Dairy, Volume 4, Issue 4 (December 2023) – 14 articles

Staphylococcus aureus (S. aureus) is one of the most prevalent contagious bacterial pathogens causing clinical bovine mastitis. In the present study, plate (A), which consists of 80 compounds (40 drug-like and 40 probe-like), was assessed from the Malaria Box against the in vitro growth of S. aureus isolated from cows naturally infected with S. aureus. Anti-Staphylococcus aureus medications that are newer and more potent than those that have been used previously were discovered. Bioinformatics analysis for the potent identified hits was performed. Three compounds—two probe-like and one drug-like—showed strong inhibitory action against S. aureus growth in vitro. Among these hits, MMV665941 exhibited the highest minimum inhibitory concentration value of 0.0078. Combination therapy was carried out using the most potent anti-S. aureus medication, MMV665941, and the traditionally used anti-S. aureus drug, amoxicillin/clavulanate (Augmentin 625^®). The atom pair fingerprint (APfp) analysis revealed that MMV665941 and Augmentin showed maximum structural similarity. Based on the results obtained, it can be concluded that the Medicines for Malaria Venture Box has a wealth of potential anti-S. aureus candidates. Full article

The effects of grass silage and barley grain preservation methods on dairy cows were evaluated using four Nordic Red dairy cows placed in respiration chambers in a 4 × 4 Latin square. Silage was conserved using a formic acid-based product (AS) or a homofermentative lactic acid bacteria inoculant (IS), while grains were dried (DB) or crimped and ensiled (EB). Fermentation profile of silages and the chemical composition of the mixed diets were very similar. The dietary treatments did not affect feed intake, milk production, and rumen fermentation except molar proportion of butyrate, and energy metabolism. Digestibility of dry matter and organic matter were higher (p < 0.05) and that of crude protein was lower (p < 0.05) for AS than IS. Feeding EB compared to DB decreased (p < 0.05) diet organic matter and starch digestibility. The cows receiving AS tended (p = 0.06) to emit more methane per day than those receiving IS, but methane yield and intensity were not different between dietary treatments. Bacteria alpha diversity was higher (p < 0.01) in barley samples than grass silages and was not affected by the diet in rumen samples. All freshly prepared rations were dominated by Lactobacillaceae, Erwiniaceae, and Pseudomonadaceae but rations based on AS than IS remained more stable over 2 days. In conclusion, grass silage and barley grain preservation methods did not affect the measured parameters in dairy cows and the preservation method can be selected based on practical on-farm factors. Full article

An increasing number of dairy farmers in New Zealand (NZ) have adopted a once-a-day (OAD) milking production system, and little is known about the impact of this production system on milk protein composition. The objective of this study was to evaluate the effect of OAD milking on the protein composition in milk from individual cows. Milk was sampled in early, mid-, and late lactation from cows kept at Massey University farms Dairy No. 1 (OAD milking) and Dairy No. 4 (TAD milking) in Palmerston North, NZ. The yields of total milk and milk solids, the proximate composition, and the protein composition were determined. Results showed that OAD milking yielded less milk and milk solids than TAD milking. However, no significant differences in protein, fat, and lactose contents were found. While the proportions of total casein (CN), total whey proteins, αs1-CN, β-CN, and β-lactoglobulin were not affected by the milking frequency, milk from a OAD milking system contained higher proportions of αs2-CN and κ-CN and lower proportions of α-lactalbumin. These proteins also changed differently throughout the milking season in a OAD milking system than in a TAD milking system. These changes in the protein composition of the milk observed in a OAD milking system could have implications for its processing properties and product quality. Full article

The study aimed to compare the physicochemical composition, fatty acid profile, phenolic content and volatile organic compounds (VOCs) of feta cheese produced in two regions in Greece (mountainous grasslands and plains). The VOC profiles of forage in the mountainous grasslands were also investigated in order to detect any relationship between the two profiles. Forbs were found to be the major functional group in the mountainous area and the most abundant VOCs were aldehydes, alcohols, and terpenes. Significant variations were observed between the main compositional features of the two types of cheeses, with the cheese produced from the milk of ewes and goats grazing in the mountainous region having a higher moisture content, lower fat content, and higher protein content. A total of 34 VOCs were identified and the most abundant groups in the cheese samples were esters, hydrocarbons, and alcohols. The fatty acid profile, phenolic content, and terpene profile of the cheese were also affected by the type of pasture. The cheese produced from the milk of ewes and goats grazing in the mountainous region also had a higher content of conjugated linoleic acid (CLA) and a lower content of saturated fatty acids (SFAs). These findings suggest that the grasslands grazed by ewes and goats in the mountainous region have a positive impact on the nutritional quality of feta cheese. Full article

