Plasminogen activation system in goat milk and its relation with composition and coagulation properties.

The activity of plasmin (PL), plasminogen (PG), and plasminogen activator (PA) and their correlation with goat milk components and milk clotting parameters were investigated. Seven late-lactating Saanen goats were used to provide milk samples that were analyzed for PL, PG, and PA activity (colorimetric assay) fat, protein, noncasein nitrogen, nonprotein nitrogen, casein content, and somatic cell count (SCC). Milk clotting parameters (rennet coagulating time = coagulation time; K20 = firming rate of curd; A30 = curd firmness) were measured with a formagraph. Average milk yield and composition were similar to those previously observed in other studies. Plasmin, PG, and PA activity, expressed as units/ml, were, respectively, 20.04 +/- 0.94, 3.21 +/- 0.04, and 1154 +/- 57.61. Plasminogen activity was surprisingly low compared with other species (bovine, ovine), but it was consistent with the high activity of PA. A negative significant correlation was observed between PL and milk casein content. The correlation coefficients between PL and casein/protein ratio and PA and casein/protein ratio were negative and significant. A positive significant correlation was observed between PL and rennet clotting time and PA and rennet clotting time. Also positive was the correlation between PL and K20 and PA and K20. The plasmin activity was negatively correlated with A30. High plasmin and plasminogen activator activity in goat milk appeared to be negatively related with coagulating properties in late lactation, most probably via degradation of casein due to plasmin activity

Hygienic characteristics and microbiological hazard identification in horse and donkey raw milk

Today the interest toward horse (Equus caballus) and donkey (Equus asinus) milk for human consumption is receiving a renewed attention because of its particular composition, hypoallergenicity, and nutraceutical properties. The realistic perspective of global use of this aliment in balanced diets, especially for infancy and geriatrics, poses the need for a more in depth knowledge on milk hygiene and on the health status of dairy animals, as a prerequisite of consumers' safety. The aim of this paper was to review the available literature on the health and hygiene parameters as well as on the potential microbiological hazards in horse and donkey milk and the risks related to their consumption. Both microbial contamination and somatic cell count are reasonably low in equine milk and also the presence of pathogens, like Escherichia coli O157, Salmonella spp., Campylobacter spp., Yersinia enterocolitica, Brucella spp., Mycobacterium spp., Bacillus cereus, Cronobacter sakazakii, Streptococcus equi subsp. zooepidemicus, Rhodococcus equi, Streptococcus dysgalactiae subsp. equisimilis, Clostridium difficile and Burkholderia mallei is low. However, in those regions of the world where the prevalence of Brucella spp. and Rhodococcus equi is high, the alimentary risks could increase. Similarly, in areas with higher incidence of immunocompromised people, the increased risks should be warned not only for pathogens but also for opportunistic microbiota

Thyroid hormones in donkey blood and milk: correlations with milk yield and environmental temperatures

Thyroid hormones (TH) are the primary endocrine stimulators of non-shivering thermogenesis and are known to stimulate lactation. Triiodothyronine (T3) is the bioactive form, mainly derived by deiodination of thyroxine (T4), and the free quote (unbound to plasma proteins) is immediately bioavailable. This study aimed to evaluate potential relationships among TH in the blood, triiodothyronine in the milk (T3M), milk yield and environmental temperature in March to July for 8 lactating donkeys. Milk yield and blood TH concentrations changed significantly over time, whereas T3M was rather stable among individuals and not affected by time of sampling. Free T3 was not correlated with free T4 or with total TH in the blood, but was weakly correlated with T3M. No relationship was found between blood TH and milk yield, which was negatively correlated with T3M, thus the absolute quantity of bioactive hormone in milk secretion is maintained. Milk yield was positively correlated with the free/total T3 and free T3/free T4 ratios and, thus, with the relative quote of the circulating bioactive hormone. Circulating T3/T4 ratios were negatively correlated with environmental temperature. It is concluded that environmental temperature, in the range of the present study (-2 to 35 °C), does not significantly entrain thyroid gland activity, which is affected more by other factors, such as inter-individual variations and physiological status (i.e., stage of lactation). However, increases in environmental temperature most likely induced decreases in deiodinase activity at the peripheral tissue level, as indicated by the decrease in the T3/T4 ratios in the blood

Cheese whey recycling in traditional dairy food chain: effects of vinegar from whey in dairy cow nutrition

Selected yeast (Kluyveromyces marxianus Y102 strain) and an acetic acid bacterium (Acetobacter aceti, DSM-G3508 strain) were used as inocula respectively in cheese whey for alcoholic and acetic fermentations. The experimental tests were carried out at both laboratory and pilot plant (20 L and 2000 L) levels. The data from the trials (working period 28 days) show increased ethanol production, increased acetic acid yield, and greater fermentation stability with biomass recycling (18.6 g L–1). Batch and fed-batch fermentation tests resulted in increased and standardized alcoholic fermentation, and allowed acetic acid recovery (average lactose consumption 56%, ethanol 6.7 g L–1 d–1 and acetic acid production 4.35 g L–1 d–1). The effects administration were then investigated on milk yield and composition, nutritional status of dairy cows and physical characteristics of total mixed ration (TMR). Twenty Holstein cows were divided into two groups; group C, receiving the traditional TMR, and group W, receiving the TMR plus 10 L wheynegar. The dietary treatment, lasted 35 days, did not affect milk yield and composition except for the urea content, significantly lowered in group W. The selection of coarse (<19 mm), medium (8-19 mm) and fine (<8 mm) dietary particles was not influenced by the wheynegar administration however a tendential lower selection against coarse particles was noted in W. The results highlight that microbial biotechnologies may significantly contribute to both the valorization of whey and the development of a stable nutrient recycling system as a ingredient in dairy cattle diet

Horse and donkey milk

Horse and donkey populations are widely distributed around the world and have been known as dairy species since ancient times. Nowadays, equid milk is carving a niche as an alternative food source for infants with cow milk allergy as well as for aged consumers, thanks to its unique components. Differences in milk components between dairy species describe the closer resemblance of equid milk to human milk even though the remarkably low fat content results in a low energy content of horse and donkey milk. Compared to cow milk, equid milk contains average higher concentrations of Fe but lower concentrations of Zn and Mn. Among the allergenic components, caseins occur in different proportions in milk from different species, i.e. αs1-casein has the highest percentage in cow milk while β-casein is the most represented in horse, goat and human milk. The horse casein micellar size is in average higher than human (64 nm) and cow milk (182 nm). Beta-lactoglobulin (absent in human milk) is the most represented whey protein in both equid (30%) and cow (50%) milk. Advances in knowledge of equid milk production for sensitive consumers are reviewed with regard to both nutrients and bioactive compounds, either endogenous or generated during the digestion process or fermentation. Besides biotechnological processes in koumiss and other fermented horse and donkey products, the primary production of milk from these monogastric species could be managed to differentiate the nutritional and functional values of the milk product for different categories of sensitive consumers