N-acetyl-β-d-glucosamine (GlcNAc)6 is extensively used as an important bio-agent and a functional food additive. The traditional chemical process for GlcNAc production has some problems such as high production cost, low yield, and acidic pollution. Therefore, to discover a novel chitinase that is suitable for bioconversion of chitin to GlcNAc would be of great value. Here, we describe the complete isolation and functional characterization of a novel exo-chitinase from Acinetobacter parvus HANDI 309 for the conversion of chitin. The identified exo-chitinase mainly produced N-acetyl-d-glucosamine, using chitin as a substrate by submerged fermentation. The A. parvus HANDI 309 biofuels producing exo-chitinase were characterized by TLC, and was further validated and quantified by HPLC. Furthermore, the optimal temperature and pH for the exo-chitinase activity was obtained in the culture conditions of 30 °C and 7.0, respectively. The maximum growth of the stationary phase was reached in 24 h after incubation. These results suggest that A. parvus HANDI 309 biofuels producing exo-chitinases may have great potential in chitin to N-acetyl-d-glucosamine conversion. The excellent thermostability and hydrolytic properties may give the exo-chitinase great potential in chitin to GlcNAc conversion in industry. This is the first report that A. parvus HANDI 309 is a novel bacterial strain that has the ability to produce an enormous amount of exo-chitinase-producing bio-agents in a short time on an industrial scale without any pretreatment, as well as being potentially valuable in the food and pharmaceutical industries.

In this study, we prepared stabilized vitamin A and C nanoemulsions, and investigated their efficacy on milk-specific proteins in bovine mammary epithelial cells (MAC-T). Emulsions of vitamin A (vit-A) and C (vit-C) were prepared using Lipoid S 75 and microfluidization. The particle size and polydispersity index (PDI) of nanoemulsified vit-A and vit-C were studied. The cytotoxic effect of nanoemulsion-free and nanoemulsified vit-A and vit-C was determined by an MTT assay. In addition, the efficacy of nanoemulsified vit-A and vit-C on the in vitro expression pattern of milk-specific proteins in MAC-T cells was investigated by quantitative RT-PCR. The results showed that the efficacies of stabilized nanoemulsions of vit-A and vit-C were 100% and 92.7%, respectively. The particle sizes were around 475.7 and 225.4 nm, and the zeta potentials were around −33.5 and −21.3 mV, respectively. The expression changes of α_s2-, β- and κ-casein were higher in the presence of a stabilized nanoemulsion of vit-A, compared with nanoemulsion-free vit-A. Furthermore, the expression changes of α_s2- and β-casein were lower and that of κ-casein was higher in the presence of a stabilized nanoemulsion of vit-C, compared with nanoemulsion-free vit-C. Thus, our findings demonstrate the efficacy of nanoemulsified vit-A and vit-C in changing the expression of milk-specific proteins in MAC-T cells.

This study aimed to determine the effects of replacing corn with hydroponically sprouted barley (HSB) in Holstein heifer feed on growth performance and blood metabolites. For this purpose, the barley was prepared with hydroponic sprouting under optimized conditions, and its chemical composition was analyzed on a dry matter (DM) basis. A total of 30 Holstein heifers that were 7 months old with an average body weight of 212.60 ± 55.00 kg were used in a completely randomized design comprising 10 repetitions and three groups over a period of 11 months. Dietary treatments included control (CON), basal diet (corn meal-based diets), and trail diets, in which 10% and 30% HSB gradually replaced corn meal. The growth performance and biochemical indices were analyzed every month. Results showed that the HSB diet increased chemical compositions compared with the control diets on a DM basis. In addition, diets with up to 30% HSB did not show any negative effects on the growth performance (body weight, height at withers, and height at rump) or selected blood metabolites of heifers compared with the CON diet. In conclusion, the use of HSB instead of corn meal did not lead to any adverse effects on growth performance or biochemical indices; therefore, HSB can be used as an alternative dietary source for raising Holstein heifers.

This study evaluated milking characteristics and milk productivity of a domestically developed automatic milking system (AMS-K) and compared its performance with a commercially imported AMS (AMS-C), under identical farm management conditions. Milking performance of AMS-K was monitored over a three-month operating period, and a comparative analysis was subsequently conducted using a total of 50 Holstein cows, with 25 cows allocated to each system based on similar parity, days in milk, and milk yield. During the three-month operation of AMS-K, milk yield per milking significantly increased in from 13.81 kg in the 1st month to 15.99 kg in the 3rd month, and daily milk yield increased by 4.01–7.52% compared with the initial operating period. Milking frequency decreased from 2.53 to 2.27 times per day, but remained higher than conventional twice-daily milking. Average milking interval increased from 9.37 to 10.34 h, which was within the optimal range (9–10 h) for AMS operation. Milking stall occupancy and teat-cup attachment times gradually increased, whereas milking time showed no significant change. Somatic cell count initially increased but stabilized after three months. Milking efficiency ranged from 2.44 to 2.56 kg/min. In the system comparison, AMS-C showed shorter milking stall occupancy time, higher milking frequency, and higher milking efficiency than AMS-K, whereas AMS-K showed higher milk yield per milking, associated with longer milking interval. Across both systems, multiparous cows exhibited longer milking intervals and higher milk yields than primiparous cows in both AMSs. Theoretical milking capacity per AMS was 54.45 cows (primiparous) and 37.77 cows (multiparous) for AMS-K, sufficient for an average Korean dairy farm. Our results demonstrate that AMS-K achieved stable milking performance, milk quality, and operational efficiency comparable to the imported AMS. AMS-K shows great potential for practical applications and commercialization in Korean dairy farms.