Assessment of the presence of Salmonella spp. in Egyptian dairy products using various detection media

Aims: To make a preliminary assessment of the incidence of Salmonella in Egyptian dairy products, and to investigate the effectiveness of various protocols for the detection of the pathogen in these products. Methods and Results: Samples of milk and related dairy products were randomly collected from local markets and examined for the presence of Salmonella. While most samples were free of the organism, isolates of Salmonella enterica subsp. enterica serovar Typhimurium PT 8 could be recovered from 'matared' cream specimens. These isolates were susceptible to antibiotics usually used to challenge infections caused by Salmonella. A combination of buffered peptone water, Muller-Kauffman tetrathionate broth, and brilliant green phenol red agar gave the best results for the detection of the pathogen. Selenite-cystine broth and Hektoen enteric agar were ineffective as an enrichment and a plating medium, respectively, in the isolation of Salmonella. A modified identification strategy that reduces the burden of serological testing of presumptive isolates is proposed. Conclusions, Significance and Impact of the Study: 'Matared' cream could be a vehicle for transmitting Salmonella. Using the above combination of media, beside the suggested modified confirmatory procedure, should increase the effectiveness and ease of the detection of Salmonella in milk and dairy products.

Chemical, physical, and sensory properties of dairy products enriched with conjugated linoleic acid

Recent studies have illustrated the effects of cis-9, trans-11 conjugated linoleic acid (CLA) on human health. Ruminant-derived meat, milk and dairy products are the predominant sources of cis-9, trans-11 CLA in the human diet. This study evaluated the processing properties, texture, storage characteristics, and organoleptic properties of UHT milk, Caerphilly cheese, and butter produced from a milk enriched to a level of cis-9, trans-11 CLA that has been shown to have biological effects in humans. Forty-nine early-lactation Holstein-British Friesian cows were fed total mixed rations containing 0 (control) or 45 g/kg ( on dry matter basis) of a mixture (1:2 wt/wt) of fish oil and sunflower oil during two consecutive 7-d periods to produce a control and CLA-enhanced milk, respectively. Milk produced from cows fed the control and fish and sunflower oil diets contained 0.54 and 4.68 g of total CLA/100 g of fatty acids, respectively. Enrichment of CLA in raw milk from the fish and sunflower oil diet was also accompanied by substantial increases in trans C18:1 levels, lowered C18: 0, cis-C18:1, and total saturated fatty acid concentrations, and small increases in n-3 polyunsaturated fatty acid content. The CLA-enriched milk was used for the manufacture of UHT milk, butter, and cheese. Both the CLA-enhanced butter and cheese were less firm than control products. Although the sensory profiles of the CLA-enriched milk, butter, and cheese differed from those of the control products with respect to some attributes, the overall impression and flavor did not differ. In conclusion, it is feasible to produce CLA-enriched dairy products with acceptable storage and sensory characteristics.

The potential therapeutic benefits of consuming 'health-promoting' fermented dairy products: a brief update

Despite the publication of a few contrary indications, the general consensus seems to be that the regular consumption of probiotic cultures, perhaps accompanied by 'prebiotic' compounds, improves the healthy operation of the digestive system of a typical consumer. Whether other benefits follow is a more contentious issue, especially for a given individual. Nevertheless, the dairy industry needs to be aware of the various ideas that are currently being explored, and this brief review seeks to summarize some recent findings.

Incorporation of cis-9, trans-11 conjugated linoleic acid and vaccenic acid (trans-11 18 : 1) into plasma and leucocyte lipids in healthy men consuming dairy products naturally enriched in these fatty acids

The present study investigated whether consuming dairy products naturally enriched in cis-9, trans-11 (c9,t11) conjugated linoleic acid (CLA) by modification of cattle feed increases the concentration of this isomer in plasma and cellular lipids in healthy men. The study had a double-blind cross-over design. Subjects aged 34-60 years consumed dairy products available from food retailers for 1 week and then either control (0.17 g c9,t11 CLA/d; 0.31 g trans-vaccenic acid (tVA)/d) or CLA-enriched (1.43 g c9,t11 CLA/d; 4.71 g tVA/d) dairy products for 6 weeks. After 7 weeks washout, this was repeated with the alternate products. c9,t11 CLA concentration in plasma lipids was lower after consuming the control products, which may reflect the two-fold greater c9,t11 CLA content of the commercial products. Consuming the CLA-enriched dairy products increased the c9,t11 CLA concentration in plasma phosphatidylcholine (PC) (38 %; P=0.035), triacylglycerol (TAG) (22 %; P < 0.0001) and cholesteryl esters (205 %; P < 0.0001), and in peripheral blood mononuclear cells (PBMC) (238 %; P < 0.0001), while tVA concentration was greater in plasma PC (65 %; P=0.035), TAG (98 %; P=0.001) and PBMC (84 %; P=0.004). Overall, the present study shows that consumption of naturally enriched dairy products in amounts similar to habitual intakes of these foods increased the c9,t11 CLA content of plasma and cellular lipids.

