Vitamin D is obtained by cattle from the diet and from skin production via UVB exposure from sunlight. The vitamin D status of the cow impacts the vitamin D content of the milk produced, much like human breast milk, with seasonal variation in the vitamin D content of milk well documented. Factors such as changes in husbandry practices therefore have the potential to impact the vitamin D content of milk. For example, a shift to year-round housing from traditional practices of cattle being out to graze during the summer months and housed during the winter only, minimises exposure to the sun and has been shown to negatively influence the vitamin D content of the milk produced. Other practices such as changing dietary sources of vitamin D may also influence the vitamin D content of milk, and evidence exists to suggest genetic factors such as breed can cause variation in the concentrations of vitamin D in the milk produced. The present review aims to provide an overview of the current understanding of how genetic and environmental factors influence the vitamin D content of the milk produced by dairy cattle. A number of environmental and genetic factors have previously been identified as having influence on the nutritional content of the milk produced. The present review highlights a need for further research to fully elucidate how farmers could manipulate the factors identified to their advantage with respect to increasing the vitamin D content of milk and standardising it across the year.

The natural source of vitamin B12 in human diets comes from animal products. For example, one glass (250 ml) of milk provides approximately 50 % of the RDA (2·4 μg/d). It was hypothesised that the provision of vitamin B12 from milk is more efficiently absorbed than the synthetic form used in vitamin supplements. Pigs (n 10) were used as a model for intestinal absorption of vitamin B12 in humans to compare the net fluxes of vitamin B12 across the portal-drained viscera (PDV; an indicator of intestinal absorption) after ingestion of meals complemented with conventional and vitamin B12-enriched (via injections to cows) milk (raw, pasteurised or microfiltrated) or with equivalent amounts of cyanocobalamin, the synthetic form used in supplements or unsupplemented. Net flux of vitamin B12 across PDV after the ingestion of milk was positive, though not influenced by milk enrichment (P>0·3) or technological processes (P = 0·8) and was greater than after ingestion of equivalent amounts of cyanocobalamin (cyanocobalamin v. all milk, P ≤ 0·003). In fact, net fluxes of this vitamin were not different from 0 after either cyanocobalamin or the meal devoid of vitamin B12 (unsupplemented v. cyanocobalamin, P = 0·7). The cumulative PDV fluxes during the 24 h following ingestion of meals complemented with milk varied from 5·5 to 6·8 μg. These values correspond to an efficiency of intestinal absorption of vitamin B12 from milk varying between 8 and 10 %. Therefore, vitamin B12, which is abundant in cows' milk, is also substantially more available than the most commonly used synthetic form of this vitamin.

We evaluated the effects of long-term daily cows' milk (CM) administration on insulin resistance induced by a high-sucrose diet. F344 rats, aged 3 weeks, were divided into two groups according to diet (dextrin-fed v. sucrose-fed). These groups were further divided into two groups receiving either CM or artificial milk (AM; isoenergetic emulsion of egg white protein, maltose, lard and minerals). Rats were fed a sucrose- or dextrin-based diet for 7 weeks and orally administered CM or AM at 25 ml/kg following an 8 h fast on a daily basis. Insulin sensitivity was evaluated via postprandial changes in serum glucose and insulin, oral glucose tolerance tests, and fasting serum insulin and fructosamine concentrations. The sucrose-fed rats showed an overall decrease in insulin sensitivity, but postprandial insulin levels were lower in the CM-treated subgroup than in the AM-treated subgroup. Peak serum glucose and insulin concentrations were highest in the sucrose-fed rats, but CM administration reduced peak glucose and insulin values in comparison with AM administration. By area under the curve analysis, insulin levels after feeding and glucose loads were significantly lower in the CM-treated groups than in the AM-treated groups. The CM-treated groups also demonstrated lower fasting insulin and fructosamine levels than the AM-treated groups. Improved insulin sensitivity due to CM administration seemed to be associated with reduced duodenal GLUT2 mRNA levels and increased propionate production within the caecum.

