Effects of feed iodine concentrations and milk processing on iodine concentrations of cows' milk and dairy products, and potential impact on iodine intake in Swiss adults.

The contribution of milk and dairy products to daily iodine intake is high but variable in many industrialised countries. Factors that affect iodine concentrations in milk and dairy products are only poorly understood. Our aim was to: (1) assess the effect of feed iodine concentration on milk iodine by supplementing five groups of five cows each with one of five dosages from 0-2 mg iodine/kg DM; (2) quantify iodine losses during manufacturing of cheese and yogurt from milk with varying iodine concentrations and assess the effect of cellar-ripening; and (3) systematically measure iodine partitioning during heat treatment and skimming of milk. Milk iodine reached a near-steady state after 3 weeks of feeding. Median milk iodine (17-302 µg/l for 0-2 mg iodine/kg DM) increased linearly with feed iodine (R2 0·96; P < 0·001). At curd separation, 75-84 % of iodine was lost in whey. Dairy iodine increased linearly with milk iodine (semi-hard cheese: R2 0·95; P < 0·001; fresh cheese and yogurt: R2 1·00; P < 0·001), and cellar-ripening had no effect. Heat treatment had no significant effect, whereas skimming increased (P < 0·001) milk iodine concentration by only 1-2 µg/l. Mean daily intake of dairy products by Swiss adults is estimated at 213 g, which would contribute 13-52 % of the adults' RDA for iodine if cow feed is supplemented with 0·5-2 mg iodine/kg DM. Thus, modulation of feed iodine levels can help achieve desirable iodine concentrations in milk and dairy products, and thereby optimise their contribution to human iodine nutrition to avoid both deficiency and excess.

The effects of a synthetic analogue of the Bovine Appeasing Pheromone on milk yield and composition in Valdostana dairy cows during the move from winter housing to confined lowland pastures.

This Research Communication describes the effects of a synthetic analogue of the Bovine Appeasing Pheromone (BAP) on milk parameters in Valdostana dairy cows during the first turning out from tie-stalls to confined lowland pastures around the farms. Thirty healthy lactating Valdostana cows were enroled in the study and randomly divided into 2 groups: experimental group (EG, n = 15) and control group (CG, n = 15). The two groups were separately housed in the same farm and managed outside in two different pens. Treatment (BAP and solution) and control (solution only) were poured on the nuchal skin area between the horns when the animals were inside the farm at the feeding rack every 7 d for 28 d (T0-T4). Milk samples were evaluated at the same time points (T0-T4). Daily milk production (kg/day) was higher in the EG than in the CG, particularly during the first day after the turning out to pasture (T1). Somatic Cell Count (103 cells/ml) was higher in the placebo group than in the EG, especially at T1. Proteins, fat, fat-free dry matter and casein (g/100 g) were not affected by the treatment. In T1 urea (mg/dl) content was higher in CG vs. EG, suggesting a more correct metabolic balance in the group treated with BAP. The use of BAP appears to modulate adaptation in ways that may improve dairy cow performance in the context of changes in management routines.

Exploring the microbiota of the red-brown defect in smear-ripened cheese by 454-pyrosequencing and its prevention using different cleaning systems.

Red-brown pigmentation can occasionally form in smeared-ripened cheese such as Fontina during the ripening process. This reaction is due to over-development of the typical microbiota present on the rind. Previous studies have demonstrated the relationship between red-brown pigmentation and the traditional utilization of wooden shelves during cheese ripening. The first part of the paper focuses on the characterisation of yeast and bacterial microbiota: plate counts and 454-pyrosequencing were performed in spoiled (n = 6) and non-spoiled cheeses (n = 6) and on the wooden shelves used during ripening. The second part shows different systems tested for cleaning the wooden shelves and avoiding the development of the red-brown defect in cheese: washing with hot water and ozone treatment. Actinobacteria, dominated on the wooden shelves, suggesting to be responsible for the red-brown pigmentation; they were also found in traces in the defected cheese samples. Galactomyces and Debaryomyces were the main species characterizing the yeast population, with Debaryomyces being the most dominant species on the shelves used during ripening of the red-brown defective cheese. Hot water treatment reduced the microbial contamination of shelves, whereas only the ozone treatment ensured complete elimination of both yeast and bacteria, resulting in the cheese rind not having the red-brown defect.

Cheese surface microbiota complexity: RT-PCR-DGGE, a tool for a detailed picture?

In this work, a culture-independent approach, based on PCR-DGGE and RT-PCR-DGGE, has been used to study the succession of bacterial communities that are encountered in Fontina PDO cheese. As already found for other smear ripened cheeses, it appeared that coryneform bacteria were actively present and could therefore be considered determinant in rind formation. DGGE profiles, especially at the RNA level, have shown the presence of Brevibacterium, Corynebacterium and Arthrobacter genera. RT-PCR-DGGE gels have lead to a richer band profile than the one obtained on the basis of DNA analysis, thus indicating that RNA analysis can highlight bacterial species that DNA analysis is not able to show. Thus, the biodiversity of the Fontina PDO surface has been described better by means of RT-PCR-DGGE, and RNA molecules should be considered a more informative target than DNA.