Total bacterial count and somatic cell count in bulk and individual goat milk around kidding: Two longitudinal observational studies.

Total bacterial count (TBC) and SCC are important quality parameters in goat milk. Exceeding the bulk milk TBC (BMTBC) thresholds leads to price penalties for Dutch dairy goat farmers. Controlling these milk quality parameters can be challenging, especially around kidding. First, we describe the variation and the peaks around kidding of TBC and SCC in census data on Dutch bulk milk over the last 22 yr. Second, to explore causes of these elevations, we studied the variation of TBC and SCC in individual goat milk from 3 wk before to 5 wk after kidding and their association with systemic response markers IFN-γ, calprotectin, BHB, BCS, and fecal consistency. We visited 4 Dutch dairy goat farms weekly for 10 to 16 wk around kidding. Some of the goats had been dried off; other goats were milked continuously throughout pregnancy. A total of 1,886 milk samples from 141 goats were collected for automated flow cytometric quantification of TBC and SCC measurement. IFN-γ, calprotectin, and BHB were determined twice in blood of the same goats; most samples were collected after kidding. The BCS and fecal consistency were scored visually before and after kidding. We found a strong correlation between TBC and SCC (Spearman's rho = 0.87) around kidding. Furthermore, in the third week before kidding, the average TBC (5.67 log10 cfu/mL) and SCC (6.70 log10 cells/mL) were significantly higher compared with the fifth week after kidding, where the average TBC decreased to 4.20 log10 cfu/mL, and the average SCC decreased to 5.92 log10 cells/mL. In multivariable linear regression models, farm and stage of lactation were significantly associated with TBC and SCC, but none of the systemic response markers correlated with TBC or SCC. In conclusion, TBC and SCC in dairy goats were high in late lactation and decreased shortly after parturition. For SCC, the dilution effect might have caused the decrease, but this was not plausible for TBC. Moreover, the excretion of bacteria and cells in goat milk was not associated with the selected systemic response markers that were chosen as a readout for general immunity status, intestinal health, and metabolic diseases. Therefore, we assume that the TBC increase before kidding and the decrease after parturition are caused by other systemic, possibly hormonal, processes. To reduce BMTBC and bulk milk SCC, it would be advisable to keep milk of goats with highest numbers of bacteria and cells in their milk out of the bulk milk during end lactation. Further studies are needed to investigate the effects of withholding this end-lactation milk from the bulk tank.

Shelf-life storage temperature has a considerably larger effect than high-temperature, short-time pasteurization temperature on the growth of spore-forming bacteria in fluid milk.

In the absence of postpasteurization contamination, psychrotolerant, aerobic spore-forming bacteria that survive high-temperature, short-time (HTST) pasteurization, limit the ability to achieve HTST extended shelf-life milk. Therefore, the goal of the current study was to evaluate bacterial outgrowth in milk pasteurized at different temperatures (75, 85, or 90°C, each for 20 s) and subsequently stored at 3, 6.5, or 10°C. An initial ANOVA of bacterial concentrations over 14 d of storage revealed a highly significant effect of storage temperatures, but no significant effect of HTST. At d 14, average bacterial counts for milk stored at 3, 6.5, and 10°C were 1.82, 3.55, and 6.86 log10 cfu/mL, respectively. Time to reach 1,000,000 cfu/mL (a bacterial concentration where consumers begin to notice microbially induced sensory defects in fluid milk) was estimated to be 68, 27, and 10 d for milk stored at 3, 6.5, and 10°C, respectively. Out of 95 isolates characterized with rpoB allelic typing, 6 unique genera, 15 unique species, and 44 unique rpoB allelic types were represented. The most common genera identified were Paenibacillus, Bacillus, and Lysinibacillus. Nonmetric multidimensional scaling identified that Bacillus was significantly associated with 3 and 10°C, whereas Paenibacillus was consistently found across all storage temperatures. Overall, our data show that storage temperature has a substantially larger effect on fluid milk shelf life than HTST and suggests that abuse temperatures (e.g., storage at 10°C) allow for growth of Bacillus species (including Bacillus cereus genomospecies) that do not grow at lower temperatures. This indicates that stringent control of storage and distribution temperatures is critical for producing extended shelf-life HTST milk, particularly concerning new distribution pathways for HTST pasteurized milk (e.g., electronic commerce), and when enhanced control of spores in raw milk is not feasible.

