Vitamin B2 concentration in cow milk: Quantification by a new UHPLC method and prediction by visible and near-infrared spectral analysis.

Until now, there are few information on vitamin B2 concentration variability in milk. In this study, a novel analytical method to quantify total vitamin B2 in milk was developed and applied on 676 samples. In parallel, spectral analysis (colorimetry and near infrared spectroscopy) were performed to develop prediction models of vitamin B2 concentration in milk. The analytical method includes an acid and enzymatic extraction followed by vitamin B2 quantification by Ultra High Performance Liquid Chromatography coupled with fluorimetry. Samples analysis showed a wide range of concentration from 0.78 to 4.58 mg/L with a mean of 2.09 ± 0.48 mg/L. Two prediction models based on colorimetric analysis allow estimation of vitamin B2 concentration in milk. Thus, this work shows an analytical method and, for the first time, a prediction method to enable enhancement of researches on vitamin B2 content of milk and its variation factors.

Carotenoid, Tocopherol, and Phenolic Compound Content and Composition in Cover Crops Used as Forage.

Secondary compounds of grassland and forage plant species such as vitamins or phenolic compounds are involved in different health-promoting effects in animals. However, information on their concentration and composition in forage plant species remains scarce. The objective of this study was to characterize the composition of secondary compounds of seven grazed cover crop plant species harvested at two stages of growth. Carotenoids and tocopherols were characterized and quantified using ultraperformance liquid chromatography with a photodiode array, and soluble phenolic compounds were characterized using high-performance liquid chromatography with diode-array detection. All species were rich in carotenoids, especially at the vegetative stage, even if the concentrations varied between plant species. Variations in tocopherol concentrations and phenolic composition were more important between plant species than between stages within species. Among the plant species tested, sainfoin (Onobrychis viciifolia Scop) contained the most secondary metabolites.

Exploration of Biological Markers of Feed Efficiency in Young Bulls.

The efficiency with which ruminants convert feed to desirable products is difficult to measure under normal commercial settings. We explored the use of potential biological markers from easily obtainable samples, that is, blood, hair, and feces, to characterize potential causes of divergent efficiency when considered as residual feed intake (RFI) or feed conversion efficiency (FCE). A total of 54 Charolais bulls, 20 in period 1 and 34 in period 2, were examined for individual dry matter intake (DMI) and growth. Bulls were offered a diet of 70:30 wrapped grass silage to concentrate for 99 d. At the conclusion of the test period, blood samples were collected for the determination of vitamins B2 and B6, and plasma used for the determination of metabolites, natural isotopic 15N abundance (15N NIA, expressed as δ15N ‰) and fractionation (Δ15Nplasma proteins-diet and Δ13Cplasma proteins-diet) and near-infrared spectroscopy (NIRS). Feces were analyzed by NIRS. Bulls were slaughtered at 15-17 months of age and carcass characteristics determined. Bulls were ranked according to RFI with extremes (SD ± 0.5; n = 31) classified as either efficient (Neg-RFI) or inefficient (Pos-RFI). Extreme bulls were then classified for FCE (high vs low FCE), changing the groups. Pos-RFI bulls consumed 14% more feed than Neg-RFI bulls for the same level of weight gain. Low FCE bulls tended to eat more, but had lower weight gains than high FCE bulls. No differences were detected in carcass conformation, fat scores, hot carcass weight, or dressing percentage. Yet, heart and bladder weights were heavier in Pos-RFI, and rumen weight tended to be heavier in Pos-RFI bulls. RFI did not affect bulk 15N or 13C fractionation. A negative correlation was observed between FCE and Δ15Nplasma proteins-diet. Inefficient bulls (Pos-RFI) had higher δ15N in glycine compared to Neg-RFI bulls. Similarly, metabolomic analysis showed a tendency for concentrations of glycine and sarcosine to be elevated in Pos-RFI bulls, whereas aspartic acid and carnosine tended to be elevated, and serine tended to be lower in High FCE. Among vitamins, only flavin adenine dinucleotide concentration was higher in the blood of bulls with High FCE. These results suggest that the two feed efficiency metrics differ in the underlying mechanisms of metabolism, where RFI is driven by differences in the energetic requirements of visceral organs and the extent of AA catabolism.

Effect of linseed fed as rolled seeds, extruded seeds or oil on fatty acid rumen metabolism and intestinal digestibility in cows.

Linseed, a source of linolenic acid, is used in ruminant diets to increase polyunsaturated fatty acids (FA) in animal products. Seed processing is known to have an impact on FA rumen metabolism, but few data are available for linseed. We studied the effect of linseed lipid on ruminal metabolism and intestinal digestibility in cows. Three modes of linseed processing: rolled linseed (RL), extruded linseed (EL) and linseed oil plus linseed meal (LO), supplemented at 7.5% of DM intake, were compared to a control diet (C). Duodenal flows, intestinal digestibility and plasma composition were determined. The duodenal flow of linolenic acid was similar among diets. The sum of t10 and t11-18:1, which were coeluted, was increased with lipid-supplemented diets and represented more than 60% of trans 18:1 for EL and LO diets. The main 18:2 isomers were c9, c12 and t11, c15 among the non-conjugated isomers, and t11, t13 among CLA. Linseed supplementation increased the duodenal flow of unsaturated intermediates of biohydrogenation, and this effect was more pronounced for extruded seeds and oil than for rolled seeds. For most 18-carbon FA, intestinal digestibility was slightly higher for C and LO diets than for RL and EL. Plasma concentrations of non-conjugated 18:2 and linolenic acid were similar among the lipid-supplemented diets. Within diet, profiles of 18:1 isomers (except c9) remained very similar between duodenal and plasma FA.