Distribution of calcium, phosphorus, sulfur, magnesium, potassium, and sodium in major fractions of donkey milk

Application of generalized additive models to explore minerals in sheep milk

This study explores the complex relationships among ovine milk minerals (Ca, P, Na, K, Mg, K, Cl, respectively) and different factors employing generalized additive mixed models (GAMM). The GAMM included milk yield (MY), parity, and breed as parametric terms, and casein, fat, lactose, pH, SCS, DIM, and sampling day as smooth functions. The objectives were to investigate how these factors could affect minerals in sheep milk and to assess whether their patterns change over time and across different concentrations of major milk components. The GAMM identified distinct patterns in the mineral concentrations between Comisana and Massese breeds, with the Massese ewes having less P, Mg, K, and Cl compared with the Comisana. Moreover, these minerals were also affected by DIM; Mg, S, and Cl were influenced by parity; and P, K, and Na changed across MY levels. Regarding milk components, all the minerals were affected by casein, fat, and lactose concentrations (excluding P for fat). Milk pH was important for Ca, K, Na, and Cl, whereas SCS affected the variability of all minerals except Ca. This study provided valuable insights on the variability of macro-minerals in sheep milk, by using GAMM and examining the trajectory of each element across factors as breed, MY, parity, and DIM, as well as across various concentrations of major milk components and their interactions. The dynamic nature of milk mineral content was evident through temporal variability, likely driven by dietary changes, environmental fluctuations, and physiological adaptations, as well as synergistic and antagonistic interactions between milk components and fixed factors. These findings enhance understanding of mineral composition in sheep milk, providing a comprehensive framework for future research on milk quality, animal health, and cheesemaking properties.

Milk Yield, Major Milk Components and Macro Minerals in Blood Serum of Lactating Donkeys, as Affected by Dietary Trace Element Supplementation and Stage of Lactation

The aim of this experiment was to test the effects of both dietary trace element supplementation and the stage of lactation on the milk yield per milking and the major milk components, as well as the blood concentrations of total Ca, P, Mg, Na, and K in lactating donkeys. Over a 3-month period, 16 clinically healthy lactating donkeys were used to collect milk and blood samples and to evaluate the milk yield per milking. The experimental subjects were randomly divided into two homogeneous groups, control (CTL) and trace element (TE). The donkeys in the TE group were fed a diet supplemented with Zn, Fe, Cu, Mn, Se, Co, and I. The dietary treatment did not significantly affect neither the milk yield per milking nor the milk macro ingredients. However, these variables were significantly affected by the stage of lactation. The serum concentrations of total Ca, P, Na, and K were not affected by the dietary treatment, but the serum Mg level in the TE group was significantly higher than that in the CTL group (26.6 vs. 25.0 mg/L). The effect of stage of lactation was found to be significant for all the investigated minerals in the blood serum, and negative trends were observed for serum Ca, P, Mg, Na, and K during the experimental period.

Unveiling Genetic Markers for Milk Yield in Xinjiang Donkeys: A Genome-Wide Association Study and Kompetitive Allele-Specific PCR-Based Approach

Lactation traits are critical economic attributes in domestic animals. This study investigates genetic markers and functional genes associated with lactation traits in Xinjiang donkeys. We analyzed 112 Xinjiang donkeys using 10× whole genome re-sequencing to obtain genome-wide single nucleotide polymorphisms (SNPs). Genome-wide association analyses were conducted using PLINK 2.0 and GEMMA 0.98.5 software, employing mixed linear models to assess several lactation traits: average monthly milk yield (AY), fat percentage (FP), protein percentage (PP), and lactose percentage (LP). A total of 236 SNPs were significantly associated with one or more milk production traits (p < 0.000001). While the two-software identified distinct SNP associations, they consistently detected the same 11, 95, 5, and 103 SNPs for AY, FP, PP, and LP, respectively. Several of these SNPs are located within potential candidate genes, including glycosylphosphatidylinositol anchored high density lipoprotein binding protein 1 (GPIHBP1), FLII actin remodeling protein (FLII), mitochondrial topoisomerase 1 (TOP1MT), thirty-eight-negative kinase 1 (TNK1), polo like kinase 1 (PLK1), notch homolog 1 (NOTCH1), developmentally regulated GTP-binding protein 2 (DRG2), mitochondrial elongation factor 2 (MIEF2), glutamine-fructose-6-phosphate transaminase 2 (GFPT2), and dual-specificity tyrosine phosphorylation-regulated kinase 2 (DYRK2). Additionally, we validated the polymorphism of 16 SNPs (10 genes) using Kompetitive Allele Specific PCR, revealing that TOP1MT_g.9133371T > C, GPIHBP1_g.38365122C > T, DRG2_g.4912631C > A, FLII_g.5046888C > T, and PLK1_g.23585377T > C were significantly correlated with average daily milk yield and total milk yield in the studied donkeys. This study represents the first genome-wide association analysis of markers and milk components in Xinjiang donkeys, offering valuable insights into the genetic mechanisms underlying milk production traits. Further research with larger sample sizes is essential to confirm these findings and identify potential causal genetic variants.

