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Horns are living tissue and cows can use their horns for thermoregulatory purposes. We investigated the effect of the presence of horns on the metabolome of milk serum and lipidome of milk fat, to assess the physiological effect of dehorning. Milk sampling took place at low ambient temperatures of −6 to 2°C. Horned and dehorned cows were kept in a mixed herd of Holstein Friesian and Brown Swiss cows. The hypothesis was that horned cows needed to increase their metabolism to compensate for additional heat loss through the presence of their horns. No differences were observed in milk yield, milk solids, and somatic cell counts between horned and dehorned cows. For the milk metabolome, horned cows showed an upregulation of several glucogenic AA that could be transformed into glucose for energy supply and a downregulation of sugar intermediates and γ-glutamylcysteine compared with dehorned cows. The fatty acid (FA) composition in horned cows showed a shift toward decreased odd medium-chain FA (C7:0, C9:0, and C11:0) and increased cis-vaccenic acid (C18:1n-7 cis-11) and stearidonic acid (C18:4n-3). The changes in milk composition related to additional heat loss in horned cows indicate a competition in C3 metabolism for glucose synthesis and de novo FA synthesis under cold stress.

The objective of this study was to evaluate the effects of the character and the removal of natural organic matter (NOM) on the formation of assimilable organic carbon (AOC) and bromate during ozone disinfection. Natural waters from two locations with different dissolved organic carbon (DOC) concentrations were tested. In addition, the DOC concentration of one of the natural waters was reduced either by ion exchange (IEX) or by granular activated carbon (GAC) filtration. The resulting four water types were tested in conventional pilot-scale ozone bubble column reactors and in a bench-scale plug flow reactor with dissolved ozone dosing. For the tested waters NOM fractions were determined with size exclusion chromatography using DOC and UVA254 detection. As expected, it was observed that for the same ozone dosages the CT is higher when NOM is removed by IEX or GAC compared to the situation without NOM removal. It is concluded that, for the waters tested, removal of the humic compounds with a molecular weight of approximately 1,000 g/mol by using IEX led to less AOC formation and less bromate formation as compared to the removal of humic compounds with a molecular weight of 300–500 g/mol by using GAC.

Ozonation experiments (2.5–5 m 3 h −1 ) were performed by dosing dissolved ozone in a continuous flow pilot-scale contactor consisting of a pipe with plug flow reactor (PFR) characteristics. In the PFR ozone, E. coli , bromate and AOC concentrations were measured from 1.3 to 1,460 seconds retention time during ozonation of natural water. The experimental data were used to develop an integrated semi-empirical dynamic model describing the measured parameters for the initial phase ( t t >~20 seconds) of ozone decomposition. It was concluded that for the natural water tested E. coli inactivation was very fast, more than 4 log units after 5 seconds for ozone dosages higher than approximately 0.6 mg-O 3 l −1 . Further it was concluded that semi-empirical models are suited for modeling of ozone decomposition, disinfection, bromate and AOC formation in natural water.

The concentrations of dissolved ozone and assimilable organic carbon (AOC) are important performance parameters in drinking water production. For the measurement of ozone, a spectral algorithm was developed that allows quantification in situ using a UV/Vis spectrometer probe. Furthermore, a strong correlation between the change in the absorption spectrum after individual treatment steps and the formation or removal of AOC in that treatment step was observed. This allowed the development of a spectral algorithm that predicts AOC formation during ozonation and subsequent removal in further treatment steps. This method has been verified at one pilot plant of the Amsterdam drinking water supply.

Experimental research was carried out for calibration and validation of a model describing ozone decay and ozone exposure (CT), decrease in UV absorbance at 254 nm (UVA254), increase in assimilable organic carbon concentration and bromate formation. The model proved to be able to predict these parameters on the basis of the applied ozone dosage. The experimental ozone dosages ranged from 0.4 mg-O3/L to 0.9 mg-O3/L for natural water with a dissolved organic carbon concentration of 2.4 mg-C/L. The UVA254 was found to be an effective parameter for estimation of rapid ozone decay for natural water under experimental conditions tested. The experimental setup consisted of a bench-scale plug flow reactor (approximately 100 L/h) with dissolved ozone dosing.

Bromate formation experiments were carried out in a 100 l/h bench-scale dissolved ozone plug flow reactor (DOPFR) with natural filtered water from the drinking water treatment plant Leiduin of Amsterdam Water Supply at gross ozone dosages of 0.7–3.4 mg/l. In the DOPFR, ozone is dosed by intensively mixing a dissolved ozone water flow (side stream) with a test water flow (mainstream). The side stream is pre-treated to remove bromide and DOC and to lower the pH. For full-scale application of the DOPFR concept, it is most cost effective to apply the smallest possible side stream. This research is done to establish the effect of decreasing the ratio of the dissolved ozone side stream to the mainstream from 1:10 to 1:25, by increasing the ozone concentration and decreasing the flow of the side stream. The results show that the dosing ratio has no influence on the bromate formation in the ozone dosing range of 0.7–1.4 mg/l. The gross ozone dosages that are currently applied at the drinking water treatment plant Leiduin are 0.8–1.0 mg/l. This means that for application of dissolved ozone dosing at Leiduin the amount of ozone that can be dissolved in the side stream will be the limiting factor for the minimal flow of the dissolved ozone side stream.

International audience; The aim of this study was to predict the fatty acid (FA) composition of bulk milk using data describing farming practices collected via on-farm surveys. The FA composition of 1,248 bulk cow milk samples and the related farming practices were collected from 20 experiments led in 10 different European countries at 44 degrees N to 60 degrees N latitude and sea level to 2,000 m altitude. Farming practice-based FA predictions [coefficient of determination (R-2) >0.50] were good for C16:0, C17:0, saturated FA, polyunsaturated FA, and odd-chain FA, and very good (R-2 >= 0.60) for trans-11 C18:1, trans-10 + trans-11 C18:1, cis-9,trans-11 conjugated linoleic acid, total trans FA, C18:3n-3, n-6:n-3 ratio, and branched-chain FA. Fatty acids were predicted by cow diet composition and by the altitude at which milk was produced, whereas animal-related factors (i.e., lactation stage, breed, milk yield, and proportion of primiparous cows in the herd) were not significant in any of the models. Proportion of fresh herbage in the cow diet was the main predictor, with the highest effect in almost all FA models. However, models built solely on conserved forage-derived samples gave good predictions for odd-chain FA, branched-chain FA, trans-10 C18:1 and C18:3n-3 (R-2 >= 0.46, 0.54, 0.52, and 0.70, respectively). These prediction models could offer farmers a valuable tool to help improve the nutritional quality of the milk they produce.

Napier grass (Pennisetum purpureum (L.) Schumach.) was studied using a 5 x 3 factorial experiment arranged in a randomised complete block design with three replications. The treatments were five fertiliser applications (0kg ha-1 N, 46kg ha-1 N and 92kg ha-1 N, 1t ha-1 and 2t ha-1 cattle manure) and three plant heights at cutting (0.5m, 1m and 1.5m). The mean dry matter (DM) yield was 8.21t ha-1 per cut but increased when the plant height at cutting increased and when the level of N fertilisation increased (P