THE ASSESSMENT OF THE BACTERIOLOGICAL CONDITION OF MILK BOTTLES

SUMMARY: A study of the relative values of a number of bacteriological tests for assessing the condition of milk bottles indicated that the colony count of the bottle rinse solution on yeastrel milk agar incubated for 4 days at 30°, combined with a clot-on-boiling test applied to 1 ml. of rinse in 9 ml. of sterile milk after incubation for 72 hr. at 19–20°, gave the most useful results.
The mean of the ratios of colony counts at 30° to those at 37° was 15·1, while it was as high as 22·9 for rinses with 37° of over 600 for an unsatisfactory bottle should be retained when the test is done at 30°. The thermoduric colony count of rinses of milk bottles, even when laboratory pasteurized in milk, did not provide any additional information to that given by the colony count at 30° made without pasteurization. A high proportion of the organisms in bottle rinses survived laboratory pasteurization in milk, the survival rate being highest in efficiently treated bottles.
The clot-on-boiling test gave results in general agreement with colony counts and served to indicate the potential influence of badly contaminated bottles on the keeping quality of milk placed in them. A substantial proportion of rinses with satisfactory colony counts reduced methylene blue within 48 hr. at 19–20°.
Colony counts at 37° were on the average much lower for bottles treated with steam than for bottles submitted to detergent treatment in various types of bottle washing machines. Treatment of bottles by steam or hypochlorite was more efficiently done on the farms than at the dairies.     

THE OCCURRENCE OF BACILLUS CEREUS IN MILK AND ON DAIRY EQUIPMENT

SUMMARY: In a survey of milk obtained from individual farms and creameries, 87% of samples were found to contain fewer than one cell of Bacillus cereus /ml. The remaining 13%, although they all yielded low counts, showed that the organism tended to occur in milk received from particular farms and creameries. On investigating sources of contaminated milk, it was found that the organism was derived chiefly from cans which, after being emptied of milk, had been allowed to stand for a long time before being washed properly and 'sterilized'. The vegetative cells of B. cereus were shown to form spores readily in thin films of diluted milk, such as may occur in a rinsed can.     

ADVISORY MICROBIOLOGICAL STANDARDS AND TOLERANCES FOR RAW MILK

SUMMARY: To study the value of recent modifications of microbiological tests used for advisory purposes, samples of tuberculin tested milk, taken at weekly intervals over a 5 year period from the Trawscoed Experimental Husbandry Farm and selected at random during a 12 months period from farms in Wales, were examined by a temperature compensated keeping quality test at 22°, colony count on Yeastrel milk agar in 3 days at 30° and coli-aerogenes colony count on violet red bile agar in 20–24 hr at 30°.
The results show that milk produced and handled under hygienic conditions can be expected to have colony counts of less than 2 × 10⁴/ml and coli-aerogenes colony counts less than 10/ml when examined within 18 hr of milking.     

SENSORY PROFILING AND POSITIONING OF COMMERCIAL SAMPLES OF MILK POWDER

Milk powders available commercially are of different qualities. The quality deviations may be due to inherent quality of the milk which in turn is dependent on various conditions like the fat content, the processing parameters, the storage time and the packaging materials used. The various brands of milk powders have been profiled sensorily for odor and flavor and also positioned using Canonical Discriminant Analysis (CDA). The study throws light on the relative qualities of the different brands, their positive and negative points and their relative position with respect to each other. The results indicate that the various types like whole milk powder, partially skimmed milk powder, skimmed milk powder and infant milk formula cluster together into the same group but the groups are separate from each other. The dominant quality attributes for the groups are different and are discussed in relation to the directional vectors.     