Effects of Methionine on Milk Performance and Milk Constituents of Lactating Donkeys

This study investigated the effects of adding methionine (Met) in milk production and the milk and blood metabolites of lactating donkeys. Eighteen healthy multiparous donkeys in early-stage lactation were selected for this study. The donkeys were randomly divided into three groups and fed diets with different levels of Met: control group (C, Met 0 g/d), Met group I (M1, Met 5 g/d), and Met group II (M2, Met 15 g/d). The total duration of the experiment was 5 weeks. Donkey milk and blood samples were collected at the end of the experiment. The milk yield and composition, milk, and serum metabolites were analyzed. The results showed that the addition of 5 g of Met significantly increased milk yield as well as the milk composition contents of protein, fat, lactoferrin, polyunsaturated fatty acid (PFA), solids, and solids-not-fat (SNF) (p < 0.05). Significant differences in metabolites were detected among the different samples of milk (p < 0.05). The addition of Met increased the levels of milk metabolites, such as myristic acid, d-glutamine, l-aspartic acid, and LPS 16:0. A total of 753 metabolites were detected in the serum, including 17 differential metabolites between C and M1 and 48 differential metabolites between C and M2. The levels of serum metabolites, such as l-ascorbate, inositol, and l-lysine, were up-regulated by the addition of Met (p < 0.05). The above results indicated that Met increased donkey milk production and milk composition yield and improved milk metabolites by regulating serum metabolites. These results provide a foundation for improving the nutritional needs of lactating donkeys and the nutritional regulation of donkey milk synthesis.

Effect of Dietary Energy Level during Late Gestation on Mineral Contents in Colostrum, Milk, and Plasma of Lactating Jennies

This study investigated the effects of dietary energy levels during late gestation on mineral content in the plasma, colostrum, and milk of jennies postpartum. Twenty-four pregnant multiparous DeZhou jennies, aged 6.0  ±  0.1 years, with a body weight of 292  ±  33 kg, an average parity number of 2.7  ±  0.1, and similar expected dates of confinement (74  ±  4 days), were randomly allocated to three groups and fed three diets: high energy (12.54 MJ/kg, HE), medium energy (12.03 MJ/kg, ME), and low energy (11.39 MJ/kg, LE). Blood samples were collected from the jugular vein of each jenny at time points of 0 h, 24 h, 48 h, 5 d, 7 d, and 14 d after parturition. Additionally, milk samples were collected through manual milking, and an analysis of the mineral content was conducted. The results showed that compared with HE, both ME and LE significantly increased the levels of calcium (Ca), phosphorus (P), zinc (Zn), selenium (Se), molybdenum (Mo), and cobalt (Co) in the plasma and Ca, P, magnesium (Mg), copper (Cu), manganese (Mn), Zn, selenium (Se), molybdenum (Mo), and Co in the milk of jennies postpartum (p < 0.05); ME also increased the levels of potassium (K), iron (Fe), and Mn in plasma and K and Fe in milk (p < 0.05). The levels of Ca, K, Mg, P, Fe, Cu, Mn, Co, Se, Zn, and Mo in plasma and milk gradually decreased with increasing postpartum time. Their contents were the highest at 0 h postpartum, rapidly decreased after 24 h postpartum, and declined to the lowest on day 14 postpartum. The interaction between dietary energy level and postpartum time showed that although the concentrations of the minerals Ca, P, K, Mg, Fe, Cu, Mn, Zn, Co, Se, and Mo decreased in jennies' plasma and milk in the treatment groups with different energy levels as postpartum time increased, the pattern of change was also influenced by dietary energy level. The influence of dietary energy level in late gestation on the mineral content of milk and plasma during the postpartum colostrum phase was higher than that during the milk phase. In conclusion, this study demonstrated that, under the current experimental conditions, the mineral content of the colostrum, milk, and plasma of jennies after parturition was dependent on the dietary energy level during late gestation.

