This research communication aimed at assessing the microbial quality and preparation practices of dahi/thayir, a popular traditional fermented milk product, in households from two distinct agroecological zones in Kerala, India, namely the high-range and central midland, We highlighted the significant variations and potential food safety concerns associated with regional differences in production methods. The local climate significantly influenced the incubation temperature of dahi/thayir, thereby influencing the types of microflora involved in the fermentation process. Data on preparation practices and sensory preferences were collected from producers during the sampling process, covering 200 households. There were significant variations in preparation practices between the two regions, particularly concerning the type of container used, inoculation rate and incubation period. Samples from the high-range region exhibited significantly higher acidity and coliform count as well as yeast and mold count than the central midland region. The household fermentation of milk is often uncontrolled, causing increased acidity levels. This uncontrolled fermentation favored the growth of contaminants such as coliforms and yeast, posing a potential threat to food safety. This study underscores the importance of understanding microbial quality variations and preparation practices in dahi/thayir production, emphasizing the need for proper fermentation techniques and hygienic practices to ensure the safety and quality of this traditional fermented milk product.

This research paper analyzes the stability of raw cow milk in the alcohol test and seeks to understand to know the factors that influence milk stability and the occurrence of unstable non-acid milk. Milk samples were collected from the cooling tanks of rural farmers in the state of Paraná twice in summer and twice in winter. The farms were classified according to the production system: pasture with supplementation and feedlot. The following variables were analyzed: stability in the alcohol test, titratable acidity, ionized calcium concentration (iCa), chemical composition of milk, somatic cell count and standard plate count. The results showed that milk stability was greater in winter vs. summer, when the milk contained higher iCa, and in the feedlot vs. pasture system. The Pearson Correlation between variables (ethanol stability, milk composition, iCa, cooling tank temperature, milk volume, number of milking, number of cows milked, fat/protein ratio, distance and travel time) were analyzed. Stability was negatively correlated with iCa concentration and positively with lactose content. Logistic regression of the risk of unstable non-acid milk at 72% alcohol (UNAM72) showed that only iCa and lactose were determinants, while evaluation of the same risk at 78% alcohol revealed iCa, titratable acidity, lactose and milk urea nitrogen as risk factors. Under the dairy farming conditions of Paraná state, the frequency of UNAM72 was low (12.16%) and was higher in summer and in pasture systems with supplementation. In conclusion, in dairy herds bred with high technological level, with adequate nutritional and health management, the frequency of UNAM is low and is related to nutritional management abnd, perhaps, heat stress, factors that alter iCa and lactose levels.

The objectives of this research were (1) to study different factors affecting milk total bacterial count (TBC) and (2) to estimate the economic value associated with TBC in Holstein dairy herds in Iran. The relationships between bulk tank TBC and farm management and economic factors were examined on 56 randomly selected intensive dairy farms. Herd management factors associated with bulk tank TBC were determined using mixed linear models. The median bulk tank TBC for the sample herds was 299 (range 81–1185) × 103 cfu/ml. The average economic premium opportunity from bulk tank TBC was US$ 1.32 per ton of milk ranging from US$ 0.02 per ton of milk for herds applying wet tissue procedures as teat cleaning material and washing the water troughs three times per day to US$ 5.20 per ton of milk for herds with dirty barns. Results showed that the following management factors were associated with low TBC and high economic value: frequency of cleaning water troughs, teat cleaning material, the frequency of milk delivery to the processor, bedding material, herd size, education level of workers, udder washing material, material of milking parlor wall, frequency of disinfection of the calving area, presence of veterinarian, water quality control, having a hospital pen and barn hygiene. In conclusion, our findings highlight the need to pay more attention to farm management issues, particularly farm hygiene practices to reduce milk TBC and so reduce the economic burden of TBC in dairy herds in Iran.