Determination of digesta flow entering the omasal canal of dairy cows using different marker systems

Four studies were conducted to compare the effect of four indigestible markers (LiCoEDTA, Yb-acetate, Cr-mordanted straw and indigestible neutral-detergent fibre (INDF)) and three marker systems on the flow of digesta entering the omasal canal of lactating dairy cows. Samples of digesta aspirated from the omasal canal were pooled and separated using filtration and high-speed centrifugation into three fractions defined as the liquid phase, small particulate and large particulate matter. Co was primarily associated with the liquid phase, Yb was concentrated in small particulate matter, whilst Cr and INDF were associated with large particles. Digesta flow was calculated based on single markers or using the reconstitution system based on combinations of two (Co + Yb, Co + Cr and Co + INDF) or three markers (Co + Yb + Cr and Co + Yb + INDF). Use of single markers resulted in large differences between estimates of organic matter (OM) flow entering the omasal canal suggesting that samples were not representative of true digesta. Digesta appeared to consist of at least three phases that tended to separate during sampling. OM was concentrated in particulate matter, whilst the liquid phase consisted mainly of volatile fatty acids and inorganic matter. Yb was intimately associated with nitrogenous compounds, whereas Cr and INDF were concentrated in fibrous material. Current data indicated that marker systems based on Yb in combination with Cr or INDF are required for the accurate determination of OM, N and neutral-detergent fibre flow. In cases where the flow of water-soluble nutrients entering the omasal canal is also required, the marker system should also include Co.

Farming and food production and development in the Shropshire Hills Environmentally Sensitive Area, 1997-2008

European agricultural and environmental policy has evolved considerably over the last 15 years. In this paper the changes in farm businesses in an Environmentally Sensitive Area in England are evaluated based on two surveys with the same farmers at the start and end of this period. The rate of participation in the environmental scheme had increased significantly at a time when Government led goals in this area had developed and become more output focussed. A combination of policy, market and animal health status changes had encouraged a number to leave cattle production, and though remaining with stock and grass they had decided against any extensive development in the direction of pluriactivity – with or without Government encouragement. This left the future of this group in some uncertainty given that two significant forms of financial support, the environmental scheme and the Hill Farm Allowance, were due to close.

The consumption of milk and dairy foods and the incidence of vascular disease and diabetes: An overview of the evidence

The health effects of milk and dairy food consumption would best be determined in randomised controlled trials. No adequately powered trial has been reported and none is likely because of the numbers required. The best evidence comes, therefore, from prospective cohort studies with disease events and death as outcomes. Medline was searched for prospective studies of dairy food consumption and incident vascular disease and Type 2 diabetes, based on representative population samples. Reports in which evaluation was in incident disease or death were selected. Meta-analyses of the adjusted estimates of relative risk for disease outcomes in these reports were conducted. Relevant case–control retrospective studies were also identified and the results are summarised in this article. Meta-analyses suggest a reduction in risk in the subjects with the highest dairy consumption relative to those with the lowest intake: 0.87 (0.77, 0.98) for all-cause deaths, 0.92 (0.80, 0.99) for ischaemic heart disease, 0.79 (0.68, 0.91) for stroke and 0.85 (0.75, 0.96) for incident diabetes. The number of cohort studies which give evidence on individual dairy food items is very small, but, again, there is no convincing evidence of harm from consumption of the separate food items. In conclusion, there appears to be an enormous mis-match between the evidence from long-term prospective studies and perceptions of harm from the consumption of dairy food items.

