were larger in TAD for just milk yield and SCS. The genetic correlation between the same trait in OAD versus TAD was all ≥0.73 with the exception of SCS (genetic correlation of 0.48) which suggests some re-ranking of sires between environments. In conclusion, differences in the scale of the genetic variance were evident for both milking frequencies and possible re-ranking was evident for SCS.