Vol. 15 No. 7 (2017)

ABSTRACT

The growing of world population and the increasing demand for meat and milk in the coming decades are posing challenges for the development of livestock industry in developing countries, including Vietnam. In this article we l briefly outlinedthe actual trends of application of reproductive technologies for the development of livestock industry in the 21 century,the current status of research and application of embryo transfer, in vitrofertilization, embryo sexing, cell and embryo cryopreservation and somatic cloning technique for both aspects of animal breeding and animal biodiversity conservation in Vietnam. By evaluating and analyzing the limitations of technology application due to the conditions of small-scale animal husbandry, the authors discussedthe necessary strategy for the further successful implementation of reproductive technologies.

Rabbits are suitable for livestock development for poverty reduction and sustainable agricultural development. At present, the development of rabbit breeding in the mode of industrial reproduction is of concern ofmany farms. In this report, we introduce some preliminaryresults on oestrus synchronization, preservationofsperms, combination of oestrus synchronizationwithartificial insemination (AI) for controllingreproduction of New Zealand rabbit in Vietnam. PMSG treatment has significantly improved receptivity of the doesandtreatment with 40 IU and 60 IU were more effective than with 20 IU in oestrus synchronization. TCG was more effective than EX1 in protection of rabbit sperms at 4oC. Both pregnant rate and litter size using AI after oestrus synchronization were higher than natural mating after normal eostrus.

In mammals, reproduction is the ability to generate next generation through the fertilization of a mature egg and a sperm. Nowadays, with the development of modern reproductive biotechnology, several advanced techniques have been applied and able to generate new generations from somatic cellsandstem cells or from immature eggs and sperms. In the present paper, the advances in reproduction over the past 20 yearsare sumarized and presented including: (1) intracytoplasmic sperm injection (ICSI) and application of this method to treat infertility and production of transgenic animals, (2) round spermatid injection (ROSI) and itsapplication on treatment of infertility without spermatozoa, (3) Somatic cell nuclear transfer (SCNT), also known as animal cloning, and (4) the method to generate new generation by pluripotent stem cells injected into tetraploid blastocysts.The application potential of the modern reproductive methods in medicine and agriculturewas discussed.

From December, 2015 to December, 2016, for the first time 1,117 frozen gender-separated embryos were imported to Vietnam. In the cooperation program between TH milk group and Sexing Technology Companythe embryos weretransferred to aherd of heifers from 13 - 16 months old in TH’s Farm in Nghia Dan, Nghe An. Total 2143 heifers were synchronized for estrus by PGF2α. 1,661/2,143 = 77.5%%, in which 1,035 /1,637= 63.2% heifers were qualifiedfor receivingembryo. 1,051 gender separated embryos were transferred to1,051 heifers (in which 1,035 estrous heifers by injection PGF2α and 16 heifers naturally estrous). After 35 days of embryo transplantation(42 days age of embryo) the pregnancy was checked by Ultrasound or by rectal palpation. 488/1,051 = 46.4% heifers became pregnant, the pregnancy rate depending onseason, farmcondition, quality and location of corpus luteum on heifer receivingembryos, and skillsof technicians. The highest pregnancy rate was52.6%and thelowest was 40.9%. During the pregnancy, 10% of pregnant heifers showed abortionand5% with stillborn. The pregnant heifers gave birth to203 normal calves, including195 female calves (96.05%)and 8 male calves (3.95%).

The research was conducted on 42 female dogs/bitches infected with pyometra. The results showed that the symptom appearing as abdominal enlargementwas (66.6%), followed by vaginal discharge (57.1%), fever (47.6%), poor feed ingestion (42.8%), polyuria (38.1%), and polydipsia (28.6%). The estrogen and progesterone levels in the diseased bitches were 12.47 ±8.95 pg/ml and 1.98 ±1.18 ng/ml,respectively. Thebitches in the anestrus had estrogen concentrations at 7.96 ±2.75 pg/ml and progesterone at 0.90 ±0.29 ng/mlwhereas thebitches at 8 - 10 week after parturition had estrogen and progesterone levels in average of 7.58 ±2.48 pg/ml and 1.10 ±0.54 ng/ml, respectively. Imported bitches often had pyometra higher infection (54.8%) than domestic bitches (45.2%). Bitches that have experienced a contraceptive injection (61.9%) had a higher infectionrate than those without contraception (38.1%). The rate of pyometra increased with age and bitches which had never given parturition had the highest infection rate,accountingfor 59.5%.

Pyometra is a common reproductive disease in female dogs, which negatively affects the reproductive performance and results in high mortality in the case of delayed diagnosis and treatment. In this study, biochemical and the haematological parameters were assessed in healthy and diseased female dogs. The dogs consisted of two groups, group 1 (control) with 10 healthy dogs and group 2 with 10 pyometra-infected dogs. The results revealed that infected dogs showed a decrease in red blood cell count and haemoglobin and mean corpuscular volume while white blood cell count (neutrophil, lymphocyte and monocyte) increased. In addition, the liver enzyme value like GOT, GPT remained constant in both healthy and diseased dogs but the parameters related to kidney function such as urine and creatine production moderately increased..