OBSERVATIONS ON THE EFFECT OF ADDED HYPOCHLORITE ON THE NUMBERS AND KINDS OF BACTERIA IN MILK

SUMMARY: In an investigation of the effect of added hypochlorite on the bacterial flora and bacterial numbers of milk no bactericidal action was apparent within 15 min of adding the disinfectant unless at least 500 p/m available chlorine had been added. After 24 hr storage at atmospheric temperature a reduction in numbers was found with 10 p/m available chlorine and this became more pronounced with increased concentrations. Micrococci seemed more susceptible to the bactericidal effect than streptococci, which formed, after 24 hr storage, the predominant residual flora where 250 and 500 p/m available chlorine had been added. Acid production by lactic streptococci was retarded at concentrations greater than 50 p/m available chlorine in a 5 hr incubation period at 30°, but after a 24 hr incubation the decrease in acid production was only apparent when 500 or 1,000 p/m available chlorine was present. Little effect on acid production by lactic streptococci was found when less than 50 p/m available chlorine had been added. The residual chlorine content of rinses of equipment sterilized in hypochlorite solutions was negligible.     

'BITTY' CREAM: THE OCCURRENCE AND SIGNIFICANCE OF BACILLUS CEREUS SPORES IN RAW MILK SUPPLIES

SUMMARY: Methods for determining the Bacillus cereus content of milks and of rinses of dairy equipment are described and their limitations discussed. Milk samples from various sources were examined throughout the year for 'bittiness' as well as for B. cereus. The organism was not detected in all samples showing bittiness. There was a marked seasonal variation in the B. cereus index of raw milk supplies; maximum numbers were obtained from July to September and minimum numbers in April and May. Rinses of farm dairy equipment yielded few B. cereus spores but milk cans not uncommonly contained large numbers, especially in the summer months, when 10·5% of cans showed more than 5 × 10³/can. Preliminary observations on other sources of B. cereus are described and some of the problems of the control of this organism in raw milk supplies are discussed.     

Phytoestrogens and Their Metabolites in Bulk-Tank Milk: Effects of Farm Management and Season

Phytoestrogens have structures similar to endogenous steroids and may induce or inhibit the response of hormone receptors. The objectives of the present study were to compare the effects of long-term vs. short-term grassland management in organic and conventional dairy production systems, compare organic and conventional production systems and assess seasonal variation on phytoestrogen concentrations in bulk-tank milk. The concentrations of phytoestrogens were analyzed in bulk-tank milk sampled three times in two subsequent years from 28 dairy farms: Fourteen organic (ORG) dairy farms with either short-term or long-term grassland management were paired with 14 conventional (CON) farms with respect to grassland management. Grassland management varied in terms of time since establishment. Short-term grassland management (SG) was defined as establishment or reseeding every fourth year or more often, and long-term grassland management (LG) was defined as less frequent establishment or reseeding. The proportion of red clover (Trifolium pretense L.) in the herbage was positively correlated with milk concentrations of the mammalian isoflavone equol. Therefore, organically produced bulk-tank milk contained more equol than conventionally produced milk, and milk from ORG-SG farms had more equol than milk from ORG-LG farms. Milk produced during the indoor-feeding periods had more equol than milk produced during the outdoor feeding period, because pastures contained less red clover than fields intended for silage production. Organically produced milk had also higher concentrations of the mammalian lignan enterolactone, but in contrast to equol, concentrations increased in the outdoor-feeding periods compared to the indoor-feeding periods. There were no indications of fertility problems on ORG-SG farms who had the highest red clover proportions in the herbage. This study shows that production system, grassland management, and season affect milk concentrations of phytoestrogens. However, compared to soy products, milk concentrations of phytoestrogens are low and future studies are required to investigate if the intake of phytoestrogens from dairy products has physiological effects in humans.     

THE ISOLATION OF COAGULASE POSITIVE STAPHYLOCOCCI FROM ROUTINE COMPOSITE MILK SAMPLES

SUMMARY: Composite morning milk samples were taken once weekly for 9 weeks from 24 dairy farms. In all 208 samples were tested, and coagulase positive staphylococci ( aureus, albus and citreus ) were isolated from 127 (61%). The week by week recovery of these staphylococci from individual farm samples varied between 11% and 88% Penicillin resistant coagulase positive strains were recovered from 20 samples (10%).     