We wished to determine if Mycoplasma bovis infection can negatively impact milk quality and production in Holstein dairy cows. For this Research Communication, milk samples (271) from Holstein cows from 3 herds were screened for M. bovis by real-time PCR. Positive (n = 21) and negative animals (n = 21) were matched by herd, age, lactations and days in milk (DIM). Pairs were evaluated in 7 stages of lactation: D1–50, D51–100, D101–150, D151–200, D201–250, D251–300, and D ≥ 301. A mixed model was used to assess the effect of groups (M. bovis+ × M.bovis−), time (lactation) and groups × time interaction. Cows positive for M. bovis had lower average milk production per day and high somatic cells count (SCC).

This study evaluated the effect of replacing soybean meal by a blend of ground corn and urea-ammonium sulphate (GCU-S) in the diet of lactating buffaloes on milk production and composition, digestibility, N balance and blood metabolites. Twelve multiparous dairy Murrah buffaloes (Bubalus bubalis), at 100 ± 4 d in milk and yielding 10 ± 2.5 kg/d, were randomly distributed in a triple 4 × 4 Latin square, with four different inclusions of GCU-S at U-S levels: 0 (control), 8.0, 16.4 and 24.1 g/kg dry matter (DM) total. Replacing soybean meal with GC-US had a significant depressing effect on absolute DM intake, which was still numerically evident but no longer significant when expressed on a body weight-related basis. Intakes of crude protein (CP) and N as well as N-urinary excretion were also significantly depressed. Digestibility of dry matter was improved and, as a proportion of DMI, intake of total digestible nutrients increased significantly. Perhaps as a result, feed efficiency (kg DMI required per kg 6% fat-corrected milk) was significantly improved. Efficiency of protein use for milk production was significantly improved, but not when expressed as milk protein output. N transfer into milk, as a proportion of total N intake, also increased significantly. However, GC-US inclusion had no significant effect on milk production or milk composition, nor did it affect serum metabolites, digestibilities (apart from dry matter) or N measures of balance apart from those mentioned above. Inclusion of this blend of ground corn with urea and ammonium suplate can be recommended for dairy buffalo because, although it decreases DMI and N-excretion, it improves DM digestibility and feeding efficiency whilst maintaining milk production and composition.

This research communication presents an automatic method for the counting of somatic cells in buffalo milk, which includes the application of a fuzzy clustering method and image processing techniques (somatic cell count with fuzzy clustering and image processing|, SCCFCI). Somatic cell count (SCC) in milk is the main biomarker for assessing milk quality and it is traditionally performed by exhaustive methods consisting of the visual observation of cells in milk smears through a microscope, which generates uncertainties associated with human interpretation. Unlike other similar works, the proposed method applies the Fuzzy C-Means (FCM) method as a preprocessing step in order to separate the images (objects) of the cells into clusters according to the color intensity. This contributes signficantly to the performance of the subsequent processing steps (thresholding, segmentation and recognition/identification). Two methods of thresholding were evaluated and the Watershed Transform was used for the identification and separation of nearby cells. A detailed statistical analysis of the results showed that the SCCFCI method is able to provide results which are consistent with those obtained by conventional counting. This method therefore represents a viable alternative for quality control in buffalo milk production.

The objectives of the current study were to detect putative genomic loci and to identify candidate genes associated with milk production traits in Egyptian buffalo. A total number of 161 479 daily milk yield (DMY) records and 60 318 monthly measures for fat and protein percentages (FP and PP, respectively), along with fat and protein yields (FY and PY, respectively) from 1670 animals were used. Genotyping was performed using Axiom® Buffalo Genotyping 90 K array. Genome-wide association study (GWAS) for each trait was performed using PLINK. After Bonferroni correction, 47 SNPs were associated with one or more milk production traits. These SNPs were distributed over 36 quantitative trait loci (QTL) and located on 20 buffalo chromosomes (BBU). For the 47 SNPs, one was overlapped for three traits (DMY, FY, and PY), six were associated with two traits (one for PP and PY and five for FY and PY) while the rest were associated with only one trait. Out of 36 identified QTL, eleven were overlapped with previously reported loci in buffalo and/or cattle populations. Some of these SNPs are placed within or close to potential candidate genes, for example: TPD52, ZBTB10, RALYL and SNX16 on BBU15, ADGRD1 on BBU17, ESRRG on BBU5 and GRIP1 on BBU4. This is the first reported study between genome-wide markers and milk components in Egyptian buffalo. Our findings provide useful information to explore the genetic mechanisms and relevant genes contributing to the variation in milk production traits. Further confirmation studies with larger population size are necessary to validate the findings and detect the causal genetic variants.

