Dominant Yeast Community in Raw Sheep's Milk and Potential Transfers of Yeast Species in Relation to Farming Practices

Irregular Findings on Teatcups in Milking Parlours in Sheep and Goat Farms and Potential Predictors

The objectives of the present study were as follows: (a) to describe the prevalence of irregular findings on teatcups in milking parlours with dairy sheep and goats after the post-milking cleaning procedures had been completed, (b) to associate staphylococcal isolation from teatcups with the presence with irregular findings and (c) to identify predictors of the presence of irregular findings on teatcups. The teatcups in the milking parlour of 255 sheep and 66 goat farms were macroscopically evaluated for the presence of irregular findings immediately after the completion of cleaning of the parlour. In total, 1115 and 303 teatcups, respectively, were assessed. A detailed interview with the farmer served to record the characteristics of the milking parlour and obtain information about husbandry and health management variables in the farm. Teatcups with macroscopically evident irregular findings were observed in 150 milking parlours (46.7%). Overall, 593 teatcups (41.8%) were found with macroscopically evident irregular findings. Dirt, milk residues and cracks or tears were recorded in the teatcups of 90.0%, 36.0% and 12.7% of parlours with irregular findings. Staphylococci were more frequently isolated from teatcups with irregular findings than from undamaged ones: from 37.4% (222/593) versus 12.8% (106/825). They were more frequently isolated from teatcups with milk residues (39.4%) and teatcups with dirt (39.0%). Via multivariable analysis, the following three variables emerged as significant predictors of presence of teatcups with irregular findings: the daily number of milking sessions, month into the lactation period at sampling and number of available milking units per animal position. The study provides, for the first time internationally, an appraisal of the frequency of problematic teatcups in the milking parlours of small ruminant farms. The analysis of predictors has provided a focus for specific management aspects, where interventions need to be performed, in order to improve the situation in farms with problems. The consequent increased staphylococcal burden on teatcups with irregular findings points to the increased risk of intramammary infections in such cases.

Diversity and succession of contaminating yeasts in white-brined cheese during cold storage

Contamination of white-brined cheeses (WBCs) with yeasts is of major concern in the dairy industry. This study aimed to identify yeast contaminants and characterize their succession in white-brined cheese during a shelf-life of 52 weeks. White-brined cheeses added herbs (WBC1) or sundried tomatoes (WBC2) were produced at a Danish dairy and incubated at 5 °C and 10 °C. An increase in yeast counts was observed for both products within the first 12-14 weeks of incubation and stabilized afterwards varying in a range of 4.19-7.08 log CFU/g. Interestingly, higher incubation temperature, especially in WBC2, led to lower yeast counts, concurrently with higher diversity of yeast species. Observed decrease in yeast counts was, most likely, due to negative interactions between yeast species leading to growth inhibition. In total, 469 yeast isolates from WBC1 and WBC2 were genotypically classified using the (GTG)₅-rep-PCR technique. Out of them, 132 representative isolates were further identified by sequencing the D1/D2 domain of the 26 S rRNA gene. Predominant yeast species in WBCs were Candida zeylanoides and Debaryomyces hansenii, while Candida parapsilosis, Kazachstania bulderi, Kluyveromyces lactis, Pichia fermentans, Pichia kudriavzevii, Rhodotorula mucilaginosa, Torulaspora delbrueckii, and Wickerhamomyces anomalus were found in lower frequency. Heterogeneity of yeast species in WBC2 was generally larger compared to WBC1. This study indicated that, along with contamination levels, taxonomic heterogeneity of yeasts is an important factor influencing yeast cell counts, as well as product quality during storage.

Effects of rearing mode on gastro-intestinal microbiota and development, immunocompetence, sanitary status and growth performance of lambs from birth to two months of age

BACKGROUND

Artificial rearing system, commonly used in prolific sheep breeds, is associated to increased mortality and morbidity rates before weaning, which might be linked to perturbations in digestive tract maturation, including microbiota colonization. This study evaluated the effect of rearing mode (mothered or artificially reared) on the establishment of the rumen and intestinal microbiome of lambs from birth to weaning. We also measured immunological and zootechnical parameters to assess lambs' growth and health. GIT anatomy as well as rumen and intestinal epithelium gene expression were also analysed on weaned animals to assess possible long-term effects of the rearing practice.