Dairy goat grazing systems in Mediterranean regions: A comparative analysis in Spain, France and Italy

In order to maintain small ruminant grazing systems it is necessary to know precisely how they work and what actions can be taken to improve them. The objective of this paper was to characterize, classify, analyse and propose improvements for the dairy goat grazing systems in three countries from the western Mediterranean area: Spain, France and Italy. A multivariate analysis was conducted with 21 indicators obtained from the data collected from 45 farms. As a result of the multivariate analysis, 82.5% of variance was explained by two principal components. The first component included proportion of cultivated pasture area and cultivated pasture area per goat. The second included goats present and forage supply per goat. After conducting a cluster analysis based on these two principal components, farms were classified into four groups. Group 1 was made up of French and Italian farms, which had a smaller territorial base but a high cultivated pasture area per goat, contributing to greater self-sufficiency in feed. However the concentrate per goat was too high in relation to milk production, which was medium. The difference between milk income and feed cost is also medium. Group 2 was basically made up of Italian farms. The farms in this group had the most extensive management systems, with a low use of inputs. However, the milk production was low, meaning that the difference between milk income and feed cost was also low. Group 3 was mainly made up of Spanish farms. On these farms the concentrate supply was excessive and the forage supply was low. The milk production per goat was medium and the difference between milk income and feed cost was small. Group 4 was made up mainly of French farms. The farms of this group had a moderate supply of concentrate although the forage supply was very high. They had a high milk production, which lead to a large difference between milk income and feed cost per goat.The main weaknesses observed are related to feeding management, particularly grazing, and to the goat productivity. In the former case research on the nutritional utilization of rangelands and pastures and correct feed supplementation is to be encouraged. In the latter, the production capacity of the goats present in these systems should be improved, without forgetting the balance between hardiness and general productivity.     

THE RATES OF GROWTH OF SOME THERMODURIC BACTERIA IN PURE CULTURE AND THEIR EFFECTS ON TESTS FOR THE KEEPING QUALITY OF MILK

SUMMARY: The growth rates of eleven representative thermoduric bacteria, comprising 3 aerobic spore formers, 3 streptococci, 1 Corynebacterium lacticum and 4 micrococci, have been determined in glucose broth and sterile pasteurized milk at 37·5°, 26° and 15°. The spore formers and streptococci were generally not affected by the presence of inhibitory factors in pasteurized milk. When multiplication of micrococci and C. lacticum occurred in milk this was only after a lag period. One micrococcus showed an unusual series of growth phases in glucose broth at 37·5°, possibly due to the appearance of mutants or to adaptation of the organism to growth at that temperature. This was not observed in pasteurized milk. C. lacticum died off when incubated in glucose broth at 37·5°.
None of the keeping quality tests was more effective than any other in detecting these organisms in milk. The micrococci and C. lacticum had little effect on the keeping quality of pasteurized milk within the period of 'commercial life'. Some of the spore formers and streptococci showed marked differences in the end-points with the clot-on-boiling and the alcohol precipitation tests.     

THE ASSOCIATIVE GROWTH OF SOME THERMODURIC BACTERIA IN PASTEURIZED MILK

SUMMARY: Three strains of aerobic spore forming bacteria have been studied in association with thermoduric streptococci in pasteurized milk at different temperatures. Generally the development of each component organism of the mixtures was unaffected in the initial stages by the presence of the other, though later the spore formers were frequently adversely affected. Acid production by the mixed cultures was compared with that of the pure cultures under the same conditions of incubation. Generally more acid was formed by the mixtures, particularly at the higher temperatures of incubation. Gas formation was noted by a culture of Streptococcus faecalis in association with the spore formers.     

STUDIES ON MILK SECRETION : THE INFLUENCE OF INANITION

In this paper data are presented on cows receiving no food but having access to all of the water which they wished. The yield and composition of the milk were determined at various times during the periods of starvation. The composition of the milk showed changes which were progressive in the sense that they followed a definite course. They were characterized by a marked lowering in the amount of milk produced, by an increase in the total solids (chiefly an increase in the percentage of fat and ash, with a slight increase in proteins), and by a pronounced decrease in the lactose. The decrease in lactose corresponded with a decrease in the dextrose content of the blood, thereby supporting the conclusion that the lactose of milk has as its precursor dextrose of the blood. All the changes in milk composition during starvation can be directly related to the simultaneous changes in the blood. The following companion paper on insulin and phloridzin as they affect milk secretion further develops these hypotheses.     

