The effect of CSN1S1 genotype and lactation stage on milk yield and composition were investigated in 80 extensively reared goats. Milk yield was recorded in early, mid and late lactation and individual milk samples were collected to determine: fat, protein, lactose and casein content, pH, freezing point, somatic cell count (SCC) and total microbic mesophilic count (TMC). Relative casein composition and amino acid profile were quantified by HPLC. Fatty acid profile was measured by gas-chromatography. Genotype did not affect milk yield, while this trait was significantly affected by lactation stage (P < 0·01). CSN1S1 BB goats produced significantly higher protein and casein percentages (P < 0·05). αs1-casein (CN) was significantly higher in BB and AB goats than AF and BF, showing intermediate values in AA goats (P < 0·01). The protein percentage and the αs1 and αs2-CN fractions were not affected by lactation stage, while the casein content and the β and κ-CN significantly increased throughout lactation (P < 0·01). C4 : 0 and C6 : 0 were not affected by genotype, while C8 : 0 and C10 : 0 were higher in the AA goats than BB; most of the long chain FA were higher in BB than AA goats. MUFA and PUFA increased in late lactation. In addition, BB goats showed higher essential amino acids, resulting in an optimal composition from the nutritional point of view, when compared with AA goats. The increase of MUFA, PUFA, essential and cis-FA in late lactation indicate that the lipid composition of goat's milk, with the progress of lactation, tends to improve its nutritional value.

Gelation is a significant operation in dairy processing. Protein gelation can be affected by several factors such as temperature, pH, or enzyme addition. Recently, the use of ultrasonication has been shown to have a significant impact on the formation of whey protein gels. In this work, the effect of ultrasonication on the gelation of casein systems was investigated. Gels were formed by the addition of 7·6 mm Tetra Sodium Pyro Phosphate (TSPP) to 5 wt% micellar casein (MC) solutions. Sonication at 20 KHz and 31 W for up to 30 min changed the surface hydrophobicity of the proteins, whereas surface charge was unaltered. Sonication before the addition of TSPP formed a firm gel with a fine protein network and low syneresis. Conversely, sonication after TSPP addition led to an inconsistent weak-gel-like structure with high syneresis. Gel strength in both cases increased significantly after short sonication times, while the viscoelastic properties were less affected. Overall, the results showed that ultrasonication can have a significant effect on the final gel properties of casein systems.

Product authenticity is an important topic in dairy sector. Dairy products sold for public consumption must be accurately labelled in accordance with the contained milk species. Linear discriminant analysis (LDA), a common chemometric procedure, has been applied to fatty acid% composition to classify pure milk samples (cow, ewe, buffalo, donkey, goat). All original grouped cases were correctly classified, while 90% of cross-validated grouped cases were correctly classified. Another objective of this research was the characterisation of cow-ewe milk mixtures in order to reveal a common fraud in dairy field, that is the addition of cow to ewe milk. Stereospecific analysis of triacylglycerols (TAG), a method based on chemical–enzymatic procedures coupled with chromatographic techniques, has been carried out to detect fraudulent milk additions, in particular 1, 3, 5% cow milk added to ewe milk. When only TAG composition data were used for the elaboration, 75% of original grouped cases were correctly classified, while totally correct classified samples were obtained when both total and intrapositional TAG data were used. Also the results of cross validation were better when TAG stereospecific analysis data were considered as LDA variables. In particular, 100% of cross-validated grouped cases were obtained when 5% cow milk mixtures were considered.

Curcumin is a bioactive polyphenolic compound extracted from turmeric with known anti-inflammatory properties, and its hydrophobic nature restricts its solubility and its bioaccessibility. Solubility may be improved upon binding of curcumin to native or treatment-modified casein micelles. The present work demonstrated that high hydrostatic pressure treatment of skim milk increases the binding of curcumin to caseins. The association of curcumin to casein micelles was assessed using fluorescence spectroscopy, either directly or by tryptophan quenching. The amount of curcumin associated with the milk proteins increased in pressure-treated milk, and a further improvement in the amount of bound curcumin was observed upon pressure treatment of a milk/curcumin mixture. However, in this case, some of the curcumin dissociated during storage, contrarily to what was observed for untreated milk. From a molecular standpoint, the data presented here indicate that structural modifications induced by high-pressure treatment and known to affect the structure of milk proteins result in a rearrangement of the amino acid residues in close proximity to the protein-associated curcumin.