In Brazil, the buffalo milk market has been growing. However, identity and quality standards have not been established for this raw material, nor have proper distinctions between buffalo milk and bovine milk been defined. Currently, the State of Rio Grande do Sul (RS) has only three producers that supply raw material for officially marketed derivatives. The aim of this study was to determine the identity and quality standards of raw buffalo milk in this region. Samples were obtained biweekly from three farm cooling tanks between June 2017 and August 2018, to reach a total of 69 samples. The averages for the results of the physicochemical parameters fat, protein, lactose, total solids, SNF (solids-not-fat), calcium, density, FP, acidity and SCC were 5.5 g/100 g, 4.06 g/100 g, 5.07 g/100 g, 15.5 g/100 g, 9.96 g/100 g, 0.161 g/100 g, 1.034 g/ml, −0.527°C, 16°D and 95 × 103 cells/ml, respectively. With reference to the microbiological parameters, the mean of the Standard Plate Count (SPC) and thermotolerant coliforms were 9,0 × 104 CFU/ml and 1.6 × 102 MPN/ml, respectively. Regarding coagulase-positive staphylococci, 36 samples tested positive (52% of total). Neither Salmonella spp. nor Listeria monocytogenes, nor antibiotic or antiparasitic residues were detected in any sample. In conclusion, the buffalo milk used as raw material for dairy products in southern Brazil demonstrated satisfactory physicochemical and microbiological characteristics, in accordance with recent scientific literature.

In this research communication I show the effect of various cow–calf contact systems on milk yield and milk composition during the periods when calves where allowed to suckle their dams and after the calves were separated in comparison to cows that were only machine milked throughout their lactation. Analyses were based on four different experiments, but conducted at the same research station and under comparable housing and feeding conditions. Nursing dams had contact to their calves during the whole day, during night-time or only twice per day shortly before milking. A control group of cows that had no contact to their offspring was part of every experiment. Data of the regular monthly milk recordings were analysed with linear mixed models. Results showed a significant effect of the suckling system on the machine milk yield over the whole lactation. While cows with night-time contact reached the milk production level of the control cows, cows with whole day or short-time contact still produced less milk after the calves were separated. Fat content was always lower during the suckling period but not afterwards. The significantly higher milk protein content in dams with calf contact requires further investigation. Somatic cell count in milk of nursing dams was slightly increased, probably due to the exposure of the teats to frequent suckling in addition to machine milkings. In conclusion, cow–calf contact systems influence the performance of cows during and after the suckling period but to varying degrees depending on the system adopted.

This research communication explores the value of routinely collected bulk tank milk quality data for estimating dairy cattle welfare at herd level. Selected bulk tank milk quality parameters (somatic cell count, total bacterial count, urea, protein and fat contents) recorded during the years 2014–2016 in 287 Italian dairy farms were compared with the animal welfare data of each farm. The welfare assessment data were extracted from the database of the Italian Reference Centre for Animal Welfare (CReNBA), which includes the outputs of the application of the CReNBA welfare assessment protocol for dairy cows, used at national level for on-farm controls. The statistical analysis was carried out using the correlation coefficient for Kendall's Tau ranks, in order to investigate the presence of a categoric relationship between the selected bulk tank milk quality parameters and the overall animal welfare score or the scores of the single areas A (farm management and staff training), B (housing) and C (animal-based measures). Somatic cell count, total bacterial count, urea and proteins demonstrated only a few statistically significant and very weak correlations with farm animal welfare data, while no significant correlations were obtained for milk fat content. Given the weak correlations found, the selected bulk tank milk parameters seems to be able to provide only limited information about the welfare level of the herd, thus it could be difficult to use them for drawing up a pre-screening model for identifying herds at risk of poor welfare.