Invited review: Redefining raw milk quality-Evaluation of raw milk microbiological parameters to ensure high-quality processed dairy products.

Raw milk typically has little bacterial contamination as it leaves the udder of the animal; however, through a variety of pathways, it can become contaminated with bacteria originating from environmental sources, the cow herself, and contact with contaminated equipment. Although the types of bacteria found in raw milk are very diverse, select groups are particularly important from the perspective of finished product quality. In particular, psychrophilic and psychrotolerant bacteria that grow quickly at low temperatures (e.g., species in the genus Pseudomonas and the family Enterobacteriaceae) and produce heat-stable enzymes, and sporeforming bacteria that survive processing hurdles in spore form, are the 2 primary groups of bacteria related to effects on processed dairy products. Understanding factors leading to the presence of these important bacterial groups in raw milk is key to reducing their influence on processed dairy product quality. Here we examine the raw milk microbiological parameters used in the contemporary dairy industry for their utility in identifying raw milk supplies that will perform well in processed dairy products. We further recommend the use of a single microbiological indicator of raw milk quality, namely the total bacteria count, and call for the development of a whole-farm approach to raw milk quality that will use data-driven, risk-based tools integrated across the continuum from production to processing and shelf-life to ensure continuous improvement in dairy product quality.

Farm management and economic factors associated with bulk tank total bacterial count in Holstein dairy herds in Iran.

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.

Efficacy of bacteriocin-based formula for reducing staphylococci, streptococci, and total bacterial counts on teat skin of dairy cows.

The use of teat dips is one of the most effective strategies to control mastitis by preventing new intramammary infections. Reducing bacterial load on teat skin helps control the spread of pathogens and spoilage and improves the quality of milk. The objective of this study was to evaluate the reduction of bacterial populations through the application of bacteriocin-based teat formulas. Teats of 12 Holstein cows received 2 different concentrations of bactofencin A, nisin, and reuterin alone or in combination, as well as iodine (positive control) and saline (negative control). Teat swabs were collected before and after application of teat formulas and analyzed for staphylococci, streptococci, and total bacteria counts. There were no differences for staphylococci, streptococci, and total bacterial counts for samples collected before application throughout the entire experiment. Reuterin-low and reuterin-high treatments reduced total bacterial count by 0.47 and 0.36 logs, respectively, whereas bactofencin A had no effect on any tested bacterial groups. Nisin-low treatment reduced staphylococci, streptococci, and total bacterial counts by 0.47, 0.30 and 0.50 logs, respectively. Nisin-high treatment resulted in 0.50, 0.50, and 0.47 log reduction for staphylococci, streptococci, and total bacterial counts. The bacteriocin consortium showed the highest reduction rates with 0.91, 0.54, and 0.90 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively, for the low-concentration consortium. Similarly, the high-concentration consortium showed reduction rates with 0.95, 0.60, and 0.82 log reductions obtained for staphylococci, streptococci, and total bacteria counts, respectively. Thus, nisin and the bacteriocin consortium showed the most promise as a teat disinfectant by reducing staphylococci, streptococci, and total bacteria counts.

Crossbreeding impacts on caecal bacterial count and antibody titres in chickens.