Several mastitis-causing pathogens are able to colonize the bovine teat canal. The objective of this study was to investigate the association between the treatment of sawdust bedding with a commercial alkaline conditioner and the bacterial counts on teat skin and in the teat canal. The study used a crossover design. Ten lactating Holstein cows that were free of udder infections and mastitis were included in the study. The animals were bedded on either untreated sawdust or sawdust that had been treated with a hydrated lime-based conditioner. Once a day, fresh bedding material was added. After 3 weeks, the bedding material was removed from the cubicles, fresh bedding material was provided, and the cows were rotated between the two bedding material groups. Teat skin and teat canals were sampled using the wet and dry swab technique after weeks 1, 2, 3, 4, 5 and 6. Staphylococcus aureus, Streptococcus uberis, Escherichia coli and other coliform bacteria were detected in the resulting agar plate cultures. The treatment of the bedding material was associated with the teat skin bacterial counts of Str. uberis, Esch. coli and other coliform bacteria. An association was also found between the bedding material and the teat canal bacterial counts of coliform bacteria other than Esch. coli. For Staph. aureus, no associations with the bedding material were found. In general, the addition of a hydrated lime-based conditioner to sawdust reduces the population sizes of environmental pathogens on teat skin and in teat canals.

In this work, the genetic variation of milk FA was investigated in three different bovine breeds, the Jersey, the Piedmontese and the Valdostana, and at different lactation stages. All animals were genotyped for 21 Single Nucleotide Polymorphisms located within nine candidate genes involved in lipid synthesis: diacylglycerol acyltransferase 1 and 2 (DGAT1, 2); stearoyl-CoA desaturase (SCD); growth hormone receptor (GHR); fatty acid synthase (FASN); acyl-CoA dehydrogenase (ACAD); fatty acid binding protein (FABP4); lipoprotein lipase (LPL); and leptin gene (LEP). The highest milk-fat Jersey breed also showed the highest content of saturated FA. Throughout lactation, the breeds showed a similar variation in the FA, with a decrease in the short-chain, this was accompanied by a general increase in the long chain FA at the end of lactation. The increase in long chain saturated FA was particularly evident in the case of the Jersey. The effect of SCD gene on the C14 desaturation index was confirmed; the DGAT1 gene was polymorphic only in the Jersey breed, but its effect was confirmed only on milk fat content; three further potential candidate genes were identified: first, the FABP4 gene, which was found to influence medium and long chain FA in all the breeds, but not the desaturation indices; second, the FASN gene, which was found to influence the amount of PUFA in the Piedmontese and the Valdostana, and third, the LPL gene, which was found to affect fat content in the Piedmontese.

Considerable inhibitory antibacterial actions were exerted by the soybean 11S subunit comparable with nisin on the proliferation of total viable count, Pseudomonas count and Enterobacteriaceae count in bovine milk stored at 4 or 25 °C for 30 d and 48 h, while 7S and lysozyme were much less effective. The maximum magnitudes of bacterial reduction by 11S and nisin were in the range 2–4 log CFU/ml. The proliferation of 3 pathogenic bacteria (Listeria monocytogenes, Salmonella Enteritidis and Escherichia coli O157:H7) artificially inoculated into raw milk stored at 4 or 25 °C were particularly and significantly (P<0·05) reduced by 11S subunit and nisin (0·5% w/v), but only slightly by 7S and moderately by lysozyme. Lactose consumption, acidity development and casein degradation during storage of bovine raw milk were attenuated during storage at 4 or 25 °C and sensorial traits were better maintained by supplementation with 11S (0·5% w/v). 11S subunit may be used a safely food preservative, if permitted.

