Dietary polymer-coated urea enhances the goats lactational performance, excretion of microbial purine derivatives and blood metabolites in the semi-arid zone of Iran

ABSTRACT. This study aimed to determine the effect of using different sources of nitrogen to supply part of degradable intake protein needs in lactating goat performance and its effect on excretion of microbial purine derivatives and blood metabolites. Thirty-two lactating Saanen goats (body weight 38.85 ± 2.14 kg and 1979 ± 0.25 g day-1 milk yield) were used in a one-way ANOVA completely randomized design. Goats were assigned to the following treatments for a 10-wk experimental period: 1) Control (canola meal as a nitrogen source); 2) Urea (0.5% urea); 3) Optigen (0.55% Optigen- Alltech. Inc., Lexington, KY) and 4) Polymer-Coated Urea (PCU- international patent number: A01K5/00, 0.7% PCU) based on dry mater intake. Non-protein nitrogen groups had a comparative effect (p > 0.05) between control and other treatments on milk composition, microbial protein synthesis and they affected on blood factors including urea, cholesterol, and ALT. Dry matter intake decreased (p > 0.05) in PCU, Optigen, Urea than Control goats. Synthesis of microbial protein in PCU goats was 22.5 g day-1 and it was greater (p > 0.05) than other treatments. Plasma cholesterol was increased in PCU and Optigen, whereas urea concentration was increased in Urea and Control goats. Milk production was higher in PCU than Urea and Control. Feed conversion ratio was improved (p > 0.05) in PCU and Optigen goats versus other treatments. This study demonstrated that polymer-coated urea can be utilized as a nitrogen source and improve goats milk performance.

摘要：本研究旨在探究不同氮源补充部分可降解采食蛋白质需求对泌乳莎能山羊生产性能的影响，及其对微生物嘌呤衍生物排泄与血液代谢物的作用。本试验采用单因素方差分析完全随机设计，选取32头泌乳莎能山羊（初始体重38.85±2.14 kg，日均产奶量1979±0.25 g）作为试验对象，试验周期为10周。试验共设置4组处理：1）对照组（以菜籽粕作为氮源）；2）尿素组（添加0.5%尿素）；3）Optigen组（添加0.55% Optigen——奥泰克公司（Alltech. Inc.），肯塔基州列克星敦）；4）包被尿素（PCU，国际专利号：A01K5/00，添加0.7% PCU），各组添加量均以干物质采食量为基准配比。与对照组相比，非蛋白氮各组在乳成分、微生物蛋白质合成方面无统计学差异（p>0.05），但会对血液中的尿素、胆固醇及丙氨酸转氨酶（ALT）等指标产生影响。与对照组相比，PCU组、Optigen组与尿素组的干物质采食量均有所降低（p>0.05）。PCU组山羊的微生物蛋白质合成量为22.5 g/天，显著高于其余各组（p>0.05）。PCU组与Optigen组的血浆胆固醇水平升高，而尿素组与对照组的血浆尿素浓度升高。PCU组的产奶量高于尿素组与对照组。与其余各组相比，PCU组与Optigen组的饲料转化率得到显著改善（p>0.05）。本研究表明，包被尿素可作为氮源应用于泌乳山羊养殖，能够有效提升其产奶性能。