1. A crossbreeding experiment was conducted using 20 sires and 120 dams from each Fayoumi (F) and Rhode Island Red (R) breeds. The F1 chicks of ½F½R and their reciprocal ½R½F crosses were used to estimate direct, maternal and heterotic effects.2. The caecal bacterial counts of Salmonella typhimurium and Enterococcus faecium and the IgA, IgG and IgM antibody titres were determined. Chicks of each genetic group (120 birds) were divided into three groups (40 birds per group) and chicks of the first group were assigned as the control group, while the second group was inoculated with S. typhimurium and E. faecium at 7 and 10 d of age (106 cfu/chick) and the third was inoculated with S. typhimurium at 10 d of age (106 cfu/chick).3. The generalised least square procedure was used to estimate cross-breeding effects. The S. typhimurium counts in the R breed was highly significant, followed by ½F½R cross, ½R½F cross, and F breed. The differences among genetic groups in E. faecium counts and caecal pH was not significant. The estimates of IgA, IgG, and IgM antibody titres were highly significant in the F breed, followed by ½R½F cross, ½F½R cross, and the R breed.4. The estimates of direct additive effects were highly significant F breed for the counts of S. typhimurium and antibody titres of IgA, IgG, and IgM. The maternal effects were highly significant F breed for S. typhimurium, E. faecium count, and antibody titres of IgA, IgG, and IgM. Estimates of direct heterosis were significant for S. typhimurium count and IgA antibody titre but not significant for E. faecium count, caecal pH, and antibody titres of IgG and IgM.5. The results showed that the Fayoumi breed could be used in breeding programmes to improve immunity traits against S. typhimurium in chickens.

Application of E-nose technology combined with artificial neural network to predict total bacterial count in milk.

Total bacterial count (TBC) is a widely accepted index for assessing microbial quality of milk, and cultivation-based methods are commonly used as standard methods for its measurement. However, these methods are laborious and time-consuming. This study proposes a method combining E-nose technology and artificial neural network for rapid prediction of TBC in milk. The qualitative model generated an accuracy rate of 100% when identifying milk samples with high, medium, or low levels of TBC, on both the testing and validating subsets. Predicted TBC values generated by the quantitative model demonstrated strong coefficient of multiple determination (R2 > 0.99) with reference values. Mean relative difference between predicted and reference values (mean ± standard deviation) of TBC were 1.1 ± 1.7% and 0.4 ± 0.8% on the testing and validating subsets involving 24 and 28 tested samples, respectively. Paired t-test implied that the difference between predicted and reference values of TBC was insignificant for both the testing and validating subsets. As low as ~1 log cfu/mL of TBC present in tested samples were precisely predicted. Results of this study indicated that combination of E-nose technology and artificial neural network generated reliable predictions of TBC in milk. The method proposed in this study was reliable, rapid, and cost efficient for assessing microbial quality milk, and thus would potentially have realistic application in dairy section.

Adjusted method of penis fixation during boar semi-automatic semen collection aiming to reduce bacterial contamination.

Semen collection has an essential role in the initial bacterial load in boar ejaculates and extended semen. The study aimed to explore the efficacy of an adjusted penis fixation in a semi-automatic collection system on reducing bacterial contamination of ejaculates in two-boar studs with different scenarios. Historically, stud A had low levels of bacterial load in raw semen, while stud B had a high level of contamination. A total of 56 mature boars had their semen collected using two methods of penis fixation: (a) Traditional: The penis was fixed directly with the artificial cervix and transferred to the adjustable clamp; (b) Adjusted: The fixation was performed with one gloved-hand, and after exteriorization, the penis was gripped using the artificial cervix with the other gloved-hand and transferred to the adjustable clamp. The bacterial load (p = .0045) and the occurrence of ejaculates >231 CFU/ml (p = .0101) were reduced in the Adjusted compared to the Traditional method. Bacterial load was reduced when using the Adjusted method in stud B (p = .0011), which showed a greater occurrence of critical factors for bacterial contamination (p ≤ .0034). The Adjusted method reduced the occurrence of ejaculates >231 CFU/ml when the preputial ostium was dirty (p = .016) and the duration of semen collection was >7 min (p = .022) compared to the Traditional method. In conclusion, the Adjusted penis fixation was efficient in reducing bacterial load of ejaculates, mainly in boar stud B, which had high contamination challenges.

Extensive countrywide field investigation of somatic cell counts and total bacterial counts in bulk tank raw milk in goat herds in Greece.