Plasma ghrelin and oxytomodulin concentrations in lactating dairy cows receiving abomasal soybean oil, corn starch, and casein infusions

The effects of increased postruminal supply of casein, corn starch, and soybean oil on plasma concentrations of the gastrointestinal hormones ghrelin and oxyntomodulin (OXM) were investigated. Four mid-lactation Holstein cows were used in a 4×4 Latin square. Treatments were continuous abomasal infusions (23h/d) for 7 d of water, soybean oil (500g/d), corn starch (1100g/d), or casein (800g/d). Jugular vein plasma was obtained every 30min for 7h on days 1 and 7. Soybean oil and casein infusion decreased preprandial plasma ghrelin concentration by approximately 20% on both d (time-by-treatment P<0.10); however, dry matter intake (DMI) was depressed only after 7 d of oil infusion. Infusion of soybean oil, corn starch, or casein did not change the plasma OXM concentration (P>0.20). The present data indicate that plasma ghrelin concentration is depressed immediately before feeding by the postruminal infusion of soybean oil and casein, but it is not affected during the postprandial period. Plasma ghrelin concentration was not altered (P>0.20), pre- or postfeeding, by increased postruminal supply of corn starch. In addition, plasma OXM concentration did not respond (P>0.20) to postruminal nutrient infusion. In conclusion, a decrease in DMI when fat is infused could be partially explained by the decrease in prefeeding plasma ghrelin concentration, but a decrease in prefeeding plasma ghrelin concentration is not always associated with a decrease in DMI, as observed for the infusion of casein. Plasma OXM concentration was not affected by postruminal infusion of macronutrients.

Associations between dairy consumption and body weight: a review of the evidence and underlying mechanisms

As the incidence of obesity is reaching 'epidemic' proportions, there is currently widespread interest in the impact of dietary components on body-weight and food intake regulation. The majority of data available from both epidemiological and intervention studies provide evidence of a negative but modest association between milk and dairy product consumption and BMI and other measures of adiposity, with indications that higher intakes result in increased weight loss and lean tissue maintenance during energy restriction. The purported physiological and molecular mechanisms underlying the impact of dairy constituents on adiposity are incompletely understood but may include effects on lipolysis, lipogeneis and fatty acid absorption. Furthermore, accumulating evidence indicates an impact of dairy constituents, in particular whey protein derivatives, on appetite regulation and food intake. The present review summarises available data and provides an insight into the likely contribution of dairy foods to strategies aimed at appetite regulation, weight loss or the prevention of weight gain.

Effect of abomasal glucose infusion on plasma concentrations of gut peptides in periparturient dairy cows

Six Holstein cows fitted with ruminal cannulas and permanent indwelling catheters in the portal vein, hepatic vein, mesenteric vein, and an artery were used to study the effects of abomasal glucose infusion on splanchnic plasma concentrations of gut peptides. The experimental design was a randomized block design with repeated measurements. Cows were assigned to one of 2 treatments: control or infusion of 1,500 g of glucose/d into the abomasum from the day of parturition to 29 d in milk. Cows were sampled 12 ± 6 d prepartum and at 4, 15, and 29 d in milk. Concentrations of glucose-dependent insulinotropic polypeptide, glucagon-like peptide 1(7–36) amide, and oxyntomodulin were measured in pooled samples within cow and sampling day, whereas active ghrelin was measured in samples obtained 30 min before and after feeding at 0800 h. Postpartum, dry matter intake increased at a lower rate with infusion compared with the control. Arterial, portal venous, and hepatic venous plasma concentrations of the measured gut peptides were unaffected by abomasal glucose infusion. The arterial, portal venous, and hepatic venous plasma concentrations of glucose-dependent insulinotropic polypeptide and glucagon-like peptide 1(7–36) amide increased linearly from 12 d prepartum to 29 d postpartum. Plasma concentrations of oxyntomodulin were unaffected by day relative to parturition. Arterial and portal venous plasma concentrations of ghrelin were lower postfeeding compared with prefeeding concentrations. Arterial plasma concentrations of ghrelin were greatest prepartum and lowest at 4 d postpartum, giving a quadratic pattern of change over the transition period. Positive portal venous-arterial and hepatic venous–arterial concentration differences were observed for glucagon-like peptide 1(7–36) amide. A negative portal venous–arterial concentration difference was observed for ghrelin pre-feeding. The remaining portal venous–arterial and hepatic venous–arterial concentration differences of gut peptides did not differ from zero. In conclusion, increased postruminal glucose supply to postpartum transition dairy cows reduced feed intake relative to control cows, but did not affect arterial, portal venous, or hepatic venous plasma concentrations of gut peptide hormones. Instead, gut peptide plasma concentrations increased as lactation progressed. Thus, the lower feed intake of postpartum dairy cows receiving abomasal glucose infusion was not attributable to changes in gut peptide concentrations.