Winter Milk Research Articles

Effect of seasonal variations and lactation times on aflatoxin M1 contamination in milk of different species from Punjab, Pakistan

During October 2009 to September 2010, aflatoxin M1 (AFM1) levels were analyzed by HPLC-FLD in 356 milk samples of different lactating species (buffalo, cow, goat, sheep and camel) from Punjab (Pakistan). Recoveries of AFM1 ranged from 92 to 97% and the limit of detection (LOD) was 0.004 μg/L. For all lactating species the mean concentration of AFM1 was significantly higher in winter season than in summer (p < 0.05). The results showed that 55, 56, 32, 58 and 27% of winter milk samples of buffalo, cow, goat, sheep and camel exceeded the EU maximum limit (0.05 μg/kg), compared with 38, 33, 21, 36 and 14% of summer milk samples, respectively. For all lactating species the mean concentration of AFM1 was significantly higher in morning milks than in evening milks (p < 0.05). The percentage of morning milk samples exceeding the EU maximum limit was 72, 67, 69, 71 and 44% for buffalo, cow, goat, sheep and camel, while for evening milks percent non compliant rates were 39, 30, 18, 33 and 25%, respectively. The level of AFM1 tended to be higher in animal species fed mainly on concentrate mixtures (buffalo and cow) than in other species grazing on fresh greens.

Discrimination of seasonality in cheeses by near-infrared technology

Owing to the importance of the season of collection of milk for cheese quality, a study was made of the usefulness of near-infrared spectroscopy (NIRS) for discriminating the seasonal origin (winter or summer) of milk and quantifying the fat content of cheeses, since fat is one of the components most affected by the season of collection of milk for the elaboration of cheeses. In the internal validation, 96% of samples from winter milk and 97% of samples from summer milk were correctly classified, while in the external validation the prediction rate of samples correctly classified was 92%. Moreover, quantitative models allowed the determination of fat in winter, summer and winter + summer cheeses. Rapid prediction of the fat content of cheeses and the seasonal origin (winter or summer) of milk was achieved using NIRS without previous destruction or treatment of samples.

Fat composition of organic and conventional retail milk in northeast England

This study of UK retail milk identified highly significant variations in fat composition. The survey, conducted over 2 yr replicating summer and winter, sampled 22 brands, 10 of which indicated organic production systems. Results corroborate earlier farm-based findings considering fat composition of milk produced under conventional and organic management. Organic milk had higher concentrations of beneficial fatty acids (FA) than conventional milk, including total polyunsaturated fatty acids (PUFA; 39.4 vs. 31.8 g/kg of total FA), conjugated linoleic acid cis-9,trans-11 (CLA9; 7.4 v 5.6 g/kg of FA), and α-linolenic acid (α-LN; 6.9 vs. 4.4 g/kg of FA). As expected, purchase season had a strong effect on fat composition: compared with milk purchased in winter, summer milk had a lower concentration of saturated fatty acids (682 vs. 725 g/kg of FA) and higher concentrations of PUFA (37.6 vs. 32.8 g/kg of FA), CLA9 (8.1 vs. 4.7 g/kg of FA), and α-LN (6.5 vs. 4.6 g/kg of FA). Differences identified between sampling years were more surprising: compared with that in yr 2, milk purchased in year 1 had higher concentrations of PUFA (37.5 vs. 32.9 g/kg of FA), α-LN (6.0 vs. 5.1 g/kg of FA), and linoleic acid (19.9 vs. 17.5 g/kg of FA) and lower concentrations of C16:0 and C14:0 (332 vs. 357 and 110 vs. 118 g/kg of FA, respectively). Strong interactions were identified between management and season as well as between season and year of the study. As in the earlier farm studies, differences in fat composition between systems were greater for summer compared with winter milk. Large between-year differences may be due to changes in weather influencing milk composition through forage availability, quality, and intake. If climate change predictions materialize, both forage and dairy management may have to adapt to maintain current milk quality. Considerable variation existed in milk fat composition between brands.

