Lin Gang, Guo Yang, Liu Bing, Wang Ruiguo, Su Xiaoou, Yu Dongyou, He Pingli
1Institute of Quality Standards and Testing Technology for Agricultural Products, Chinese Academy of Agricultural Sciences, Key Laboratory of Agrifood Safety and Quality, Ministry of Agriculture and Rural Affairs, Beijing, 10081 People's Republic of China.
2College of Animal Science, Zhejiang University, Key Laboratory of Animal Nutrition and Feed in East China of Ministry of Agriculture and Rural Affairs, Hangzhou Zhejiang, 310058 People's Republic of China.
J Anim Sci Biotechnol. 2020 May 22;11:54. doi: 10.1186/s40104-020-00457-y. eCollection 2020.
The objective of this study was to determine the effects of supplementing Cu on growth performance, Cu metabolism and Cu-related enzyme activities of weanling pigs fed diets with two different Cu sources, and to estimate optimal Cu requirements and relative bioavailability from these two sources for pigs.
Weanling pigs were allocated to 14 treatments arranged factorially, including 6 added Cu levels (5, 10, 20, 40, 80, 160 mg/kg), and 2 mineral sources (tribasic Cu chloride, TBCC and copper proteinate, CuPro), as well as one negative control (0 mg/kg added Cu level) and one maximum allowed level treatment (200 mg/kg TBCC) for the entire 38-d experiment. Growth performance, mineral status and enzyme activities were measured at the end of this study.
Increasing levels of Cu showed linear and quadratic responses ( 0.01) for final BW, ADG and FCR regardless of the sources. Supplementation with TBCC (> 80 mg/kg) and CuPro (> 20 mg/kg) significantly decreased ( 0.05) diarrhea incidence of weanling pigs. There were linear and quadratic increases ( 0.01) in bile, hepatic, and intestinal Cu concentrations, fecal Cu contents, and plasma enzyme activities (alkaline phosphatase, ceruloplasmin, Cu, Zn-Superoxide dismutase (Cu/Zn SOD), and glutathione peroxidase), whereas plasma malondialdehyde decreased ( 0.01) linearly and quadratically as dietary Cu level increased. Similarly, pigs fed CuPro absorbed and retained more Cu and excreted less Cu than those fed TBCC when supplemented 80 mg/kg and above. Optimal dietary Cu requirements for pigs from 28 to 66 d of age estimated based on fitted broken-line models ( 0.05) of bile Cu, plasma Cu/Zn SOD and growth performance were 93-140 mg/kg from TBCC, and 63-98 mg/kg from CuPro accordingly. According to slope ratios from multiple linear regression, the bioavailability value of CuPro relative to TBCC (100%) was 156-263% ( 0.01).
The findings indicated that Cu recommendation from current NRC (5-6 mg/kg) was not sufficient to meet the high requirement of weanling pigs. Cu from CuPro was significantly more bioavailable to weanling pigs than TBCC in stimulating growth and enzyme activities, decreasing diarrhea frequency and fecal Cu contents to the environment.
本研究的目的是确定在给断奶仔猪饲喂两种不同铜源日粮时添加铜对其生长性能、铜代谢及铜相关酶活性的影响，并估计仔猪对这两种铜源的最佳铜需求量和相对生物学利用率。
断奶仔猪按析因设计分为14个处理组，包括6个添加铜水平（5、10、20、40、80、160mg/kg）、2种矿物质来源（碱式氯化铜，TBCC和蛋白铜，CuPro），以及一个阴性对照（添加铜水平为0mg/kg）和一个最大允许水平处理（200mg/kg TBCC），整个试验为期38天。在本研究结束时测定生长性能、矿物质状态和酶活性。
无论铜源如何，铜水平的增加对末重、平均日增重和料重比均呈线性和二次响应（P<0.01）。添加TBCC（>80mg/kg）和CuPro（>20mg/kg）显著降低（P<0.05）断奶仔猪腹泻发生率。胆汁、肝脏和肠道铜浓度、粪便铜含量以及血浆酶活性（碱性磷酸酶铜蓝蛋白、铜锌超氧化物歧化酶（Cu/Zn SOD）和谷胱甘肽过氧化物酶）呈线性和二次增加（P<0.01），而随着日粮铜水平的增加，血浆丙二醛呈线性和二次下降（P<0.01）。同样，当添加量在80mg/kg及以上时，饲喂CuPro的仔猪比饲喂TBCC的仔猪吸收和保留更多的铜，排出的铜更少。根据拟合的折线模型（P<0.05），基于胆汁铜、血浆铜锌超氧化物歧化酶和生长性能估计的28至66日龄仔猪的最佳日粮铜需求量，来自TBCC的为93-140mg/kg，来自CuPro的为63-98mg/kg。根据多元线性回归的斜率比，CuPro相对于TBCC（100%）的生物学利用率值为156-263%（P<0.01）。
研究结果表明，当前美国国家研究委员会（NRC）推荐的5-6mg/kg铜不足以满足断奶仔猪的高需求。在刺激生长和酶活性、降低腹泻频率以及减少粪便铜向环境排放方面，CuPro中的铜对断奶仔猪的生物学利用率显著高于TBCC。
