Réduire les fuites de nitrate au moyen de cultures intermédiaires : conséquences sur les bilans d'eau et d'azote, autres services écosystémiques

La présence de nitrate en excès dans les eaux de surface et les nappes phréatiques pose des problèmes de santé publique et de dégradation de l’environnement. C’est d’abord un enjeu de santé publique notamment pour les nappes phréatiques, avec la nécessité de distribuer une eau de boisson présentant une teneur inférieure à la norme de potabilité qui est de 50 mg de nitrate par litre. C’est aussi un enjeu de protection de l’environnement pour les eaux de surface, en particulier pour certains bassins versants proches de la mer, comme en Bretagne ; le transfert rapide du nitrate des zones agricoles vers la mer induit une eutrophisation des zones côtières

Conversion of t11t13 CLA into c9t11 CLA in Caco-2 Cells and Inhibition by Sterculic Oil

Background : Conjugated linoleic acids (CLA), and principally c9t11 CLA, are suspected to have numerous preventive properties regarding non-infectious pathologies such as inflammatory diseases, atherosclerosis and several types of cancer. C9t11 CLA is produced in the rumen during biohydrogenation of linoleic acid, but can also be synthesized in mammalian tissues from trans-vaccenic acid (C18:1 t11) through the action of delta-9 desaturase (D9D). For several years, it is also known that c9t11 CLA can be synthesized from conjugated linolenic acids (CLnA), i.e. c9t11c13 CLnA and c9t11t13 CLnA. This study aimed at investigating to which extent and by which route c9t11 CLA can be produced from another isomer of CLA, the t11t13 CLA that is structurally very similar to c9t11t13 CLnA, in Caco-2 cells

Performance comparison of UV and FT-Raman spectroscopy in the determination of conjugated linoleic acids in cow milk fat.

The determination of conjugated linoleic acids (CLA) in cow milk fat was studied by using UV (210-250 nm) and Fourier transform (FT)-Raman (900-3400 cm (-1)) spectroscopy in order to determine the best spectrophotometric technique for routine analysis of milk fat. A collection of 57 milk fat samples was randomly divided into two sets, a calibration set and a validation set, representing two-thirds and one-third of the samples, respectively. All calculations were performed on the calibration set and then applied to the validation set. The CLA content ranged from 0.56 to 4.70%. A comparison of various spectral pretreatments and different multivariate calibration techniques, such as partial least-squares (PLS) and multiple linear regression (MLR), was done. This paper shows that UV spectroscopy is as reliable as FT-Raman spectroscopy to monitor CLA in cow milk fat. The best calibration for FT-Raman was given by a PLS model of seven factors with a standard error of prediction (SEP) of 0.246. For UV spectroscopy, PLS models were also better than MLR models. The most robust PLS model was constructed with only one factor and with SEP=0.288

In vitro effects of hop pellets and oak extracts in combination on ruminal fermentation parameters

Description of the subject. Hop and oak extracts have been found to possess anti-methanogenic and protein-sparing effects in the rumen. Objectives and method. An in vitro incubation with ruminal fluid was conducted to study the effects of increasing inclusions of hop pellets and oak extracts, alone or in combination, on ruminal fermentation parameters. Results. The combination of hop pellets and oak extracts reduced total volatile fatty acid (VFA) production compared with the control (no additive), whereas these additives alone had no effect. The acetate/propionate ratio decreased with the combination of hop pellets and oak extracts, as compared to the control, whereas these additives alone had no effect. Hop pellets at the highest dose alone or in combination with oak extracts reduced the methane (CH4) production, as compared to the control. The CH4/VFA molar ratio was lower than the control for hop pellets at the highest dose combined with oak extracts, whereas the additives used alone had no effect. Ammonia N concentration was reduced by oak extracts treatments at the highest dose alone or in combination with hop pellets, as compared to the control. Conclusions. Hop pellets and oak extracts altered in vitro rumen fermentation with some responses being non-linear when used in combination. © 2018, FAC UNIV SCIENCES AGRONOMIQUES GEMBLOUX. All rights reserved

Vitamin E status and the dynamics of its transfer between mother and pup during lactation in grey seals (Halichoerus grypus)

Concentrations of vitamin E, a powerful antioxidant, were measured in milk and serum of 18 grey seal (Halichoerus grypus) mothers and in the serum of their pups sampled up to 6 times between parturition and weaning on the Isle of May, Scotland, in 1998 and 2000. The vitamin E concentration in colostrum (89.4 +/- 22.5 mg/kg milk; mean +/- SD) was 4.5 times greater than that in later milk (20.9 +/- 5.0 mg/kg milk). It then remained constant until the end of lactation. The decline in concentration of vitamin E in grey seal milk corresponded to a drop in the vitamin E concentration in mothers' serum between parturition (14.0 +/- 4.8 mg/L serum) and the second half of the lactation period during which the serum vitamin E concentration remained stable (9.6 +/- 3.2 mg/L serum). Circulating vitamin E concentrations varied significantly among mothers but there was no relationship with mother's age. Despite these differences between mothers, individuals produced milk with very similar vitamin E concentrations. The vitamin E concentration in grey seal pups' serum was low at birth (lowest concentration 3.1 mg/L serum) but increased sharply to a peak around days 1-3 (31.2 +/- 5.2 mg/L serum). It then fell, before stabilizing until the end of lactation (21.1 +/- 4.5 mg/L serum), reflecting the changes reported in the milk

Determination by Fourier Transform Raman Spectroscopy of Conjugated Linoleic Acid in I(2)-Photoisomerized Soybean Oil.

The potential of Fourier transform (FT)-Raman spectroscopy to quantify the total conjugated linoleic acid (CLA) content was evaluated to find a technique for the routine control of CLA synthesis by chemical procedures. The calibration and validation samples were obtained by photoisomerization of linoleic acid contained in soybean oil. The catalyst was iodine (I(2)), and the light source was the green line (514.5 nm) of an argon ion laser. The criteria to select the best partial least-squares (PLS) calibration model were a low standard error of prediction (SEP), a high correlation coefficient (R), and the selection of relevant variables of the Raman spectrum to reduce spectral interferences. The total CLA content of the 22 samples ranged from 0.05 to 3.28% of total lipids. The best PLS calibration model was obtained with three optimal factors, a SEP of 0.22, and a R of 0.97. This calibration model was obtained after baseline correction of the CC stretching region (1642-1680 cm(-1)), which contained sufficient spectral information for reliable CLA quantification