Dairy goat farming is an important sector of the agricultural industry in Greece, with an annual total milk production exceeding 450 000 l and accounting for over 25% of all goat milk produced in the European Union; this milk is used mainly for cheese production. Despite the importance of goat milk for the agricultural sector in Greece, no systematic countrywide investigations in the bulk-tank milk of goats in Greece have been reported. Objectives were to investigate somatic cell counts (SCC) and total bacterial counts (TBC) in raw bulk-tank milk of goat herds in Greece, study factors influencing SCC and TBC therein and evaluate their possible associations with milk content. Throughout Greece, 119 dairy goat herds were visited for milk sampling for somatic cell counting, microbiological examination and composition measurement. Geometric mean SCC and TBC were 0.838 × 106 cells ml-1 and 581 × 103 cfu ml-1, respectively. Multivariable analyses revealed annual frequency of check-ups of milking system and total milk quantity per goat (among 53 variables) to be significant for increased SCC; no factor emerged (among 58 variables) to be significant for increased TBC. Negative correlation of SCC with total protein was found; mean total protein content in the bulk-tank milk in herds with SCC >0.75 × 106 cells ml-1 was 5.1% lower and in herds with SCC >1.5 × 106 cells ml-1, it was 7.8% lower.

Risk factors for poor colostrum quality and failure of passive transfer in Scottish dairy calves.

Failure of passive transfer (FPT) has health, welfare and economic implications for calves. Immunoglobulin G (IgG) concentration of 370 dairy calf serum samples from 38 Scottish dairy farms was measured via radial immunodiffusion (RID) to determine FPT prevalence. IgG concentration, total bacteria count (TBC) and total coliform count (TCC) of 252 colostrum samples were also measured. A questionnaire was completed at farm enrollment to investigate risk factors for FPT and poor colostrum quality at farm-level. Multivariable mixed effect logistic and linear regressions were carried out to determine significant risk factors for FPT and colostrum quality. Prevalence of FPT at calf level was determined to be 14.05%. Of 252 colostrum samples, 111 (44.05%) failed to meet Brix thresholds for colostrum quality. Of these 28 and 38 samples also exceeded TBC and TCC thresholds, respectively. Increased time between parturition and colostrum harvesting was numerically (non-significantly) associated with a colostrum Brix result <22%, and increased time spent in a bucket prior to feeding or storing was significantly associated with high TBC (≥100 000 cfu/ml and also ≥10 000 cfu/ml). High TBC values in colostrum were significantly associated with lower serum IgG concentrations. This study highlights associations between colostrum quality and FPT in dairy calves as well as potential risk factors for reduced colostrum quality; recommending some simple steps producers can take to maximise colostrum quality on farm.

Pathogen-specific changes in composition and quality traits of milk from goats affected by subclinical intramammary infections.

We investigated the effects of pathogens associated with subclinical intramammary infections on yield, composition and quality indicators of goat milk. By means of a longitudinal study, individual half udder milk samples (n = 132) were collected at different lactation periods and assessed for milk yield and physicochemical composition, somatic cell count (SCC), total bacteria count (TBC) and microbiological culture. Staphylococci species accounted for the great majority of the isolates (96.1%). Intramammary infections significantly reduced fat and total solids in goat milk and increased both SCC and TBC. However, these indicators were significantly higher in udder halves affected by S. aureus compared with other staphylococci species.

Neutrophil and CD4+ milk cell count related to natural incidence of mastitis in Jersey cattle.

This Research Communication describes the relation between somatic cells and microbial content in milk from Jersey cattle. Milk samples were classified in groups: healthy, dirty and mastitic (from Staphylococcus spp., Escherichia coli, Coliforms). The somatic cells in each of those groups were analysed by two methods - flow cytometric and automatic fluorescent cell counting. Those methods were compared. Total somatic cell count (SCC), neutrophil count, and lymphocytes with cluster of differentiation 4 (CD4+cells) were determined. There was a positive relationship between microbes and somatic cells. It was noticed that the neutrophil count was generally increased together with SCC, whilst the CD4+ cell count was higher in healthy milk samples (about 8%) compared to mastitic ones (about 3%). Lower number of CD4+ cells (from 1 to 4%) was determined in samples positive for Staphylococcus spp. but with lower SCC (from 2.7 to 4.0 × 105 cells/ml). Also, the number of CD4+ cells in Staphylococcus spp.-positive samples increased (to 4.8%) together with higher SCC, something that was not observed in the other mastitic samples. Knowledge of those relations could be useful for veterinary medical tests in the initial phase of inflammation.

