Characterization of pivotal metabolites influencing the production of milk components in dairy goats.

Simple SummaryAlthough somatic cell count is not a sensitive biomarker to identify mastitis in goats, the current study revealed a relationship between this indicator and goat milk composition. While data on goat milk fatty acids and especially on amino acid variations according to somatic cell count influence are very minimal, the main goal of this study was to evaluate the relation of different somatic cell count levels in goat milk with goat milk yield, milk composition, fatty acid, and amino acid profiles of Alpine and Saanen goat breeds. The research revealed some statistically significant relationships between somatic cell count and amino acids and fatty acids, suggesting that improving milk quality by reducing somatic cell count may benefit farmers by improving goat milk’s fatty acid and amino acid composition and may serve as a biomarker for dairy goats. However, future studies with more goats are needed to confirm these results.The main goal of this study was to evaluate the relation of different SCC levels in goat milk with goat milk yield, milk composition, FA, and AA profiles. Whereas the investigated herd was composed of Alpine and Saanen goats, the influence of breed on milk parameters and milk yield was also assessed. The research was carried out in 2022 at a Lithuanian dairy goat farm with 135 goats (Saanen = 66 and Alpine = 69) without evidence of clinical mastitis. The current research revealed a relationship between SCC with goat milk yield and composition. Goats with a high SCC had significantly lower milk yield (p < 0.001), lower content of lactose (p < 0.01), fat (p < 0.001) and higher protein content (p < 0.05) in their milk. The increase in most AA was significantly associated with increased SCC. The higher quantity of Asp, Glu, Ala, Met, His, Lys, Arg, EAA, NEAA, and TAA (compared with the low SCC group) (p < 0.05–0.01), Leu, Tyr, and BCAA (compared with the low and medium SCC group) were found in the milk of the high SCC group (p < 0.05–0.01). The distribution of the main FA groups was also related to SCC and showed a significant decrease in SCFA (p < 0.01–0.001) and an increase in LCFA, PUFA, and BCFA in the high SCC group (p < 0.05). All individual AA and their groups (EAA, NEAA, TAA, BCAA) were significantly lower in the milk of the Saanen goat breed (p < 0.001). The most individual FA ranged between goat breeds, while the total amount of SFA, UFA, and MUFA wasn’t affected by breed (p > 0.05). The research revealed a statistically significant relationship between SCC, AA, and FA, suggesting that these traits may be used as a biomarker in the goat selection process.

Short communication: Effect of αS1-casein (CSN1S1) and κ-casein (CSN3) genotypes on milk composition in Murciano-Granadina goats

Genetic components of milk Fourier-transform infrared spectra used to predict breeding values for milk composition and quality traits in dairy goats

Two experiments were carried out to investigate how milking in mid-line (ML) affects the lipolysis level and milk composition in goat livestock, in comparison with low-line (LL) milking. The first experiment took place, in triplicate, on an experimental farm. For each replicate, a crossover design (62 goats, two treatments, ML and LL, in two periods each lasting 4 days) was used. Milk samples were taken daily at 0 and 24 h after milking. In the first experimental replicate, some enzymatic coagulation cheeses were made, which were assessed by a panel of tasters at 50 and 100 days of maturation. In the second experiment, the lipolysis level and composition of tank milk from 55 commercial dairy goat farms (25 ML and 30 LL) were analysed, in milk samples taken in three different weeks. The results of the first experiment showed that ML milking increased free fatty acid (FFA) concentration in raw goat's milk significantly (0.71 v. 0.40 mmol/l, respectively). However, in the milk samples taken from commercial farms the FFA concentration remained unaffected by the milking pipeline height (0.59 v. 0.58 mmol/l for ML and LL, respectively). No significant differences were found in the milk composition, nor in the sensory characteristics in the cured cheeses, which suggests that factors other than the milkline height are able to influence the level of lipolysis under commercial conditions. Therefore, ML milking should not be discouraged, provided that the correct functioning and management of the milking operation and milk storage on the farm is guaranteed.