Effect of lactation on the distribution of mineral elements in goat milk

The distribution of mineral elements in milk is crucial for their absorption and utilization, however, there has been limited attention given to the status of mineral elements in goat milk. In this study, goat milk was collected at 4 lactation periods (1-3, 90, 150, 240 d) and separated into 4 fractions (fat, casein, whey, and aqueous phase). The concentrations of Mg, Ca, Na, K, Zn, Fe, Cu, Mn, Co, Ni, Mo, and Cr in 4 fractions were analyzed using an inductively coupled plasma emission spectrometer. Our findings reveal that Ca, Zn, Fe, Cu, Mn, and Cr exhibit the highest levels in casein, while Mo demonstrates the highest content in whey. Additionally, Mg, Na, K, and Ni display the highest concentrations in the aqueous phase. Specifically, the contents of Ca, Cu and Fe in casein decrease from 1-3 to 150 d of lactation but increase from 150 to 240 d of lactation. Furthermore, the content of Mg in the aqueous phase decreases from 1-3 to 90 d of lactation but increases from 90 to 240 d of lactation. The content of Na and K in the aqueous phase decreases from 1-3 to 150 d of lactation. Notably, the content of Mo in whey increases from 1-3 to 150 d of lactation and decreases from 150 to 240 d. Our research contributes to the advancement of understanding the bioavailability of mineral elements in goat milk.

Microbial Quality of Donkey Milk during Lactation Stages

The microbial community in donkey milk and its impact on the nutritional value of donkey milk are still unclear. We evaluated the effects of different lactation stages on the composition and function of donkey milk microbiota. The milk samples were collected at 1, 30, 60, 90, 120, 150, and 180 days post-delivery. The result showed that the microbial composition and functions in donkey milk were significantly affected by different lactation stages. The dominant bacterial phyla in donkey milk are Proteobacteria (60%) and Firmicutes (22%). Ralstonia (39%), Pseudomonas (4%), and Acinetobacter (2%) were the predominant bacterial genera detected in all milk samples. In the mature milk, the abundance of lactic acid bacteria Streptococcus (7%) was higher. Chloroplast (5%) and Rothia (3%) were more plentiful in milk samples from middle and later lactation stages (90-180 d). Furthermore, the pathogens Escherichia-Shigella and Staphylococcus and thermoduric bacteria Corynebacterium, Arthrobacter, and Microbacterium were also detected. Donkey milk is rich in beneficial bacteria and also poses a potential health risk. The above findings have improved our understanding of the composition and function changes of donkey milk microbiota, which is beneficial for the rational utilization of donkey milk.

Distribution of Calcium, Phosphorus and Magnesium in Yak (Bos grunniens) Milk from the Qinghai Plateau in China

This research was aimed to assess the distribution of calcium, phosphorus and magnesium within the casein micelles of yak milk. To this aim, nine bulk yak milk samples (Y-milk), collected in three yak farms located in the Chinese province of Qinghai, were compared to nine bulk cow milk samples used as a reference. A quite similar content of colloidal calcium (0.80 vs. 0.77 mmol/g of casein; p > 0.05), a higher content of magnesium (0.05 vs. 0.04 mmol/g of casein; p ≤ 0.01) and a lower content of colloidal phosphorus (0.48 vs. 0.56 mmol/g of casein; p ≤ 0.01) between yak and cow casein micelles were found. Moreover, the yak casein micelles showed a lower value of prosthetic phosphorus (0.20 vs. 0.26 mmol/g of casein; p ≤ 0.05) compared to the cow micelles. The lower values of colloidal and prosthetic phosphorus in yak casein micelles suggest that the yak casein is less phosphorylated than the cow one.