The aims of present study were to evaluate the prevalence of mastitis, identify factors influencing disease incidence and test treatment methods in Phu Dong dairy farm in Gia Lam-Ha Noi. The results by California Mastitis Test showed that the prevalence of clinical mastitis was lower than that of sub-clinical cases (10.43% and 25.36%). Based on methylene blue decolorization test, 90% of testing milk samples could be used within 24 -48 hours. The percentage of milk samples discolorized by the dye within 30 minutes was 3.33%. The risk of infection was influenced by the stage of milking. The highest incidence was found in the first month of lactation then reached lowest point at fourth month. The infection rate continued to increase from sixth month toward the end of the lactation period. Age was positively correlated the disease incidence. Cows with higher levels of cross-bred rate had higher rates of mastitis. Treatment with neomycin/amoxicillin combined with pumping inside the infected udders and proper care was effective.

A research was carried out to determine reproductive performance of female goats in Nho Quan - Ninh Binh. Results showed that the first insemination age and weight at first cycle were lower in Co goats compared to the cross-bred goats (BT x Co). The heating time after calving wasshorter in Co goats compared to the cross-bred goats (BT x Co). The interbirthintervalwas shorter in Co goats compared to the cross-bred goats (BT x Co). The litter sizer was higher in the cross-bred goats (BT x Co). 49.15 - 50.00% in Co goats and 52.43% in cross-bred goats (BT x Co). Had two calves per litter. The litter size of 3 calves was lower in Co goats than that in cross-bredgoats (BT x Co). Weight of calveat birth was negatvely correlated with the litter size. The survival rate of goats at weaning were lower in the cross-bred goats (BT x Co) compared to Co goats.

The objective of this study was to evaluate(1) cow - calf reproduction system and (2) effects of concentrate supplement at pre - and post partrum on reproduction performance of Brahman cows. Total 66 cattle raising households (10%) in Tay Giang commune, Tay Son District, Binh Dinh province) were surveyed. In addition, 255 Cross-bredBrahman cows were evaluatedforreproductiveperformance, and 163 calves were weighted from birth to 6 months of age. On - farm experiment and demonstration of the effect of pre- and post-partum supplementary feeding on cow-calf performance were conducted from January 2014 to December 2016. The survey results showed that the cow - calf system in the communes has been moving from extensive to semi-intensiveone. Cows accounted for 50% of cattle surveyed, of which 90% were Zebu crossbred. Cow feeding systems were mostly grazing and stall feeding (97%). A long calving interval (15.9 months), lack of nutrition for cows at pre - and post - partum, and poor feeding management were identified. The experiment showed that improved supplementation for cows at pre - and post - partum could shorten calving to conception interval from 212 to 176 days (P < 0.05). The on - farm demonstration confirmed that post - partum supplementation can reduce calving interval and the techniques were well accepted by farmers in the region.

Metritis in dairy cows is a common disease that causes considerable economic loss to dairy cow husbandry. This study aimed to assess the status ofmetritis in dairy cows in livestock farms and to recommend an appropriate treatment protocol. The study consisted of direct survey and interviewof cow breeders, information gathered from local veterinary staff, antimicrobial susceptibility testing, percentage of cured cases, treatment time and fertility of cows following treatment. Results indicated that the proportion of metritis of dairy cows in livestock farms in some localitiesin Nortvietnamwas22.05%, in which63.49%in postpartumperiod and36.51%in insemination waiting period. Among all inflamations,endometrial inflammation, uterine inflammationand endometrial inflammationwas 80.42%, 15.34% and4.23%, respectively. Norfloxacin combined with PGF2α was highly effective fortreatment metritis in dairy cows.

The use of antibioticsfor the cow metritis treatment has many advantages, however, raises concerns about antibiotic residues in the meat and dairy products as well as increasing antibiotic resistance of pathogenic bacteria. Herbs have been increasingly demonstrated their significant role in the pharmaceutical industry as a biosafety solutionandan alternative to synthetic chemical drugs. The present study aimed to examine the anti-bacterial activity of herbal extracts(Polyalthia longifolia var.Pendula, Lignum Caesalpiniae sappari, Excoecaria cochinchinensis Lour.,Clerodendron fragrans Vent, Wedelia calendulaceae Less, Cudrania tricuspidata, Pseuderanthemum (Ness)Radik, Lactuca indica L)against Staphylococcusspp. and Streptococcusspp.isolated from cow metritis. The resultsshowed that the extractionefficiency varied from 9.60% (Lignum Caesalpiniae sappari) to 14.32% (Wedelia calendulaceae Less). At the concentration of 100 mg/ml, all the extracts showed good anti-bacterial activity against Staphylococcusspp. and Streptococcusspp. For Streptococcusspp., the bacterial inhibition zone varied from 11.80 mm (Cudrania tricuspidata(Carr) to 25.00 mm (Clerodendron fragrans Vent). The diameter of the bacterial inhibition zone of Staphylococcusspp. varied from 10.28 mm (Cudrania tricuspidata(Carr)) to 25.30 mm (Wedelia calendulaceae Less). The extract solution of Clerodendron fragransVent and Wedelia calendulaceaeLess showed the highest anti-bacterial activity. This extract remained its anti-bacterial activity against Staphylococcus spp. and Streptococcusspp. at concentration of 0.20mg/ml.