Contamination of milk and dairy products with pathogenic and spoilage bacteria may result in huge economic loss due to recalls of products. This study aimed to identify spore-forming bacteria from raw milk and characterise those for toxin production and their spoilage ability. Bovine raw milk collected from dairy farms in the Manawatu region of the North Island of New Zealand was tested for the presence of both aerobic and anaerobic spore-forming bacteria using standard culture-based techniques, as well as genomic analysis. The spore-forming bacteria were investigated for the presence of toxin genes and their spoilage potential. A low number of aerobic spore-forming bacteria were detected in raw-milk samples collected from the four farms in summer and winter. The 16S rRNA sequence types similar to important food spoilage bacteria like C. beijerinckii, C. sporogenes, B. licheniformis and members of the Paenibacillus genus, as well as potentially toxigenic bacteria such as B. cereus and C. perfringens were isolated. Genes responsible for important toxin production were present in some of the tested spore-forming bacteria. This pilot study highlights the presence of various spoilage and pathogenic spore-forming bacteria in raw milk from these farms. A low number of spore-forming bacteria indicates the implementation of good hygienic farm practices and management to reduce the contamination of raw milk with spore-forming bacteria. Full article

This review focuses on the potential opportunities to incorporate functional ingredients like probiotics in the dairy fat-rich matrix to develop functional foods. Many dietary guidelines and the relevant literature have in general indicated many benefits of consuming milk-fat-rich products for the human body. Milk fat contains essential nutrients, including fat-soluble vitamins; short-, medium-, and long-chain with odd and branched chain fatty acids; essential amino acids; and calcium, which are all known for their bioactive properties. In addition, the incorporation of probiotics, which are known for their bioactive properties, could further enhance the products’ attributes. However, direct probiotic addition is known to encounter viability challenges during manufacturing and storage. There is thus an opportunity to introduce a value-added range of dairy fat-rich products imparting bioactive and functional benefits. The current review is an attempt to consolidate information in this area and explore further avenues for the value addition of dairy fat-rich products. Full article

Dulce de leche is a South American traditional dairy product. However, due to the high sugar content, it is unsafe for consumers with special physiological conditions, such as diabetes. Light foods were developed to meet those demands whilst maintaining the sensory characteristics. The present study aimed to develop and characterize a formulation of light dulce de leche, using sweeteners to substitute sucrose, and gums as thickening and stabilizing agents. The physicochemical assays follow the AOAC manual, and the microbiological parameters were set according to MERCOSUL’s legislation. Thirty potential consumers perform the nine-point hedonic scale for product acceptance and the seven-point scale for buying intention. Compared to the traditional formulation, the product had better rheological properties, but a lighter color. All the raw materials and final products were considered safe by the recommended microbiological and toxicological standards; however, the product showed discrepancies to the physicochemical requirements. The formulation had an overall medium acceptance and low buying intention. The product had deficiencies, needing other compounds to reach the desired characteristics. Even though it leads to a more expensive final product, it is possible to adjust the product and allow access to more selective consumers or with restrictions. Full article

The aim of this study was to compare selection indices for important traits in intensive Spanish goat breeds in four economic scenarios, using the Florida as most representative breed of this production system in Spain. For this analysis, we considered the following traits: milk yield (MY), fat plus protein yields (FPY), casein yield (CY), somatic cell score (SCS), reproductive efficiency (RE), litter size (LS), mammary system (MS), final score (FS), body capacity index (BCI), and length of productive life (LPL). We estimated the genetic parameters and EBVs of most of these traits with REML methodology, while LPL was modeled through survival analysis. Four scenarios were proposed, depending on the overall objective for improvement: (1) milk production, (2) milk production and cheese extract, (3) cheese extract, and (4) milk production, cheese extract and sale of animals. Then, within each scenario, three different types of indices were designed using the different primary and secondary objectives/criteria considered suitable to improve the overall objective. The results indicated that selecting only for primary traits yielded the highest genetic response for all the scenarios. Including secondary traits led to positive correlated responses in those traits, but a decrease in the responses in the primary criteria. Full article

