The pH and calcium activity of reconstituted skim milk solutions (9–21% w/w milk solids non-fat) on heating and after cooling were studied as a function of milk pH prior to heating (pH 6·2–7·2 at 25°C) and added calcium complexing agents (phosphate or EDTA). The pH decreased as the temperature was raised from 25 to 90°C and the magnitude of the pH decrease was greater with increase in initial pH at 25°C before heating or milk concentration. The pH decrease on heating from 25 to 90°C in skim milk solutions with added calcium complexing agents was lower than that of milk without the addition of these salts. The calcium activity decreased on heating from 25 to 60°C. The magnitude of the change decreased with increase in initial pH at 25°C before heating and milk concentration. The decrease in calcium activity on heating from 25 to 60°C for skim milk solutions with added calcium complexing agents was lower than that of milk solutions without the addition of calcium complexing agents. The changes in pH and calcium activity on heating milk were largely reversible after cooling the milk. The results suggested that the pH and calcium activity at high temperatures are a function of the milk composition. Knowledge of the initial pH prior to heating alone is not sufficient for predicting the changes that occur during heating.

The viability of five single-strain and one three-strain probiotic cultures was assessed during Pategrás cheese ripening. Probiotics were inoculated into cheese-milk after a pre-incubation step – intended to improve their survival – or directly as a lyophilised culture; control cheeses without probiotics were also obtained. pH of probiotic and control cheeses was similar, except in probiotic cheeses containing the strain Lb. acidophilus B or the mixed culture. In these cases, the probiotic cheeses were more acid than their respective control cheeses. All the probiotics tested maintained counts above 107 cfu/g during the shelf-life settled for the product. Strains of the Lb. casei group: Lb. paracasei, Lb. casei and Lb. rhamnosus reached and kept the highest cell concentration during cheese ripening, followed by Lb. acidophilus and bifidobacteria. The direct addition of the probiotic cultures was more efficient than their inoculation after a pre-incubation step, for all the probiotics assayed. We have provided evidence that support the use of Pategrás cheese as a performing food-based vehicle for probiotic bacteria.

The effects of dry period omission on oxidative stress and metabolic indicators around calving were studied. Seventeen Italian Friesian cows were randomly assigned to two groups, homogeneous for milk yield and parity, and managed either with a traditional 55-d dry off period (n=8) or continuously milked till parturition (n=9). Between 60 d before expected calving and 90 d after calving, body condition (BCS) was recorded and blood samples were collected to measure cortisol, urea, cholesterol, glucose, NEFA, triglycerides, insulin, malondialdehyde (MDA), total glutathione (GSH) and glutathione peroxidase (GPx) activity. BCS changes after calving were not different between the two groups. The normally dried group showed lower (P<0·05) glucose concentrations on day 7 before calving, greater (P<0·01) non-esterified fatty acid concentrations at 7 d and 15 d after calving, and greater (P<0·01) triglyceride concentrations for all the period before calving. On the other hand, plasma MDA was not different between groups. On average, plasma GSH concentrations were greater in continuously milked cows after calving (P<0·05), while plasma GPx was greater with continuous milking up to parturition (P<0·01). The results confirmed that omitting the dry period leads to an improved energy balance. The degree of oxidative stress was not detrimental for animal health, and the slight modifications of GPx observed prepartum were possibly related to continuous milk secretion. The differences in plasma GSH observed after calving may depend upon sulphur amino acid sparing in continuously milked cows.

The present study aimed to assess the effect of information about organic production on Pecorino cheese liking and consumer willingness to pay. Mean scores of perceived liking were similar for organic cheese (OC) and conventional cheese (CC). Expected liking scores were higher for OC than for CC (P<0·001). For OC the expected liking was significantly higher (P<0·001) than the perceived liking expressed in blind conditions (negative disconfirmation), whereas for CC the expected liking was significantly lower (P<0·001) than the perceived liking expressed in blind conditions (positive disconfirmation). Consumers assimilated their liking for OC in the direction of expectations, as the difference actual vs. perceived liking was significant (P<0·001). However the assimilation was not complete, as also the difference actual liking vs. expected liking was significant (P<0·001). Consumers showed a willingness to pay OC (mean±se=4·20±0·13 €/100 g) higher than the local retail price for conventional (1·90 €/100 g) and even organic cheese (3·00 €/100 g). We conclude that the information about organic farming can be a major determinant of cheese liking and consumer willingness to pay, thus providing a potential tool for product differentiation, particularly for small scale and traditional farms.

