Efficacy of praziquantel against Centrocestus formosanus metacercariae infections in common carp( Cyprinus carpio Linnaeus)

[目的]探讨3种不同药物处理方式对台湾棘带吸虫引起的鲤鱼幼鱼急性鱼鳃传染病(开放性鳃病)的防治效果.[方法]在试验初期,将1620条鲤鱼幼鱼(70日龄)鱼鳃自然感染台湾棘带吸虫,随后分成4组,分别采用CuSO4、福尔马林和吡喹酮不同方式处理6周,与对照(自然喂食、不使用任何化学药剂)比较防治鲤鱼幼鱼急性鳃传染病的效果.[结果]感染台湾棘带吸虫的幼鱼生长缓慢,其身长和体重增长均较慢.施药后,幼鱼台湾棘带吸虫后期囊幼虫感染强度减少.在每千克饲料中分别添加50和75 mg吡喹酮喂食幼鱼5d,可以杀死鱼鳃中所有的台湾棘带吸虫后期囊幼虫,且鱼鳃恢复正常;面使用25 mg吡喹酮,仅有35％的后期囊幼虫死亡.所有不同浓度CuSO4处理(0.3、0.4和0.5mg/kg冲洗浸泡24 h及以3.0、4.0和5.0 mg/kg冲洗浸泡10m)和福尔马林处理(20、25和30 mg/kg冲洗浸泡及200、250和300 mg/kg短时间冲洗浸泡)均不能杀死台湾棘带吸虫后期囊幼虫.[结论]经普通化学药剂CuSO4或福尔马林冲洗浸泡,不能防治由台湾棘带吸虫后期囊幼虫引起的鲤鱼开放性鳃病,但50～75 mg吡喹酮/kg饲料可以在5d内治疗该病.     

Evaluation of genetic richness among Vietnamese native pig breeds using microsatellite markers

We have elucidated genetic relationships of Vietnamese native pigs (VNP) using preliminarily collected samples by a single‐nucleotide polymorphism (SNP) array. In order to confirm our previous results and compare with the results of a previous study using microsatellite (MS) markers, we aimed to characterize genetic diversity and population structure in wider varieties (24 breeds from 21 Provinces) of VNP across the country using 20 polymorphic MS markers recommended by ISAG/FAO (International Society for Animal Genetics/Food and Agriculture Organization) for diversity study. In this study, we collected 1,136 DNA samples of the VNPs and three exotic breeds. Our results revealed that the average number of alleles and allelic richness across the loci in VNPs were 10.0 and 7.6, which were higher than those of exotic breeds. Genomic components among VNPs were subjected to the sampling locations. Interestingly, Co Binh Thuan showed remarkable genetic feature compared to the other VNPs, because the habitation of Co Binh Thuan was relatively far from the other breeds. The results of this study provided useful information for exploitation, conservation, and development trends of the VNP breeds. More recently, African swine fever caused significant damage to most of the VNP populations. Therefore, our findings will help a reconstruction scheme of the VNP genetic resources.     

In vitro propagation of the African mahogany <Emphasis Type="Italic">Khaya senegalensis</Emphasis>

A protocol was developed for shoot proliferation and plantlet formation of Khaya senegalensis, an important medicinal and timber plantation species introduced to Australia and southern Asia from western and central Africa. We assessed effects of the plant growth regulators, benzyladenine, kinetin, naphthalene acetic acid and gibberellic acid, on shoot proliferation and subsequent plantlet conversion. Shoot proliferation over four passages was higher in media containing benzyladenine than in media containing other growth regulators, and optimal proliferation from seed of three different sources was consistently obtained in medium containing 4.4 μM benzyladenine. Shoots from this medium were converted to plantlets at high frequencies (76–90%) after treatment with 19.6 μM indole-3-butyric acid, and almost all plantlets were successfully acclimatized to nursery conditions. These methods provide the means for establishing in vitro and ex vitro clone banks of juvenile K. senegalensis trees for field selection of desired genotypes and tropical plantation establishment.     

Effects of size and nitrite exposure on respiration,oxygen partitioning,and growth of obligate air-breathing fish Channa striata

The effects of fish size and nitrite level on metabolic rate and growth were investigated in the obligate air-breathing snakehead Channa striata, which is an important aquaculture species in Vietnam. Channa striata displayed respiratory size dependence, whereby the standard metabolic rate (SMR) and routine metabolic rate (RMR) decreased progressively in an exponential manner as fish size increased from 50 to 200 g. A mildly elevated nitrite level of 5% of the LC₅₀ 96 h (12 mg NO₂^?/L or safe concentration) induced significant increases in Channa striata SMR and RMR, which were almost double that of the control at the same size. At mild elevation, nitrite caused no significant effect on fish growth and survival during 3 months of rearing. However, both growth and survival rates of fish reared at severely elevated nitrite levels were significantly lower than those of the control; in particular, survival rates were under 50%. While changes in size reduced SMR and RMR, the percentage of air oxygen partitioning remained unchanged. Channa striata upregulation of SMR and RMR and air-breathing regulation were not significantly proven in this study. In summary, maintaining water environments at levels lower than 12 mg NO₂^?/L with ample oxygenation will not affect the growth and survival rate of snakeheads.

