Nutritional quality of donkey milk during the lactation

Simple SummaryDonkey milk, because of its nutritional quality, is a more interesting product for the human diet. Moreover, due to its similarity to human milk, it is an optimal substitute for breast milk for babies. The aim of this study is to provide new insights on donkey milk production, which characterizes gross and mineral composition of Ragusano donkey breed milk. Compared to cow milk, donkey milk is characterized by a lower content of dry matter, high lactose amount, low protein, and a very low-fat content. In addition, the casein content is lower than cow’s milk. The most abundant macro element was K, followed by Ca, Na, and P. Most of the constituents are diminishing their content during lactation. In conclusion, the Ragusano breed showed a good aptitude for milk production. The composition of the milk confirmed its nutritional quality. Moreover, this research can have important positive impacts. The Ragusano breed has a long lactation and a high level of production that can ensure good income for farmers. Moreover, given its nutritional values, a larger consumption of donkey milk would be desirable and could promote the breeding of the donkey, which is an endangered species all over the world, as a profitable alternative for farmers.Donkey milk is increasingly being proposed as a natural alternative milk for various categories of consumers, especially infants and the elderly population. However, its potential production, gross, and mineral composition have not been deeply investigated yet. Sixty-two individual milk samples were collected monthly from nine Ragusano donkeys reared in a specialized dairy farm. Milk yield as well as chemical and mineral composition, including macro and micro elements, were investigated over an entire lactation, from the second to the ninth month of milking. Milk yield averaged 1.64 kg/day, which highlights good aptitude of the Ragusano breed for the production of milk. Gross composition was characterized by low content of dry matter (8.19%), a high amount of lactose (6.07%), low protein (1.34%), and very low-fat content (0.16%). Whey proteins represented 58% of the total protein, and proteose-peptones accounted for 0.35 ± 0.07 g per 100 g. Total ash content was 0.36 g per 100 g and represented 4.40% of the dry matter. The most abundant element was K, which was followed by Ca, Na, and P. As expected, the micro elements Fe, Zn, and Cu were found in low amounts or in traces. Dry matter, fat, whey proteins. The total ash, Ca, P, Mg, and mineral ratios were significantly affected by the lactation stage.

The content of alpha-lactalbumin and three species of caseins, 42K, 29K, and 25K, have been measured along with the levels and activities of their mRNAs in the rat mammary gland. Changes in these values were followed during gestation and lactation. An increment of 3- to 4-fold over the virgin level was observed for both alpha-lactalbumin and 42K casein during the 1st day of gestation. From this point on, the level of 42K remained unchanged during the 1st week of gestation and increased thereafter. After the increment of the 1st day, the alpha-lactalbumin content decreased rapidly during the 2nd day of gestation, continued to decrease more slowly until the 12th day, and then started to increase thereafter. During the 2nd and 3rd week of gestation. the amounts of alpha-lactalbumin within the gland increased continuously but not uniformly and caseins accumulated rapidly with a tendency to plateau around the 13th to 16th day of gestation. The relative proportions remained, respectively, 42K greater than 29K greater than 25K greater than alpha-lactalbumin until parturition. At the onset of lactation, both alpha-lactalbumin and casein content increased sharply, the relative proportion for caseins changed to 42K greater than 25K greater than 29K greater than alpha-lactalbumin and remained so throughout the lactation period. alpha-Lactalbumin and casein mRNA activity, as judged by the wheat germ translational system, remained unchanged during the 1st week of gestation, then showed a steady but not uniform increase from the 7th day of gestation until parturition. These activities increased sequentially during lactation, alpha-lactalbumin reaching a plateau by the 1st week, caseins between the 1st and 2nd week, and other mRNAs by the end of the 2nd week of lactation. By the 21st day of lactation, the activity of all mRNA had declined. The levels of alpha-lactalbumin mRNA and 16 S doublet casein mRNA sequences measured with the cDNA probes increased by about 8-fold for alpha-lactalbumin mRNA and 6-fold for casein mRNA during the 1st week of gestation. These levels declined slightly early in the 2nd week and then continued to increase until parturition with a shoulder in the levels around the 13th to 16th day. During lactation, these levels increased until the 8th to 12th day and from then on declined. The content of alpha-lactalbumin and caseins, as well as the measurement of sequences and activities of their mRNAs, showed that in the rat mammary gland these differentiated functions are already expressed at the onset of gestation. Both concentration and activity of mRNA are out of phase with protein levels during the 1st week of gestation but they remain in phase thereafter.