This paper presents an alternative method to estimate somatic cell count (SCC) in cows' milk. SCC is an important indicator in the detection of inflammatory reactions within the udder in cows and Direct Optical Microscopy (DOM) is the present reference method for SCC but, owing to its dependence on human operators, it is extremely costly, time-consuming and potentially subjective. The industrial method of choice is Epifluorescence (EF), which has the potential for impressive throughput and acceptable precision, but requires huge inversions and handling of highly toxic reactives and waste. In this paper, an advantageous method that involves application of a low-cost Video Microscopy (VM) system is analysed and discussed, including a comparison between DOM and VM, and an example of application of both methods to evaluate EF counts. We conclude that VM is sufficiently precise and very cheap to implement and operate.

Two monoclonal antibodies (MAb) raised against bovine κ-casein were developed and applied in an automated optical biosensor (Biacore 3000) to create easy and fast direct and inhibition biosensor immunoassays (BIA) for the detection of cows' milk in the milk of ewes and goats. With both assay formats, low limits of detection (<0·1%) and fast run times (around 5 min) were obtained. For sample preparation, milk was diluted in buffer (direct assay) or in an antibody-containing buffer (inhibition assay) only. For quantitative analysis, calibrants of cows' milk in ewes' or goats' milk were used. Advantages of the direct BIA are: the single reagent format (biosensor chip immobilized antibodies only); the use of small amounts of antibodies (2 μg for >350 tests); and the wide measurement range (0·1 to 10% cows' milk). Despite these advantages, the inhibition BIA (using κ-casein immobilized on the chip) was preferred because of the possible application of non-purified Mab, the higher responses, the higher sensitivity at relevant low percentages of cows' milk and its robustness (>800 cycles per chip).

We analysed the effects of goats' milk (GM) on the nutritive utilization of Ca and P in rats with resection of 50% distal small intestine in comparison with cows' milk (CM) and a standard non-milk diet. The three test diets contained 200 g protein and 100 g fat/kg. The apparent digestibility coefficient (ADC) of Ca and P were considerably higher in the two groups of rats given the GM diet than those given the other two diets. Ca and P retention did not decrease by effect of intestinal resection with GM diet. In both groups of animals, serum Ca and P levels and ionic Ca were higher in the case of the GM diet than the other two diets, whereas the parathyroid hormone levels were lower. Ca content in femur, sternum and longissimus dorsi muscle was higher in rats given the GM diet. P content in femur and sternum was higher among the two groups of rats given a milk-based diet (GM or CM), especially with GM diet. The GM diet has beneficial effects on nutritive utilization of Ca and P in control rats and those with resection of the distal small intestine.

A new polymerase chain reaction (PCR)-based method was developed to detect cows' milk in goat cheese. This method is based on mitochondrial DNA (mtDNA) control region sequence variations. DNA extractions from 150 mg of cheese were carried out using a spin column-based method. Subsequent PCR amplifications of DNA were performed with cow specific primers, demonstrating the ability to detect cows' milk in a variety of cheeses. This simple approach provides high quality DNA, and is shown to be very sensitive, with a detection limit of less than 0·1% of cows' milk. Analysis of an agarose gel digital image allows a rough estimation of the percentage of cows' milk used in adulteration.

Total substitution of soyabean protein for animal protein in the diet has been repeatedly shown to lower plasma cholesterol levels in hypercholesterolaemic individuals. A new, highly palatable, high-protein soya drink may allow replacement of a significant percentage of animal protein in the diet. The soya drink was given, within a crossover design v. a cows' milk preparation of similar composition and taste, to twenty-one severely hypercholesterolaemic patients (mean baseline plasma cholesterol 8·74 mmol/l) with a history of resistance to or intolerance of statin treatment. Each dietary supplement was given for 4 weeks, with a 4-week interval between treatments, Plasma lipid levels were monitored every 2 weeks during each dietary sequence. The concomitant dietary treatment, which had been followed for a long time by all patients, was carefully monitored throughout the study. The soya supplementation reduced plasma total cholesterol level by 6·5%, when given first, and by 7·4% when given after cows' milk. When given first, cows' milk resulted in a small, non-significant reduction of plasma cholesterol level (-3·9%), and when given after soya, it changed total plasma cholesterol to a minimal extent (-1·6%). Changes in total and LDL-cholesterol levels after 2 and 4 weeks of soya v. cows' milk treatment were, thus, respectively -6·1, -7·0 and -6·2, -7·8% (both P < 0·05). These first data from a double-blind study confirm a significant cholesterol-lowering effect of soyabean protein, even when only partly replacing animal protein in the diet, in individuals with extreme plasma cholesterol elevations.