Donkey Feeding During Maintenance, Pregnancy, and Lactation: Effects on Body Weight, Milk Production, and Foal Growth

Plasma Hormone and Metabolomics Identifies Metabolic Pathways Associated with Growth Rate of Dezhou Donkeys

BACKGROUND

The growth traits of donkeys from the same farm under the same feeding conditions often vary.

METHODS

In this study, Plasma hormone level and LC-MS-based metabolomics was used to identify the metabolic pathways and the key metabolites associated with the growth rate of Dezhou donkeys.

RESULTS

The level of IGF-1 in the SG was significantly higher than that in the FG. The differentially abundant metabolites were related mainly to lipid metabolism, in which arachidonic acid metabolism, linoleic acid metabolism and steroid hormone biosynthesis played key roles. The main differentially abundant metabolites 2,3-dinor-8-iso-PGF2α, 11-DH-TXB2, 8(R)-HPETE, PGJ2, c9, t11-CLA, 12,13-DHOME, 9,10-DHOME, 9(10)-EpOME, 13-HPODE, DHEAS, testosterone, and corticosterone played important roles in metabolic homeostasis and affected the adaptation of donkeys to cold environments.

CONCLUSIONS

The present study revealed that the growth rate of donkeys is mainly influenced by their adaptation to the environment, providing a more in-depth study on the relationship between plasma metabolomics and growth rate in donkeys.

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.

The Milk Compositions and Blood Parameters of Lactating Dezhou Donkeys Changes With Lactation Stages

The aim of this study was to investigate the changes in milk compositions and blood parameters of Dezhou donkeys during the lactation. Milk and serum samples from six lactating Dezhou donkeys were collected at 1, 30, 60, 90, 120, 150 and 180 days of lactation. The results displayed that the milk yield during the lactation first increased and then gradually decreased, with the peak milk production period of 30-60 days after parturition. Compared with other lactation stages, milk fat, milk protein, milk solids and solids non-fat (SNF) were higher in early lactation (p < 0.05). Conversely, the milk of late lactation stage had a higher lactose content (p < 0.05); The mineral elements content in donkey milk decreased with the prolongation of lactation period (p < 0.05); The blood serum prolactin (PRL), insulin-like growth factor 1 (IGF-1), total protein (TP), albumin (ALB), glucose (GLU), total cholesterol (TG), triglyceride (TC), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), high density lipoprotein (HDL) and low density lipoprotein (LDL) were higher in early lactation stage (p < 0.05), similar to changes in milk compositions during lactation. The correlation analysis results showed that the milk yield was positively correlated with PRL, IGF-1 and ALP, and negatively correlated with ALB (p < 0.05); the milk composition, such as milk fat, protein, solids and SNF were positively correlated with blood GLU, LDH, TP, ALB, TC, TG, HDL and LDL (p < 0.05). The above results indicated that the lactation stage had significant effects on milk production, milk composition, blood biochemical indicators and hormone of lactating donkeys. This study investigated the changes of Dezhou donkeys' milk performance and blood parameters with lactation stages for the first time, which may contribute to the exploration of the nutritional value of donkey milk and provide theoretical support for the nutritional regulation and utilisation of donkey milk.

Is there sufficient evidence to support the health benefits of including donkey milk in the diet?

Donkey milk has attracted attention due to its distinctive nutritional composition and potential health advantages, particularly because of its whey protein content, which includes lysozyme, α-lactalbumin, lactoferrin, and β-lactoglobulin and vitamin C, among other components. These elements contribute to immunoregulatory, antimicrobial, antioxidant, and anti-inflammatory properties, positioning donkey milk as a possible therapeutic option. In addition, due to the low levels of caseins, the casein-to-whey protein ratio, and the β-lactoglobulin content in donkey milk, it presents an optimal alternative for infant formula for individuals with cow's milk allergies. Moreover, research into donkey milk's potential for cancer prevention, diabetes management, and as a treatment for various diseases is ongoing, thanks to its bioactive peptides and components. Nevertheless, challenges such as its low production yield and the not fully understood mechanisms behind its potential therapeutic role necessitate more thorough investigation. This review consolidates the existing knowledge on the therapeutic possibilities of donkey milk, emphasizing its importance for human health and the need for more detailed studies to confirm its health benefits.