Variability in chemical composition of eggplants and sweet peppers

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.

This study focused on the effects of transglutaminase (TGase), exopolysaccharide (EPS)‐producing starter culture or skim milk powder addition on some properties of low‐fat set yoghurt. The incorporation of TGase to yoghurt did not affect the acidity of the experimental samples. However, the proteolytic activity of the starter culture significantly decreased in TGase‐treated yoghurt. Addition of TGase to yoghurt with a low dry matter content (11.08%) resulted in low serum separation and gel firmness and viscosity close to those of yoghurt with a higher dry matter content (14.81%). According to the sensory results, it would be possible to produce an acceptable product with a low dry matter and low fat content using TGase. The results shown that the use of EPS‐producing starter cultures for the purpose of improving the texture properties of low dry matter content yoghurt could not be recommended.

Se estudió el rendimiento y composición de la leche, y rendimiento de los cabritos de la cabra Roja Kalahari en la zona húmeda. Se recogieron datos de veintiséis (26) cabras Rojas de Kalahari durante un periodo de 119 días. La etapa de lactación fue una fuente significativa de variación para la extracción de leche (p

The efficacy of injecting primiparous cows of a dual purpose breed (Deutsches Fleckvieh) with a BST prolonged release formulation (500 mg Sometribove s.c.) was tested in a cross-over design. Seven cows were given 500 mg BST in the 10th through 19th week of lactation and a placebo in the 24th through 33rd week. A second group of seven cows received a placebo in the 10th through 19th week and BST in the 24th through 33rd week. Blood samples were taken from the jugular vein (via a permanent cannula) in the 13th, 17th, 23rd, 27th and 31st week of lactation over a period of 24 hrs at 30 min intervals. During the periods of BST treatment the amount of FCM (amount of milk corrected to 4% fat content) was higher in treated than in non-treated animals by 3.6 kg (19.8%) and 3.2 kg (22.5%) respectively. Milk fat levels were elevated significantly during both treatment periods. Milk protein concentration showed a significant rise during the second half of lactation only. There was no influence on lactose content. Blood concentration of somatotropin and IGF-I rose during treatment by a factor of 3-4. Insulin, T3, T4 and FTI as well as glucose, urea and GOT showed no changes or changes within physiological ranges. Free fatty acids and beta-hydroxybutyrate rose during treatment.

Proteins in donkey milk (DM) have special biological activities. However, the bioactive proteins and their expression regulation in donkey milk are still unclear. Thus, the differentially expressed proteins (DEPs) in DM in different lactation stages were first investigated by data-independent acquisition (DIA) proteomics. A total of 805 proteins were characterized in DM. The composition and content of milk proteins varied with the lactation stage. A total of 445 candidate DEPs related to biological processes and molecular functions were identified between mature milk and colostrum. The 219 down-regulated DEPs were mainly related to complement and coagulation cascades, staphylococcus aureus infection, systemic lupus erythematosus, prion diseases, AGE-RAGE signaling pathways in diabetic complications, and pertussis. The 226 up-regulated DEPs were mainly involved in metabolic pathways related to nutrient (fat, carbohydrate, nucleic acid, and vitamin) metabolism. Some other DEPs in milk from the lactation period of 30 to 180 days also had activities such as promoting cell proliferation, promoting antioxidant, immunoregulation, anti-inflammatory, and antibacterial effects, and enhancing skin moisture. DM can be used as a nutritional substitute for infants, as well as for cosmetic and medical purposes. Our results provide important insights for understanding the bioactive protein differences in DM in different lactation stages.

