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221.
Tran D Hung Jermey T Brawner David J Lee Roger Meder Mark J Dieters 《Southern Forests》2016,78(3):225-239
Ten growth or wood-quality traits were assessed in three nearby Corymbia citriodora subsp. variegata (CCV) open-pollinated family-within-provenance trials (18 provenances represented by a total of 374 families) to provide information for the development of a breeding program targeting both pulp and solid-wood products. Growth traits (diameter at breast high over bark [DBH], height and conical volume) were assessed at 3 and 7 years of age. Wood-quality traits (density [DEN], Kraft pulp yield [KPY], modulus of elasticity [MoE] and microfibril angle [MfA]) were predicted using near-infrared spectroscopy on wood samples collected from these trials when aged between 10 and 12 years. The high average KPY, DEN and MoE, and low average MfA observed indicates CCV is very suitable for both pulp and timber products. All traits were under moderate to strong genetic control. In across- trials analyses, high (>0.4) heritability estimates were observed for height, DEN, MoE and MfA, while moderate heritability estimates (0.24 to 0.34) were observed for DBH, volume and KPY. Most traits showed very low levels of genotype × site interaction. Estimated age–age genetic correlations for growth traits were strong at both the family (0.97) and provenance (0.99) levels. Relationships among traits (additive genetic correlation estimates) were favourable, with strong and positive estimates between growth traits (0.84 to 0.98), moderate and positive values between growth and wood-quality traits (0.32 to 0.68), moderate and positive between KPY and MoE (0.64), and high and positive between DEN and MoE (0.82). However, negative (but favourable) correlations were detected between MfA and all other evaluated traits (?0.31 to ?0.96). The genetic correlation between the same trait expressed on two different sites, at family level, ranged from 0.24 to 0.42 for growth traits, and from 0.29 to 0.53 for wood traits. Therefore simultaneous genetic improvement of growth and wood property traits in CCV for the target environment in south-east Queensland should be possible, given the moderate to high estimates of heritability and favourable correlations amongst all traits studied, unless genotype × site interactions are greater than was evident. 相似文献
222.
223.
Lindahl J Boqvist S Ståhl K Thu HT Magnusson U 《Tropical animal health and production》2012,44(2):239-245
Japanese Encephalitis Virus (JEV) is considered an important reproductive pathogen in pigs. Most studies of the reproductive
impact of JEV have been conducted in areas where the disease occurs in seasonal epidemics. In this study, the associations
between seropositivity for JEV, measured with an IgG ELISA, and the number of piglets born alive and stillborn were investigated
in a tropical area endemic for JEV in Vietnam. Sixty percent of sows from four farms in the Mekong delta of Vietnam were seropositive
to JEV and the Odds Ratio for a sow being infected was highest (6.4) in sows above 3.5 years (95% confidence interval 2.2–18.3).
There was an association between increasing Optical Density (OD) values from the ELISA and the number of stillborn piglets
in sows less than 1.5 years, but no effect of seropositivity could be shown when all sows were studied. OD values had an effect
(p = 0.04) on the number of piglets born alive in the statistical analysis only when interacting with the effect of the breeds.
An increase in mean OD value of the herd was correlated (p < 0.0001) with an increase in the number of piglets born alive. In this study, there was evidence of a negative association
between seropositivity for JEV and the reproductive performance only in sows less than 1.5 years in endemic areas. This could
be explained by a year-round infection with the virus, which would lead to immunity in many gilts before their first pregnancy.
This, in turn, may imply that JEV infection in pigs is of minor importance for the reproductive performance in endemic areas. 相似文献
224.
Pig performance increases with the addition of dl-methionine and l-lysine to ensiled cassava leaf protein diets 总被引:1,自引:0,他引:1
Two studies were conducted to determine the impact of supplementation of diets containing ensiled cassava leaves as the main
protein source with synthetic amino acids, dl-methionine alone or with L-lysine. In study 1, a total of 40 pigs in five units, all cross-breds between Large White and Mong Cai, with an average initial
body weight of 20.5 kg were randomly assigned to four treatments consisting of a basal diet containing 45% of dry matter (DM)
from ensiled cassava leaves (ECL) and ensiled cassava root supplemented with 0%, 0.05%, 0.1% and 0.15% dl-methionine (as DM). Results showed a significantly improved performance and protein gain by extra methionine. This reduced
the feed cost by 2.6%, 7.2% and 7.5%, respectively. In study 2, there were three units and in each unit eight cross-bred (Large
White × Mong Cai) pigs with an initial body weight of 20.1 kg were randomly assigned to the four treatments. The four diets
were as follows: a basal diet containing 15% ECL (as DM) supplemented with different amounts of amino acids l-lysine and dl-methionine to the control diet. The results showed that diets with 15% of DM as ECL with supplementation of 0.2% lysine +0.1%
dl-methionine and 0.1% lysine +0.05% dl-methionine at the 20–50 kg and above 50 kg, respectively, resulted in the best performance, protein gain and lowest costs
for cross-bred (Large White × Mong Cai) pigs. Ensiled cassava leaves can be used as a protein supplement for feeding pigs
provided the diets contain additional amounts of synthetic lysine and methionine. 相似文献
225.