High fat dairy products, such as butter and margarine can be contaminated during the milk production process with a residue called Trichloromethane (TCM), which results from the use of chlorine based detergent solutions. Although, TCM concentrations in Irish products are not at levels that are a public health issue, such contamination can cause marketing difficulties in countries to which Irish products are being exported. In an attempt to reduce such milk residues, a template procedure was developed, tried and tested on 43 farms (from 3 processing companies). This involved identifying farms with high TCM milk, applying corrective action in the form of advice and recommendations to reduce TCM and re-measuring milks from these farms. Trichloromethane in milk was measured by head-space gas chromatography with electron capture detector. The TCM reduction strategy proved successful in significantly reducing the levels in milk in the farms tested, e.g. TCM was reduced from 0·006 to the target of 0·002 mg/kg (P < 0·05). The strategy was then applied to farms who supplied milk to six Irish dairy processors with the objective of reducing TCM in those milks to a level of ⩽0·002 mg/kg. Initially, milk tankers containing milks from approximately 10–15 individual farms were sampled and analysed and tankers with high TCM (>0·002 mg/kg) identified. Individual herd milks contributing to these tankers were subsequently sampled and analysed and farms supplying high TCM identified. Guidance and advice was provided to the high TCM milk suppliers and levels of TCM of these milk supplies were monitored subsequently. A significant reduction (minimum P < 0·05) in milk TCM was observed in 5 of the 6 dairy processor milks, while a numerical reduction in TCM was observed in the remaining processor milk.

As grain prices rise, the search for alternative glycogenic precursors in animal feed becomes increasingly important, and this study was conducted to determine if the replacement of starch with glycerol, as an alternative glycogenic precursor, affects the milk metabolic profile and milk coagulation ability, and therefore the quality of the milk. Eight primiparous mid-lactation Holstein cows were fed during a replicated 4 × 4 Latin square trial with four different isoenergetic rations: (1) control (T0) fed a total mixed ration (TMR) with barley meal; (2) group T1, decreased barley content, replaced isoenergetically with 1 kg crude glycerol; (3) group T2, the barley meal was replaced with 2 kg of crude glycerol; and (4) group T3 the barley meal was replaced with 3 kg of crude glycerol. Rumen, blood and milk samples were collected at the end of every 21-d treatment period. Rumen samples were analysed for proportion of total volatile fatty acid (VFA), blood samples for insulin and glucose, and milk for metabolites (e.g. citric-acid cycle compounds). The change in glycogenic precursors had a positive effect on rumen VFA proportions; the proportion of propionic acid increased (P < 0·001). Milk protein (P < 0·001) and curd firmness (P < 0·001) both increased. The increase in milk protein concentration may have been due to an increase in microbial protein. Regarding the milk metabolic profiles, different signals were positively associated with coagulation ability and change in the diet. Based on this study, changing the glycogenic precursor in animal diet in this way is possible, and may have no immediate deleterious consequences on milk quality or cow health. Indeed, there is evidence for benefits from this substitution.

The objective of this study was to determine the effect of cow genetic strain on fatty acid (FA) profiles in adipose tissue and milk. Adipose samples from two subcutaneous (shoulder and tail-head) and three visceral (kidney channel, mesenteric and omental) depots were obtained post mortem from New Zealand (NZ; n = 8) and North American (NA; n = 8) Holstein–Friesian cows. At the time of slaughter cows were in similar body condition (NZ: 4·0 ± 0·03, NA: 4·0 ± 0·02; ±sd) and stage of lactation (NZ: 90 ± 11·2 d; NA: 83 ± 4·3 d; ±sd). Milk was collected during the a.m. milking prior to slaughter and milk fat was extracted. Adipose and milk fat FA were quantified using gas chromatography. NZ cows had a lower proportion of saturated FA in shoulder, tail-head and omental adipose tissue and a greater proportion of mono-unsaturated FA and an elevated Δ9-desaturase index in shoulder and tail-head adipose tissue. The proportions of individual FA differed between adipose depots, with proportions of de-novo FA greater in subcutaneous compared with visceral adipose depots. Milk from NZ cows contained greater concentrations of short chain FA (C8 : 0–12 : 0) and CLA, and less cis-9 18 : 1 than milk from NA cows. Regression analysis identified moderate associations between milk FA and shoulder adipose tissue FA for 18 : 2 (R2 = 0·24), 18 : 3 n − 3 (R2 = 0·39), and polyunsaturated fatty acids (R2 = 0·38). Results from this study support the hypothesis that genetic strain dictates FA profiles in adipose tissue and milk and may alter the metabolic status of the various adipose depots differently. The data further support the premise that genetic strain affects the metabolic status of the various adipose depots differently. Elucidating the mechanisms that regulate the different adipose depots in the NZ and NA strains will increase our understanding of tissue mobilization and replenishment.

