Characterization of milk fatty acids based on genetic and herd parameters

The objective of this study was to characterize the fatty acids (FA) in milk based on genetic and herd parameters to investigate the origin of the different FA in milk. Milk samples of 1912 Dutch Holstein-Friesian cows were analysed for 39 different FA including odd and branched-chain fatty acids. The proportion of variation caused by genetic and herd effects was calculated. In addition, genetic and herd correlations among the fatty acids were estimated and a clustering technique was used to visualise these correlations. The results indicated that in Dutch milk C12:0 is not completely synthesised de novo but also partly blood derived. It was suggested that C20:0 in milk is formed from the action of elongase enzymes on C18:0 and that the odd-chain FA C5:0-C13:0 and a part of C15:0 and C17:0 are synthesised de novo while the other part of C15:0 and C17:0 is blood derived. Furthermore, this work gives an overview of the opportunities to change the concentration of individual FA both by breeding and feeding. It is clearly shown that the extent to which the individual FA can be changed varies greatly and is dependent on the origin of the different FA in milk

Calcium-binding capacity of organic and inorganic ortho- and polyphosphates

The aim of this research was to determine the calcium-binding capacity of inorganic and organic ortho- and polyphosphates. This calcium-binding capacity can be used to influence the stability of, for example, casein micelles in dairy systems. Four phosphates were selected: disodium uridine monophosphate (Na2UMP, organic orthophosphate), disodium hydrogen phosphate (Na2HPO4, inorganic orthophosphate), sodium phytate (SP, organic polyphosphate), and sodium hexametaphosphate (SHMP, inorganic polyphosphate). Concentrations of up to 100 mmolL-1 phosphate were added to a 50 mmolL-1 CaCl2 solution. The samples were prepared at pH 8.0 and were analyzed before and after sterilization for calcium-ion activity, conductivity, pH, sediment, and turbidity. Both SHMP and SP are strong chelators, as calcium ions bind to these phosphates in the ratio of 3:1 and 6:1, respectively. Calcium ions also strongly bind to Na2HPO4, but in a ratio of 3:2 with insoluble Ca3(PO4)2 complexes as result. The equilibrium position of Na2UMP is not strong towards the chelated complex, and significant levels of free calcium and free phosphate can exist. An equilibrium constant of Lmol-1 was determined for calcium uridine monophosphate (CaUMP) complexes. Both calculation of the equilibrium constant and analysis on the CaUMP precipitate confirmed a reactivity of 1:1 between calcium and Na2UMP. The CaUMP complexes are well soluble at ambient temperature, and insoluble complexes appear after sterilization, because the solubility of CaUMP decreases during heating. Finally, we concluded that the structure of phosphate molecules determines their calcium-binding capacity rather than organic or inorganic origin of phosphate

Het gaat bij melk om het samenspel tussen de vele nutrienten

Regelmatig wordt Toon van Hooijdonk er mee geconfronteerd dat mensen weinig meer weten van melk dan alleen dat er calcium in zit. Dat er zoveel meer nutriënten aanwezig zijn in melk is spaarzaam bekend. 'Juist de samenhang tussen al die nutriënten is belangrijk', zegt de hoogleraar Zuivelkunde

Dairy in a sustainable diet: a question of balance

The demand for dairy products is growing rapidly, especially in emerging markets. Dairy products are nutrient rich and, therefore, an important food group for ensuring nutrient security in the future. In many countries, dairy contributes significantly to nutrient intake. Meta-analyses have shown that consumption of dairy may reduce the risk of chronic diseases and thereby lower healthcare costs. Milk production and processing contribute to greenhouse gas emissions, estimated at 2.7% (cradle-to-retail) of the world’s total. Evaluating the position of dairy in the diet should take into account the impact of both nutritional and environmental factors. Local conditions are also important; in many parts of the world, the cow is an efficient converter of human-inedible resources into nutrient-dense food. Increased productivity of cows is a decisive factor in realizing sufficient milk production with optimal resource efficiency and minimal greenhouse gas emission. Models that optimize total diets, rather than individual food products, for their nutritional and environmental impact are the preferred approach for developing realistic alternative consumption strategies

Hoe efficiënt is de energie- en eiwitconversie door melkvee?

Melk speelt wereldwijd een belangrijke rol bij het voorzien in de nutriëntenbehoeften van de mens. De koe zet voor mensen niet-eetbaar eiwit uit voer om in eiwit van hoge kwaliteit. Steeds vaker rijst de vraag of deze eiwitconversie voldoende toegevoegde waarde heeft en hoe dit zich verhoudt tot de milieudruk van de zuivelproductie. Professor Toon van Hooijdonk van Wageningen Universiteit ontwikkelt samen met collega's een model om dit inzichtelijk te maken

Hoe efficiënt is de energie- en eiwitconversie door melkvee?

Melk speelt wereldwijd een belangrijke rol bij het voorzien in de nutriëntenbehoeften van de mens. De koe zet voor mensen niet-eetbaar eiwit uit voer om in eiwit van hoge kwaliteit. Steeds vaker rijst de vraag of deze eiwitconversie voldoende toegevoegde waarde heeft en hoe dit zich verhoudt tot de milieudruk van de zuivelproductie. Professor Toon van Hooijdonk van Wageningen Universiteit ontwikkelt samen met collega's een model om dit inzichtelijk te maken