Vol. 18 No. 10 (2020)

African swine fever (ASF) is a highly infectious disease in the domestic and wild pig populations causing tremendous damage to the global swine industry. ASF was first reported in Vietnam on February 1st, 2019 and the disease has spread to 63 provinces in just 7 months. This study aims to investigate the molecular and biological characteristics of ASF viruses isolated from tissue samples of ASF-infected pigs collecting from the northern provinces of Vietnam. The results of virus isolation showed that five ASFV strains had been successfully isolated on PAM (Porcine Alveolar Macrophage) cells, virus titer ranging from 106-107,5 HAD50/ml. The results of the growth curve of the virus on PAM cells disclosed that, with the multiplicity of infection (MOI) = 1, the highest achieved virus titer was 108.160.21HAD50/ml after 96 hours post-infection. The sequencing results of the B646L (p72) gene showed that all present ASFV strains shared 100% nucleotide and amino acid sequence identity with each other. Phylogenetic analysis revealed that all isolated strains belonged to genotype II.

The Bang Troi chicken is one of the Vietnamese native chicken breeds, which is raised mainly in Hoang Bo district, Quang Ninh province. The study was conducted to determine external characteristics and reproductive performance of Bang Troi chicken. In experiment 1, 400 chicks from newborn to 20 weeks of age were raised to record the appearance characteristics and some dimensions of Bang Troi chicken. In experiment 2, 171 chickens from 21 to 74 weeks of age were raised to assess their reproductive performances. Results showed that 1 day-old chicks had 71% with pale yellow feathers, 29% darker yellow brown; at 20 weeks of age, 20% of males had yellow mixed with black, 65% of yellow wings account and 15% of yellow apricot flowers; 65% hens had gray feathers, 15% yellow and 20% apricot, 87% single crested, 13% bud crested; Bang Troi chicken legs were small and short, 92% yellow legs, 8% lead legs. At 20 weeks of age, Bang Troi chicken had an average back length of 19.44cm; the breast length was 12.96cm; the wing length was 19.44cm; thigh length was 10.24cm and shin was 4.76cm. The body weight at laying rate of 5% was 1.69kg; peak production was 2.25kg. Egg yield at 74 weeks of age reached 97.87 eggs; the average farrowing rate was 26.38%; The average egg weight was 48.43g. The rate of egg embryos was 94.83%.

The study was conducted to detect antigen of African swine fever virus (ASFV) in the tissues of infected pigs, therefore, contributing to clarifying the pathogenesis of the virus and providing a scientific basis for the selection of disease samples suitable for research and diagnostics. Nine organs of 5 ASFV positive pigs were collected and stained immunohistochemistry to detect viral antigen. Resultsshowed that the ASF virus antigen was highly concentrated in organs such as lymph nodes and spleen, the lungs, liver and kidney; followed by brain, heart, intestines and stomach.Antigenwas detected in macrophage cells, mononuclear cells in many different organs, hepatocytes and renal tubular epithelial cells.

Faced with the highly complicated situation of the African Swine Fever, this study aimed to provide solutions to stabilize livelihoods for pig’s farmers, through a stratified random survey of 60 pig-breeding households in September 2019, combining descriptive statistical analysis and multivariate linear regression. Results showed that the number of heavily affected households accounted for 43.3%; slightly affected households only 15%, and unaffected households 41.7%. The majority of farmers' information on the African swine fever was late, in July and August, accounting for 88.9%. The price decreased from 42 to 25 thousand VND/kg of live pigs. The African swine fever incidence was influenced by three factors, viz the number of employees involved inbreeding, the biogas system, and the African-swine-fever outbreak time. There were 81,67% of farmers who changed their livelihoods, mainly raising biosecure chickens and super meat ducks. The proposed solutions included encouraging the farmers to change their livelihoods according to local recommendations, loan and technology support, and people's participation; for pig maintaining households, their prevention would be carried out according to local guidelines, promptly updating disease information, restricting people to enter the breeding area, not using human leftovers for pigs during the epidemic season, and checking barn hygiene and Biogas systems.

