基于Meta分析的生猪氮排泄量预测模型构建

本试验旨在利用Meta分析探究常规饲粮下生猪氮排泄量及其变异范围,并建立不同生长阶段生猪氮排泄量的预测模型。检索2000—2021年中外文数据库(Web of Science、PubMed、ScienceDirect、中国知网、维普和万方)中相关文献,以文献中不同阶段生猪的摄入氮(NI)、粪氮(FN)、尿氮(UN)和总氮排泄量(NE)数据为基础,使用倒方差法对生猪氮排泄量进行Meta分析,建立不同阶段生猪氮排泄量的预测模型。结果表明:保育猪、育肥前期猪和育肥后期猪的NI与FN、UN和NE均有较强的相关性(P<0.01),不同生长阶段生猪基于NI的氮排泄量预测模型为:保育猪NE=0.460NI-2.255,FN=0.197NI-1.314,UN=0.264NI-0.965;育肥前期猪NE=0.583NI-5.370,FN=0.139NI+1.340,UN=0.446NI-6.788;育肥后期猪NE=0.698NI-10.251,FN=0.143NI+0.422,UN=0.551NI-10.451。本试验通过Meta分析建立了基于生猪NI的各生长阶段的FN、UN和NE预测模型,可用于预测不同生长阶段生猪的氮排泄量,为养殖粪污资源化利用提供基础参数和方法支撑。

Nitrogen and phosphorus intake by phytoplankton in the Xiamen Bay

This paper describes a time series experiment examining the nitrogen and phosphorus intake of natural phytoplankton communities by a microcosms approach.Seawater samples containing natural phytoplankton communities were collected from waters around Baozhu Islet in inner Xiamen Bay and around Qingyu Islet in the outer bay.The goal was to elucidate the relationship between phytoplankton population enhancement,the biological removal of nitrogen and phosphorus from the seawater,and the phytoplankton nitrogen and phosphorus intake ratio based on nitrogen and phosphorus removal from seawater by phytoplankton,to provide a basis for detecting prewarning conditions for red tide and the assessment of red tide events.Two key results were obtained:1.During the experiment,the nitrogen and phosphorus seawater concentrations in samples from these two sites were negatively and closely correlated to the logarithm of the phytoplankton cell concentration and to the value of the apparent oxygen increment.The ratio of the intake coefficients was 3.5:1 for phosphorus and 1.1:1 for nitrogen for the phytoplankton between these samples from around Baozhu Islet and Qingyu Islet,respectively.This indicates that the intake capabilities of phytoplankton for nitrogen in the two waters are essentially identical.However,for phosphorus,the capability was much higher in the Baozhu Islet waters than the Qingyu Islet waters.In other words,the phytoplankton in Qingyu Islet waters produced more biomass while consuming the same amount of phosphorus as the other waters;2.The phytoplankton nitrogen and phosphorus intake ratio from the Baozhu Islet and Qingyu Islet waters was 20:1 and 36:1,respectively.The latter waters had a significantly higher ratio than the former and both were higher than the Redfield Ratio.These results indicate that nitrogen and phosphorus intake ratios by phytoplankton can vary significantly from region to region.