An effective strategy for enhancing the bioactive fatty acids (FA) in sheep milk could be dietary supplementation with a moderate level of a combination of soybean oil with fish oil (SFO) without negative effects on milk yield and its chemical composition. Thus, the objective of this study was to determine the effects of a moderate forage diet supplementation with SFO on milk chemical composition and FA profile, as well as on plasma FA. Twelve dairy sheep were assigned to two homogenous sub-groups. Treatments involved a control diet without added oil, and a diet supplemented with 23·6 g soybean oil and 4·7 g fish oil per kg dry matter (DM) of the total ration. The results showed that SFO diet had no effect on milk yield and chemical composition. In blood plasma the concentrations of trans-11 C18:2 (VA), C18:2n-6, C20:5n-3 (EPA) and C22:6n-3 (DHA) were significantly higher while those of C14:0, C16:0 and C18:0 were lower in sheep fed with SFO diet compared with control. The SFO supplementation of sheep diet increased the concentrations of VA, cis-9, trans-11 C18:2 CLA, trans-10, cis-12, C18:2 CLA, EPA, DHA, monounsaturated FA (MUFA), polyusaturated fatty acids (PUFA) and n-3 FA and decreased those of short chain FA (SCFA), medium chain FA (MCFA), the saturated/unsaturated ratio and the atherogenicity index value in milk compared with the control. In conclussion, the SFO supplementation at the above levels in a sheep diet, with moderate forage to concentrate ratio, improved the milk FA profile from human health standpoint without negative effects on its chemical composition.

Goat milk protein was hydrolysed with subtilisin and trypsin. As input variables, temperature was assayed in the interval 45–70 °C for subtilisin and 30–55 °C for trypsin, while the enzyme-substrate ratio varied from 1 to 5%. The effect of the input variables on the degree of hydrolysis and ACE-inhibitory activity (output variables) was modelled by second order polynomials, which were able to fit the experimental data with deviations below 10%. The individual maximum values of the degree of hydrolysis and the ACE-inhibitory activity were found at conflicting conditions of temperature and enzyme-substrate ratio. Since such maximum values could not be reached simultaneously, a bi-objective optimisation procedure was undertaken, producing a set of non-inferior solutions that weighted both objectives.

Staphylococcus aureus isolates from dairy cow mastitis are not always consistent with the characteristic morphology described, and molecular investigation is often needed. The aim of the study was to develop a duplex real-time PCR assay for rapid identification of Staph. aureus isolates, targeting both nuc and Sa442. Overall, 140 isolates collected from dairy cow mastitis in 90 different herds, were tested. All strains had been identified using morphological and biochemical characteristics. DNA from each strain was amplified in real-time PCR assay, to detect nuc or Sa442. Thereafter, a duplex real-time PCR assay was performed, and specificity of the amplified products was assessed by high resolution melting curve analysis. Out of 124 Staph. aureus isolates, 33 did not show the typical morphology or enzymic activity; in 118 strains, the two melt-curve peaks consistent with nuc and Sa442 were revealed, while 2 isolates showed only the peak consistent with Sa442. Four isolates bacteriologically identified as Staph. aureus, were PCR-negative and were further identified as Staph. pseudintermedius by sequencing. Staph. pseudintermedius and coagulase-negative staphylococci did not carry nuc or Sa442. The results showed the correct identification of all isolates, comprehending also coagulase—or nuc-negative Staph. aureus, while other coagulase-positive Staphylococci were correctly identified as non-Staph. aureus. Both sensitivity and specificity were 100%. High resolution melting analysis allowed easy detection of unspecific products. Finally, the duplex real-time PCR was applied directly to 40 milk samples, to detect infected mammary quarters. The assay confirmed the results of bacteriological analysis, on Staph. aureus-positive or—negative samples. Therefore, the proposed duplex real-time PCR could be used in laboratory routine as a cost-effective and powerful tool for high-throughput identification of atypical Staph. aureus isolates causing dairy cow mastitis. Also, it could be applied directly to milk samples, to detect Staph. aureus mammary infections avoiding bacteriological analysis.