Milk quality as affected by feeding regimens in a country with climatic variation

To investigate the influence of climatic conditions and season on milk composition, bulk tank milk was sampled on 5 occasions during a period of 15 mo from 20 Swedish dairy farms. These farms included 5 organic and 5 conventional farms in central Sweden and 7 traditional conventional farms and 3 conventional farms growing maize for silage in southern Sweden. Feed data and milk yield were recorded and milk was analyzed for content of fatty acids, carotenoids, and tocopherol. Differences between milk from the 2 regions and between summer and winter seasons were shown. Milk from central Sweden differed from milk from southern Sweden in that it had a higher content of carotenoids, tocopherol, short-chain fatty acids (C4–C14), C18:0, and C18:3 n-3 and a lower content of C16. Summer milk samples had a lower fat content and contained higher amounts of C18:1 cis-9 and conjugated linoleic acid cis-9,trans-11, and lower amounts of C4 to C16 compared with winter milk. Differences between farm types from central Sweden were lower content of conjugated linoleic acid cis-9,trans-11 and higher content of C18:3 n-3 in organic milk compared with conventional milk. In southern Sweden the use of maize silage caused lower milk content of carotenoids and C18:3 n-3 when compared with traditional feeding. Differences in milk composition could be related to climatic differences because legumes are more dominating in the leys of central Sweden and maize growing is limited to southern Sweden.

Organic management strategies and its effect on clover-based grassland production

In Ireland, there is a price premium for supplying 50% of organic milk during the winter (September to March). Ireland’s temperate climate is advantageous for milk production from clover-based swards over a long growing season. In 2008/2009, an experiment was conducted at Moorepark Dairy Production Research Centre, Solohead Research Farm (52°51'N, 08°21'W). The aim was to substantially lower winter feed costs for organic winter milk production systems, through the supply of 50% of the diet from grass-clover swards during the autumn and winter. The systems of production evaluated had: (i) mean calving date 17 February, stocking rate 2.15 cows/ha, fertilizer N input 90 kg ha−1 y−1 (Control); (ii) mean calving date 17 February, stocking rate 1.6 cows/ha, no fertilizer N (S-NFN) and (iii) mean calving date 16 April, stocking rate 1.6 cows/ha between calving and 1 September and a stocking rate of 1.2 cows/ha between 1 September and 18 February, no fertilizer N (W-NFN). Cows were turned out to pasture after calving and the number of days at pasture was recorded as 1 day when cows were outside day and night and 0.5 when cows were outside only by day. Cows were randomised to production system (18 cows per system) based on lactation number and calving date. Animal production data (milk production, milk composition, live weight and body condition score (BCS)) were subjected to ANOVA. Milk yield and yields of fat, protein and lactose in the third entire week of lactation were used as covariates for the analysis of the corresponding varibles. Pre-calving live weight and body condition score (BCS) were used as covariates when analysing live weight and BCS, respectively. There were no (P > 0.05) differences between systems in production of milk, milk composition (Table 1) or live weight and BCS during or at the end of lactation. The W-NFN system produced 48% of total milk output between 1 September and 18 February. Exceptionally high rainfall during summer and autumn 2008 led to difficult grazing conditions and, consequently, cows in the control system were housed by night from 7 October and fulltime from 23 October. This is approximately 5 weeks earlier than normal at Solohead for spring calving herds. Lower stocking rates on the NFN systems allowed cows to be kept outside for longer (P 0.05) difference in days at pasture between the NFN systems (Table 1). A long grazing season was possible with the late-calving W-NFN herd. A calving date later than 16 April is necessary to produce 50% of annual milk output between September and March.

Physicochemical properties of milk fat from three breeds of cows during summer and winter feeding

Abstract. The investigations included total 515 milk samples which were collected from 309 cows of the main dairy cows’ breeds used in Poland, i.e. Polish Holstein-Friesian Black-White variety (n=150), Polish Holstein-Friesian Red-White variety (n=77) and Simmental (n=82). There was determined a content of fat, protein and dry matter, a share of fat globules ranging in size, i.e. &lt;6 μm, 6-10 μm and &gt;10 μm as well as a fatty acids profile. It was shown that milk gained from Holstein-Friesian cows was characterized with a higher level of fat dispersion (over 70 % globules of &lt;6 μm diameter and a higher percentage of short- and long-chain fatty acids (ca. 19 %). The Simmentalers’ milk had a higher protein : fat ratio (about 0.89), a lower fat dispersion level (8.21 % globules of &gt;10 μm diameter) and the highest share of the polyunsaturated fatty acids (3.28 %). Cows nutrition included pasture forage during summer (independently on the breed) had a significant influence (P≤0.01) on increased polyunsaturated fatty acids percentage (mean by 0.51 %). The winter milk, however, showed a significantly higher content of dry matter, fat and protein as well as a higher share of big-sized milk globules.