The biosynthesis of milk and its components is an important biological process in dairy cattle which determines the milk quality. Milking interval has an influence on milk components biosynthesis and the dairy farm labor cost as well as the management. Different milking interval resulted in different milk yield and its respective components. Thus, this study aimed to observe the effect of milking interval on the synthesis of milk components in Indonesian Friesian Holstein. In total, 3562 data of milk components were retrieved from the evening (10 hours, milking time 03.00 PM) and morning (14 hours, milking time 05.00 AM) milking interval, 1781 data in each. Milk components were observed as the percentage of fat, protein, lactose, and total solids non-fat. The result shows that evening milking has higher (p<0.05) percentage of fat, protein, lactose and solids non-fat compared to morning milking which was 4.067±0.68 vs. 3.68±0.62%; 2.68±0.13 vs. 2.62±0.12%; 4.02±0.20 vs. 3.94±0.18%, and 7.32±0.35 vs. 7.17±0.33%, respectively. This study concluded that a longer milking interval tends to give more time for the synthesis of milk components when compared to the short one.The biosynthesis of milk and its components is an important biological process in dairy cattle which determines the milk quality. Milking interval has an influence on milk components biosynthesis and the dairy farm labor cost as well as the management. Different milking interval resulted in different milk yield and its respective components. Thus, this study aimed to observe the effect of milking interval on the synthesis of milk components in Indonesian Friesian Holstein. In total, 3562 data of milk components were retrieved from the evening (10 hours, milking time 03.00 PM) and morning (14 hours, milking time 05.00 AM) milking interval, 1781 data in each. Milk components were observed as the percentage of fat, protein, lactose, and total solids non-fat. The result shows that evening milking has higher (p<0.05) percentage of fat, protein, lactose and solids non-fat compared to morning milking which was 4.067±0.68 vs. 3.68±0.62%; 2.68±0.13 vs. 2.62±0.12%; 4.02±0.20 vs. 3.94±0.18%, and 7.32±0.35 vs. 7.17±0...

A number of studies have addressed the relations between climatic variables and milk composition, but these works used univariate statistical approaches. In our study, we used a multivariate approach (canonical correlation) to study the impact of climatic variables on milk composition, price, and monthly milk production at a dairy farm using bulk tank milk data. Data on milk composition, price, and monthly milk production were obtained from a dairy company that purchased the milk from the farm, while climatic variable data were obtained from the National Institute of Meteorology (INMET). The data are from January 2014 to December 2016. Univariate correlation analysis and canonical correlation analysis were performed. Few correlations between the climatic variables and milk composition were found using a univariate approach. However, using canonical correlation analysis, we found a strong and significant correlation (rc = 0.95, p value = 0.0029). Lactose, ambient temperature measures (mean, minimum, and maximum), and temperature-humidity index (THI) were found to be the most important variables for the canonical correlation. Our study indicated that 10.2% of the variation in milk composition, pricing, and monthly milk production can be explained by climatic variables. Ambient temperature variables, together with THI, seem to have the most influence on variation in milk composition.

The variation in the casein genes has a major impact on the milk composition of goats. Even though many casein polymorphisms have been identified so far, we do not know yet whether they are evolutionarily ancient (i.e., they existed before domestication) or young (i.e., they emerged after domestication). Herewith, we identified casein polymorphisms in a data set of 106 caprine whole-genome sequences corresponding to bezoars (Capra aegagrus, the ancestor of domestic goats) and 4 domestic goat (Capra hircus) populations from Europe, Africa, the Far East, and the Near East. Domestic and wild goat populations shared a substantial number of casein SNP, from 36.1% (CSN2) to 55.1% (CSN1S2). The comparison of casein variation among bezoars and the 4 domestic goat populations demonstrated that more than 50% of the casein SNP are shared by 2 or more populations, and 18 to 44% are shared by all populations. Moreover, the majority of casein alleles reported in domestic goats also segregate in the bezoar, including several alleles displaying significant associations with milk composition (e.g., the A/B alleles of the CSN1S1 and CSN3 genes, the A allele of the CSN2 gene). We conclude that much of the current diversity of the caprine casein genes comes from ancient standing variation segregating in the ancestor of modern domestic goats.