This study compares the colouring capacity of Brevibacterium aurantiacum (BA), Brevibacterium BL and Arthrobacter species AS in relation to deacidified media made from lactic curd (Epoisses), mixed curds (Munster) and rennet curds (Livarot or Reblochon). BA colouring capacity proved to be constant, leading to a dark orange colour, irrespective of the deacidified media. However, it gave too dark a colour for Reblochon. The strains BL and AS were not adapted to the colouring of Epoisses deacidified medium. On the Livarot or Munster deacidified medium, these two strains provided a light yellow orange colour range that was not suitable for these cheeses. However, these two strains (BL and AS) produced a suitable colour for Reblochon deacidified medium.

Diet is a relatively simple way to modify milk fat yield and composition in dairy cows as the end-products of digestion are precursors or inhibitors of milk fat synthesis. The individual effects of these end-products are well-known, but it is still not known whether these nutrients have an additive effect or an interaction effect on milk fat secretion. Thus our objective was to investigate the effects of two of these nutrients on milk fat secretion, trans-10, cis-12 conjugated linoleic acid (CLA) and propionic acid (C3) supplied alone or together, under the same experimental conditions. Four Holstein dairy cows were used in a 4×4 Latin square design with 14-d periods. Treatments were control, CLA (duodenal infusion of 1·85 g/d of trans-10, cis-12 CLA), C3 (ruminal infusion of 500 g/d of C3) and CLA+C3 (duodenal infusion of 1·85 g/d of trans-10, cis-12 CLA plus ruminal infusion 500 g/d of C3). Infusions of trans-10, cis-12 CLA reduced milk fat content and yield by 18% whereas C3 infusions had no significant effect on milk fat secretion. Trans-10, cis-12 CLA decreased the yields of all milk fatty acids (FA). This reduction was proportionally greater for FA synthesized de novo than for preformed long-chain FA. Infusions of C3 decreased the yields and percentages of 4:0 and 18:0 and increased the yields and percentages of all odd-chain FA. Interactions between trans-10, cis-12 CLA and C3 infusions on milk fat content, yield and FA composition were never significant. Overall, this study showed that trans-10, cis-12 CLA has different and greater effects on milk fat secretion than C3. Moreover, under our experimental conditions, their effects on milk FA yields, which reflect their effects on mammary lipogenesis, were additive, whatever their individual effect.

The oxidative process in milk fat, resulting in spontaneous oxidized off-flavour (SOF), is commonly assumed to depend on contents of pro- and antioxidants in milk and availability of fatty acids acting as their substrate. An important antioxidant in milk is α-tocopherol whereas the most potent prooxidant is the metal ion copper. The separate effects of α-tocopherol, copper, and milk fatty acid profile, and their combined effect on SOF development were examined in milk from 44 multiparous cows fed different roughage types and different amounts of dietary, unsaturated fat. A clear association between concentrations of copper and poly-unsaturated fatty acids in milk and the risk for developing SOF was found. Heritability estimates suggest that occurrence of SOF is partly under genetic control which indicates that milk quality may be compromised if breeding bulls are selected that carry genotypes predisposing for milk prone to develop SOF.

This paper reports the results of a study that aimed to assess whether liver functionality defined by liver activity index (LAI) is associated with inflammatory and immune parameters in blood and milk. LAI is an index including the average blood levels of albumin, lipoproteins and retinol-binding protein measured three times in the first month of lactation (at 5, 15 and 30 days in milk). The aim was to assess the relationship of this index with blood and udder immune and inflammatory status as a means of identifying as early as possible cows at risk of disease. The research was carried out using 10 multiparous Italian-Friesian dairy cows of average genetic merit. Cows were retrospectively ranked in three groups according the LAI level. Blood samplings were performed at different intervals before and after calving; quarter milk samples were taken only after calving with the same schedule as blood samples. Leucocytes, oxidative burst, blood lysozyme and N-acetyl-β-d-glucosaminidase (NAGase) curves showed large overlapping among the three LAI group curves during the follow-up period. Four blood (complement, sialic acid, haptoglobin and reactive oxygen metabolites) and three milk (somatic cell count, lysozyme and NAGase) parameters showed larger and more consistent differences among LAI groups. Complement showed higher values and sialic acid showed lower values in high LAI group when compared with the other two LAI groups. Two other markers of inflammatory status (haptoglobin and reactive oxygen metabolites) showed the lowest values in high LAI cows. A consistent and significant reduction of milk NAGase and milk lysozyme in high LAI group was observed. The results suggest that cows with the highest liver functionality index have also the highest levels of some immune markers and the lowest levels for inflammatory markers at blood (already before calving) and mammary levels. Finally, cows with low LAI index, being more susceptible to metabolic and infectious diseases, should be carefully monitored to identify as early as possible the development of a disease.