The impact of gel fingernail polish application on the reduction of bacterial viability following a surgical hand scrub.

OBJECTIVE: To determine the effect of gel nail polish application on the reduction of bacterial viability immediately after a surgical hand scrub. STUDY DESIGN: Randomized controlled trial. SAMPLE POPULATION: Ten fingernails each from 40 female health care professionals and students. METHODS: Participants' fingernails were randomized to receive no polish or gel nail polish during a manicure from a licensed manicurist. One day and 14 days after manicure, participants' fingernails were sampled before and after a surgical hand scrub with chlorhexidine gluconate. The samples for each fingernail were serially diluted, plated on a Trypsin sheep blood agar and MacConkey's agar plate, and incubated for 36 h. For each plate, bacterial colony forming units (CFU)/ml were determined. Mixed linear models were used to assess factors associated with the logarithmic reduction of viable bacterial counts from pre- to post-surgical scrub. RESULTS: In the final model, no association was detected between gel nail polish and reduction of viable bacterial count (p = .09). On Day 14, among longer nail lengths (2 to <3-mm and ≥3-mm), surgical scrubs resulted in greater reduction in bacterial counts in left-handed than right-handed participants (p < .01). Increasing nail length was correlated with increased CFU/ml post-scrubbing (p < .001). CONCLUSION: Application of gel nail polish did not seem to affect the ability of surgical scrub to reduce bacterial viability 1 and 14 days after a manicure. CLINICAL IMPACT: This study does not provide evidence to prevent application of gel nail polish on short fingernails in surgeons prior to surgical hand scrub with chlorhexidine gluconate.

Impact of antibiotics on spermatozoa quality and bacterial load of chilled-stored camels (Camelus dromedarius) semen.

This experiment was conducted to assess the effect of different antibiotics in tris-fructose egg yolk-based diluent on bacterial load and sperm quality of dromedary camels during processing and cold storage. Ten semen ejaculates were collected from five male dromedary camels. Each sample was fractioned into four equally divided aliquots and diluted in one of four tris-fructose egg yolk. The first extender contained no antibiotic (NC). The second extender included streptomycin sulphate (1000 µg/ml) and benzyl penicillin (1000 IU/ml) (SP). The third extender was supplied with 250 µg/ml gentamicin sulphate (Gent). The fourth extender contained 500 µg/ml gentamicin sulphate,100 µg/ml tylosin tartrate, 300 µg/ml lincomycin hydrochloride and 600 µg/ml spectinomycin hydrochloride (GTLS). After dilution, the extended semen samples were cooled to 5 °C within 2 h and finally stored at 5 °C for 72 h. Microbial concentration, motility of spermatozoa, live spermatozoa, plasma membrane and acrosome integrity percentages were evaluated just after dilution at 35 °C, 0, 24, 48 and 72 h from the start of cooling to 5 °C. The results revealed that the diluent containing gentamicin had significantly (P<0.05) maximum motility percentage at the different examination intervals. The pattern of live spermatozoa percentage was varied between the different treatments at different examination intervals. The diluent supplied with Gent was distinguished with a significant peak percentage (P<0.05) of swelled spermatozoa among the other antibiotics supplied diluents. The number of colony-forming units isolated from the semen samples kept in diluent containing no antibiotics was significantly (P<0.05) higher than that isolated from the diluents supplemented with antibiotics. In conclusion, the semen diluents fortified with gentamicin generally keep the motility, acrosomal and plasma membrane integrity and live spermatozoa for 72-h preservation of dromedary semen.

Properties of conventional and alternative bedding materials for dairy cattle.