1. It was planned to study the variations of the protein content of milk during the lactation period.2. The total protein nitrogen and the casein nitrogen were determined by approved methods in about 380 weekly samples of milk taken from twentyseven individual cows of different breeds and at different stages of lactation, from February to July 1937. The albumin+globulin nitrogen was calculated in each case by difference.3. The statistical analysis of the figures was made by the methods of “factorial arrangement” and by “pairing”, and also by the estimation of the 95% probability range of the mean of the figures available for each week of lactation.4. It was found that the percentage of total protein nitrogen decreases very significantly from the beginning until the 4th week of lactation, and then rises slowly until the end of lactation, the rise being more pronounced to wards the end. The same was true for casein nitrogen and for albumin+globulin nitrogen, but with the latter only the decrease at the beginning and the rise at the end were sharp. The rise for the rest of the lactation curve, although it did exist, was very slow.5. The lactation curves for the yield of total protein nitrogen, casein nitrogen and albumin + globulin nitrogen were practically parallel with the lactation curve for the yield of milk.6. The correlations between the yield of milk and the percentages of total protein nitrogen, casein nitrogen and albumin + globulin nitrogen are studied and the correlation tables with all details are given for each. It is noteworthy that the regression lines are not linear and that with a poor milker an increase of 1 lb. in yield of milk corresponds to a relatively high decrease in the percentage of protein nitrogen, whereas with a high milker this decrease is relatively much smaller.7. The correlations between the yield of milk and the yield of total protein nitrogen, casein nitrogen and albumin + globulin nitrogen are examined and the correlation tables are given. It is shown that there is a close correlation between the yield of milk and its protein content, from which the conclusion is drawn that a very low protein food does not decrease the percentage of protein in milk as one might expect, but decreases the yield of milk and increases the percentage of protein in milk. On the other hand, an increase of adequate protein in the ration may raise the yield of milk if it is not at its maximum level.8. It is emphasized that the above conclusions are drawn from a study carried out on a group of cows, and may not be strictly applicable to individual cows.

Fat in human milk varies during a feed, during the day and throughout the period of lactation. Fatty acid (FA) composition varies over the course of the day and during lactation. Aim: To evaluate FA composition in human milk, from 7 days (transitional milk) to 16 weeks of lactation (mature milk) and to assess the composition stability of these FA throughout this period. Methods: Mothers living in urban area of Porto who accepted to participate in the study were selected according to inclusion criteria (healthy term newborn exclusively breast-feeding). Pooled human milk was collected from all feedings over 24 hours at the following times: 7 days and 4, 8, 12 and 16 weeks of lactation. FA were analysed through capillary gas chromatography. Comparisons were made (Oneway ANOVA). Correlations between FA were made through Pearson and Spearman correlation coefficient. Results: 31 mothers completed the follow-up period. Total saturated fatty acids (SFA) progressively increased from 40.50 ± 3.72 (% wt/wt) at 7th day up to 43.08 ± 4.61 at the 16th week of lactation, whereas total monounsaturated fatty acid decreased from 33.04 ± 2.58 (% wt/wt) to 31.48 ± 3.32, in the same period. Arachidonic acid (AA) markedly decreases with the stage of lactation. Docosahexaenoic acid (DHA) content decreases lightly from the 7th day to the 4th week of lactation, remaining stable throughout the rest of the lactation period. No significant correlation was found between the levels of linonleic and a-linolenic acid, and their long-chain metabolites AA and DHA. Conclusions: Despite fluctuations in the contents of AA and DHA, the ratio AA/DHA did not significantly change throughout the period of lactation. The ratio AA/DHA remained constant during the study, suggesting a protective mechanism, as AA and DHA are essential structural components of all tissues and particularly of retina and neuronal tissues.

On-line measure of donkey's milk properties by near infrared spectrometry

The effects of breed, stage of lactation, age and seasonality on the compositional quality of milk are discussed. The Jersey breed has the highest fat and protein contents, 51.9 and 38.5 g/kg milk, respectively, followed by the Guernsey breed, with 46.4 and 36.3 g/kg milk. The British Holstein has the lowest fat and protein contents, at 37.3 and 32.0 g/kg milk, respectively, whilst the Ayrshire is intermediate between the Channel Island and the Friesian and Holstein breeds. The range of fat within a breed may be over 20 g/kg milk. The variation in protein content is less than this value but may be over 10 g/kg milk. Lactose values vary less than those for fat and protein. Mean lactose values are 45.5 g/kg, with a range from 41.0 to 50.0 g/kg milk.The protein content of milk is high in early lactation, falls rapidly to reach a minimum at approximately 6 weeks after calving, increases slowly to 6 months after calving and then increases rapidly to the end of lactation. The fat content of milk is also high in early lactation and falls to a minimum between the 6th and 10th weeks of lactation. It then rises in a manner similar to protein. Converse changes occur with lactose: the content is low in colostrum and increases to twice its initial value within the 1st week. It remains steady until the 5th or 6th week of lactation, after which it declines slowly and then more rapidly towards the end of lactation.The fall in the fat content of milk from the 1st to the 5th lactation is progressive and of the order of 2 g/kg milk. Solids-not-fat content declines by approximately 4 g/kg. This fall in solids-not-fat is largely a fall in lactose; the change in protein content is small. In Friesian herds, a decrease in average lactose content from 46.9 to 44.7 g/kg milk from 1st to 3rd lactation and over has been observed.The average fat content of bulk milk in England and Wales is highest in October and November and lowest in May and June. The protein content of milk falls to a low level in March, rises rapidly during April and May and shows a slight fall in July, followed by an increase until October, when a progressive fall occurs during the winter months. The lactose content of milk does not vary as much as protein, with values being 0.5 g/kg higher in June and 0.8 g/kg lower in September than the overall average.