Role of input self-sufficiency in the economic and environmental sustainability of specialised dairy farms

Increasing input self-sufficiency is often viewed as a target to improve sustainability of dairy farms. However, few studies have specifically analysed input self-sufficiency, by including several technical inputs and without only focussing on animal feeding, in order to explore its impact on farm sustainability. To address this gap, our work has three objectives as follows: (1) identifying the structural characteristics required by specialised dairy farms located in the grassland area to be self-sufficient; (2) analysing the relationships between input self-sufficiency, environmental and economic sustainability; and (3) studying how the farms react to a decrease in milk price according to their self-sufficiency degree. Based on farm accounting databases, we categorised 335 Walloon specialised conventional dairy farms into four classes according to their level of input self-sufficiency. To this end, we used as proxy the indicator of economic autonomy – that is, the ratio between costs of inputs related to animal production, crop production and energy use and the total gross product. Classes were then compared using multiple comparison tests and canonical discriminant analysis. A total of 30 organic farms – among which 63% had a high level of economic autonomy – were considered separately and compared with the most autonomous class. We showed that a high degree of economic autonomy is associated, in conventional farms, with a high proportion of permanent grassland in the agricultural area. The most autonomous farms used less input – especially animal feeding – for a same output level, and therefore combined good environmental and economic performances. Our results also underlined that, in a situation of decrease in milk price, the least autonomous farms had more latitude to decrease their input-related costs without decreasing milk production. Their incomes per work unit were, therefore, less impacted by falling prices, but remained lower than those of more autonomous farms. In such a situation, organic farms kept stable incomes, because of a slighter decrease in organic milk price. Our results pave the way to study the role of increasing input self-sufficiency in the transition of dairy farming systems towards sustainability. Further research is required to study a wide range of systems and agro-ecological contexts, as well as to consider the evolution of farm sustainability in the long term.     

Economic efficacy of anthelmintic treatments in dairy sheep naturally infected by gastrointestinal strongyles

The aim of the present paper was to assess benefit of strategic anthelmintic treatments on milk production in six commercial dairy sheep farms, located in southern Italy, whose animals were naturally infected with gastrointestinal strongyles. On each farm, two similar groups were formed, one untreated control group and one treated group. In all the treated groups, the strategic anthelmintic schemes were based on: (i) only one treatment with moxidectin in the periparturient period (February, Farm No. 6), or; (ii) two treatments, i.e. the first with moxidectin performed in the periparturient period (February, Farms Nos. 1, 2, 3 and 4) or in the postparturient period (April, Farm No. 5), and the second with netobimin at the mid/end of lactation (June, Farms Nos. 1, 2, 3, 4 and 5). Faecal egg count reduction (FECR) tests were performed on each farm in order to asses the anthelmintic efficacy of the drugs used. In addition, milk yield measurements for each animal fortnightly in each farm for the lactation period were performed. In terms of FECR, both moxidectin and netobimin were effective in all the 6 studied farms. Regarding milk production, overall in the 6 study farms the mean daily milk productions of the treated groups were higher than those of the control group. However, there were important differences between the 6 farms, i.e. the increase of milk production in the treated groups versus the control groups was as follows: +18.9% (Farm 1), +30.4% (Farm 2), +4.0% (Farm 3), +37.0% (Farm 4), +5.5% (Farm 5) and +40.8% (Farm 6). The results of the study showed that the economic efficacy of an anthelmintic treatment is not a cause-effect issue, but is a multifactorial issue which depends upon the quali-quantitative parasitological status of the animals, the pathogenesis of the species of parasites, the virulence of the strains of parasites, the local epidemiology, the timing of treatment, the breed of animal in terms of genetics and production types, nutrient supply.     