The bedding material used in barns for dairy cows has a significant effect on animal welfare and performance. Bedding influences the duration in which animals remain lying down and, consequently, the processes of rumination and milk production. It is crucial to have a complete understanding of the properties of bedding materials and the effects of alternative bedding materials on dairy cattle. This paper aims to evaluate the physical, chemical, and biological properties of various alternative and conventional bedding materials for dairy cattle for use in compost bedded pack or freestall barn systems. We analyzed 50 samples of 17 bedding materials produced in 3 European countries. We analyzed physical properties including the water holding capacity, porosity, moisture content, bulk density, dry bulk density, and particle size. Chemical analyses were performed to determine the total N, total organic C, and C:N ratio. In the biological analyses, the Escherichia coli count, total bacteria count, coliform count, and Klebsiella spp. count were assessed. The results demonstrated how the physical properties of the bedding materials may influence the chemical and biological properties. All of the materials presented adequate chemical properties to be used as bedding material. The physical properties of the bedding materials differed widely among the materials except for the dry bulk density, which presented no difference. Moreover, the contamination of each studied microorganism was observed for each bedding material to determine which material had the lowest level of contamination. Posidonia oceanica, Miscanthus grass, and spelt husks could be considered as a potential alternative material for use as bedding material for dairy cows in both systems (i.e., composted bedded pack and freestall). This experiment illustrated the importance of performing thorough physical, chemical, and biological analyses before implementing a material as bedding for dairy cattle.

Effect of forest biomass as bedding material on compost-bedded pack performance, microbial content, and behavior of nonlactating dairy cows.

Compost-bedded pack (CBP) barns for dairy cows mainly use sawdust as bedding material. The objective of this study was to compare forest biomass to sawdust as bedding material for CBP. Variables evaluated included CBP moisture, temperature and C:N ratio, bedding microbial counts, and behavior and welfare measures of nonlactating cows. The experimental design was a crossover where two 11-wk periods were performed. Treatments were CBP with sawdust (CBP-S) as a control treatment and CBP with forest biomass (CBP-FB) as the experimental bedding material. Weather conditions, intake, CBP temperature, CBP moisture, and welfare assessment were measured during the entire periods. We took CBP samples for microbiological analysis and video recordings for animal behavior assessment in wk 11 of each period. The CBP management was the same in both treatments and periods, based on twice-daily tilling at a 30 cm depth, and the addition of 0.8 kg/m2 of new bedding material per day. Ambient temperature and environmental humidity were 9.1°C and 82.5% in period 1, and 13.2°C and 75.3% in period 2. Average DMI and water consumption were 17.4 ± 0.86 kg/d and 50.9 ± 7.84 L/d in period 1, and 16.3 ± 0.96 kg/d and 56.3 ± 8.02 L/d in period 2. Average of temperature, moisture, and C:N ratio of CBP were 32.2°C, 63.6%, and 44:1 in CBP-S, and 24.3°C, 66.4%, and 35:1 in CBP-FB, respectively. Temperature was higher in CBP-S than in CBP-FB, and in period 2 compared with period 1. Moisture was higher in CBP-FB than in CBP-S in period 1, but did not differ between treatments in period 2. The C:N ratio was higher in CBP-S than in CBP-FB in both periods. Total bacteria count and Bacillus spp. were similar between treatments. Klebsiella spp. counts in CBP-S were higher than in CBP-FB, and Streptococcus spp. and yeasts and fungi counts in CBP-S were lower than in CBP-FB. Total coliforms, Escherichia coli, and Staphylococcus aureus counts in CBP-S were higher than in CBP-FB in period 1, but did not differ between treatments in period 2. No differences were detected in lying time (15.5 h/d), and time needed to lie down was higher in CBP-FB (5.3 s) than in CBP-S (4.6 s). We found that CBP performance and cow comfort in CBP-FB were lower than in CBP-S, but microbial counts of some species were better controlled in CBP-FB than in CBP-S.

Use of glycerol and propylene glycol as additives in heat-treated goat colostrum.

This experiment aimed to evaluate the suitability of glycerol and propylene glycol to reduce microbial count and preserve immune properties in heat-treated goat colostrum. Colostrum samples from 11 goats were each divided into 9 aliquots. Different concentrations (2, 6, 10, and 14%; vol/vol) of either glycerol or propylene glycol were added to the aliquots. Phosphate buffer solution was added to one aliquot, which was set as the control (CG). After the respective additions, all colostrum samples were heat treated at 56°C for 1 h. After cooling, aerobic mesophilic bacteria were cultured. The samples were frozen until free fatty acid, IgG, IgA, and IgM concentrations and chitotriosidase activity were measured. No differences were found in aerobic mesophilic bacteria counts between either 10 or 14% glycerol and propylene glycol additives. These additions reduced bacterial count to a greater extent than CG, and 2 or 6% additions. Colostrum IgG concentration was not affected by either of the additives or their concentrations. The propylene glycol additive reduced IgA and IgM concentrations and chitotriosidase activity, compared with CG. Conversely, glycerol did not affect any of the studied immune variables. In conclusion, glycerol addition to goat colostrum before heat treatment is suitable to enhance bacterial reduction, whereas colostrum immune properties were not affected.