Differences of the Plasma Total Lipid Fraction from Pre-Foaling to Post-Foaling Period in Donkeys

Simple Summary

An association between increased metabolic demands and reduced dry matter intake is observed from late gestation to early lactation in donkeys. Furthermore, little is known about the nutritional and energy requirements of this period in animals. Changes in energy metabolism make donkeys more susceptible to metabolic diseases such as hyperlipemia, which is characterized by the mobilization of fatty acids from adipose tissue. A better knowledge of this period could improve animal husbandry, well-being, and health. The aim of this study was to analyze the plasma total lipid fraction, to highlight metabolic changes from the pre-foaling to post-foaling periods, using the gas chromatography technique. Our findings reveal a greater risk of metabolic disease in late gestation to early lactation in donkeys.

Abstract

The period from late gestation to early lactation is characterized by changes in energy metabolism. The aim of the current study was to analyze the plasma total lipid fraction using gas chromatography (GC) analysis, in order to highlight metabolic changes from the pre-foaling to post-foaling periods. Eleven pluriparous dairy jennies (mean age of 11.88 ± 3.79 years) belonging to the Amiata donkey breed were enrolled. Blood sampling was performed at 15 days before foaling (T0), and 15 (T1), 30 (T2), 60 (T3), and 90 (T4) days after foaling, for biochemical and GC analysis. A total of 37 fatty acids were identified in plasma samples: 4 medium chain (MCFA), 24 long chain (LCFA), and 9 very-long chain (VLCFA) fatty acids. Among them, 20 fatty acids changed significantly, and two fatty acid showed a trend toward significance. Furthermore, the LCFA, saturated, unsaturated, monounsaturated, and polyunsaturated ω-3 fatty acids changed significantly during the study period. The main alterations were between T0 and the other time points and appeared to be related to lipid metabolism, cellular structure and function, and inflammatory and immune responses. Our findings reveal greater energy requirements at the end of gestation compared to early lactation in donkeys.

Effects of the Physiological Status and Diet on Blood Metabolic Parameters in Amiata Dairy Donkeys

Simple Summary

This study investigated the physiological responses of donkeys feeding two different diets during maintenance, pregnancy and lactation. To investigate how the metabolic state influences dairy production, we also assessed the relationships between the blood metabolic profile and milk quality. We found that pregnancy and the first months of lactation led to lower feed intake and increases in blood non-esterified fatty acids (NEFAs), which was linked to the difficulty that the jennies have in meeting the higher energy needs. The intake of the concentrate in the diet was associated with the increase in blood glucose, both during maintenance and lactation. Higher NEFA were related to lower de novo synthesized milk fatty acids, whereas higher plasma B-HBA were related to higher somatic cell count. This paper contributes to the knowledge of physiological responses of jennies during milk production phases and provides information for donkey milk producers.

Abstract

Body weight changes and blood metabolic parameters in jennies feeding two different diets and in three physiological statuses were investigated (maintenance vs. pregnancy; maintenance vs. lactation). The relationships between blood metabolic profile and milk quality were also evaluated. Fourteen jennies were allocated to two groups (1: pregnant/lactating; 2: non-pregnant, non–lactating). Pregnant jennies and maintenance jennies (during the first 10-week measurement period) fed a diet consisted of ad libitum grass hay (diet 1); lactating jennies and maintenance jennies (during the last 10-week measurement period) fed ad libitum grass hay plus 2 kg/head/day of concentrate (diet 2). Blood sampling was performed on the jennies of both groups; individual milk samples were also collected during the first 70 days in milk. Higher blood NEFA (p < 0.05) were found in pregnant compared to maintenance jennies (diet 1) (68 vs. 37 μmol/L). Lactating jennies showed higher (p < 0.01) average blood NEFA (268 vs. 26 μmol/L) and glucose (66 vs. 55 mg/dL) compared to the maintenance (diet 2). Blood glucose was positively correlated to milk fat (p < 0.05), while negative significant correlations between de novo milk fatty acids and NEFAs were observed. Positive correlations between plasma B-HBA and somatic cell count (p < 0.01) were also found.