Comparative analysis of the diversity of aerobic spore-forming bacteria in raw milk from organic and conventional dairy farms

Bacterial contamination of raw milk can originate from different sources: air, milking equipment, feed, soil, faeces and grass. It is hypothesized that differences in feeding and housing strategies of cows may influence the microbial quality of milk. This assumption was investigated through comparison of the aerobic spore-forming flora in milk from organic and conventional dairy farms. Laboratory pasteurized milk samples from five conventional and five organic dairy farms, sampled in late summer/autumn and in winter, were plated on a standard medium and two differential media, one screening for phospholipolytic and the other for proteolytic activity of bacteria. Almost 930 isolates were obtained of which 898 could be screened via fatty acid methyl ester analysis. Representative isolates were further analysed using 16S rRNA gene sequencing and (GTG)(5)-PCR. The majority of aerobic spore-formers in milk belonged to the genus Bacillus and showed at least 97% 16S rRNA gene sequence similarity with type strains of Bacillus licheniformis, Bacillus pumilus, Bacillus circulans, Bacillus subtilis and with type strains of species belonging to the Bacillus cereus group. About 7% of all isolates may belong to possibly new spore-forming taxa. Although the overall diversity of aerobic spore-forming bacteria in milk from organic vs. conventional dairy farms was highly similar, some differences between both were observed: (i) a relatively higher number of thermotolerant organisms in milk from conventional dairy farms compared to organic farms (41.2% vs. 25.9%), and (ii) a relatively higher number of B. cereus group organisms in milk from organic (81.3%) and Ureibacillus thermosphaericus in milk from conventional (85.7%) dairy farms. One of these differences, the higher occurrence of B. cereus group organisms in milk from organic dairy farms, may be linked to differences in housing strategy between the two types of dairy farming. However, no plausible clarification was found for the relatively higher number of thermotolerant organisms and the higher occurrence of U. thermosphaericus in milk from conventional dairy farms. Possibly this is due to differences in feeding strategy but no decisive indications were found to support this assumption.     

Effect of high temperature-humidity conditions on milk production of dairy herds grazed on farms in a pasture-based feed system

The influence of stressful temperature-humidity conditions on output from dairy cows on farms near Wauchope (31°S Lat.), Australia, was examined by comparing weekly milk production and Temperature-Humidity Index (THI) values over a two-year period (1973 to 1975). Production during weeks with relatively high THI values (70 or over) was higher than production in weeks with lower temperature-humidity stress. In autumn and winter when THI values were low, the quantity and quality of pasture available was inadequate to sustain high levels of milk production. Short-term (weekly) responses of milk output to changes in temperature-humidity conditions above THI values of 70 were not consistent, either in terms of the direction or magnitude of production change. THI values may not have been high enough to adversely affect week-to-week production from predominantly Jersey herds, although some depression in lactation yields may have occurred. The reduction in digestibility and palatability of grasses during late summer appeared to be of greater importance in influencing production patterns than the direct effects of stressful temperature-humidity conditions on cows.     