The aims of the study were to determine the long-term effects of dietary supplementation with microalgae (SCIM) on milk and blood fatty acid (FA) composition and reproductive hormones in early lactation dairy cows. Sixty Holstein–Friesian dairy cows (30 per treatment) were unsupplemented (Control) or supplemented with 100 g of SCIM (Schizochytrium limacinum sp.) per cow per day from 25 ± 0.5 d post-partum for 98 d. Intake and milk yield were recorded daily, with milk samples collected at weeks 0, 1, 2, 4, 8 and 14, and blood samples collected from 12 representative pairs per treatment at weeks 0, 2, 4, 8, and 14 for subsequent analysis of FA, β-hydroxybutyrate, non-esterified fatty acids and glucose. At 33 ± 0.9 d postpartum the oestrus cycle of 24 cows (12 per treatment) were synchronized and plasma 13,14-dihydro-15-keto PGF2α (PGFM) concentrations determined following an oxytocin challenge. Data were analysed by repeated measures analysis of variance. There was no effect of treatment on dry matter intake, milk yield or milk fat content, with mean values across treatments of 22.1 and 40.6, and 37.2 g/kg respectively. Milk fat concentration of C22:6 n-3 increased rapidly in cows receiving SCIM, reaching a maximum of 0.38 g/100 g FA by week 14. Similarly, blood concentration of C22:6 n-3 increased to 1.6 g/100 g FA by week 14 in cows fed SCIM. There was no effect of treatment on plasma metabolites, but plasma glucose was lower in cows fed SCIM compared to the Control at week 2, and higher in week 8. There was no effect of treatment on peak plasma PGFM concentration or area under the curve. It is concluded that feeding SCIM rapidly increases blood and milk concentrations of C22:6 n-3 which are maintained over time, but does not improve plasma PGFM in dairy cows.

The experiments reported in this research paper aimed to investigate differences in the levels of chlorate (CHLO), perchlorate (PCHLO), trichloromethane (TCM) and iodine residues in bulk tank (BT) milk produced at different milk production periods, and to monitor those levels throughout a skim milk powder (SMP) production chain (BTs, collection tankers [CTs], whole milk silo [WMS] and skim milk silo [SMS]). Chlorate, PCHLO and iodine were measured in SMP, while TCM was measured in the milk cream. The CHLO, TCM and iodine levels in the mid-lactation milk stored in the WMS were lower than legislative and industrial specifications (0.0100 mg/kg, 0.0015 mg/kg and 150 µg/l, respectively). However, in late-lactation, these levels were numerically higher than the mid-lactation levels and specifications. Trichloromethane accumulated in the cream portion after separation. Perchlorate was not detected in any of the samples. Regarding iodine, the levels in mid-lactation reconstituted SMP were higher than that required by manufacturers (100 µg/l), indicating that the levels in milk should be lower than 142 µg/l. The higher residue levels observed in late-lactation could be related to the low milk volume produced during that period and changes in sanitation practices, while changes in feed management could have affected iodine levels. This study could assist in controlling and setting limits for CHLO, TCM and iodine levels in milk, ensuring premium quality dairy products.