Goat farming is a common practice on the island of Grenada, West Indies. In the years post-Hurricane Ivan (2004), the dairy goat industry has been gradually evolving into a commercial entity, in order to provide goat milk and milk products to the community. Vital to the sustainability of this industry is the maintenance of a high-quality and reproducible product. However, there are no data available on the current composition of goat milk in Grenada. This preliminary study was undertaken to assess the composition of goat milk to assist farmers in the further development of the Grenada goat milk industry. Using a commercial milk analyzer, 115 goat milk samples from four Grenada parishes were analyzed. The results gave an average of dairy goat milk composition in Grenada, including values for fat (4.53%), protein (3.47%), non-fat solids (9.07%), lactose (4.91%), and total solids (13.60%). Milk values were significantly different among the four parishes, with St. Patrick having the lowest values and St. Andrew the highest. Additionally, there was no significant difference between values derived for Grenada versus those recently reported in the neighboring island of Trinidad. The composition of goat milk in Grenada and the differences among parishes is hypothesized to be influenced in large part by nutrition. Future plans are underway 1) to advise goat farmers on the husbandry and feeding of goats to optimize the quality of milk and 2) to perform updated analyses on the milk composition post-implementation.

Production performance and milk composition of late lactation dairy goats fed diets based on silages of four different forage species

The aim of the study was to determine the relative day-to-day variation in yield and composition of zebu cows. Ten multiparous zebu cows in day 41 ± 1.6 of lactation were used in the study. After a 14 day adaptation period, milk production was recorded daily for four consecutive weeks. Cows had access to natural pasture for 6.5 h per day and were also supplemented with hay, cottonseed cake and molasses. The cows were hand-milked and calves were used to stimulate milk ejection before and during milking. Average yield of saleable milk was 2.08 ± 0.23 l/day with a relative day-to-day variation of 18 -21%. The variation of saleable milk was 23 - 25% for fat, 12 - 14% for protein, 6% for lactose and 8% for somatic cell count. The variation in fat content was higher in strip milk (19 - 46%) than in saleable milk. The results indicated a larger variation in composition of milk from hand-milked Bos indicus Zebu than from machine‑milked Bos taurus cows. The most likely reasons for the difference in variation are the suckling by the calf and that hand-milking entails larger variation in the degree of emptying machine-milking does. Key words: Zebu, cow, milk, day-to-day variation, milk composition.

Effect of feeding systems on composition of goat milk and yield of Domiati cheese

BackgroundGoat milk is increasing valued for its superior nutritional profile, digestibility, and unique compositional properties. Protein acetylation, a pivotal post-translational modification, plays a critical role in the regulation of biosynthesis and metabolic processes. This study aims to identify key acetylated proteins and their modification sites governing milk production and the synthesis of milk components in dairy goats. Our findings establish a mechanistic foundation for elucidating molecular regulation of lactation and enhancing milk quality through targeted breeding strategies.ResultsThe acetylome profile of mammary gland tissues in dairy goats was successfully established. A total of 862 significantly acetylated proteins were identified across two lactation phases, and a total of 2,028 acetylation modified sites were identified in mammary gland tissues in dairy goats. Differentially acetylated proteins were predominantly localized in the cytoplasm (39.98%). From these, 54 key acetylated proteins, including MTOR, BCAT2, QARS1, GOT1, GOT2, BDH1, ACSS1, STAT5B, FABP5, and GPAM were identified as candidates potentially involved in milk protein synthesis, milk lipid synthesis, lactose synthesis, and other lactation-related biological processes in dairy goats.Among them, the acetylation modification of the β-hydroxybutyrate dehydrogenase 1 (BDH1) protein was characterized in dairy goats. The HDACs family was identified as primary regulators mediating the deacetylation of BDH1. Acetylation of BDH1 promoted the expression of LXRα, ACSL1 and SCD1genes, while its deacetylation induced the expression of SCD1, FASN and ACSL1 genes. BDH1 acetylation/deacetylation significantly reduced the expression of the SREBP1 gene. Furthermore, BDH1 acetylation promoted the formation of lipid droplets and the synthesis of triglycerides in mammary epithelial cells of dairy goats (GMECs).ConclusionsThis study established, for the first time, the comprehensive acetylome of mammary gland tissue in dairy goats, revealing a substantial number of differentially acetylated proteins and modification sites. We demonstrate that acetylation of BDH1—regulated by HDACs—promotes lipid droplet biogenesis and triglyceride synthesis in GMECs through transcriptional modulation of key lipogenic genes (LXRα, ACSL1, SCD1, FASN) and suppression of SREBP1. These findings provide novel mechanistic insights into the post-translational regulation of mammary lipid metabolism during lactation.