ON THE MECHANISM OF MILK SECRETION : THE INFLUENCE OF INSULIN AND PHLORIDZIN

The four types of experiments on milk secretion herein described really fall into one general class so far as the physiological effects produced are concerned. Starvation lowers the blood sugar and raises the osmotic pressure of the blood. The experiment using parathyroid hormone with or without starvation may have its effects interpreted as simply due to starvation since 1000 units of this hormone produced no visible effects on the blood calcium or milk constituents different from those of starvation. Since insulin produces a marked and rapid drop in blood sugar it too may be looked upon as a rapid starvation effect. It has some other important effects, however. Briggs et al. (21) have shown that potassium and phosphorus of the blood are decreased and Luck, Morrison, and Wilbur (22) indicate a reduction in the amino acids of the blood in insulin treatment. Phloridzin lowers the threshold for sugar retention with the consequence that in time it tends to lower the sugar of the blood to an even greater extent than that noted in starvation. It tends to depress the potassium, to increase the phosphorus content of the blood, and to cause the body to burn protein rather than carbohydrate, thus increasing nitrogen excretion. All of the experiments are characterized by a sharp reduction in the milk yield. Cary and Meigs (23) have studied like reductions in milk yield produced by varying the energy or protein of the diet. They conclude that such decrease in milk production may be interpreted as due to the direct effect of the starvation and the consequent reduction of the energy and protein available to milk secretion. The reduction in milk yield for the experiments herein described can undoubtedly be attributed to the same causes as those cited by Cary and Meigs. The experiment where Cow 47 was given a full ration and at the same time injected with large quantities of insulin is of particular interest in this connection. The ration was adequate and the cow ate well, yet her production declined to a fifth of her normal milk yield. Her chart shows that there was a slight reduction in her blood sugar when insulin was introduced into the blood stream. It seems furthermore likely that this sugar was not as available to milk secretion, since there appears to be more than a corresponding drop in the lactose content of the milk. The work of Luck et al. would seem to indicate that there should be a like drop in the amino acids of the blood. These two conditions would lead, according to the work of Cary and Meigs, to a reduction in the concentration of the nitrogen of the milk. Actually, in the experiment as it was performed, the nitrogen increased to a value about 40 per cent above normal. A somewhat similar conflict is noted in two of the other three insulin experiments where starvation accompanied insulin injection. To this extent it would seem that the factor deserving most emphasis in its immediate effect on milk yield is the energy available, and that the later and more secondary factor is the amino acid concentration of the blood. In the starvation experiments, the butter fat percentage of the milk rises rather uniformly with the duration of starvation. In the insulin experiments, however, the charts appear to show a marked reduction in this butter fat percentage immediately after the introduction of insulin. This is particularly noticed after the second and third injections. Since the dextrose of the blood tends to be reduced and made unavailable to the general physiological processes by the presence of the large excess of insulin, and since this reduction of the butter fat percentage is noted as an accompanying phenomenon, it would appear that the blood dextrose plays a part in the synthesis of milk fat as well as being the source of the milk lactose, possibly as a source of energy in converting body fat to butter fat. In this regard the results for the treatment of Cow 47 with phloridzin are of importance. As noted by others, the introduction of phloridzin causes a marked rise in the fat percentage of the milk. The lactose per cent is also higher than that noted in starvation. Since phloridzin, by lowering the threshold for the blood sugar, causes large quantities of it to be drained from the body through the urine, and therefore reduces the reserve supply, it follows that if the insulin hypotheses are correct we should expect an eventual lowering of the lactose and of the fat below the starvation level. During the last of the experiment this is what was actually observed. The effects of starvation and of insulin furnish concordant proof for the theory that the lactose of milk is derived from the sugar of the blood. The fact that the different constituents of the milk, the fat, the lactose, the nitrogen, and the ash, do not exactly parallel each other in their behavior throughout these experiments indicates that they have in all probability separate origin. This is particularly true of the butter fat percentage, which appears to have a rate of secretion which is more or less independent of the other constituents, and higher in amount. This result would fall in line with the conclusion of the writers in a previous paper in which it was indicated that the fat of the blood was very likely deposited in the udder as fat corresponding to body fat from which source it was metabolized into the fat of milk shortly before it was needed for milk secretion. The wide variation brought about in the constituents of the milk by the treatment all point to the conclusion that in milk secretion a balance is maintained between the osmotic pressure of the milk and of the blood. Thus when the sugar of the milk is reduced either through starvation or by insulin the ash constituents rise to compensate for this reduction and make the osmotic pressure of the milk similar to that of the blood. These results further appear to indicate that the salts and the sugars are more or less independent in their passage and metabolism into milk from the other constituents. These observations are therefore in line with those obtained by Jackson and Rothera (14) and by Davidson (15) in their brilliant experiments where they modified milk secretion by returning milk or milk sugars and salts to the udder. These experiments give direct proof for the conclusion that modifications of the blood of dairy cattle produce direct and predictable modification of the milk secreted.     