Beverage iodine levels in Germany

Sales of iodized table salt (household use, bulk containers) have been flat in Germany since 1996/1997. Nevertheless, the amount of iodide excreted with the urine has been steadily increasing in the German population since 1993. We investigated the beverage iodine levels as possible source of the increased input of iodine into the food chain. No systematic studies on this topic have yet been carried out in Germany. A total of 510 samples were drawn from large grocery discounters who supply all German states with their products (35% fruit and vegetable juices, 35% beers, 10% pooled milk and yoghurt drinks, 10% mineral water, 10% soda). (1) Water-based beverage samples are prepared by solid-phase extraction and iodine concentration is determined by HPLC and electrochemical detection, (2) the samples of milk and milk products are prepared by trichloroacetic acid precipitation and centrifugation, and iodide concentration is determined by HPLC and electrochemical detection. Because the iodine concentrations in the beverage samples showed a left-skewed distribution, all expressed values are median values. Low iodine concentrations were observed in the water-based beverages: fruit and vegetable juices 2.92 μg I−/l, beers 2.91 μg I−/l, mineral waters 0.5 μg I−/l, sodas 0.5 μg I−/l. The median value measured in pooled milk and its derived products was 117 μg I−/l and 126 μg/l, respectively. As expected, the iodine was lower in summer milk than winter milk (\( \tilde{x} = 108\,{\upmu {\text{g I}}}^{ - } /{\text{l}} \)and \( \tilde{x} = 1 3 4. 2\,{\upmu {\text{g I}}}^{ - } /{\text{l}}, \) respectively). Although not statistically significant, beers from Northern Germany had higher concentrations of iodine than from Southern Germany (\( \tilde{x} = 3. 6 {\text{ vs}}. 0. 5\,{\upmu {\text{g I}}}^{ - } /{\text{l}} \)). In conclusion, based on our results, milk and milk products (117 μg I−/l and 126 μg/l, respectively) contribute significantly to the increased nutritional iodine supply of the German population.

Seasonal variation in the fatty acid composition of milk supplied to dairies in the mountain regions of Switzerland

The influence of typical feeds from five mountain regions of Switzerland (altitude of grass-based feed (GBF) during the summer and winter seasons: 1247 (± 465) m and 1136 (± 310) m, respectively) on the fatty acid (FA) composition of bovine milk fat was studied over one year (from May 2004 to April 2005). Compared with winter, summer milk had a significantly lower concentration of saturated FA (SFA) (−8.6%) and significantly higher contents of monounsaturated FA (MUFA) (+19.9%), polyunsaturated FA (PUFA) (+21.7%), conjugated linoleic acid (CLA) (+70.1%), and trans FA other than CLA (+56.7%). Summer and winter milk from mountains did not significantly differ with respect to the contents of branched, n-3 and n-6 FA. However, the content of the main n-3 FA (α-linolenic acid) was significantly higher in summer than in winter milk and its content was positively correlated with increasing percentages of GBF and altitude.

Seasonal changes of CLA isomers and other fatty acids of milk fat from grazing dairy herds in the Azores

AbstractBACKGROUND: Season of the year associated with dietary changes has been recognized as a factor implicated in milk fat fatty acid (FA) profile in dairy cows. However, a lack of information exists concerning cows grazing all year round as is practiced in the Azores, where cows are supplemented in winter with maize silage plus concentrates, while in spring the higher grass allowance only requires supplementation with concentrate. The main objective of this study was to detect any seasonal variation of FA profile of milk fat from milk sampled in bulk tanks of 12 Azorean dairy herds.RESULTS Compared to winter milk, milk fat from spring presented a higher proportion of CLA cis‐9,trans‐11 (14.3 versus 9.6 g kg−1 FA), C18:1 trans‐11 (32 versus 22 g kg−1 FA), C18:2 trans‐11,cis‐15 (3.7 versus 2.2 g kg−1 FA), CLA trans‐11,cis‐13 (0.34 versus 0.23 g kg−1 FA) and C18:3 n‐3 (5.7 versus 5.4 g kg−1 FA). The C18:2 n‐6/C18:3 n‐3 ratio was lower (P &lt; 0.05) in spring. Branched‐chain FA, except the anteiso‐C15:0, were higher in spring, while odd‐chain FA (C15:0) were higher in winter.CONCLUSION: Dairy herd management in the Azores presents a seasonal variation of milk fat FA composition, where the spring milk may present increased potential benefits for human consumers. Copyright © 2008 Society of Chemical Industry