Shift in Circulating Serum Protein Fraction (SPF) Levels of Pregnant Jennies and Nutritional Related Aspects at Early-, Mid- and Late Gestation

A viable tool for the monitoring of the systemic condition of the pregnant jenny may be the determination of serum protein fraction (SPF) levels, including metabolic profiling. Tissue development and composition of the growing fetus requires the mother to provide adequate nutrients to its body parts and organs. In this regard, body fluid distribution and strategic molecule transportation can be screened using SPF electropherograms and analysis of intermediate metabolites. The nutritional and health status of 12 jennies (age: 5-8 years; BW at the start: 135-138 kg; Body Condition Score, BCS [1 to 5 points] = 2.25-2.50; 4th month of gestation) were monitored throughout gestation (approximate gestation period 350-356 d). All animals were pasture-fed and were offered hay ad libitum. Individual blood samples were collected within the 4th, 7th, and 10th month following conception (ultrasound scanning). Serum biochemistry, in particular, the analysis of 6 fractions of serum proteins was carried out. The significant decrease in circulating albumin in jennies from mid- to late-gestation (p < 0.001) suggests a considerable role of dietary amino acids in the synthesis of protein for fetal tissue formation as well as body fluid distribution and blood pressure control of the jenny in those stages. Moreover, α1-globulin decreased significantly in late gestation (p < 0.047), corresponding to major organ development in the terminal fetus and supported by lipid transportation in the bloodstream of the jenny. Similarly, α2-globulin decreased in late gestation (p < 0.054) as haptoglobin, an important component for the transport of free circulating hemoglobin, is likely used for fetal synthesis. Mid-gestation, appears to be a crucial moment for adequate dietary nutrient supplementation in order to prevent homeostasis perturbation of jennies, as observed in this trial.

Cyathostomin fecal egg count and milk quality in dairy donkeys

This study was performed to assess the possible relationship between gastrointestinal strongylid infections and milk quantity and quality in donkeys used for milk production. Individual fecal and milk samples were collected from 16 multiparous lactating jennies of Amiatina breed at their 6th month of lactation. Statistical analysis was carried out between strongylid eggs per gram of faeces (EPG) and milk parameters. All animals were found to shed cyathostomin eggs, with EPG ranging from 150 to 1900. A higher milk production was observed in animals showing an EPG< 250, but this result was statistically not significant. Conversely, significant higher concentrations of milk urea and pH values, and lower concentrations of milk lactose, were observed in jennies with an EPG >1000. In conclusion, results from this study suggest that cyathostomin EPG values > 1000 may affect milk quality in dairy donkeys. Considering the novelty of these findings, more data needs to be collected to determine EPG thresholds to be used as a good marker for parasite infections influencing milk performance and quality in donkeys.

A preliminary investigation into the unsaponifiable fraction of donkey milk: Sterols of animal origin, phytosterols, and tocopherols

We investigated the main sterols, phytosterols, and the α- and γ-tocopherol content in donkey milk during the first 2 mo of lactation. Cholesterol was the main sterol in milk (mean ± standard deviation = 0.97 ± 0.443 g/100 g of fat). Lanosterol was the main minor sterol of animal origin, followed by desmosterol (0.003 ± 0.001 and 0.001 ± 0.001 g/100 g of fat, respectively). Of the phytosterols, β-sitosterol was the main sterol of vegetal origin in donkey milk (0.005 ± 0.002 g/100 g of fat), but lower levels of campesterol, brassicasterol, and stigmasterol were also recorded. Mean levels of α- and γ-tocopherol were 0.01 ± 0.007 and 0.003 ± 0.001 g/100 g of fat, respectively. We observed no significant changes in sterol or tocopherol content during the first 2 mo of lactation. The presence of lanosterol in donkey milk is of particular interest, because lanosterol is a potential drug and has important physiological effects. The presence of phytosterols, which are considered nutraceutical molecules, enhances the nutritional quality of donkey milk fat for consumers.