Dairy goat breeding is developing dynamically in the world and in Russia. To scientifically substantiate the breeding strategy of dairy goats, meat-dairy goats and dairy-meat ones, it is necessary to expand information about the composition of goat milk and the nature of correlations between its components. In the article, the composition of goat milk of dairy goats, meat-dairy goats and dairy-meat ones is considered in the comparative aspect. The correlation coefficients between the indicators studied by infrared spectroscopy and flow cytometry using automatic CombiFoss 7 DC analyzer are presented. It was found that milk of dairy-meat and meat-dairy goats significantly exceeded milk of dairy goats in terms of the mass fraction of fat, protein, levels of saturated and unsaturated fatty acids, lactose and urea. At the same time, the level of differential cells was significantly lower. The nature of the relationship between mass fraction of fat and other components of milk in goats with different severity of milk productivity was the same both in strength and in orientation. A high positive relationship (r = 0.65…0.99) was revealed between the mass fraction of fat and the content of fatty acids, both saturated (SFA, LCFA, MCFA) and unsaturated (MUFA, PUFA, SCFA). Differences in the nature of the relationship between the content of casein and lactose, casein and DSCC were established. For milk of dairy-meat and meat-dairy goats, it was low negative (r = –0.27 and –0.31), for milk of dairy goats – low positive (r = 0.29 and 0.28). Differences were also found between mass fraction of true protein and fatty acids, MDB and the level of somatic cells. Mass fraction of true protein in milk of dairy goats was weakly negatively correlated with LCFA, SCFA, KSK and DSCC (r = –0.16…–0.32), in milk of dairy-meat and meat-dairy goats this relationship was weakly positive (r = 0.14…0.26).

Baobab fruit (Adansonia digitata) is a nutritious but grossly underutilized food resource with great potentials for improving the productivity of milking goats in Nigeria. Twenty four Red Sokoto goats fed diets containing 0, 10, 20 and 30% baobab pulp and seed meal (BPSM) were used to evaluate the influence of baobab fruit on yield and composition of goat milk. The experimental design adopted was the completely randomized design. Animals were exercised daily inside a fenced paddock where they had access to forage. Dry matter (DM) intake, milk yield, feed conversion ratio (FCR) and milk composition in the goats were measured over a period of 84 days. There were significant (P<0.05) differences in intake, milk yield and FCR of the goats. DM intake increased from 21.5 to 27.5 % of live weight (LW) and milk yield from 333.8 to 441.9 g/day with inclusion of BPSM in the diet. FCR was 1.40, 1.30, 1.28 and 1.29 for 0, 10, 20 and 30% BPSM diets respectively. Milk composition was also significantly (P<0.05) influenced by level of baobab meal in the diet. Total solids in milk increased from 12.23 to 14.10 %; protein from 3.50 to 4.08 %; and fat from 3.38 to 4.45 % with BPSM in the diet. Addition of BPSM to the diet enhanced feed intake and milk production in Red Sokoto goats raised in the derived savanna of Nigeria.

Goat milk has gained global attention for its unique nutritional properties and potential health benefits. Advancements in functional genomic technologies have significantly progressed genetic research on milk composition traits in dairy goats. This review summarizes various research methodologies applied in this field. Genome-wide association studies (GWAS) have identified genomic regions associated with major milk components, with the diacylglycerol acyltransferase 1 (DGAT1) gene and casein gene cluster consistently linked to milk composition traits. Transcriptomics has revealed gene expression patterns in mammary tissue across lactation stages, while the role of non-coding RNAs (such as miRNAs and circRNAs) in regulating milk composition has been confirmed. Proteomic and metabolomic studies have not only helped us gain a more comprehensive understanding of goat milk composition characteristics but have also provided crucial support for the functional validation of genes related to milk components. The integration of multi-omics data has emerged as an effective strategy for elucidating complex regulatory networks from a systems biology perspective. Despite progress, challenges remain, including refining reference genomes, collecting large-scale phenotypic data, and conducting functional validations. Future research should focus on improving reference genomes, expanding study populations, investigating functional milk components, exploring epigenetic regulation and non-coding RNAs, and studying microbiome-host genome interactions. These efforts will inform more precise genomic and marker-assisted selection strategies, advancing genetic improvements in milk composition traits in dairy goats.