RESULTS

Total VFA concentrations were higher in mothered lambs at 2 months of age, while artificially-reared lambs had lower average daily gain, a more degraded sanitary status and lower serum IgG concentration in the early growth phase. Metataxonomic analysis revealed higher richness of bacterial and eukaryote populations in mothered vs. artificially-reared lambs in both Rumen and Feces. Beta diversity analysis indicated an evolution of rumen and fecal bacterial communities in mothered lambs with age, not observed in artificially-reared lambs. Important functional microorganisms such as the cellulolytic bacterium Fibrobacter succinogenes and rumen protozoa did not establish correctly before weaning in artificially-reared lambs. Enterobacteriaceae and Escherichia coli were dominant in the fecal microbiota of mothered lambs, but main E. coli virulence genes were not found differential between the two groups, suggesting they are commensal bacteria which could exert a protective effect against pathogens. The fecal microbiota of artificially-reared lambs had a high proportion of lactic acid bacteria taxa. No difference was observed in mucosa gene expression in the two lamb groups after weaning.

CONCLUSIONS

The rearing mode influences gastrointestinal microbiota and health-associated parameters in offspring in early life: rumen maturation was impaired in artificially-reared lambs which also presented altered sanitary status and higher risk of gut dysbiosis. The first month of age is thus a critical period where the gastrointestinal tract environment and microbiota are particularly unstable and special care should be taken in the management of artificially fed newborn ruminants.

Microbial Dynamics of a Specialty Italian Raw Ewe's Milk Cheese Curdled with Extracts from Spontaneous and Cultivated Onopordum tauricum Willd

Milk coagulants prepared by maceration of flowers harvested from both spontaneous and cultivated Onopordum tauricum Willd. and a commercially available coagulant obtained from Cynara cardunculus L. (control) were assayed for small-scale manufacturing of Caciofiore, an Italian specialty raw ewe's milk cheese produced in a family run dairy farm located in the Marche region (Central Italy). The microbiota of the three thistle-based milk coagulants and their effect on the microbial dynamics of raw milk cheeses during fermentation and maturation (from day 0 up until day 60) were investigated through a combined approach based on viable counting and Illumina DNA sequencing. In both the control and experimental cheeses, despite the slight differences emerged depending on the coagulant used, Lactococcus lactis and Debaryomyces hansenii were the prevalent species among bacteria and fungi, respectively. Moreover, raw ewe's milk was the main factor affecting the evolution of both the bacterial and fungal microbiota in all cheeses. The overall similarities between control and experimental cheeses herein analyzed supports the exploitation of Onopordum tauricum Willd. as an alternative milk coagulating agent for production of Caciofiore and, more in general, raw ewe's milk cheeses.

Efficiency of Manchega Sheep Milk Intended for Cheesemaking and Determination of Factors Causing Inefficiency

Understanding the factors that determine and regulate cheese yield would allow, through deterministic parametric efficiency models, the determination of the most appropriate milk characteristics for the industry, and the estimation of a technological value for these characteristics. The present study aims to evaluate coagulation performance of Manchega sheep milk intended for cheesemaking and explores two models to determine milk technological efficiency. For this purpose, 1200 Manchega sheep milk samples were collected, and analyses were performed for composition, milk coagulation properties (MCP), somatic cell count (SCC), and milk color values. A first model was built based on curd yield (CE) and a second one based on dry curd yield (DCE). GLM and MANCOVA analyses were used to identify the factors that determine curd yield efficiency, which mainly depended on pH, casein, and lactose content and, to a lesser extent, on the speed of coagulation and curd firmness. When comparing both models, differences were linked to the water retention capacity of the curd. Based on this, the DCE model was considered much more accurate for prediction of coagulation efficiency in a wider variety of cheeses, as it does not seem to be affected by moisture loss.