Heat treatment of bovine colostrum: I. Effects on bacterial and somatic cell counts, immunoglobulin, insulin, and IGF-I concentrations, as well as the colostrum proteome.

The objective of this study was to investigate the effects of heat treatment on colostral low-abundant proteins, IgG and IgA, insulin, and insulin-like growth factor I (IGF-I), as well as bacteria and somatic cells. First-milking colostrum samples >8 L and Brix % > 22.0 were harvested from 11 Holstein cows on a commercial dairy in New York State and split into 2 aliquots using single-use colostrum bags. One aliquot of each pair was cooled on ice immediately after harvest (raw, R; n = 11), and the other was heat-treated for 60 min at 60°C (heat, H; n = 11). All samples were analyzed for IgG and IgA via radial immunodiffusion assay and insulin and IGF-I concentrations by radioimmunoassay. Total bacterial counts and somatic cell counts (SCC) were determined using standard plate culture techniques and flow cytometry, respectively. Samples from a subset of 5 pairs (n = 10) were further analyzed by nano liquid chromatography-tandem mass spectroscopy, after ultracentrifugation at 100,000 × g for 60 min at 4°C to enrich the low-abundant protein whey fraction. Data were analyzed using either paired t-test or Wilcoxon signed-rank test or using an online software package to analyze proteomics data. Outcomes of proteomics analysis were fold change ≥1.5 between pairs, and paired t-tests with false discovery rate-adjusted P-value < 0.05. The median reduction of IgA concentrations was 8.5% (range: 0-38.0%) due to heat treatment, whereas IgG concentrations did not change due to treatment. Insulin concentrations decreased by a median of 22% (7-45%), and IGF-I decreased by 10% (0-18%) in H samples. Heat treatment was associated with a median reduction of SCC of 36% (0-90%) in paired samples, as well as a median reduction in total bacterial count of 93% (45-100%) in H versus R samples. Proteomics analysis identified a total of 328 unique proteins that were present in all 10 samples. Nine of the 25 proteins that decreased by at least 1.5-fold in H compared with R were identified as complement proteins. We conclude that heat treatment of colostrum is associated with a reduction in the concentration of bacterial counts and SCC, IgA, insulin, and IGF-I. In addition, proteomics analysis of colostral whey identified several complement components and other proteins that decreased in abundance due to heat treatment. Although IgG concentrations were unaffected and a reduction in bacterial counts was achieved, the change in several immunologically active proteins and growth factors may have biologically important effects on the developing immune system of the neonate fed heat-treated colostrum.

Bulk tank milk quality data is unlikely to give useful information about dairy cow welfare at herd level.

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.

Quantitatively determining the total bacterial count of raw goat milk using dielectric spectra.

The objective of this study was to evaluate dielectric spectra as a means of quantitatively determining total bacterial count (TBC) of raw goat milk. The dielectric spectra, including dielectric constant (ε') spectra and dielectric loss factor (ε″) spectra, and TBC of 154 raw goat milk samples were measured using network analyzer and plate count methods, respectively. Owing to the poor linear relationship between TBC in logarithm and permittivities at a single frequency, chemometrics was used to reduce noise, identify outliers, select effective variables, and divide sample sets. Several linear models, such as multiple linear regression, ridge regression, and least absolute shrinkage and selection operator, were established to determine TBC based on the effective spectra of ε', ε″, and their combination (ε'+ε″). The results indicated that the models built using the spectra of ε'+ε″ and ε' had excellent TBC prediction performance. The best model was multiple linear regression based on ε'+ε″ spectra with the residual predictive deviation of 3.26. This study shows that the dielectric spectra had great potential to quantitatively and rapidly determine TBC of raw milk.