Variation in retinol and carotenoid content of milk and milk products in The Netherlands

Retinol and carotenoids were measured in Dutch milk and dairy products using a validated approach based on complete extraction of fat, followed by mild saponification and analysis by high-performance liquid chromatography. Raw milk, full fat milk, semi-skimmed milk and butter contain about 10 μg retinol and 6 g carotenoids per g fat. Values for retinol equivalents in milk are 10–20% higher than the values published in the Dutch food composition table. β-Carotene comprises 90% of total carotenoids present in cow's milk, contrary to values published for human milk, which show more equally distributed carotenoids. Winter milk contains 20% less retinol and β-carotene compared to summer milk. Retention of retinol and β-carotene per g fat in hard cheese is one third to one half relative to the corresponding raw milk. In liquid and semi-liquid dairy products (pasteurized milk, buttermilk, vanilla custard, and yoghurt) retention of both compounds is above 80%. Recovery of carotenoids using the validated method is better than that reported by others previously.

Seasonal evolution of volatile compounds content and aromatic profile in milk and cheese from grazing goat

The objective of this study was to characterise the sensory profile of goat milk and cheese evaluated in three different seasons on the basis of alcohols, ketones, esters and terpenes content and profile. For this purpose, a trained panel of eight people was used, which sniffed the pure compounds corresponding to those found in all the products. One group of 15 lactating goats grazed a local pasture from March to July. Daily grazing time was approximately 8 h/day. During winter, spring and summer, herbage intake and the contribution of each species to the grazing diet were estimated by difference of herbage mass weight. Volatile organic compounds (VOC) content in herbage diet, milk and cheeses was determined by a multiple dynamic headspace extraction and GC–MS. The “fragrance” profile was described using the single pure compounds found in milk and cheese. The results showed that from winter to spring especially ketones content increased in milk, while no variation was observed for the other compounds. Summer milk was characterised mostly by terpenes. Also, the “fragrance” profile changed with grazing season. Winter milk was characterised by wood pulp-hay, green-herbaceous and blue-cheese notes, while in the spring by wood pulp-hay, blue-cheese, hot milk and musty. In the summer, the profile totally changed. In this season resinous, citrus, mint and fruity were the dominant notes. In comparison to herbage and milk, cheeses were less rich in volatile compounds. Not significant variation was observed in cheeses from a season to another, but their sensory profile was dominated by sweet odour.

Simulating the influence of management decisions on the nutrient balance of dairy farms

In order to evaluate the influence of management decisions on the nutrient balance of dairy farms a simulation model was developed. Three farm systems have been simulated: zero grazing, winter milk and summer milk. From the simulated farm systems the zero grazing farm has in all scenarios the lowest N-surplus. The winter milk farm system has a higher N-surplus than zero grazing but lower than the summer milk farm system. The results further indicate the positive effects of maize feeding in addition to grazing. More maize in the ration is especially good to lower the N-surplus during the grazing period in the summer. The benefits of more maize in the ration decrease when the fertilizer application rates decrease.

Modelling the bi-peak lactation curves of summer calvers in New Zealand dairy farm systems

New Zealand dairy cows traditionally calve in late winter, so their peak lactation demands are met by the increased growth of pasture in spring, and they are dried off in autumn before the decreased growth in winter. Financial premiums are offered to encourage farmers to produce milk in winter by calving cows in summer or autumn (out-of-season calving). This requires farming systems that can feed lactating cows in winter, which may include extra silages and fertilisers. The associated extra costs must be weighed against the value of the winter premium. This paper assesses the ability of Dexcel’s Whole Farm Model (WFM) to simulate out-of-season calving by comparing the model output with the observed data from an out-of-season calving trial run at Dexcel’s No. 2 dairy in Hamilton from 1998 to 2001. Trial data showed the typical lactation curve for July calvers with 1 peak in early lactation, whereas for January calvers the curve was atypical with a lower peak in early lactation and a second peak in late lactation. July and January calvers were described in the animal metabolic submodel (‘Molly’) at the start of the simulations by using observed liveweights at the beginning of the season and estimated peak daily milk yields. The management submodel used best-practice policies and the pasture submodel was driven by actual climate data. The WFM with an unmodified ‘Molly’ (without the photoperiod effect) did not predict the flatter bi-peak lactation curves of the January calvers. Driving forces responsible for the differences in the shape of lactation curves were identified and a sine function reflecting the photoperiod effect on lactation hormones was incorporated into ‘Molly’. This reduced the mean prediction error of milk yields for January calvers from 46 to 19%, and for July calvers, from 19 to 15%. The modified ‘Molly’ also showed potential to predict the atypical lactation curves of October and April calvers. After evaluating the WFM, farm systems can be simulated by altering factors such as stocking rate, fertiliser quantity and timing, and proportion of the herd calving out of season. Model output can be used for cost–benefit analysis of a wide variety of potential systems.