The effect was quantified of coagulase-negative staphylococci (CNS) intramammary infections on quarter- and cow-level somatic cell count (SCC) and on bulk milk somatic cell count (BMSCC) in different BMSCC cohorts in Dutch dairy herds. Two datasets were used for this purpose. In the first dataset, on 49 randomly selected dairy farms a total of 4220 quarter milk samples of 1072 cows were collected of all cows and heifers with a test-day SCC ⩾250 000 and ⩾150 000 cells/ml, respectively, and of 25% of cows and heifers below these thresholds. In the second dataset, on 39 selected dairy farms a total of 8329 quarter milk samples of 2115 cows were collected of all cows with a test-day SCC ⩾250 000 cells/ml following two consecutive SCC <250 000 cells/ml, and of heifers using the same SCC criteria but with a threshold of 150 000 cells/ml. These cows and heifers were defined as new high SCC. In both datasets, CNS was the most frequently isolated pathogen, 11% in the first dataset and 12% in the second dataset. In both datasets, quarters with CNS IMI had a lower SCC than quarters infected with major pathogens, and a higher SCC than culture-negative quarters. The same was found for SCC at cow level. Coagulase-negative staphylococci were more often found in quarters with SCC ⩾200 000 cells/ml in dairy farms with a BMSCC <150 000 cells/ml compared with dairy farms with a higher BMSCC. Prevalence of CNS in cows and heifers with a high SCC was higher in dairy farms with a BMSCC <150 000 cells/ml compared with dairy farms with a medium or high BMSCC: 30, 19 and 18%, respectively. This indicates that CNS IMI as a cause of subclinical mastitis is relatively more important in dairy farms with a low BMSCC and may become a point of attention in udder health management on that type of farm.

This study aimed to reduce the time taken to detect low numbers of Cronobacter sakazakii inoculated onto environmental swabs (100, 10 or 1 cfu per swab) using a simple plating procedure for application in a dairy testing laboratory. Three types of environmental swabs (Biolab FlexiSwab™, gauze swabs and the Whatman SwabCheck Polywipe™ sponge) were inoculated with either Cron. sakazakii in single culture or Cron. sakazakii together with Citrobacter freundii. A 5-h enrichment procedure of swabs in Cronobacter enrichment broth at 37°C prior to plating was then compared with no enrichment or 24-h enrichment. The 5-h enrichment procedure was as efficient at detecting Cron. sakazakii on environmental swabs at low cell concentrations (100 cfu per swab), and in pure culture or in competition with other coliforms (Citrobacter), as pre-enrichment for 24 h. This protocol was also successful in detecting 10 cfu per swab 80% of the time. The results also indicated that the type of swab selected for use in environmental safety programmes is influential on the outcome, with the FlexiSwab™ and gauze swabs being the most efficient swabbing materials evaluated in this study.