     

Risk factors for porcine reproductive and respiratory syndrome outbreaks in Vietnamese small stock farms

AIM: To examine risk factors that could have played a role in the 2010 porcine reproductive and respiratory syndrome (PRRS) outbreak in Yenhung district, Quangninh province, North-Vietnam, with the purpose of establishing why existing control measures implemented after previous outbreaks had failed to prevent further outbreaks.

METHODS: A case-control study was carried out in Yenhung district. Data were obtained by an interview-based questionnaire survey. The sampling unit was households, which equated to small-scale pig farms. A total of 150 case and 150 control households were selected at communes affected by the 2010 PRRS epidemic during April to June. Risk factors were analysed using binary logistic regression and unconditional multiple logistic regression.

RESULTS: Households infected with PRRS were significantly associated with multiple variables belonging to three main groups: (1) location of the farms: i.e. farms positioned <1,000?m from a pig abattoir or within 500?m of local markets or 100?m of main roads; (2) farm management: i.e. where there was non-application of weekly farm disinfection, feeding uncooked swill, new introduction of purchased pigs without isolation, or usage of water from irrigation systems for raising pigs; (3) people and animal contact: i.e. where households kept animals with either no confinement or partial confinement, had visits by family members to other affected farms or had frequent visits by neighbours. The use of water from irrigation systems was found to be the risk factor most strongly associated with infected households in the 2010 outbreak (OR=22; 95% CI=12–42).

CONCLUSIONS: The results show that the epidemiology of PRRS in Quangninh province was linked to sociological and cultural practices, and that effective PRRS control needs an integrated approach coupled with behavioural changes in the pig raising practices of the general public. Failure to recognise this could explain why further outbreaks have occurred.     

The impacts of hammer-mill screen size and grain particle size on the performance of broiler chickens offered diets based on two red sorghum varieties

1. The two red grain sorghums were extensively characterised. Kafirin, polyphenolic compounds, free, conjugated and bound phenolic acids, phytate concentrations and starch pasting profiles were determined.

2. The experiment consisted of a 2 × 4 factorial array of dietary treatments comprising two red sorghum varieties (Tiger and Block I) ground through 4 hammer-mill screen sizes (2.0, 3.2, 4.8 6.0 mm) prior to incorporation into nutritionally equivalent diets. Eight steam-pelleted dietary treatments were each offered to 7 replicates (6 male Ross 308 birds per cage) from 7 to 28 d post-hatch.

3. Effects of dietary treatments on growth performance, relative gizzard and pancreas weights, nutrient utilisation, apparent starch and protein (N) digestibility coefficients and disappearance rates from 4 small intestinal segments were determined.

4. The 2.0-mm hammer-mill screen generated an average geometric mean particle size of 794 μm and the 6.0-mm screen a mean particle size of 1405 μm. However, hammer-mill screen size did not influence weight gain or FCR. The 6.0-mm screen size generated significantly higher starch and protein (N) digestibility coefficients in the distal jejunum and distal ileum than the 2.0-mm hammer-mill screen.

5. Tiger sorghum was superior to Block I sorghum, as significant advantages were observed for feed conversion ratios (3.25%), AME (0.37 MJ), ME:GE ratios (4.15%), AMEn (0.53 MJ), distal ileal starch digestibility coefficients (2.46%) and protein (N) digestibility coefficients in the distal jejunum (4.66%), proximal ileum (1.96%) and distal ileum (2.16%). The inferior Block I sorghum contained more kafirin (67.1 versus 51.3 g/kg), phytate (9.79 versus 8.40 g/kg), total phenolic compounds (4.68 versus 4.12 mg GAE/g), flavan-4-ols (7.98 versus 5.04 ABS/ml/g), total phenolic acids (554 versus 402 μg/g) and total ferulic acid (375 versus 281 μg/g) in comparison to Tiger sorghum.     