This paper reviews the effects of extended lactation (EXT) as a strategy in dairy cattle on milk production and persistency, reproduction, milk quality, lifetime performance of the cow and finally the economic effects on herd and farm levels as well as the impact on emission of greenhouse gas at product level. Primiparous cows are able to produce equal or more milk per feeding day during EXT compared with a standard 305-d lactation, whereas results for multiparous cows are inconsistent. Cows managed for EXT can achieve a higher lifetime production while delivering milk with unchanged or improved quality properties. Delaying insemination enhances mounting behaviour and allows insemination after the cow’s energy balance has become positive. However, in most cases EXT has no effect or a non-significant positive effect on reproduction. The EXT strategy sets off a cascade of effects at herd and farm level. Thus, the EXT strategy leads to fewer calvings and thereby expected fewer diseases, fewer replacement heifers and fewer dry days per cow per year. The optimal lifetime scenario for milk production was modelled to be an EXT of 16 months for first parity cows followed by an EXT of 10 months for later lactations. Modelling studies of herd dynamics indicate a positive effect of EXT on lifetime efficiency (milk per dry matter intake), mainly originating from benefits of EXT on daily milk yield in primiparous cows and the reduced number of replacement heifers. Consequently, EXT also leads to reduced total meat production at herd level. For the farmer, EXT can give the same economic return as a traditional lactation period. At farm level, EXT can contribute to a reduction in the environmental impact of dairy production, mainly as a consequence of the reduced production of beef. A wider dissemination of the EXT concept will be supported by methods to predict which cows may be most suitable for EXT, and clarification of how milking frequency and feeding strategy through the lactation can be organised to support milk yield and an appropriate body condition at the next calving.

Free fatty acid (FFA) concentrations can be elevated in raw milk due to improper handling and management at the dairy farm, and high concentrations of FFA can lead to off flavors in milk. This study aimed to describe how the herd production system, milking system, feeding and technological factors impact on FFA concentrations in bulk tank milk. FFA concentrations in bulk milk samples from 259 organic and 3326 conventional herds were analyzed by FT-IR during one year. The FFA content was significantly lower in bulk milk from organic than conventional herds. This was most evident during the summer half-year when the organic cows graze pasture. Bulk milk from automatic milking systems (AMS) and tie-stalls contained greater concentrations of FFA than any other milking parlor systems. In AMS, high milking frequency was found to be the most significant contributor to elevated FFA content in milk. Moreover, a strong interaction was found between milking interval and production system (organic vs. conventional). The technical factors, pre-cooling, onset time for cooling after milk inlet, contact between milk and agitation also impacted on the FFA concentration, whereas other technical factors including centrifugal pump type, length and height of pumping line and type of AMS manufacturer were found to be without significant effect on FFA. Feeding variables, based on feeding plans and evaluation, only explained a small part of the variation in bulk milk FFA. Overall, this study demonstrated that AMS compared to other milking system contributes significantly to increased FFA concentration in bulk tank milk, and within AMS high milking frequency contributes to increased FFA concentration.

Feeding greatly affects milk yield and composition. The research is highlighting the potential of genetic polymorphism at some loci to affect milk yield and quality traits. These loci can be up/down regulated depending on the production environment; therefore, we hypothesized that milk yield and composition could differ when cows with different genotype at SCD, DGAT1 and ABCG2 loci are reared in different feeding systems. The polymorphisms of SCD, DGAT1 and ABCG2 genes were investigated in Modicana breed. In all, three polymorphic sites, responsible for the genetic variation of quantitative trait loci and therefore defined quantitative trait nucleotides, were genotyped: the transition g.10329C>T in 5th exon determines a substitution p.A293V in the SCD, the dinucleotide mutation g.10433-10434AA>GC in 8th exon responsible for p.K232A substitution in the DGAT1 and the transition g.62569A>C in the 14th exon responsible for p.Y581S substitution in the ABCG2 gene. In the sample of 165 Modicana cows, SCD and DGAT1 genes resulted polymorphic; the alleles g.10329T and g.10433-10434GC were the most frequent in SCD and DGAT1 (0.73 and 0.91) respectively, whereas ABCG2 locus was monomorphic for allele A (p.581Y). Sequencing analysis was carried out on 14 samples with different genotypes to confirm the results of the PCR-RFLP protocols. Based on the genotypes at SCD locus, 47 Modicana cows were selected for the nutritional trial: 24 cows in a semi-intensive farm, with 2 h/day grazing on natural pasture, and 23 cows in an extensive farm, with 8 h/day grazing on natural pasture. Monthly, milk yield and composition were evaluated and individual milk samples were analyzed for fatty acids composition by gas chromatography. No differences in milk yield, fat, protein, lactose, casein and urea were associated to SCD genotype. Feeding systems affected milk yield and composition. No significant genotype×feeding system interaction was observed for milk yield and composition. Fatty acids composition was significantly affected only by the feeding system. Significant interactions were found between SCD genotype and feeding system for six fatty acids: 4:0, 6:0, 8:0, 10:0, 12:0 and t11 18:1. We concluded that the feeding system was the factor that mostly affected milk production and composition; moreover, our results do not confirm what reported in literature as regard the effect of the SCD polymorphism on milk fatty acid composition. The high amount of pasture seemed to have resized the SCD polymorphism effects because of the different fatty acids composition of the diet.

