A simple daily dynamic feeding regimen for reducing phosphorus consumption and excretion in laying hens

Phosphorus metabolism in laying hens is a highly dynamic process over the course of the 24 h egg-laying cycle.Adjusting the phosphorus feeding regimen according to the daily egg-laying cycle may help to improve phosphorus utilization efficiency.Hy-Line Brown layers(n=120;70 wk old)were offered 4different phosphorus daily regimens:(1)RR,fed regular phosphorus at both 09:00 and 17:00;(2)RL,fed regular phosphorus at 09:00 and low phosphorus at 17:00;(3)LR,fed low phosphorus at 09:00 and regular phosphorus at 17:00;(4)LL,fed low phosphorus at both 09:00 and 17:00.The regular and low phosphorus diets contained 0.32% and 0.14% non-phytate phosphorus,respectively.The feeding trial lasted for 12 wk.As a result,layers on the RL regimen had decreased laying rate(P<0.05;5 to 8,9 to 12,and 1 to 12 wk)when compared to all other regimens.Layers on the LL regimen had decreased eggshell thickness and specific gravity(P<0.05;wk 8)when compared to all other regimens,and had decreased egg shell strength(P<0.05;wk 8)when compared to RL and LR regimens.When compared to the RR regimen(a common practice in the industry),layers on the LR regimen had:(1)identical laying performance and egg quality(P>0.05);(2)decreased phosphorus excretion(P<0.05)during the period of09:00 to 17:00;(3)increased jejunal calbindin D28k protein expression(P<0.05)2 h after feeding in the morning;(4)decreased serum fibroblast growth factor 23 and calcitriol levels(P<0.05),decreased jejunal type Ⅲ sodium-phosphate cotransporter 2 gene and protein expression(P<0.05),and decreased renal type Ⅲ sodium-phosphate cotransporter 1 protein expression(P<0.05),2 h after feeding in the afternoon.In summary,when dietary phosphorus was supplemented in accordance with daily serum phosphorus rhythms(i.e.,the LR regimen),laying performance and egg quality were well supported whilst significantly decreasing phosphorus consumption and excretion.Thus,serum phosphorus rhythms will need to be carefully maintained when developing dietary phosphorus-reduction strategies in laying hens.

动态保压注塑成型的动态数值仿真与实验结果分析

为实现动态保压注塑成型(OPIM)的智能精密制造,以哑铃型拉伸试样构建几何模型,以Dynamic feed系统还原保压阶段中复杂的动态流动场,运用Moldflow模拟仿真出OPIM全过程.通过与传统注塑成型(CIM)的对比研究,探究了OPIM在保压阶段的熔体流动情况、皮芯结构上熔体温度以及剪切速率分布与大小的变化.通过二维广角X射线衍射(2D-WAXD)、扫描电子显微镜(SEM)以及显微镜实验对模拟结果进行验证.结果表明,在OPIM过程中,熔体在较低黏度下可反复通过型腔,在型腔厚度方向上产生温度梯度,形成强剪切场,进而诱导分子链伸直,形成串晶结构,从而提高了OPIM制品性能,模拟与实验结果一致.

Bulking sludge for PHA production:Energy saving and comparative storage capacity with well-settled sludge

Two acetate-fed sequencing batch reactors （SBR） were operated under an aerobic dynamic feeding （ADF） model （SBR#2） and with anaerobic phase before aerobic phase （SBR#1） to select mixed cultures with a high polyhydroxyalkanoates （PHA） storage response. Although kinetic selection based on storage response should bring about a predominance of floc-formers, a bulking sludge with storage response comparable to well-settled sludge was steadily established. An anaerobic phase was introduced before the aerobic phase in the ADF model to improve the sludge settleability （SBR #1）, however, due to the consequent increased feast/famine ratio, the performance of SBR #1, in terms of both the maximum PHB （polyhydroxybutyrate） cell content and APHB, was lower than that of SBR #2. SBR #2 gradually reached a steady state while SBR #1 failed suddenly after 50 days of operation. The maximum specific substrate uptake rate and storage rate for the selected bulking sludge were 0.4 Cmol Ae/（Cmol X.hr） and 0.18 Cmol Ac/（Cmol PHB.hr）, respectively, resulting a yield of 0.45 Cmol PHB/（Cmol Ae） in SBR #2 in the culture enrichment phase. A maximum PHB content of 53% of total suspended solids and PHB storage rate of 1.36 Cmol Ac/（Cmol PHB.hr） was achieved at 10.2 hr in batch accumulation tests under nitrogen starvation. The results indicated that it was feasible to utilize filamentous bacteria to accumulate PHA with a rate comparable to well-settled sludge, Furthermore, the lower dissolved oxygen demand of filamentous bacteria would save energy required for aeration in the culture enrichment stage.

Comparative study of polyhydroxyalkanoates production from acidified and anaerobically treated brewery wastewater using enriched mixed microbial culture

The production of polyhydroxyalkanoates(PHA) from wastewaters using microbial mixed cultures(MMC) has been attracting increased interest because of PHA's biodegradability characteristics. Production of PHA by an MMC enriched with PHA-accumulating bacteria was compared using anaerobically treated and acidified brewery wastewaters under various feeding strategies, namely pulse and batch feed addition. To obtain an enriched MMC, a sequencing batch reactor was inoculated with activated sludge fed with acetate and subjected to aerobic dynamic feeding. The enriched MMC was able to accumulate PHA up to 72.6% of cell dry weight(CDW) with pulse addition of acetate controlled by the dissolved oxygen(DO) concentration in the reactor. In a batch accumulation experiment with acetate,the PHA content achieved(28.5% CDW) was less than that of the pulse feeding strategy with the same amount of acetate(～2000 mg C/L). Using anaerobically treated and acidified brewery wastewater fed in pulses, the maximum PHA accumulated by the enriched MMC was similar for both wastewaters(45% CDW), in spite of the higher volatile fatty acid concentration in acidified brewery wastewater. The pulse feed addition controlled by the DO concentration was difficult to implement for wastewater as compared to acetate because the difference in DO concentration between substrate availability and depletion was low. For the batch addition of acidified wastewater, a slightly lower PHA content(39%CDW) was obtained. These results show that both brewery wastewaters can be utilized for PHA production with a similar maximum PHA storage capacity.