The aims of this study were to test the assumption that tissue-type plasminogen activator (t-PA) and plasminogen (PG) are closely associated with the casein micelle and form a functional complex that rules casein degradation. This assumption was essentially verified for bovine milk under conditions wherein the plasmin system was activated by treatment with casein hydrolysate. It was also shown that urokinase-type PA (u-PA), the second type of plasminogen activator present in milk, was not involved in casein degradation. In agreement with previous studies, we show that treatment with casein hydrolysate precipitously reduced mammary secretion, disrupted the tight junction integrity (increase in Na+ and decrease in K+ concentrations), induced hydrolysis of casein, and activated various elements of the innate and acquired immune system. In the present study, we have identified t-PA as the principal PA, which is responsible for the conversion of PG to plasmin. It was found that t-PA and plasminogen are present in freshly secreted milk (less than 10 min from its secretion), suggesting that they are secreted as a complex by the mammary gland epithelial cells. Further research is needed to provide the direct evidence to verify this concept.

A concurrent determination of folate versus folic acid in milk by microbiological assay (MA) with Lactobacillus rhamnosus as the assay organism, Enzyme Linked Immuno Sorbent Assay (ELISA) by competitive binding rapid ELISA kit (RIDASCREEN®) and high-pressure-liquid chromatography (HPLC) was done for detection of the folate form and its level. MA gave total folate content as Lb. rhamnosus showed similar response to most folate isomers formed by the tri-enzyme treatment in comparison with the other two methods which specifically estimated the folic acid. In case of ELISA, specificity was apparently limited to folic acid and dihydro folic acid and thereby showed a lower response for other folate derivatives. Estimation by HPLC with UV detector was highly specific and hence only folic acid could be detected without any cross reactivity. Among the different methods HPLC was observed to be the most sensitive method for determination of folic acid and hence can efficiently determine the folic acid fortification level while MA remained highly efficient, sensitive and reproducible method for estimation of total folate indicating its potential use for dietary folate estimation.

The overall objective of this study was to evaluate agreement between rectal (RT) and vaginal temperature (VT) measured with the same temperature loggers in dairy cows. Three experiments were conducted. The study began with a validation in vitro of 24 temperature loggers comparing them to a calibrated liquid-in-glass thermometer as a reference method. The association and agreement between the 24 temperature loggers with the reference method was r=0·996 (P<0·001) with a negligible coefficient of variance (0·005) between the loggers. In-vivo temperature loggers were tested in 11 healthy post-partum cows (Experiment 2) and 12 early post-partum cows with greater body temperature (Experiment 3). Temperature loggers were set to record VT and RT at 1-min intervals. To prevent rectal and vaginal straining and potential expulsion of temperature logger an epidural injection of 2·5 ml of 2% Procain was administered. Association between RT and VT was r=0·92 (P<0·001; Experiment 2) and r=0·94 (P<0·001; Experiment 3) with a negligible difference of −0·1 and 0·01 °C. Bland-Altman plots demonstrated agreement between RT and VT for healthy and early post-partum cows with greater body temperature in Experiments 2 and 3, respectively. Furthermore the intra-class correlation coefficient between RT and VT measured with identical loggers within cows of Experiments 2 and 3 also demonstrated greater agreements (P<0·001). Therefore, continuous VT monitoring with temperature loggers can be used as a measure of body temperature in dairy cows.

Calcium-fortified foods, especially milk and dairy products are recommended to be consumed daily for groups in risk of nutritional deficiency, including children, young adults, menopausal women, pregnant women and the elderly, however Ca-supplementation promotes gallstone formation because Ca is a nucleating factor. The objective of the current study was to assess the influence of cow or goat milk-based diets, either normal or Ca-supplemented, on bile composition, biochemical parameters and hepatic antioxidant status. Weanling male rats were randomly divided into six groups, fed standard, goat or cow milk-based diets, either with normal Ca content (5·0 g/kg), or Ca-supplemented (10·0 g/kg), for 2 weeks. Bile cholesterol concentration and output was higher in rats fed goat milk in comparison with those fed with standard and cow-milk-based diet. Ca-supplementation increased lithogenic index with the standard and cow-milk based diets, this change was not observed with the goat milk diet. Activities of plasma transaminases were also lower in the animals fed Ca-supplemented goat milk, in comparison with the other diets assayed. In general, Ca-supplement in the diet led to an increase in the hepatic oxidative damage, with an increase in the activities of all the antioxidant enzymes studied in the standard and cow milk diet, but not with goat milk. The habitual consumption of goat milk has positive effects on the plasma lipid profile, biliary composition and hepatic antioxidant defence. In addition, under our experimental conditions, Ca-supplementation of this type of milk does not increase the lithogenic index, or hepatic oxidative damage.