Native fat globules of different sizes selected from raw milk: thermal and structural behavior

The aim of this study was to characterize differences in the thermal and structural behavior between different sized native milk fat globules. A novel microfiltration process permits the selection of native small fat globules (SFG, 1–3 μm) and large fat globules (LFG, >5 μm) in raw milk, that were analyzed by X-ray diffraction (XRD) coupled to differential scanning calorimetry (DSC). There were no major differences in triglyceride crystalline structures between SFG and LFG, after eliminating thermal history and the influence of cooling rates. The three main 3L and 2L crystalline structures appearing under slow cooling existed regardless of globule size. The supercooling increased for the SFG, mainly due to heterogeneous nucleation in winter milk, and also to compositional variations in spring milk. Differences appeared regarding stabilized crystalline forms at 20 °C and subsequent cooling: the SFG contained less 2L triglyceride structures than the LFG. These results can be important in dairy manufactures using tempering periods.

Ventilation Effects on Air Quality and on the Yield and Quality of Ewe Milk in Winter

The effects of ventilation on air quality, and on the welfare and production performance of dairy ewes were assessed in a 6-wk trial conducted during the winter of 2002. Thirty-six midlactation Comisana ewes were divided into three groups of 12, which were randomly balanced for parity, time of lambing, and number of lambs suckled. Treatments were low (LOV), moderate (MOV), and programmed ventilation regimen (PROV). In LOV and MOV rooms, fans provided 10 ventilation cycles of 40min each at a fan speed of 1 and 2 m/s, respectively. In the PROV room, the fan was programmed to maintain a 70% relative humidity. Mean ventilation rates were 23, 47, and 73m3/h per ewe in LOV, MOV, and PROV rooms, respectively. Air concentrations of microorganisms and dust, and of gaseous pollutants were measured twice weekly. Cell-mediated immune response to phytohemagglutinin at d 1, 21 and 42, and humoral response to chicken egg albumin at d 11, 21, 30, and 40 were determined. At d 39, ewes were injected with 2 IU of porcine adreno-corticotropic-hormone/kg body weight0.75, and subjected to blood sampling for evaluation of cortisol concentrations immediately before and 1, 2, and 4h after adreno-corticotrophic-hormone injection. Milk yield was recorded daily. Individual milk samples were analyzed weekly for composition, renneting parameters, and somatic cell count. The LOV treatment resulted in higher air concentrations of NH3 and CO2 than the MOV and PROV treatments. Greater amounts of total and respirable dust were found in the PROV room than in the LOV and the MOV rooms. The LOV ewes had lower milk yield than the PROV ewes, lower milk casein content, and higher rate of clot formation than the MOV and PROV ewes. The ventilation regimen did not affect the immune and endocrine responses of the ewes. Results suggest that an intermittent ventilation regimen, providing a mean ventilation rate of 47m3/h per ewe at a fan speed of 2 m/s, is required to sustain the yield and cheese-making ability of ewe milk during the winter season.

Iodine concentration in Norwegian milk and dairy products.

The present study was conducted to determine the iodine concentration in Norwegian-produced milk and a selection of dairy products. The iodine concentration of eighty-five samples of milk and dairy products was analysed by inductively coupled plasma-MS. Low-fat milk and organic milk were sampled from nineteen and seven different locations in Norway, respectively, during the summer and winter season of 2000. Other milk and dairy products were chiefly collected during the summer season. Low-fat milk from the summer season had significantly lower median iodine concentration (88 microg/l, range 63-122 microg/l) compared with low-fat milk from the winter season (232 microg/l, range 103-272 microg/l). The median iodine concentration of organic summer milk (60 microg/l) was significantly lower than the iodine concentration of organic winter milk (127 microg/l). There were no significant differences in the low-fat-milk samples with regard to geographical sampling location. Whey cheese (Tine Gudbrandsdalsost) iodine concentration was significantly higher (803 microg/kg) than the median iodine concentration in casein cheeses such as Jarlsberg and Norvegia of 201 and 414 microg/kg, respectively. With a recommended iodine intake of 150 microg/d for adults, a daily intake of 0.4 litres milk meets the requirement with 25 % during the summer and more than 60 % during the winter season. Thus, milk and dairy products are important determinants of iodine intake in Norway.

