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Dairy by-products – whey and permeate thereof – are widely used in both food and animal feed (including ruminant feed) production worldwide. In the study, which took place from 18 August to 16 December 2020, an experiment was performed with Holstein dairy heifer calves by feeding them milk acidifier (PP) obtained from whey permeate. Organic acids in acidifiers lower the pH level of the feed, and their antimicrobial effect creates environment unsuitable for pathogenic microorganisms to develop. The liquid acidifier obtained by fermentation can also serve as a functional feed ingredient – a source of B vitamins, protein and energy. In addition, reduction of the spread of antimicrobial resistance requires alternative ways how animal health is cared for both in Latvia and Europe, especially by natural means. The study was aimed at investigating the effect of the new product in a triple (divided) and single (undivided) feeding system on the calf growth and health. It covered 30 heifers born during the period from 18 August to 16 September 2020 and kept in SIA LLU MPS “Vecauce” dairy cow shed “Līgotnes” under equal housing conditions. The study groups were completed gradually, dividing the newborn heifers into three groups – E1, E2 and K (n=10 in each group). The mean live weight (at birth) in all groups was similar: 36.9±1.09 (E1), 39.3±0.69 (E2) and 38.7±1.33 (K) kg (p≥0.05). Control (K) group heifers received pasteurized whole milk without acidification. The heifers of the experimental groups – E1 and E2 – were fed 2-3 times a day with less acidified (pH 4.6–5.2) or once a day with more acidified (pH 4.2–4.6) pasteurized bulk milk. Acidified milk was fed to the animals from 7 to 75 days of age introducing the feed gradually. Animal health (appearance, fecal consistency and appetite) was assessed daily. One animal ate an average 533.6±3.45 (E1), 553.7±3.08 (E2) and 547.8±2.48 (K) liters of milk (d. 2–75) and 23.6±2.51 (E1), 24.2±3.03 (E2) and 30.7±3.64 (K) kg of concentrates between the ages of 2 and 75 days. Significant (p <0.05) differences were found only in the amount of milk eaten, which was smaller in the E1 group. Upon the cessation of milk feeding at 75 days of age, heifers reached the live weight of 105.0±3.76 (E1), 108.0±2.61 (E2) and 106.8±2.65 (K) kg, but the daily weight gain was 908±46.5, 917±32.7 and 909±24.4 g/d. Although the results of the E2 group were higher, the difference between the groups was not significant (p≥0.05). Fecal consistency, assessed on a point system from 0 to 4, also did not differ significantly between the groups (p≥0.05). During the first 30 days of life, it showed an average of 0.12±0.027 (E1), 0.12±0.035 (E2) and 0.07±0.019 (K) points. It should be noted that no cases of diarrhea (above 2 points) were observed in any animal throughout the study. The results confirm that PP can be used to acidify the milk fed to calves under both divided and undivided feeding; moreover it saves the time required for feeding. Milk acidifier can be added to milk directly as it does not need to be diluted, therefore use of the product is more convenient and safer than other more concentrated commercial products. The research received funding from the ERDF Post-doctoral Research Support Program No.1.1.1.2/16/I/001. Research application “Processing of Whey into Value-Added Products for Food Industry and Agriculture” Nr.1.1.1.2/VIAA/2/18/307, Investment in kind: SIA LLU MPS “Vecauce” and JSC “Smiltenes Piens”. [ABSTRACT FROM AUTHOR]

This research was focused on whey ultrafiltration permeate (UF) fermentation by genetically unmodified (wild) organisms. We chose five classical Propionibacterium (Prb) strains that are attributed to the dairy subclass. The optimal temperature for Prb growth is around 28-30°C, however, for energy saving purposes the aim of this study was to observe the organic acid, especially propionic acid (PA) and biomass production of the chosen Prb (DSM 20273 Acidipropionibacterium acidipropionici = A, DSM 20272 Acidipropionibacterium acidipropionici = B; DSM 4902 Prb. freudenreichii = E; DSM 20535 Acidipropionibacterium jensenii = J; DSM 20276 Acidipropionibacterium thoenii = T) at the room temperature (22±0.5°C). As expected, all the strains were able to convert lactose into acid, however, with different efficiency, thus the production of PA by Prb is strain -dependent. The higher productivity of PA was observed in samples with strains T, J, and B in a 26-day period, however, it should be noted that also the strain E showed high efficiency in a shorter (6-day) period. The highest concentration of PA was produced by strain T, and it reached 3.7±0.13 g L-1 within a 26-day period. The concentration of the PA produced depends on the duration of fermentation, and on the proportions of other acids produced as well. An individual strain initially can produce PA more slowly than others, but over time can be effective, which may be related to adaptation to environmental conditions. We also observed the presence of background microflora in whey permeates – most likely lactic acid bacteria. Lactic acid was produced most rapidly and was the most abundant acid produced from whey UF. [ABSTRACT FROM AUTHOR]