Milk quality

Vitamin E supplementation has been shown to have positive effects on milk quality in a conventional commercial dairy herd. Milk obtained from cows that received supplemental vitamin E had lower somatic cell counts and plasmin concentrations than corresponding values in milk obtained from control cows. The reduction in plasmin as a result of vitamin E supplementation is very beneficial to the dairy industry because plasmin reduces the cheese-yielding capacity of milk, affects the coagulating properties of milk and its overall ability to withstand processing during cheesemaking (Politis et al., 2004). 

The requirements of dairy cattle for B-vitamins, determined almost half a century ago, concluded that a ruminant animal does not require an exogenous supply of B-vitamins because its rumen microflora should synthesise enough of these compounds to avoid deficiency. Since then, dairy cows have greatly increased their average milk and milk component yields. More recent studies have shown that B-vitamin supply in dairy cows is increased by supplementation, although losses in the rumen are extensive (Santschi et al., 2005). Whilst there are few reports of B-vitamin supplementation affecting milk quality, supplemental biotin has been shown to directly improve milk yield (Majee et al., 2003). 

The trend towards the Holstein breed in the UK over the last 20 years has led to problems in relation to milk quality. While these cows have the potential to produce high yields by the greater partitioning of nutrients into milk, their efficiency in converting metabolisable feed energy into milk has not increased... 

Studies into the effect of frequency of milking on milk quality compared once-daily and twice-daily milking and showed that milk yield was significantly reduced and milk fat and protein concentrations were increased, with once-daily milking compared with twice-daily. Furthermore, casein concentrations in the milks were similar, but once-daily milk had higher whey protein content (O Brien et al., 2002). 

A study of 28 dairy farms in The Netherlands found that the introduction of an automatic milking system led to a reduction in milk quality compared to conventional farms, owing to an increase in the total bacterial plate count and of free fatty acids (Klungel et al., 2000). 

Economic effects of changing systems and management practices to improve milk quality... 

Deeth H C, (1993), Lipase activity and its effect on milk quality, Australian Journal of Dairy Technology, 48, 96-98. 

Klungel G H, Slaghuis B A and Hogeveen H (2000), The effect of the introduction of automatic milking systems on milk quality , Journal of Dairy Science, 83, 1998-2003. 

Mariani P and Battistotti B (1999), Milk quality for cheesemaking , Proceedings of the ASPA XIII Congress, Piacenza, June 21-24, 499-516. 

Butler G., Stergiadis S., Eyre M. and Leifert C. (2006). Effect of production system and geographic location on milk quality parameters , Aspects of Applied Biology, 80, 189-193. 

Both clinical and sub-clinical mastitis are usually accompanied by an increase in the somatic cell count (SCC a measure of white blood cells (95%) such as macrophages, segmented neutrophil granulocytes or lymphocytes) in milk. SCCs above a certain level are an indication of immune-system activation and are used as an indicator of sub-clinical , latent or chronic udder infections/mastitis (Concha, 1986 Ostensson et al., 1988), which were shown to affect milk quality, composition and shelf life. Dairy companies therefore impose SCC thresholds or reduce payments to farmers if certain thresholds are exceeded (Hamann, 2001 Urech et al., 1999). 

Deterioration (lipase (commercially, probably the most significant enzyme in milk), proteinase, acid phosphatase and xanthine oxidase) or preservation (sulphydryl oxidase, superoxide dismutase) of milk quality. 

Lipp, M. (1995) Review of methods for the analysis of triglycerides in milk fat application for studies of milk quality and adulteration. Food Chem., 54, 213-221. 

Christen, G.L., Wang, W.-C., Ren, T.-J. 1986. Comparison of the heat resistance of bacterial lipases and proteases and the effect on ultra-high temperature milk quality. J. Dairy Sci. 69, 2769-2778. 

Rasmussen, M.D., Frimer, E.S., Horvath, Z., Madsen, N.P., Klastrup, O., Jensen, N.E. 1988. Milking system with separate air and milk transport. Effect on yield, milkability, milk quality, udder health and vacuum conditions. Dairy Sci. Abstr. 50, 232. 

Existing randomized, controlled trials are insufficient to establish an effect of hormonal contraception, if any, on milk quality and quantity. Current recommendations are to avoid combined OCs in the first 6 weeks postpartum and to use them with caution during the 6-month postpartum period. 

Quality in market milk is hard to define. Many attemp been made to tell what is meant by quality iu market milk, bt has been much difference of opinion. Dr. E. 0. Jordan says, the exhaustively studied and relatively simple water standa subject to such exceptions and reservations, it is certainly no expected that bacterial standards for food will be any mor> factory. H. A. Harding says, Many factors combine to de the quality of milk, apparently thus far, no one has succeede fully analyzing the city milk situation as to formulate a ci expression for milk quality. ... 

Like the cheese maker, the manager of a milk condensing factory must go out and size up the conditions under which his milk is produced. He must apply milk quality tests along with the establishment of minimum standards for milk production. He must do this in order to insure uniformity in the quality of his milk supply. Such... 

The overall effect of these various practices, i.e., improved milk quality, pasteurization, defined starters, enclosed cheesemaking equipment, rapid cooling, and low ripening temperature, is the production of very mild cheese, free of off-flavors. While the latter is, obviously, a desirable development, not all consumers are happy with the very mild flavor of modem Cheddar. 

Supply chain Milk quality and supply chain management... 

A flow injection method based on the catalytic action of iodide on the colour-fading reaction of the FeSCN2+ complex was proposed and applied in order to determine iodine in milk. At pH 5.0, temperature 32°C and measurements at 460 nm, the decrease in absorbancy of Fe -SCN (0.10 and 0.0020 mol /I) in the presence of N02" (0.3 mol/ 1) is proportional to the concentration of iodide, with a linear response up to 100.0 pg/1. The detection limit was determined as 0.99 pg/1 and the system handles 48 samples per hour. Organic matter was destroyed by means of a dry procedure carried out under alkaline conditions. Alternatively, the use of a Schoninger combustion after the milk dehydration was evaluated. The residue was taken up in 0.12 mol/1 KOH solubilization. For typical samples, recoveries varied from 94.5 to 105%, based on the amounts of both organic matter destroyed. The accuracy of the method was established by using a certified reference material (IAEA A-11, milk powder) and a manual method. The proposed flow injection method is now applied as an indicator of milk quality on the Brazilian market (de Araujo Nogueira et al., 1998). 

Castillo, M. A., and Vargas, M. G, Development of capillary electrophoretic methods for bovine milk quality control, Presented at the 12th Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical and Industrial Applications of Capillary Electrophoresis and Microchip Technology, Queretaro, Mexico, 2-5 December, 2006. 

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