Air Quality, Management Practices and Calf Health in Italian Dairy Cattle Farms

Simple Summary

Calf mortality is an important factor of economic loss in dairy operations. Among the factors which can affect calf health, air quality in calf housing has rarely been studied. In the present research, the relations among air quality in the calf pens, management practices, microclimatic conditions and calf health and mortality were studied in 25 Italian dairy cattle farms. Microbial air quality in the calf pens was found to be related to temperature and humidity, design and position of the pen, some management practices and calf health and mortality. Maintaining dry bedding and controlling microclimatic conditions in the calf pen can be useful practices to promote good air microbiological quality in the calf pen, improving calf health and reducing mortality.

Abstract

Among factors that can affect calf health, microbial quality of the pen air is poorly studied. In 25 Italian dairy farms, data concerning air quality in the calf pens, hygiene of pens and equipment, microclimatic conditions, calf health and management were collected during the winter season (January-March 2020 and December-March 2021). The average air Standard Plate Count (SPC) of 85 pens was 4.51 (SD = 0.52) log₁₀ cfu/m³ whereas the average air ammonia concentration was 0.66 (SD = 0.53) ppm. Positive correlations were found between average Temperature Humidity Index (THI) in the pen and air SPC, night maximum THI and air SPC and between SPC and yeast, mould and ammonia concentration in the pen air. The concentrations of E. coli, Enterobacteriaceae and yeasts in the pen air were higher and calf cough increased as the renewal interval of bedding material became longer. High bedding dry matter and low THI were associated with low air SPC, good calf health scores and low mortality. Maintaining low bedding humidity and controlling microclimatic conditions can contribute to enhancing air microbiological quality in the pen and reduce calf diseases and mortality.

Organic Farm Bedded Pack System Microbiomes: A Case Study with Comparisons to Similar and Different Bedded Packs

Animal housing and bedding materials influence cow and farm worker exposure to microbial pathogens, biocontrol agents, and/or allergens. This case study represents an effort to characterize the bacterial and fungal community of bedding systems using an amplicon sequencing approach supplemented with the ecological assessment of cultured Trichocomaceae isolates (focusing on Penicillium and Aspergillus species) and yeasts (Saccharomycetales). Bedding from five certified organic dairy farms in northern Vermont USA were sampled monthly between October 2015 and May 2016. Additional herd level samples from bulk tank milk and two bedding types were collected from two farms to collect fungal isolates for culturing and ecology. Most of the microorganisms in cattle bedding were microbial decomposers (saprophytes) or coprophiles, on account of the bedding being composed of dead plant matter, cattle feces, and urine. Composition of bacterial and fungal communities exhibited distinct patterns of ecological succession measured through time and by bedding depth. Community composition patterns were related to management practices and choice of bedding material. Aspergillus and Penicillium species exhibited niche differentiation expressed as differential substrate requirements; however, they generally exhibited traits of early colonizers of bedding substrates, typically rich in carbon and low in nitrogen. Pichia kudriavzevii was the most prevalent species cultured from milk and bedding. P. kudriavzevii produced protease and its abundance directly related to temperature. The choice of bedding and its management represent a potential opportunity to curate the microbial community of the housing environment.

Impacts of Milking and Housing Environment on Milk Microbiota

The aim of the present study was to determine the effects of farming environments on microbiota in raw milk and to assess the relationship among microbes by 16S rRNA sequencing methods. Samples of raw milk, cow trough water, teat dip cup, teat, teat liner, dairy hall air, cowshed air, feces, feed, and bedding from two farms were collected. The two highest abundant bacterial groups of Moraxellaceae and Staphylococcaceae were found in milk and teat liner samples, respectively, at Zhengzhou farm, Henan Province. Moreover, the two highest abundant bacterial groups of Enterobacteriaceae and Moraxellaceae were found in milk and teat dip cup samples, respectively, at Qiqihar farm, Heilongjiang Province. Source Tracker analysis revealed that the teat liner and teat dip cup were the most important contributors of microbes in milk samples at Zhengzhou farm and Qiqihar farm, respectively, which could be attributed to the management level of the farm. Therefore, disinfection and cleaning procedures should be developed to improve the quality of raw milk.