Monitoring milk quality traits and the classification of raw milk are important steps for generating high-quality dairy products. Given the important roles of the BRG1/BRM-associated factor 60c (BAF60c) gene in the regulation of physiological growth and production, the objective of the current study was to analyse the association between the BAF60c gene and milk quality and establish a gene-based method for pre-evaluating raw milk quality. For this purpose, DNA was isolated from 507 milk samples and genotyped using the polymerase chain reaction-restricted fragment length polymorphism method. Milk quality traits including milk protein percentage (MPP), milk fat percentage (MFP), lactose percentage (LP) and total solids content (TSC) were also evaluated from the same 507 milk samples. The newly found 6060 T > C mutation of the BAF60c gene was associated significantly with MPP and LP, but not with MFP and TSC. The results demonstrated that this mutation could be used for the pre-evaluation of MPP and LP; therefore, raw milk could be graded according to different genotypes.

Milk mineral concentration is important from both the perspective of processing milk into dairy products and its nutritive value for human consumption. Precise estimates of genetic parameters for milk mineral concentration are lacking because of the considerable resources required to collect vast phenotypes quantities. The milk concentration of calcium (Ca), potassium (K), magnesium (Mg), sodium (Na) and phosphorus (P) in the present study was quantified from mid-IR spectroscopy on 12 223 test-day records from 1717 Holstein-Friesian cows. (Co)variance components were estimated using random regressions to model both the additive genetic and within-lactation permanent environmental variances of each trait. The coefficient of genetic variation averaged across days-in-milk (DIM) was 6.93%, 3.46%, 6.55%, 5.20% and 6.68% for Ca, K, Mg, Na and P concentration, respectively; heritability estimates varied across lactation from 0.31±0.05 (5 DIM) to 0.67±0.04 (181 DIM) for Ca, from 0.18±0.03 (60 DIM) to 0.24±0.05 (305 DIM) for K, from 0.08±0.03 (15 DIM) to 0.37±0.03 (223 DIM) for Mg, from 0.16±0.03 (30 DIM) to 0.37±0.04 (305 DIM) for Na and from 0.21±0.04 (12 DIM) to 0.57±0.04 (211 DIM) for P. Genetic correlations within the same trait across different DIM were almost unity between adjacent DIM but weakened as the time interval between pairwise compared DIM lengthened; genetic correlations were weaker than 0.80 only when comparing both peripheries of the lactation. The analysis of the geometry of the additive genetic covariance matrix revealed that almost 90% of the additive genetic variation was accounted by the intercept term of the covariance functions for each trait. Milk protein concentration and mineral concentration were, in general, positively genetically correlated with each other across DIM, whereas milk fat concentration was positively genetically correlated throughout the entire lactation with Ca, K and Mg; the genetic correlation with fat concentration changed from negative to positive with Na and P at 243 DIM and 50 DIM, respectively. Genetic correlations between somatic cell score and Na ranged from 0.38±0.21 (5 DIM) to 0.79±0.18 (305 DIM). Exploitable genetic variation existed for all milk minerals, although many national breeding objectives are probably contributing to an indirect positive response to selection in milk mineral concentration.