The rheological properties, e.g., viscosity and yield stress, of fermented concentrated milk products (protein content > 8%) are strongly dependent on their volume fraction. Post-treatment with high-power ultrasound can reduce the volume fraction of these products and, hence, lead to reduced crowding effects and thus lower viscosities and yield stress. Besides that, the particle size distribution (span) should stay unaltered. Increasing the energy input during the sonication of fat-free fresh cheese with a protein content of 8.9 ± 0.4% decreased the volume fraction below the limit for concentrated products (ϕ = 0.4), while the particle size also decreased. This led to a narrowed span and, hence, the viscosity should have increased; however, the results showed that viscosity and yield stress were decreasing. Consequently, the influence of the span was neglectable for concentrated fermented milk products with volume fractions below the concentrated area. Furthermore, the sonicated samples showed no syneresis over a storage time of two weeks. The sonicated samples reached similar rheological properties to commercial stirred yogurt, which demonstrated the suitability of high-power ultrasound as a post-treatment to tailor the rheological properties of high-protein fermented milk products. Full article

The age at first calving (AFC) is one of the most used indicators to evaluate the efficiency of rearing systems in dairy herds. The objective of the present study was to evaluate the association between AFC and different parameters of productive and reproductive efficiency in dairy cows of Holstein and Jersey breeds and their crosses, reared under pasture-based conditions. A retrospective longitudinal study was carried out with information on the performance of 77,311 cows with birth and culling dates between 1990 and 2016 from 654 specialized dairy herds located in mid and high-altitude regions of Costa Rica. Cows were classified into five classes according to their age in months at first calving (≤24, 25–27, 28–30, 31–33, ≥34). A generalized linear mixed model was used to assess the effect of AFC and breed factors on milk production (first lactation, lifetime total, and per day of life), open period (first calving and lifetime total), and herd life. The mean AFC was 29.5, 29.1, and 28.0 months for Holstein, Holstein × Jersey, and Jersey, respectively. The AFC was significantly associated (p < 0.01) with all the variables evaluated. Cows with AFC ≤ 24 presented a higher (p < 0.01) milk production (total lifetime and per day of life), as well as a longer herd life, compared to cows in classes of AFC > 28 m. The reduction in AFC contributes to a significant increase in the production and reproduction efficiency of pasture-based dairy herds. This effect was consistent across the three breed groups. Full article

Milk and milk products are the main nutritional foods for all age groups, especially for infants and children. Milk may be dangerous to consume due to the presence of a harmful substance called Aflatoxin M1 (AFM1). The objective of this study was to assess the levels of AFM1 in milk, particularly those that exceed the standards set by the European Union (50 ng/L), the Food and Drug Administration (500 ng/L), and the Iranian National Standards Organization (100 ng/L). The study included one hundred and eighty samples of raw cow’s milk from various retail dairy markets in Gorgan, with 45 samples collected during each season. The level of Aflatoxin M1 in the samples was measured using the enzyme-linked immunosorbent assay (ELISA) technique. AFM1 was detected in 139 (72.2%) raw cow milk samples with a range of 3.5–357 ng/L. All of the samples collected had Aflatoxin M1 concentration levels that were below the maximum limit of 500 ng/L set by the FDA. However, 41 samples (22.7%) exceeded the EU’s limit of 50 ng/L, and 26 samples (14.4%) exceeded the INSO’s limit of 100 ng/L for Aflatoxin M1 in raw cow’s milk. The lowest and highest AFM1 levels of contamination were detected in the summer and winter seasons, which constituted 32 (71.1%) and 38 (84.4%) samples, respectively. The consumption of raw cow milk can lead to health risks for individuals from various age groups because regulatory limits are not being followed. Full article