The transfer of ingested α-linolenic acid (ALA) and linoleic acid (LA) determines the nutritional quality of milk, but the factors determining this transfer are unclear. The present experiment investigated the influence of roughage to concentrate proportions and the effect of concentrate types on milk fat composition. Respectively, six lactating dairy cows were fed one of three isoenergetic (5·4±0·05 MJ net energy for lactation/kg dry matter; DM) and isonitrogenous (215±3·5 g crude protein/kg DM) diets, consisting of ryegrass hay only (33 g fatty acids/kg DM; ALA-rich, no concentrate), maize (straw, whole maize pellets and gluten; 36 g fatty acids/kg DM; LA-rich; 560 g concentrate/kg DM), or barley (straw and grain plus soybean meal; 19 g fatty acids/kg DM; LA-rich; 540 g concentrate/kg DM). The fatty acid composition of feeds and resulting milk fat were determined by gas chromatography. The ALA concentration in milk fat was highest (P<0·001) with the hay-diet, but the proportionate transfer of ALA from diet to milk was lower (P<0·001) than with the maize- or barley-diets. The LA concentration in milk fat was highest with the maize-diet (P<0·05, compared with hay) but relative transfer rate was lower (P=0·01). The transfer rates of ALA and LA were reciprocal to the intake of individual fatty acids which thus contributed more to milk fat composition than did roughage to concentrate proportions. The amount of trans-11 18:1 in milk fat was lowest with the barley-diet (P<0·001) and depended on the sum of ALA and LA consumed. The milk fat concentration of cis-9, trans-11 18:2 (rumenic acid) was more effectively promoted by increasing dietary LA (maize) than ALA (hay). Amounts of 18:0 secreted in milk were four (maize) to seven (hay) times higher than the amounts ingested. This was suggestive of a partial inhibition of biohydrogenation in the maize-diet, possibly caused by the high dietary LA level.

The impact of fresh legume types or silage on the composition of milk fatty acids and transcription of enzymes involved in the synthesis of milk fat in cows was studied. Three groups of cows grazed high proportions of white clover, red clover and lucerne, respectively. A fourth group of cows was fed maize/grass silage. The cows grazing high proportions of legumes produced significantly more 18:1 trans-11, 18:2 cis9-trans11, 18:2 trans10-cis12 and 18:3 fatty acids than cows fed silage. White clover and lucerne grazing resulted in significantly lower output of 18:1 trans9 in milk than red clover grazing and maize/grass silages. Transcription of stearoyl-CoA desaturase (SCD) in mammary tissue was significantly increased by grazing high proportions of legume whereas fatty acid synthase and acetyl-CoA carboxylase were not affected by type of feeding. Furthermore, average milk fat globule diameter was correlated to daily milk fat yield but was not affected by feeding. Although the fresh forage affected the transcription of SCD in mammary tissue, the largest effects were on the trans11-based fatty acids. It is concluded that type of forage, i.e. fresh or silage, had a greater impact on rumen fermentation pattern than on transcription of enzymes involved in the synthesis of milk fat.

The objective of this study was to investigate whether there is a difference in chemical composition and particularly in fatty acid (FA) profile, with emphasis on cis-9, trans-11 CLA, of milk obtained from conventional and organic dairy sheep and goats farms under the farming conditions practiced in Greece. Four dairy sheep and four dairy goat farms, representing common conventional production systems and another four dairy sheep and four dairy goat farms, organically certified, representing organic production and feeding systems were selected from all over Greece. One hundred and sixty two individual milk samples were collected from those farms in January–February 2009, about three months after parturition. The milk samples were analyzed for their main chemical constituents and their FA profile. The results showed that the production system affected milk chemical composition: in particular fat content was lower in the organic sheep and goats milk compared with the corresponding conventional. Milk from organic sheep had higher content in MUFA, PUFA, α-LNA, cis-9, trans-11 CLA, and ω-3 FA, whereas in milk from organic goats α-LNA and ω-3 FA content was higher than that in conventional one. These differences are, mainly, attributed to different feeding practices used by the two production systems. The results of this study show that the organic milk produced under the farming conditions practiced in Greece has higher nutritional value, due to its FA profile, compared with the respective conventional milk.

Optimization of the cultivation conditions and medium components for folate production by the highest folate producing Streptococcus thermophilus strain RD102 was carried out using a 23 central composite design and surface modelling method of response surface methodology. As folate production was observed to be growth-associated, hence the desired responses selected for the optimization were both folate production and growth. The selected factors based on preliminary investigations were incubation period, concentrations of p-amino benzoic acid (PABA) the growth precursor, and lactose as carbon source. The optimum concentrations of PABA and lactose were found to be 300 μm and 3% respectively at 72 h incubation. The optimized conditions resulted in an increase in folate production by 26% compared with control conditions (0% PABA and lactose at 37°C). Using the method of experimental factorial design and response surface analysis, it was possible to determine optimal operating conditions to obtain a higher folate production by Strep. thermophilus. Therefore, this study constitutes a step in developing strategies to modulate the folate level to a higher level.