Twelve dairy cows in early lactation were offered low (L; 215 g/kg) or high (H; 449 g/kg) dry matter(DM) content silages, prepared using material from the same sward. In addition, all animals received 9 kg/day, of supplements based on barley (B), sugar-beet pulp (SB) or a 50: 50 mixture of the two (B: SB), in two equal portions at 07:30 and 14:30 h. The six treatments were offered in an incomplete Latin square design. Mean intakes of H (14·4 kg DM per day) were significantly higher than intakes observed for L (10·0 kg DM per day) (P &lt; 0·001). Within silage type, highest intakes were observed for cows receiving the SB supplement (P &lt; 0·01). Higher intakes of H were reflected in higher total milk yield (P &lt; 0·05) as well as fat (P &lt; 0·05) and protein (P &lt; 0·01) yield. Milk protein concentration was greater for animals receiving silage H (P &lt; 0·001), with lower values being observed for animals consuming SB (P &lt; 0·05), within silage type. Time spent eating, duration and number of meals were similar for either silage and the higher intakes of H silage reflected greater intake rates (g DM per min) (P &lt; 0·001) resulting in larger meal sizes (P &lt; 0·001). All chewing indices (time spent eating silage, ruminating and total time chewing per kg DM ingested) were greater for the L silage (P &lt; 0·001). It is concluded that the benefits in forage intake with higher DM grass silages, for high yielding dairy cows, are associated with consequential benefits in milk yield and milk protein content. The most likely explanation for the greater intakes is a faster particle breakdown in the rumen allowing larger meal sizes before animals became constrained. The higher intakes of silage when animals consumed the SB supplement may be due to a slower rate of fermentation of the supplement, which was more closely matched to that of silage. Although not significant there was a tendency for differences in silage intake between animals receiving B compared with SB supplements to be greater for animals receiving the H silage suggesting that supplementation strategies to ensure optimal forage utilization may differ for silages of differing DM content.

Effects of concentrate supplementation strategies during the transition period and milking frequency in early lactation on seasonal winter-calving organic dairy cows

Environmental factors drive changes in plant functional traits, which in turn promote community recovery. The environmental conditions of the community are different at different recovery stages. Changing environmental factors may drive the changes in plant functional traits at the community level and affect species adaptation. We studied plant communities in five different recovery stages (herb, grass and shrub, shrub, tree and shrub, and tree) in the karst plateau of Zhenning, Guizhou (The vegetation in the study area has undergone a gradual natural recovery process after the forests were deforested in 1958–1960). We studied functional traits and their links to environmental factors. The main results include the following. (1) Over time, plant height, leaf dry matter content, leaf nitrogen content and leaf phosphorus content increased significantly in the tree stage, while leaf thickness and specific leaf area decreased significantly in the tree stage. (2) Soil organic carbon, soil N content, soil P content, soil C:P and soil C:K showed an increasing trend, and were significantly higher in tree stage than in other stages. Soil potassium content fluctuated and soil bulk density decreased gradually, reaching the lowest value in the tree stage, but the difference was not significant. (3) During the restoration process, the functional characteristics changed from a combination of plant communities with high specific leaf area and low dry matter content with a short plant height to plant communities with low specific leaf area and high dry matter content with a tall plant height. (4) As recovery proceeded, the study area gradually changed from a soil nutrient‐poor environment to a nutrient‐rich environment. Overall, the environmental factors vary greatly during the recovery of plant communities in karst areas. The plant community shifts from an aggressive (resource acquisition) to a conservative (environmental barrenness resistance) ecological strategy. The soil phosphorus content and soil C:K are the main environmental factors affecting the changes in functional traits during the restoration of karst plant communities in Zhenning.