A study on sperm cryopreservation and artificial insemination of Dong Tao chicken breed was conducted. Three experiments were carried out (1) Assessement of semen parameters of Dong Tao cocks in hot and cold seasons; (2) Comparison of efficiency ofcryopreservationof Dong Tao chicken sperm using rice straws (0.25 and 1.00 ml) and pellets; and (3) Evaluation of insemination efficiency of Dong Tao hens by cryopreserved sperms. SixDong Tao cocks and 48 Dong Tao hens (10 - 14 months old) were usedin this experiment. The results showed that Dong Tao cock’s semen quality wasgood and better in hot season compared to cold season. Sperm cryopreservation in cryo - straw forms wasbetter than in cryovial form. Thawed sperm quality parameters of 1 ml cryo - straw sperm samples were better than in 0.25 ml cryo - straw sperm samples. Artificial insemination with thawed sperms from1 ml cryo - strawsamples yielded highest percentage of fertilized eggs(70%),equal tonatural insemination.

An experiment was carried out with two treatments corresponding to two stocking densities (200 and 400 postlarvae12/m2) with 4 replicates to determine the effect of stocking density on growth performance, survival and economic efficiency of intensive white leg shrimp farming in Quang Nam province. The results showed that with density of 200 and 400 postlarvae12/m2 after 90 days of stocking, the final weight, yield, survival and profit were 13.04 and 10.9 g/each shrimp; 15.55 and 20.66 tons/ha/crop; 65.24 and 56.86%; 489.2 and 62.8 million VND/ha/crop.

The combination of morphological taxonomy and molecular genetics methods is required for effective and accurate identification of Tra catfish (Pangasianodon hypophthalmus). The identification based on morphological characteristics is possible to identify accuratelyPangasiidae species that simply relieson number of spines, pelvic fins, pectoral fins, etc. In addition, sequence analysis of cytochrome c oxidase I (COI) andcytochrome b (Cytb) genes along with specialized softwares provide significantly reliable results, which contribute information to confirm the morphological classification. In this study, idetification based on molecular genetics method revealed 99-100% similarity in nucleotide sequences of COI and Cytb genes between 30 fish samples collected in An Giang and Ben Tre provinces with Tra catfish Pangasianodon hypophthalmus species. Our finding confirms the superiority and necessity of combining two identifications methods, morphological taxonomy and molecular genetics methods.

In this study, we determined serotypes and antibiotic resistance of Salmonella isolates from several samples (including water samples, caecal contents, and swab samples) collected from two pig slaughterhouses in Hung Yen province) . 43/48 isolates strains were identified as belong to 9 serovars of Salmonella and 5/48 strains that did not identify serotypes. S.derby was the most common 20,83% and then S. typhimurium (18,75), and S. enteritidis (10,42%). Isolated strains in this study are strongly resistant to Streptomycin 96,67%, Tetracyline 83,33%, Ampicillin 63,33%, Trimethoprim 46,67%, Gentamycin 33,33%, Nalidixic acid 36,67%. Samonella isolated strains are susceptible to some new antibiotics such as Nofloxacin, Nitrofurantion , Ciprofloxacin, Ceftazidime.

The study was carried out to determine in vitro anti-bacterial effects of nanodrugs (Polyme_Ag_Fe3O4_Antibotics) on bacterial strains caused acute hepatopancreatic necrosis disease (AHPND) in shrimp. The Vibrio parahaemolyticus strain KC12.020 was used in this study at concentration of 108 cfu/ml. Results showed that the inhibition zone against the AHPND-caused bacterial strain of the nanodug, Polyme_Ag_Fe3O4_Doxycylin, was about 17.25 mm when the tested antibiotic dose was equal to only one-half of the recommended dose of Doxycylin. The effective anti-bacterial effect of the nanodrug, Polyme_Ag_Fe3O4_Ciprofloxcin, was similar to the antibacterial activity of the Ciprofloxacin used alone (the inhibitory diameter was 16.25 mm) when the tested antibiotic dose was equal to one-fifth (1/5) of the dose of Ciprofloxacin is recommended. However, the Polyme_Ag_Fe3O4_Ciprofloxcin product will not be used for trial at farm level because its usage has recently been banned in aquaculture. Other nanodrugs, Polyme_Ag_Fe3O4_Oxytetracyclin, Polyme_Ag_Fe3O4_Doxycyclin, and Polyme_Ag_Fe3O4_Doxycyclin_Florphenicol, are needed to further study because they did not show clearly the antibacterial activities against AHPND-caused bacterial strain in this study. These results indicated the potential use of nanodrugs (Polyme_Ag_Fe3O4_Antibiotics) in treatment of AHPND in shrimp.