Suitability of cross-bred cows for organic farms based on cross-breeding effects on production and functional traits

Data from 113 Dutch organic farms were analysed to determine the effect of cross-breeding on production and functional traits. In total, data on 33 788 lactations between January 2003 and February 2009 from 15 015 cows were available. Holstein–Friesian pure-bred cows produced most kg of milk in 305 days, but with the lowest percentages of fat and protein of all pure-bred cows in the data set. Cross-breeding Holstein dairy cows with other breeds (Brown Swiss, Dutch Friesian, Groningen White Headed, Jersey, Meuse Rhine Yssel, Montbéliarde or Fleckvieh) decreased milk production, but improved fertility and udder health in most cross-bred animals. In most breeds, heterosis had a significant effect (P < 0.05) on milk (kg in 305 days), fat and protein-corrected milk production (kg in 305 days) and calving interval (CI) in the favourable direction (i.e. more milk, shorter CI), but unfavourably for somatic cell count (higher cell count). Recombination was unfavourable for the milk production traits, but favourable for the functional traits (fertility and udder health). Farm characteristics, like soil type or housing system, affected the regression coefficients on breed components significantly. The effect of the Holstein breed on milk yield was twice as large in cubicle housing as in other housing systems. Jerseys had a negative effect on fertility only on farms on sandy soils. Hence, breed effects differ across farming systems in the organic farming and farmers can use such information to dovetail their farming system with the type of cow they use.     

Variation in carbon footprint of milk due to management differences between Swedish dairy farms

To identify mitigation options to reduce greenhouse gas (GHG) emissions from milk production (i.e. the carbon footprint (CF) of milk), this study examined the variation in GHG emissions among dairy farms using data from previous CF studies on Swedish milk. Variations between farms in these production data, which were found to have a strong influence on milk CF, were obtained from existing databases of 1051 dairy farms in Sweden in 2005. Monte Carlo (MC) analysis was used to analyse the impact of variations in seven important parameters on milk CF concerning milk yield (energy-corrected milk (ECM) produced and delivered), feed dry matter intake (DMI), enteric CH4 emissions, N content in feed DMI, N-fertiliser rate and diesel used on farm. The largest between-farm variations among the analysed production data were N-fertiliser rate (kg/ha) and diesel used (l/ha) on farm (CV = 31% to 38%). For the parameters concerning milk yield and feed DMI, the CV was approximately 11% and 8%, respectively. The smallest variation in production data was found for N content in feed DMI. According to the MC analysis, these variations in production data led to a variation in milk CF of between 0.94 and 1.33 kg CO2 equivalents (CO2e)/kg ECM, with an average value of 1.13 kg CO2e/kg ECM. We consider that this variation of ±17%, which was found to be based on the used farm data, would be even greater if all Swedish dairy farms were included, as the sample of farms in this study was not totally unbiased. The variation identified in milk CF indicates that a potential exists to reduce GHG emissions from milk production on both the national and farm levels through changes in management. As milk yield and feed DMI are two of the most influential parameters for milk CF, feed conversion efficiency (i.e. units ECM produced/unit DMI) can be used as a rough key performance indicator for predicting CF reductions. However, it must be borne in mind that feeds have different CF due to where and how they are produced.     

ROLL TUBES AND AGAR STRIP TUBES FOR THE BACTERIAL COLONY COUNT OF MILK

SUMMARY: Roll-tube colony counts, using the Astell equipment, were lower than the corresponding Petri dish counts with 27 out of 31 raw milks (87%). The difference between the counts by the two methods was greater than 25% of the plate count for 12 (39%) of the samples.
When the same dilution of milk was used for both strip-tube and plate colony counts, about equal numbers of samples gave counts from the strip tubes above and below about the colony count from plates. When, in order to obtain a more reasonable strip-tube count, the plates and strip tubes were prepared from different dilutions of the milk, the counts from the latter were, with only 3 exceptions out of 35 milks, below those from the former. The difference between the counts was greater than 25% of the plate count for 15 (43%) of the milks, a figure similar to that obtained in comparing roll-tube and plate colony counts.