The microbiome of bulk tank milk: Characterization and associations with somatic cell count and bacterial count.

Numerous studies have evaluated associations between bacterial groups and milk quality parameters. However, to our knowledge, no research has been published that has analyzed associations between the microbiome and quality parameters of bulk tank milk (BTM). Thus, the aims of this study were to identify the core microbiome of BTM and to examine associations between the microbiome and milk quality parameters. Four hundred seventy-two BTM samples from 19 different dairy farms located in New York State were analyzed by next-generation sequencing and quantitative PCR of the 16S rRNA gene to assess the milk microbiome and measure total bacterial load, respectively. Flow cytometry was used to determine bacterial and somatic cell counts. Heatmaps were constructed and simple linear regressions and response screening analysis were performed. To facilitate data analysis and interpretation of the results, we dichotomized the BTM samples into high (HSCC, >200,000) and low somatic cell count (LSCC, ≤200,000) and into high (HSPC, >3.6) and low log10 SPC (LSPC, ≤3.6). Spoilage-causing, spore-forming, and pathogenic bacteria of importance to the dairy industry were identified in the core microbiome. In addition, the taxa Thermoanaerobacterium and 5-7N15 were identified in the core microbiome; to our knowledge, these genera have not been previously identified in milk samples. Several bacterial genera were encountered in significantly higher relative abundances in the HSCC group when compared with the LSCC group, including Corynebacterium, Streptococcus, Lactobacillus, Coxiella, Arthrobacter, and Lactococcus. Additionally, several bacterial taxa were found in significantly higher relative abundances in the HSPC groups versus the LSPC groups: Acinetobacter, Enterobacteriaceae, Corynebacterium, and Streptococcus. In addition, Streptococcus was highly correlated with HSPC, and this genus was the second most abundant bacterial taxon detected in samples classified as HSCC. Bacterial diversity (Shannon index) was negatively correlated with bacterial load, suggesting that the microbiomes of high-bacterial load BTM samples are dominated by smaller groups of bacterial taxa. In conclusion, the associations described corroborated current knowledge about pathogens and spoilage bacteria in relationship to milk quality, and also indicated that other bacterial taxa should be a focus of further investigations.

The Lactococcus genus as a potential emerging mastitis pathogen group: A report on an outbreak investigation.

The bacterium Lactococcus lactis is widely used in food production and in medical applications, and is considered safe for human and animal use. However, studies have also linked Lactococcus bacteria to infection. For example, certain variants of Lactococcus species have been associated with bovine mastitis (e.g., Lactococcus lactis and Lactococcus garvieae). In this study, we investigated an outbreak of bovine mastitis thought to be associated with Lactococcus bacteria by using microbiological and molecular techniques. We used bacterial isolation, next-generation sequencing, DNA fingerprinting, and other methods to test our hypothesis that Lactococcus microbes were the primary pathogen causing the mastitis outbreak. Twenty-eight Lactococcus isolates were obtained from mastitic milk of 28 dairy cows. The isolates were identified as L. lactis (27 isolates) and L. garvieae (1 isolate). Phylogenetic analysis based on 16S rDNA gene sequence comparison indicated similarity among the L. lactis isolates as well as between the isolates and reference sequences. The DNA fingerprinting analysis based on random amplified polymorphic DNA results of the 27 L. lactis isolates identified different random amplified polymorphic DNA profiles, which suggests they originated from multiple sources. Microbiome analysis determined Lactococcus to be the dominant genus in the majority of the mastitic milk samples, whereas it was found in low relative abundance in healthy milk samples. The Lactococcus genus was detected in all environmental samples tested, and sampling of bulk tank milk corroborated that Lactococcus was not abundant in healthy milk from the same dairy herd. In summary, our findings suggest that Lactococcus bacteria are a potential etiological agent in the mastitis outbreak studied. Further studies should be conducted to understand the importance of Lactococcus, especially L. lactis, as pathogenic microbes in veterinary medicine and food safety.

Cholesterol and iron availability in yolk of laying hens feed with annatto ( Bixa orellana).

Pigmented egg yolks are more attractive. Popular culture treats annatto as a powerful anticholesterolemic agent, besides being widely used in the form of industry pigment. This work evaluated the effects of the addition of annatto (Bixa orellana L.) in the feed of hens, verifying a possible alteration of cholesterol in the yolks, content of carotenes, and iron and available iron, over time. One hundred and twenty-five hens divided in control (0% - T1) and four annatto-added treatments (0.5% - T2; 1.0% - T3; 1.5% - T4, and 2.0% - T5) were used. Eggs were collected at 23, 25, 27, 29 and 30 weeks. The animals were randomly separated into five groups of five animals each. The cholesterol was measured by the colorimetric method, vitamin A (ß and α carotene) by spectrophotometry, total iron by atomic absorption spectrophotometry, and dialysable iron by dialysis. Tukey's test was used at the 5% level for comparison of the averages. Regarding cholesterol, treatments T2 and T3 did not differ significantly. However, other treatments differed ( P ≤ 0.05) from the control, decreasing the cholesterol level as the percentage of annatto in the feed increased. In time, there was a significant increase ( P ≤ 0.05). For ß and α carotene, T5 presented statistically higher values than the others ( P ≤ 0.05). With regard to total iron, T5 had higher values than the others. Dialysable iron was also higher, probably due to the increase in carotenes. Thus, we can conclude that the use of annatto in the feed of layer hens is useful, as it provokes the reduction of cholesterol and promotes an increase in the content of iron and carotenes in eggs.

[Nutritional evaluation of rice flour fermented with Rhizopus oligosporus]. / Avaliação nutricional de farinha de arroz fermentada com Rhizopus oligosporus.

In order to increase the proteic content of rice meal, fermentation with Rhizopus oligosporus was performed. During fermentation, samples were taken at the times of 0,20,30,40,50,60,70 and 80 hours. These samples were oven dried and further analysed. The amino acid composition of rice meal had lysine and threonine the most limiting ones. After fermentation the lysine content increase and the more limiting were the sulfur amino acids methionine and cystine (76.04%), threonine (91.03%) and lysine (97,04%. With the aim of verifying the biological value of the protein a bioassay was carried out. The fermented rice meal presented a higher digestibility value and the net protein utilization for the fermented rice meal lower than for the non fermented one.