Feeding livestock with n-3 fatty acid (FA) sources (linseed, for example) is a common strategy to improve lipid quality of meat and milk products. However, in monogastric animals, linseed tegument decreases digestibility and alphalinolenic acid (ALA) uptake, while the whole linseed is well used by ruminants. In a context of increasing sustainability of feeding systems, providing monogastric animals and ruminants with linseed products adapted to their digestive systems is an important issue. This research paper addresses the hypotheses: (i) sieved extruded linseed (SEL) specific for ruminants is as or more effective than standard extruded linseed (ii) microalgae DHA Gold® is an interesting source of docosahexaenoic acid (DHA) in feedstuff and (iii) the effects of SEL and microalgae on milk characteristics are complementary and additive. Thirty-two cows were divided into 4 groups with different dietary n-3 fatty acid sources using a continuous design. All the diets were fed as mixed rations based on maize silage, energy concentrate and soybean meal. The first group received a control diet (CTRL) with no additional fat. The 3 other groups received SEL, microalgae DHA Gold® (ALG) and a mixture of microalgae DHA Gold® and SEL (SEL/ALG). Milk was collected from morning milkings after six weeks of dietary treatment. In SEL and SEL/ALG, ALA increased (+0·32 and +0·26% unit, respectively), and DHA increased in ALG and SEL/ALG (+0·43 and +0·15% unit, respectively) compared to CTRL, as a consequence of the initial composition of the n-3 FA sources. In SEL, milk yield, fat and protein contents, milk fat globule size and spontaneous lipolysis (measured to evaluate suitability for milk processing) were not different compared with CTRL. In ALG and SEL/ALG, milk yield decreased (−2·8 and −6·0 kg/d, respectively), fat content was halved, and fat globule size was reduced (−1·46 and −1·31 µm, respectively) compared to CTRL. Spontaneous lipolysis increased in ALG (+0·12 mEq/kg of milk) compared to CTRL. Protected microalgae and the doses of microalgae in the diet need further investigation to prevent FA modification in the rumen and the consequent deleterious effects on milk fat.

Cattle’s relationship with humans is a crucial factor regarding their welfare. In dairy cows, interactions with humans occur regularly during milking. We tested the effect of gentle interactions (stroking, talking in a gentle voice) during milking on avoidance distance and milk composition, yield and flow characteristics as well as behaviour during milking. Over the course of 15 days, an experimenter interacted gently with 14 German Holstein cows for 2 min during morning and evening milkings, totalling 60 min; the experimenter stayed at a similar distance to 12 control cows of the same breed for the same amount of time. There were no significant differences between the groups in behaviour during milking. Over the course of the experimental phase, avoidance distance at the feeding rack decreased significantly in stroked but not in control cows. The treatment did not improve any of the measures of milk composition, yield or flow; on the 1st day of the treatment, milk ejection was impaired in stroked cows, which points towards an effect of the novelty of the treatment. We conclude that gentle interactions during milking improve the relationship between cows and a human. Possible reasons for the absence of an effect on milk characteristics are that cows may not have perceived the interactions as positive or that a ceiling effect occurred due to otherwise optimal milking routines.

Heating oil and oilseeds results in oxidation products that affect ruminal biohydrogenation of polyunsaturated fatty acids, altering milk fatty acids profile, and could be transferred to milk. An experiment was conducted to investigate the effects of oil heating on rumen and milk fatty acids profile and the transfer of oxidation products to milk. Sunflower oil was heated at 150°C for 15 h and given to lactating dairy cows in a 2×2 arrangement: two groups of two cows, equipped with a ruminal cannula and receiving two diets (containing either heated or unheated oil) during two experimental periods. Oil heating generated hydroperoxides and/or hydroxyacids and aldehydes, in particular trans-2,trans-4-decadienal. In milk, heated oil only significantly decreased trans-11-C18:1 and cis-9,trans-11-CLA percentage compared to non-heated oil, and slightly increased cis-9,cis-12-C18:2 percentage, which was probably linked to an inhibition of the ruminal Δ12 isomerase by oxidative products in the rumen. However, feeding highly oxidized oil did not result in the appearance of hydroperoxides or hydroxyacids in milk and did not increase milk aldehydes content.