Influence of Environmental and Productive Factors on the Biodiversity of Lactic Acid Bacteria Population from Sheep Milk

Simple Summary

The dairy sheep sector in Spain is of great importance in the socioeconomic field. For this reason, obtaining quality milk has become a priority objective in the sector. In this context, the environment of dairy farms could affect the microbial communities present in milk, and therefore, the study of lactic acid bacteria (LAB) in this environment could be fundamental for the quality of milk and its dairy products. The objective of this study was to investigate the LAB population present in dairy sheep milk and the possible routes of contamination between the livestock environment and the milk on 12 sheep farms with different livestock practices in Castilla-La Mancha. The results showed that certain agricultural practices favour the presence of LAB in milk in addition to the fact that a significant transference between the livestock environment and bulk tank milk could exist.

Abstract

Milk is a typical and satisfactory medium for the growth of lactic acid bacteria (LAB). These microorganisms are of vital importance in the quality of the milk since they contribute to its preservation and give differential organoleptic properties to the final product. Furthermore, LABs can act as biocontrol agents in the dairy industry by inhibiting the growth of undesirable bacteria present in milk and by improving the quality of dairy products such as cheese. In this context, knowing the transfer routes used by LABs from the livestock environment to the milk is of great importance within the dairy industry. Therefore, the objectives of the present study were to expand the knowledge of the LAB population present in the milk of Manchego ewe by means of DNA sequencing techniques and to evaluate the possible transfers of LAB species based on the management of each dairy farm. Samples of bulk tank milk, air (from the milking parlour and from the livestock housing), animal feed and teat surface (taken from 10 sheep per farm) were collected in 12 traditional livestock farms in Castilla-La Mancha (Spain), where each farm presented differences regarding their farming practices. A mixed-effects model was used to evaluate the effects of livestock practices on the distribution of LAB species. Results showed that the vast majority of species identified in the milk had an isolate that was also found in other matrices, which could indicate a microbial transference via the livestock environment to the milk. In addition, the mixed model showed that the factors that positively influence the LAB count were the low-line milking system and the daily use of acid detergent in cleaning the milking machine.

Farming Practices Influence Antibiotic Resistance and Biogenic Amine Capacity of Staphylococci from Bulk Tank Ewe's Milk

Staphylococci are one of the main microorganisms responsible for intramammary infections in sheep, causing important economic losses for farmers and eventually health problems in humans, especially by the consumption of dairy products made with raw milk containing toxic compounds, such as biogenic amines or antibiotic resistant bacteria. This study aimed to check the presence and safety of staphylococci in bulk tank ewe's milk from different farms, and to determine the relationship between the presence of these staphylococci and farming practices, by applying nonlinear canonical correlation models (OVERALS). Two-hundred and fifty-nine staphylococci from milk samples from eighteen farms were genotyped and representative isolates of the major clusters were identified as belonging to Staphylococcus (S.) aureus, S. epidermidis, S. arlettae, S. lentus, S. simulans, and S. chromogenes species. Identified isolates were assayed in terms of their safety, by evaluating resistance to antimicrobial drugs and the aminobiogenic capacity, using both phenotypic and genetic assays. Antibiotic resistance phenotypic assay revealed that 82.9% were resistant to some antibiotics, although in the genotypic assay only the genes tetM, ermB, ermC, and grlA were detected. Fifty-three percent were high biogenic amine (BA) producers, being putrescine the most produced amine. A lowered risk of finding antibiotic-resistant and BA-producing staphylococci is related to some farming methods such as enrolling in a breeding program, use of good farming practices, postdipping teat disinfection, hygienic livestock housing, or periodic check of the milking machine.