Effects of microbial fermented litter and perches on the welfare quality and growth performance were studied in colored broiler. A total of 360 broiler chickens (Ho × Luong Phuong) at four- weeks- old were housed in 4 treatment groups, 30 broilers per group and 3 replication pens, under semi-commercial conditions over 9 weeks. Birds were housed in one of 4 treatment groups including the control group (DC, chickens raising under rice husk bedding), TN1 (DC + bamboo perches), TN2 (DC + microbial fermented litter), and TN3 (combined both TN1 and TN2). The weight of bird individuals from pens was recorded weekly for performance assessment. At the end of the experiment, bird individuals from pens were held and kept for assessment of comb scratches, plumage cleanliness, hock burns, footpad dermatitis, and breast deformities. Results showed that the birds housed with TN1 and TN3 groups had a greater proportion of plumage cleanliness, crooked breast and a lower proportion of comb scratches compared to birds with DC and TN2 groups (P <0.05). Treatments did not significantly affect hock burns and footpad dermatitis (P >0.05). In addition, the treatment groups had no significant effect on parameters such as mortality rates, growth performances, and feed conversion ratio (P >0.05). It was concluded that colored broilers housed in pens supplemented withbamboo perches and both bamboo perches and fermented microbial litter under semi-commercial conditions have the potential of improving animal welfare without positive effects on the performance.

This study was conducted to describe the growth and determine the best growth models to estimate body weight and average daily gain (ADG) of stress-negative Piétrain pigs raised in Dong Hiep livestock farm, Hai Phong province and animal farm of Vietnam National University of Agriculture from December 2007 to December 2015. Four functional growth Logistic, von Bertalanffy, Gompertz and Richards models were be used to estimate body weight, ADG of Piétrain pigs at birth (1198 intact male and 1141 gilts), weaning (808 intact maleand 773 gilts), 60 days (472 intact male and 483 gilts), 5.5 months (94 intact maleand 108 gilts), 7.5 months (228 intact male and 292 gilts). Richards, Gompertz functions had the highest coefficient of determination (0.968 and 0.966) and the lowest AIC (16813 and 17498), residual variance (23,6633 and 30,4267). Average daily gain from 60 days to 7.5 months of intact male (487 and 492 g per day) and gilts (493 g per day) were predicted by Richards, Gompertz similar an actual ADG. The growth of stress-negative Piétrain pigs can be well described withthe Richards and Gompertz functions.

This study was conducted at Ky Son pigs research station of Thuy Phuong Pig Research and Development Center - National Institute of Animal Science from 2015 to 2020 to evaluate the effects of breed (Landrace and Yorkshire), generation (initial, 1 and 2), season (spring, summer, autumn and winter) and parity (1, 2, 3, 4, 5 and 6) on reproductive performance of Landrace (L) and Yorkshire (Y) sows. The reproductive traits were collected from 320 sows (160 L and 160 Y) with 1549 litter (781 L and 768 Y) of 6 parities, including 80 sows (40 L and 40 Y) of the initial generation imported from France, 120 sows (60 L and 60 Y) of the first and 120 sows (60 L and 60 Y) of the second generation. The results show that breed, generation and parity affected the number born alive, number of weaned pigs, litter weight at birth and litter weight at weaning (P <0.0001); however, the season did not affect these traits (P >0.2839). The reproductive performance of Y sows was higher than that of L for litter sizes and litter weights at birth and weaning (P <0.0001). Sows from French genetic resource had a high reproductive performance: number born alive (12.82 and 13.59 piglets), number of weaned pigs (11.37 and 12.01 piglets), litter weight at birth (19.62 and 20.39 kg), litter weight at weaning (74.43 and 79.06 kg, respectively for L and Y) and increased over generations (P <0.0051). Landrace and Yorkhire pigs from French genetic resources can be used to multiply a purebred nucleus and create F1 sows from two breeds in Northern Vietnam.