The detection of lame cows is a challenging and time-consuming issue for dairy farmers. Many farmers use the milking time to monitor the condition of their animals. Because lame cows often show increased stepping when standing to relieve pressure on aching claws, we investigated whether lame cows showed increased activity in the milking parlor. On 20 Swiss dairy farms, 647 cows were scored on lameness with a five-point locomotion score and categorized as clinical lame and non-lame cows in order to see if there are differences in behavior between these two groups (non-lame = scores 1 and 2; lame = scores 3, 4, and 5). During one evening milking, the behavior of the cows was analyzed. A three-dimensional accelerometer, attached to the milking cluster, detected the hind leg activity indirectly via the movements of the milking unit. Additionally, head movements, as well as weight shifting and the number of steps with the front legs, were analyzed from video recordings. Owing to a high percentage of false positive hind leg activities in some milkings measured by the sensor, only 60% of the collected data were evaluated for behavior (356 cows/milkings on 17 farms). Twenty-seven percent of the investigated cows were classified as lame. The lameness prevalence was increasing with increasing parity. Lame cows showed a higher hind leg activity during milking as well as a higher frequency of front steps and weight shifting events during their stay in the milking parlor than non-lame cows. No relation between the status of lameness and the number of head movements could be seen. Observation of increased stepping and weight shifting of individual animals during milking by the farmer could be used as an additional indicator to detect lame cows, but further investigations are required. Full article

Escherichia coli is a major player in foodborne illnesses, capable of forming biofilms on dairy facilities, leading to milk contamination. Thus, we examined the capacity of E. coli strains from raw milk bulk tanks to form biofilms on surfaces made of polystyrene, stainless steel, and silicone; the potential links between biofilm formation with genes responsible for fimbriae and virulence factors of extra-intestinal E. coli (ExPEC); and the susceptibility of biofilm-forming isolates to iodine and chlorhexidine digluconate. Out of 149 E. coli strains, 42.28% (63/149) formed biofilm on polystyrene, 56.38% (84/149) on silicone, and 21.48% (32/149) on stainless steel. The frequency of genes was: fimH (100%), hlyA (5.4%), irp2 (2.7%), sitA (10.7%), ompT (43.6%), and traT (98%). No biofilm developed when disinfectants were used prior to biofilm formation. However, iodine and chlorhexidine digluconate allowed 25.40% (16/63) of isolates displaying growth after a mature biofilm was formed. The presence of biofilm on different surfaces emphasizes the vital need for thorough equipment cleaning, both in farms and in industrial dairy settings. Rapid disinfection is crucial, given the reduced susceptibility of potentially pathogenic E. coli after biofilm maturity. Full article

Hyperketonemia is common in cows postpartum and is associated with a decrease in milk production, reproductive efficiency, and increased risk of periparturient diseases and early culling from the herd. The objective of this research was to determine if feeding an exogenous source of propionate increased milk and milk component yield and reduced the incidence of hyperketonemia and other health events in Holstein dairy cows. Cows were systematically enrolled in the control group (C) or sodium propionate treatment group (SP) in a randomized block design. A subset of cows was sampled for blood glucose and betahydroxybutyrate (BHB) concentrations in milk at 3, 7, and 14 days using a NovaMax^® Plus™ meter (Nova Diabetes Care, Inc., Billerica, MA, USA). Data were analyzed using a mixed model. Average blood BHB and glucose concentrations during the postpartum period did not differ between treatments for multiparous or primiparous cows (C = 0.53 ± 0.02, SP: 0.55 ± 0.02 mmol BHB/L, p = 0.5; C = 44.0 ± 0.77, SP = 43.0 ± 0.78 glucose mg/dL, p = 0.6). However, the prevalence of hyperketonemia and metritis was high in primiparous cows (C = 35.6% and 19.8%, respectively; SP = 35.8% and 18.9%, respectively). Blood glucose was inversely related to BHB concentration for cows below 40 mg/dL blood glucose. Feeding sodium propionate during the postpartum period increased milk fat yield (C = 1.71; SP = 1.86 kg/day, p = 0.01), tended to increase milk yield in multiparous cows (C = 39.3; SP = 40.5 kg/day, p = 0.06) and increased milk fat yield in primiparous cows (C = 1.18; SP = 1.27 kg/day, p = 0.02). Including sodium propionate in the total mixed ration is beneficial to reduce health events and increase milk fat production in multiparous cows but may only increase milk fat production in primiparous cows. Full article