Nguyen ST Honma H Geurden T Ikarash M Fukuda Y Huynh VV Nguyen DT Nakai Y 《Research in veterinary science》2012,93(2):848-852
We investigated the prevalence and risk factors associated with Cryptosporidium oocysts shedding in pigs in Central Vietnam. A total of 740 single fecal samples collected from diarrheic and non-diarrheic pigs on 89 farms were screened by the modified Ziehl-Neelsen staining method. Prevalence at the animal and the farm levels were 18.1% (134/740) and 71.9% (64/89), respectively. Risk factors for the infection were identified using univariate and multivariate logistic regression analysis. The results revealed that age, sanitary condition and topography were significantly associated with oocyst shedding (P<0.05). Pre-weaned piglets were at the highest risk for infection, followed by post-weaners, sows and finishing pigs. Good sanitary conditions showed positive effects in decreasing oocysts shedding. Topographically, Cryptosporidium was more common in mountainous zone than that in coastal delta zone. There was an association between the occurrence of diarrhea and the level of Cryptosporidium oocyst excretion within infected pigs. This is the first epidemiological investigation of prevalence and risk factors of Cryptosporidium in pigs in Vietnam. 相似文献
226.
Sam Thi Nguyen Duc Tan Nguyen Thoai Van Nguyen Vu Vy Huynh Duc Quyet Le Yasuhiro Fukuda Yutaka Nakai 《Tropical animal health and production》2012,44(8):1847-1853
The aims of this study were to investigate the prevalence of natural Fasciola infections in both the definitive hosts (cattle) and the intermediate hosts (Lymnaea snails) in central Vietnam. A total of 1,075 fecal samples, randomly collected from cattle in Binh Dinh, Khanh Hoa, and Phu Yen provinces, were examined for Fasciola eggs by a sedimentation method. The overall prevalence of Fasciola was 45.3?%. A subset of the animals (235) was also screened for antibodies against Fasciola by an enzyme-linked immunosorbent assay. Overall, 46.3?% of these animals were shedding Fasciola eggs while 87.2?% were Fasciola seropositive. A lower prevalence of Fasciola was observed in calves ??2?years of age (37.6?%) compared to that in cattle >2?years of age (53.7?%) (p?<?0.05). The prevalence in the rainy season (50.8?%) was significantly different to that in the dry season (38.1?%) (p?<?0.05). Of the 3.269 Lymnaea viridis and 1.128 Lymnaea swinhoei examined, 31 (0.95?%) and seven (0.62?%), respectively, were found to be infected with Fasciola. This appears to be the first epidemiological survey of the prevalence of Fasciola in cattle and snails in these three provinces in central Vietnam. 相似文献
227.
Hue KT Van do TT Spörndly E Ledin I Wredle E 《Tropical animal health and production》2012,44(2):267-276
The objective of the experiment was to study different adaptation strategies to avoid HCN intoxication when feeding fresh
cassava foliage to sheep. Twenty-four Phan Rang lambs (initial weight = 19.6 kg at 5.5 months of age) were used in the study.
The four experimental diets contained guinea grass (Panicum maximum) supplemented with concentrate at 1.5% of body weight (BW) as dry matter (DM) (control) or supplemented with fresh cassava
foliage (FCF) that was introduced into the diet with an adaptation period of 0 (FCF-0), 7 (FCF-7) or 21 (FCF-21) days before
reaching the target feeding level of 2% of BW. The average intake of FCF expressed as DM was not different amongst the supplemented
treatments and ranged from 1.4 to 1.5% of BW but gradually increased during the first 7 days without any adaptation. The hydrogen
cyanide consumed varied from 5.1 to 5.4 mg/kg BW and no difference between treatments with cassava foliage in the diet was
found. The live weight gain was significantly higher in the treatments control and FCF-7 compared to FCF-21. No significant
differences in heart rate, respiration rate and rumen movement were found between diets. The thiocyanate concentration in
the urine of the lambs increased concomitantly with the increase in fresh cassava foliage offered during the first part of
the experiment. In conclusion, an adaptation period of approximately 7 days seems to be favourable in combined diets where
cassava foliage is offered in quantities up to 2% of BW. This level of intake could enhance the intake and LWG of the lambs
without any documented effects on heart rate, respiration rate or rumen movements. 相似文献
228.
Measuring wood density by means of X-ray computer tomography 总被引:1,自引:0,他引:1
Charline Freyburger Fleur Longuetaud Frédéric Mothe Thiéry Constant Jean-Michel Leban 《Annals of Forest Science》2009,66(8):804-804
229.
H. P. Ritzema Le Dinh Thinh Le Quang Anh Dang Ngoc Hanh Nguyen Viet Chien Trinh Ngoc Lan R. A. L. Kselik Bui Thi Kim 《Irrigation and Drainage Systems》2008,22(1):19-34
The irrigation and drainage systems in the Red River Delta in Vietnam were designed and constructed in the 1950s and 60s.
These systems are well established and provide water to virtually all of the irrigable land in the Delta. The land is cropped
intensively: on average just over two crops a year. The irrigation and drainage systems are complex: dual purpose channels
and pumping stations are used. In the 1990s, the systems were rehabilitated and upgraded. A review showed that irrigation
projects performed reasonably well, but the two core drainage projects performed less than anticipated. In the Red River Delta,
with its low elevations, drainage rather than irrigation is often the limiting factor affecting agricultural production. To
investigate these constraints in more detail, a participatory research study on the effectiveness of drainage was conducted
in two drainage areas in the Red River Delta. The study started with a participatory pre-investigation to identify and quantify
the constraints in the functioning of the drainage systems. Next, the drainage system was modelled and computer simulations
were used to develop conceptual designs to improve the functioning of the systems. Finally, recommendations to improve the
institutional capacity of the drainage system management were formulated, again in close cooperation with the stakeholders.
These recommendations cover a whole range of technical issues: small-scale improvements in the farmers’ fields, modifications
in the main and secondary drainage systems, including the control structures, up to recommendations to increase the efficiency
of the pumping stations. Next to these technical innovations, recommendations to reform the complex institutional setting
have been formulated. 相似文献
230.