In growing pigs,nutritive value and nutrient digestibility of distillers’ by-products obtained from two varieties of rice

In South-East Asia, rice distillers’ by-product (RDP) is a widely abundant feedstuff whose adequate incorporation into pig diets is still questionable. Especially, effects of RDP on nutrient digestibility of growing pigs fed corn-soybean meal-based diet are lacking. The objective of this study was to determine nutrient digestibility and energy value of ordinary (ORDP) and glutinous (GRDP) rice distillers’ by-product in growing pigs. Two groups of 12 castrated crossbred barrows (Duroc × Landrace × Yorkshire), about 3 months old, 38?±?1.04-kg initial body weight, were each allocated to a 15-day experiment in which pigs were divided into three isonitrogenous diet-groups. The animals were housed individually in metabolism cages for separated collection of feces and urine. Each diet-group was provided either a control corn-soybean meal diet or a diet in which corn and soybean meal were partly replaced by ORDP or GRDP at 15 or 30% on diet dry matter basis. Glutinous by-product especially showed higher levels in crude protein, neutral/acid detergent fiber, total branched-chain amino acids, and butyric acid. When compared to the control diet, ORDP tented to increase DM intake (P?= 0.054) but decreased energy (P?< 0.001) and crude protein (P?< 0.04) digestibility, while GRDP decreased DM intake (P?< 0.001). Both GRDP and ORDP products negatively affected digestibility of ether extract. The average digestible and metabolizable energy of ORDP and GRDP were 17.0 and 16.6, and 17.7, and 17.1 MJ/kg DM, respectively. In conclusion, these results show that both RDP, and especially GRDP, are highly valuable protein and energy sources for pig production.

     

Effects of body condition score (BCS) on steroid‐ and eicosanoid‐metabolizing enzyme activity in various mare tissues during winter anoestrus

The objective of this study was to determine the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non‐pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5′‐diphospho‐glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activity of CYP1A in adrenals was increased (p ≤ .05) in BCS 5 versus BCSs 4 and 6. Activity of CYP1A in the liver was increased (p = .05) in BCS 4 versus BCSs 5 and 6. Activity of CYP1A was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and kidney. Activity of CYP2C was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and endometrium. Activity of CYP3A was only detectable in the liver. Activity of UGT in the kidney was decreased (p = .02) in BCS 4 versus BCSs 5 and 6. Activity of UGT was threefold greater (p < .0001) in the liver than in the kidney, whereas activity of UGT was ninefold greater (p < .0001) in the kidney than in the ovary and endometrium. In general, BCS did not alter the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses. However, tissue differences in these enzymes indicated abundant hepatic metabolism in horses, which is similar to other livestock species.     

Effects of tropical climate and water cooling methods on growing pigs'' responses

We report a study on crossbred growing pig ((Duroc × Pietrain) × Large White) that measured the effect of tropical conditions on respiration rate (RR), skin temperature (ST), rectal temperature (RT) and productivity and determined the efficacy of two simple cooling methods. The experiment was a randomized complete block design using 120 growing pigs. The factors were cooling system and pen design. The effects of two cooling systems (water bath (WB) and sprinkling (S)) were evaluated and compared with a control (CON). Cooling systems were tested in pens with (Y) or without an additional outdoor yard (NY). The pens were similar to those used in small-scale pig keeping in South-East Asia. The inside pen size was 2.5 × 3 m, the yard was 2.5 × 2 m. The same experimental design was used in two blocks: one block was in the wet season with average ambient temperature (T) of 27.5 °C and average relative humidity (RH) of 74.7% and the other was in the dry season with average T of 28.7 °C and average RH of 62.8%. In each block a batch of 60 pigs was reared in 12 pens (five pigs per pen). Pigs had free access to feed and water. Results showed that cooling and pen type significantly affected most parameters. The bath and S reduced RR by 4.2 and 5.2 min^− 1, respectively (P < 0.01), and ST by 0.3 and 0.4 °C, respectively, (P < 0.05). Rectal temperature was not influenced by any treatment. The bath significantly reduced number of defecations and urinations in the resting area in pens NY (P < 0.001). A yard reduced the number of excretions in the resting area (P < 0.01). There were significant interaction effects of cooling and pen type on lying, lateral lying, and huddling (P < 0.01; P < 0.001; P < 0.01, respectively). Daily weight gain was 6 g d^− 1 more with WB and 50 g d^− 1 more with S (P < 0.05). The biggest daily weight gain was achieved when S was combined with a pen NY (P < 0.01).

We conclude that the physiologic and behavioral responses and hence productivity of group-housed growing pigs raised under tropical climate conditions benefited from the simple cooling systems tested and were affected by the presence of a yard. A fall in the high respiration rate indicated that cooling with the bath or sprinkling alleviated the pigs' heat stress.