Characterisation of Bacillus cereus isolated from milk silo tanks at eight different dairy plants

Raw milk was collected over 1 year from silo tanks at eight different dairy plants. On the average the level of spores and the percentage of psychrotrophic isolates was higher in summer milk (median 198 spores L–1; 48% psychrotrophs) than in winter milk (median 86 spores L–1; 35% psychrotrophs). Systematic differences in the average level of psychrotrophic spores were found between some dairies. There was an over all high diversity in the Bacillus cereus flora but the percentage of unique RAPD-patterns (fingerprints) among isolates differed between the dairies (34–54%). For all dairies mesophilic isolates with identical RAPD-patterns from up to 6 sampling occasions were found. An indication of a mesophilic in house flora was found at the dairy with 34% unique RAPD-patterns and the lowest percentage of psychrotrophic isolates (27%). In some dairies clusters of RAPD-patterns from psychrotrophic isolates were found. Eight of the RAPD-patterns were found among isolates from several of the investigated dairies indicating that some strains of B. cereus are widely spread and that certain strains may be selected for in the silo tank environment.

Presence of aflatoxin M1 in milk for human consumption in Argentina

Aflatoxin M1 (AFM1) appears in milk or dairy products as a direct result of the ingestion of food contaminated with aflatoxin B1 (AFB1) by cattle. The exposure of infants to AFM1 is something to worry about because milk is a main nutrient for children. Our aim is to carry out a study to determine the contamination degree of milk in our region during winter. Samples were collected in a period March–September (winter milk). In all cases, AFM1 levels were lower than the limits recommended for dairy products. However, as AFM1 is considered a probable human carcinogen (2B type), it is necessary to maintain control.

Interaction between propionibacteria and starter / non-starter lactic acid bacteria in Swiss-type cheeses

Thermophilic lactic acid bacteria, propionibacteria (PAB) and facultatively heterofermentative lactobacilli (FHL) form the main flora of Swiss-type cheeses. The aim of this work was to investigate their interactions and impact on product quality, and in particular on the de- fect of late fermentation. For this purpose Emmental model cheeses were produced according to a twice-replicated 2 4 full factorial experimental design. The four factors were: (1) The type of cultures of PAB, one with a weak (Prop 96) and the other one with a strong aspartase activity (Prop 90). (2) The addition or not of a culture of FHL composed of 3 Lactobacillus caseistrains. (3) The addition or not of a culture of 4 Lactobacillus helveticusstrains. (4) The season: winter (hay feeding) or summer (grass feeding). FHL and PAB counts, organic acids, proteolysis, eye formation were followed during ripening. Prop 90 showed a higher growth and fermentation role resulting in a higher number of eyes and an increased risk of late fermentation compared to Prop 96. PAB growth was also favoured in cheeses manufactured with winter milk which had a slightly higher water content. The addition of L. helveticustended to increase the risk of late fermentation. On the other hand the addition of FHL in- hibited lactate fermentation, with a more marked effect on Prop 96 culture. In conclusion the defect of late fermentation can be prevented by using PAB with weak aspartase activity, by adding FHL and by omitting L. helveticus. Emmental cheese / propionibacteria / aspartase activity / Lactobacillus casei / Lactobacillus helveticus

The Effect of Locality and Season on the Composition of South African Whole Milk

The aim of this study was to determine the effect of locality (region) and season on the nutrient composition of South African whole milk as consumed. Whole milk was collected in main cities identified within five climatic regions in South Africa in summer (January and February) and in winter (June, July and August) over a period of 24 months (N=200) and analysed for nutrient composition.The nutrient composition of whole milk in South Africa differed between the five localities and between winter and summer. Most of the variation could be related to the differing composition of the feed and practices (implying the level of feeding and the quality of the cow's diet). These results were confirmed by the analyses of variance results for whole milk, which showed highly significant differences for 44 of the 52 nutrients analysed between localities. CVA showed that locality was responsible for 72% of the variation in the data. When the effect of season was investigated, the analyses of variance results for whole milk showed highly significant differences for 36 of the 52 nutrients analysed between seasons. In the CVA with the season by locality interaction, a clear separation between the nutrient composition of summer and winter milk was observed.