The impact of nutrient density in terms of energy and/or protein on live performance,metabolism and carcass composition of female and male broiler chickens of two commercial broiler strains

The objective of this study was to investigate the effects of diet composition on performance, slaughter yield and plasma metabolites, as different modern broiler strains show different responses to feed intake. Broilers of two commercial strains and of both sexes received one of three diets being different in energy and/or protein level [control diet, low energy/low protein diet (LM/LP) and low protein diet (LP)]. Low energy/low protein diet chickens were characterized by significantly lower body weights and feed intake compared with their LP and control counterparts. Broilers of the Cobb strain or broilers that were fed the control diet were most efficient in converting energy to body weight. No significant differences in plasma metabolites were detected due to diet composition or genotype. The diet with the lower energy and crude protein levels reached the lowest slaughter yield but the highest drumstick and wing percentages. The lowest mortality percentages were observed for broilers fed the LM/LP diet, and Cobb birds appeared to be more sensitive for metabolic disorders resulting in death. It is obvious from this study that different genotypes respond differently to changes in diet composition and therefore have adjusted nutritional requirements.     

Use of in Vitro Gas Production Technique to Investigate Interactions between Rice Straw and Cassava Hay

A semi-automated in vitro gas production （GP） system was used to investigate the associative effects on GP of rice straw （RS） supplemented with 0, 25, 50, 75 and 100% cassava hay （CH）. Rate of GP increased with increasing levels of CH inclusion （P〈0.05）. Potential GP values were also affected by CH levels in the substrates,     

In vitro Evaluation of Feed Enzyme Compound Produced by Aspergillus sulphureus in Solid-state Fermentation

Three trials were conducted to analyze a multi-enzyme compound produced by Aspergillus sulphureus in solid-state fermentation (SSF) as a potential feed additive.The results of the first trial showed that there were at least 5 non-starch polysaccharide enzymes:xylanase,β-glucanase,pectinase,mannase and carboxy methyl cellulase (CMCase) contained in the compound.Xylanase and β-glucanase showed good activities at pH 2.5-7.0,which were in the range of 649-1046 U/g and 444-648 U/g,respectively.Pectinase showed good activity in acidic solution (pH 2.5-3.0),which ranged from 195 to 917 U/g.Mannase showed high activity of 235-298 U/g at pH 3.5-4.5 and the activity of CMCase was relatively constant at pH 2.5-7.0,which was in the range of 38.2-78.6 U/g.The second trial was aimed to test the stability of the enzymes in gastric liquor (pH 2.6) of finishing pigs and Na2HPO4-gastric liquor (pH 5.5).After 6 h incubation at 40℃ in gastric liquor,the retained activity of xylanase,β-glucanase,pectinase,mannase and CMCase was 26.3%,65.0%,71.0%,74.8% and 85.6%,respectively.While after 6 h incubation at 40℃ in Na2HPO4-gastric liquor,the retained activity of xylanase,β-glucanase,pectinase,mannase and CMCase was 87.9%,91.1%,92.3%,95.0%,and 97.5%,respectively.The third trial was carried out in a jejunum liquor (pH 5.8,200 mL),which contained 0.2 g of the multi-enzyme compound and 10 g of soybean hull or wheat bran,respectively.After 8 h incubation at 40℃,18.7% of soybean hull and 20.1% of wheat bran could be degraded to soluble saccharide,respectively.Compared with the traditional methods for feed enzyme testing which involve feeding animals for 1-3 months,enzyme assay in this way was relatively convenient.     

100 years of Sediment History of Heavy Metals in Daya Bay, China

Interdisciplinary studies on aquatic environments and cross-validation of laboratory vs. field results will likely increase the need for simultaneous use of large- and small-scale ultrafiltration systems. In this study, a comparison of two ultrafiltration systems differing in scale (PrepScale and PelliconXL, Millipore; membrane areas 0.54 m² and 0.005 m², respectively), was made for the cut-offs 3 and 300 kDa. Large systems are useful for their high permeate throughput, while small systems are necessary when the amount of sample is limited. The ability of PrepScale and PelliconXL systems to provide comparable results for organic carbon fractionation was studied for polysaccharide solutions and natural freshwaters. In the latter, the colloidal proportions of different trace metals (V, Cr, Mn, Co, Ni, Cu, Sb, and U) were also determined. Although the colloidal proportions obtained with PelliconXL 3 kDa were sometimes slightly higher than with PrepScale 3 kDa (principally for DOC and U in natural waters), Mann–Whitney statistical test showed no significant difference in the overall fractionation properties of the two systems. Our observations show that reaching high concentration factors lead to a strong modification of colloids size distribution in the range 50–2,000 nm and thus low concentration factors are preferable to preserve the colloid integrity.     