Milk from Halari Donkey Breed: Nutritional Analysis, Vitamins, Minerals, and Amino Acids Profiling

This current research set out to characterize Halari donkey milk by investigating its nutritional constituents, including its proximate analysis, water activity, titratable acidity, energy, and microbiological analysis. A comprehensive profiling of vitamins, minerals, and amino acids was also carried out. It was found that the composition of Halari donkey milk was consistent with previously published donkey milk literature and was comparable to that of human milk. Halari donkey milk has low 0.86 ± 0.04% fat content, 2.03 ± 0.03% protein content, 0.51 ± 0.05% ash content, and high 5.75 ± 0.15% lactose content making it sweet and palatable. The energy content of Halari donkey milk was 40.39 ± 0.31 kcal/100 g, and the water activity ranged from 0.973 to 0.975. Titratable acidity was 0.03 ± 0.01%. Halari donkey milk can be considered acceptable and microbiologically safe, having low total plate count and yeast and mould counts. Mineral testing revealed that Halari donkey milk included significant amounts of magnesium, sodium, calcium, potassium, phosphorus, and zinc. The concentration of different vitamins and amino acids such as isoleucine and valine also contribute to the nutritional value of Halari donkey milk.

Macro Minerals and Trace Elements in Milk of Dairy Buffaloes and Cows Reared in Mediterranean Areas

Aim of this study was to evaluate the differences in Ca, P, K, Na, Mg, Zn, Fe, Cu, Mn, Se, Mo, Co, Li, B, Ti, Rb, and Sr concentrations in milk from buffaloes and cows reared in the same farm in Mediterranean areas and fed diets including the same ingredients. Individual milk samples were obtained from 32 Mediterranean buffaloes and 29 Italian Friesian cows and samples of milk, dietary ingredients and drinking water were analyzed for the investigated chemical elements by inductively coupled plasma-mass spectrometry. Data about milk element concentrations were processed by one-way analysis of variance. Buffalo milk contains higher concentrations of Ca, P, Mg, Zn, Fe, Cu, B, Ti, and Sr, and lower concentrations of K, Na, Mo, Li, and Rb compared to cow milk, whereas milk from both species contains similar concentrations of Mn, Se, and Co. The concentrations of the investigated elements in the diet were similar for both species and the differences observed between buffalo and cow milk were not dependent on environmental factors.

Distribution of selected trace elements in the major fractions of donkey milk

The aim of this study was to evaluate the concentrations of Zn, Cu, Mn, Se, Mo, Co, Li, B, Ti, Cr, Rb, Sr, Cd, and Pb in donkey milk and their distribution in major milk fractions (i.e., fat, casein, whey proteins, and aqueous phase). Individual milk samples were provided by 16 clinically healthy lactating donkeys. Subsequent centrifugation, ultracentrifugation, and ultrafiltration were carried out to remove fat, casein, and whey proteins to obtain skim milk, a supernatant whey fraction, and the aqueous phase of milk, respectively. Concentrations of the elements were measured in whole milk and fractions by inductively coupled plasma-mass spectrometry, and the concentrations associated with fat, casein, and whey proteins were then calculated. The effect of removal of fat, casein, and whey proteins was determined by repeated-measures ANOVA. The fat fraction of donkey milk carried a small (∼4.5% to 13.5%) but significant proportion of Mo, Co, Ti, Cr, and Sr. The casein fraction in donkey milk carried almost all milk Zn, a majority of Cu and Mn, and most of Mo, Ti, and Sr. Relevant proportions, between 20% and 36%, of Se, Co, and Cr were also associated with caseins. The majority of Se, Co, Li, B, Cr, and Rb, and relevant proportions of Mn, Mo, Ti, and Sr were found in soluble form (ultracentrifuged samples) and distributed between whey proteins and the aqueous phase of milk (ultrafiltered samples). Whey proteins in donkey milk carried the majority of milk Se and Co. All Li and B was present in the aqueous phase of milk, which also contained most Rb and Cr, and 17% to 42% of Mn, Se, Mo, Co, Ti, and Sr.