Vol. 2 No. 1 (2019): Vietnam Journal of Agricultural Sciences

A study was conducted to estimate the optimal levels of energy, protein, and fiber in the diets of New Zealand White (NZW) growing rabbits fed on fresh green forage available in North Vietnam. Mathematical modelling of nutrient-response curves was applied for the study. A total of 125 male growing rabbits at 6 weeks of age were randomly divided into 25 groups of 5 each to be fed on diets with an array of different levels of metabolizable energy (ME), crude protein (CP), and acid detergent fiber (ADF) by means of varying the ratio between fiber rich grasses, viz. elephant grass (Pennisetum purpureum), Setaria grass (Setaria sphacelata), or Para grass (Brachiaria mutica), and protein rich forages, viz. water spinach (Ipomoea aquatica) vines, sweet potato (Ipomoea batatas) vines, or Trichantera leaves (Trichanthera gigantea), in the basal diets. The average daily gain (ADG) and feed conversion ratio (FCR) were used as key responses of the rabbits to varied levels of ME, CP, and ADF in the diets. The results showed that the levels of ME, CP, and ADF in the diets strongly affected the ADG and FCR of the rabbits following curvilinear patterns with the highest ADG and lowest FCR when the diet contained 2106-2162 Kcal ME kg-1 DM with 16.5-16.8% CP and 21.9-22.4% ADF. Therefore, these levels of nutrients were considered to be optimal in the diets of NZW growing rabbits fed on local forages.

The association of the RNF4, RBP4, and IGF2 genotypes and their additive genetic effects with litter size in purebred Landrace and Yorkshire sows were studied. The results revealed significant associations between the RNF4 and RBP4 genotypes with the total number of piglets born (TNB) and number of piglets born alive (NBA) traits (P <0.05). The RNF4 CC genotype had greater TNB and NBA than the TT genotype in both breeds. The RBP4 BB genotype had greater TNB and NBA than the AA genotype in the Landrace breed. Significant additive effects of the RNF4 and RBP4 genes on the TNB and NBA were detected (P <0.05). No significant associations of the IGF2 genotypes and their additive effects with any reproductive traits were observed in both Landrace and Yorkshire sows (P >0.05). The results suggested that the RNF4 and RBP4 genes could be useful in selection for increasing TNB and NBA traits in pigs.

The aim of this study was to evaluate the biological efficiency and main bioactive components of three G. lucidum strains, viz. GA1, GA2, and GA3, cultivated in Tam Dao town. The results demonstrated that all strains were capable of growing well on PDA medium supplemented with rice bran. The time required for complete colonization was 9 days. All tested strains of G. lucidum were able to adapt to climate conditions and produce fruiting bodies with satisfactory yield (13-17%), and therefore, they could be considered suitable candidates for commercial cultivation of G. lucidum in Tam Dao. No significant differences in polysaccharide content were observed among all strains. High concentrations of lucidenic N acid (0.33 mg g-1) and ganoderic acid (2.38 mg g-1) were determined in strain GA3. However, the highest ganodermanontriol content was detected in the strain GA1 with 0.3 mg g-1.

Chlorogenic acid is a natural antioxidant that is widespread in the plant kingdom and can be found at a high content level in green coffee beans. This secondary metabolite in green coffee beans has potent biological properties including antioxidant, anti-inflammatory, anti-cancer, anti-obesity, anti-hypertension, and anticonvulsant. In this study, the extraction of chlorogenic acid from Vietnamese green coffee beans was optimized using the response surface methodology. A second-order polynomial model with three important variables (liquid-to-solid ratio, temperature, and extraction time) was used. A rotatable central composite design consisting of 21 experimental runs with three replicates at the center point was applied to describe the experimental data. The experimental results properly conformed to the constructed model (R2 = 0.8549). The optimized conditions were as follows: 40% ethanol (v/v), a liquid-to-solid ratio of 11.77, at 85oC for 64 min. Four extractions were performed in parallel using the optimal conditions to validate the model. The experimental values highly agreed with the predicted value (P <0.05).

This article introduces a virtual private network (VPN) system deployed in a 70m2 operator station and greenhouse at Vietnam National University of Agriculture. The VPN system was not limited by geographical distance and allowed for remote monitoring of environmental parameters, viz. light (10-16000lux), soil moisture (20-100%), temperature (20-60oC), and ambient humidity (30-90%) with tolerances of ± 5% of the set/measured values. The signals from the sensor system were recorded with a sampling time of 6 seconds. The designed interface made it easy for Vietnamese users. The system was initially established, and tested successfully with Gerbera in the greenhouse. The VPN system allowed for remote programming, stable operation, and no loss of data during the signal collecting process, and allowed users to fully and quickly react when the system crashed or when the user needed to upgrade or maintain the greenhouse system.