This study aimed to determine the best model to explain the growth curve of F1(BBB x Lai Sind) bulls using non-linear function models such as Logistic, von Bertalanffy, Gompertz, Brody, and Negative Exponential. For this purpose, live weight records of a total 60 F1(BBB x Lai Sind) consisted of 30 bulls and 30 heifers, reared in Ba Vi district, Hanoi city were used. In order to select the best model, the coefficient of determination (R2) and parameters of ME, MSE, MAE, MPE, MAPE were utilized. Results showed that, in both bulls and heifers, von Bertalanffy and Brody functions had the highest R2 and lowest ME, MSE, MAE, MPE, MAPE; followed by Gompertz function. Logistic and Negative Exponential functions had lower values of the above parameters. Age and body weight at the inflection point ranged from 15.47 to 20.41 months; and 400.13 to 415.44kg for bulls; 10.05-14.29 months and 255-276.27kg for heifers, respectively. Therefore, von Bertalanffy function is recommended to use for prediction of live weight on the age of F1(BBB x Lai Sind).

The aims of this study were to assess the effects of adding chicken egg yolk and caffeine in TCG (Tris-Citrate-Glucose) extender on the quality of goat semen preserved some goat breeds in Vietnam. Semen samples of 9 bucks belonging to 3 goat breeds, including Saanen, Boer and Alpine, (3 bucks/breed) were collected using artificial vagina, then diluted at a ratio of 1:10 with TCG extender added 0%, 5%, 10%, 15%, and 20% chicken egg yolk and 0,02; 0,03 and 0,04g caffeine/l. The diluted semen samples were preserved at 5 and 15C, respectively. The sperm motility and sperm morphological parameters of the preserved semen samples were assessed and compared after 24h, 72h, and 120h of preservation. Results showed that addition of 0,03g caffeine/l in TCG extender gave a better quality of preserved goat semen at both temperatures. At 5C, TCG extender added 10% of chicken egg yolk gave a better quality of preserved goat semen and could be used for artificial insemination after 72h of preservation. At 15C, TCG extender added 15% of chicken egg yolk resulted in a better quality of preserved goat semen and could be used for artificial insemination after 24h of preservation.

This study was carried to determine the growth performance, meat productivity and quality of 3/4 Dong Tao (ĐT) and 1/4 Luong Phuong (LP) crossbred chickens raising. The growth performance was determined on the 180 chicks from one day of age to 24 weeks. We first randomly divided all the chicks into 3 cocks and 3 hens to determine the meat yield and meat quality at 16, 20 and 24 weeks of age. The survival rate of 3/4ĐT and 1/4LP from one day of age to 24 weeks was 98.33%. At 24 weeks, the alive weight was 3068.33 g for cocks and 2046.67 g for hens. The average daily gain of chickens gradually increased from 1 to 12 or 13 weeks for hens and cocks, respectively and then decreased. From 19 to 20 weeks of age, the growth rate was very low with ADG/day at 12.9 g (cocks) and 8.21 g (hens). The FCR of chickens in period 20 weeks was 4.47 and in period 24 weeks was 5.15. The 3/4ĐT and 1/4LP chickens had a high meat yield and good quality of meat. In conclusion, it is possible to use the 3/4 Dong Tao and 1/4 Luong Phuong in the production of broiler chickens.

This study was performed to evaluate the influence of a protein rich diet as a provocative factor on producing the clinical disease after infection with three weak β-haemolytic Brachyspira species (B. innocens, B. murdochii and B. intermedia) in fattening pigs.A total of 67 pigs with an average body weight of 15.6 ± 3.1kg were fed a diet containing 50% extracted soybean meal for seven days. The results of the experimental groups (infection with weakly haemolytic Brachyspira species B. innocens, n = 15, B. murdochii, n = 24 and B. intermedia, n = 10) were compared with those of the positive control group (infection with B. hyodysenteriae, n = 15) and the negative control group (n = 3; no inoculation). The results showed that all 15 pigs inoculated with B. hyodysenteriae developed mucohaemorrhagic diarrhea after an incubation period of one to 13 days. In contrast, diarrhea could not be detected in the three groups inoculated with weakly haemolytic Brachyspira species. These groups also showed no significant difference in the average weight gain and feed conversion ratio with no pathological findings typical for dysentery among themselves. It can be therefore concluded that the examined strains of weakly haemolytic Brachyspira species could colonize and proliferate in the mucosa of the large intestine after the experimental infection. Faecal shedding occurred regularly, but no clinical symptoms of swine dysentery could be produced in the experimental pigs.