Lactoperoxidase (LP) was isolated from whey protein by cation-exchange using Carboxymethyl resin (CM-25C) and Sulphopropyl Toyopearl resin (SP-650C). Both batch and column procedures were employed and the adsorption capacities and extraction efficiencies were compared. The resin bed volume to whey volume ratios were 0·96:1·0 for CM-25C and ⩽0·64:1·0 for SP-650 indicating higher adsorption capacity of SP-650 compared with CM-25C. The effluent LP activity depended on both the enzyme activity in the whey and the amount of whey loaded on the column within the saturation limits of the resin. The percentage recovery was high below the saturation point and fell off rapidly with over-saturation. While effective recovery was achieved with column extraction procedures, the recovery was poor in batch procedures. The whey-resin contact time had little impact on the enzyme adsorption. SDS PAGE and HPLC analyses were also carried out, the purity was examined and the proteins characterised in terms of molecular weights. Reversed phase HPLC provided clear distinction of the LP and lactoferrin (LF) peaks. The enzyme purity was higher in column effluents compared with batch effluents, judged on the basis of the clarity of the gel bands and the resolved peaks in HPLC chromatograms.

During the normal course of lactation, mammary metabolic activity and blood flow are closely correlated. Six lactating goats were used in this experiment to test the hypothesis that the capillary network and the capillary enzyme, carbonic anhydrase (CA; EC 4.2.1.1) are important regulatory factors involved in the coordination of mammary blood flow (MBF) and metabolic activity. Milk vein blood velocity was determined as a measure of MBF, and fine needle mammary biopsies were obtained at different time points during lactation and by the end of a 14-d bovine somatotropin (BST) treatment initiated 3 months post partum. In mammary sections, CA activity was determined histochemically and alveolar and capillary structures by image analyses upon azure blue staining. In early lactation, alveoli were large and surrounded by many small capillaries with high CA activity. As lactation progressed, capillaries almost tripled in size, whereas number of capillaries surrounding each alveolus decreased by 1/3, and CA activity more than halved. BST treatment did not affect capillary traits but increased number of alveoli in mammary sections, and BST thus appeared to be targeted mostly towards the mammary epithelial cell. Milk vein blood velocity decreased over the course of lactation, when capillary area markedly increased, suggesting that control of mammary blood perfusion is not at the level of the capillary itself, but at pre- or post-capillary sites. We suggest that the observed changes in capillary diameter and CA activity with progressing lactation contributes to reduce efficiency of nutrient and waste product exchange across the capillary-mammary epithelial cell barrier, and this could be an important factor in regulation of mammary (epithelial cell) metabolic activity and lactation performance.

The objective of this study was to investigate the effect of ruminal infusion of soybean oil (SBO) with either a moderate- or high-forage diet on fat concentration, yield and composition in milk from dairy cows. Six rumen-fistulated Holstein dairy cows (639±51 kg body weight, 140±59 days in milk) were used in the study. Cows were randomly assigned to one of two dietary treatments, a high forage:concentrate (HFC, 74:26) or a moderate forage:concentrate (MFC, 56:44) total mixed ration. Cows were fed at 08.00 and 13.00 h and pulse-dosed ruminally at 13.00 h over a 10-min duration with 2% of diet dry matter of SBO. Ruminal pH was recorded continuously. Cows receiving the MFC treatment had lower daily mean ruminal pH and ruminal pH was below 6·0 for a longer duration compared with the HFC treatment (640 vs. 262 min/d, P<0·05). Cows receiving the MFC treatment had a greater reduction (diet by week interaction, P<0·05) in milk fat concentration and yield than cows receiving the HFC treatment (42 vs. 22% and 45 vs. 21%, respectively). Additionally, cows receiving the MFC diet had a greater reduction in milk fat concentration (g/100 g FA) of FA <C16 (14 vs. 8%), and a greater increase in concentration of FA >C16 (17 vs. 9%), trans-10 18:1 (159 vs. 21%) and trans-9, cis-11 conjugated linoleic acid (121 vs. 55%) (P<0·05) compared with cows receiving the HFC diet. This study demonstrated that cows fed the MFC diet had lower ruminal pH and showed a greater rate of milk fat depression when infused with SBO.