Culture-based fisheries in small reservoirs in northern Vietnam: effect of stocking density and species combinations

This study was conducted in 20 reservoirs, ranging in size from 4 to 30 ha, in the mountainous, northern region of Vietnam, in ThaiNguyen and YenBai provinces, over two growth cycles in 2002/03 and 2003/04. The reservoirs are leased by farmers for fishery activities from the provincial administration, and the trials were managed by the lessee farmers. Three species combinations in ratios (by fingerling weight) of grass carp: silver carp: bighead carp: common carp: mrigal 1:2:1:1:3 (A), 1:3:1:1:2 (B) and 1:2:1:1:2 (C) were used as seed stock. The overall mean yield of stocked fish in 2002/03 and 2003/04 growth cycles in reservoirs in ThaiNguyen and YenBai provinces was 165 (±21) and 190 (39), and 287 (±22) and 325 (±24) kg ha^?1 respectively. The yield in reservoirs in both provinces, in both growth cycles and irrespective of the species combinations, increased in relation to stocking density. In reservoirs in ThaiNguyen Province, the species combination B gave the lowest yield (both growth cycles and overall), and differed significantly (P<0.05) from combinations A and C. The stocking efficiency (ratio of the yield of stocked fish in kg ha^?1 to the weight of the stocked fish in kg ha^?1) in reservoirs in ThaiNguyen Province ranged from 2.9 to 5.1 over the two growth cycles and that in YenBai from 2.8 to 3.9. There was no discernible trend between growth cycles and/or between species combinations. The major cost incurred was for fingerling procurement. In all instances, a net profit was accrued. The mean (±standard error (SE)) net profit ha^?1 (in 10³VN dong; approximately 15 500 VND=1 US$) was 885 (±270) and 864 (±214), and 1322 (±176) and 1600 (±150) for the growth cycles 2002/03 and 2003/04 for reservoirs in ThaiNguyen and YenBai provinces respectively. Between the two growth cycles, the net profit increased in eight and three reservoirs from YenBai and ThaiNguyen, respectively, the maximum increase being recorded in Khuan Gio (165%) and Dong Man (39%) reservoirs.     

The Expression of Epidermal Growth Factor (EGF) and its Receptor (EGFR) During Post‐Natal Testes Development in the Yak

Growth factors play critical role in cell proliferation, regulate tissue differentiation and modulate organogenesis. Several growth factors have been identified in the testes of various mammalian species in last few years. In present investigation, the objective was to determine the expression of epidermal growth factor (EGF) and the epidermal growth factor receptor (EGFR) in yak testicular tissue by relative quantitative real time polymerase chain reaction (RT‐PCR), Western blot (WB) and immunohistochemistry (IHC) from mRNA and protein levels. The testicular tissues were collected from male yak at 6 and 24 months old. Results of RT‐PCR and WB showed that the expression quantity of EGF and EGFR at 24 months of age was higher than at 6 months, and the increase rate of EGFR on mRNA and protein levels was higher than the increase rate EGF during post‐natal testes development. Positive staining for EGF and EGFR was very low and mainly localized to Leydig cells testes at 6 months of age with immunohistochemistry, and seminiferous tubules were not observed. At 24 month of age, both the EGF and EGFR could be detected in Leydig cells, peritubular myoid cells, sertoli cells and germ cells of the yak testes. However, EGF and EGFR were localized to preferential adluminal compartment and basal compartment in the seminiferous tubules, respectively. In conclusion, the findings in present studies suggest that EGF and EGFR as important paracrine and/or autocrine regulators in yak testes development and spermatogenesis.