Data_Sheet_1_Use of reclaimed urban wastewater for the production of hydroponic barley forage: water characteristics, feed quality and effects on health status and production of lactating cows.pdf

The safety of reclaimed urban wastewater (RUW) for the production of hydroponic barley forage (HBF) was evaluated in terms of effluent and forage characteristics, as well as the health and performance of lactating cows. The study was conducted on a dairy farm equipped with two hydroponic chambers producing approximately 620 kg/d of HBF as fed. For experimental purposes, HBF was produced using RUW collected from an aqueduct plant processing urban wastewater in a membrane bioreactor treatment chain. A feeding trial was carried out with HBF derived from RUW. Sixty lactating cows were randomly assigned to two balanced groups fed a standard total mixed ration (TMR) or a TMR in which 10 kg of HBF replaced 1 kg of oat hay and 0.5 kg of maize. The experimental period lasted 7 weeks, including a 2-week adaptation period, during which each cow underwent a physical examination, BCS scoring, blood sampling for a complete blood count and biochemical panel, recording of body weight and milk yield and quality, including fatty acid composition and heavy metal content. Ruminal pH was continuously monitored by reticulorumen boluses, and nutrient digestibility and N balance were determined at week 7. RUW showed an acceptable microbial load and an overall good quality as irrigation water, even though the supply of N and P did not influence the yield and quality of HBF. The characteristics of HBF reflected the quality of RUW supplied to the hydroponic chambers and no anomalous components (i.e., high ion concentration) were found. Feeding RW-derived HBF to lactating cows had no major positive or negative effects on animal health and production, including milk quality, ruminal pH, in vivo digestibility, and N balance. The use of RUW under the conditions tested appears to be safe for the health status of lactating cows and the quality of the milk obtained. Overall, the results do not reveal any major limitations for the use of tertiary wastewater as irrigation water for the hydroponic production of forage barley, so that a wider use of wastewater in hydroponic systems seems realistic.

本研究针对再生城市污水（reclaimed urban wastewater, RUW）用于水培大麦饲草（hydroponic barley forage, HBF）生产的安全性展开系统性评估，分别从出水与饲草品质、泌乳母牛的健康状况及生产性能三个维度开展分析。
实验依托一座配备两套水培培养舱的奶牛养殖场完成，该系统每日可生产约620 kg（以饲喂量计）的水培大麦饲草。实验所用的水培大麦饲草，均采用某采用膜生物反应器（membrane bioreactor）处理工艺的城市污水处理输水厂采集的再生城市污水培育而成。
随后开展饲喂试验：将60头泌乳奶牛随机分为两组，对照组饲喂标准全混合日粮（total mixed ration, TMR），实验组则以10 kg水培大麦饲草替代1 kg燕麦干草与0.5 kg玉米，整合至全混合日粮中。
实验周期共计7周，包含2周适应期。适应期内，对每头奶牛进行体格检查、体况评分（body condition scoring, BCS）、采集血样以完成全血细胞计数与生化指标检测，同步记录其体重、产奶量及乳品质，其中乳品质指标涵盖脂肪酸组成与重金属含量。研究采用瘤胃植丸对瘤胃pH进行持续监测，并于第7周测定营养物质消化率与氮平衡。
实验结果显示：再生城市污水的微生物负荷处于可接受范围，作为灌溉用水整体品质良好，尽管其氮、磷供给未对水培大麦饲草的产量与品质产生显著影响。水培大麦饲草的品质与培育所用再生城市污水的品质相匹配，未检出高离子浓度等异常成分。以再生城市污水培育的水培大麦饲草饲喂泌乳奶牛，未对动物健康与生产性能（包括乳品质、瘤胃pH、体内消化率及氮平衡）产生显著的正负向影响。
在本实验设定的条件下，使用再生城市污水对泌乳奶牛的健康状态与所产牛乳的品质均无安全隐患。整体而言，本研究结果未发现三级处理出水（tertiary wastewater）作为灌溉用水开展大麦饲草水培生产的显著限制因素；因此，在水培饲草生产系统中推广应用污水具备现实可行性。