本试验旨在研究全混合日粮( TMR)饲喂泌乳奶牛群摄入养分偏离的原因分析及对生产性能的影响。选取30个高产牛群,每个牛群采样5 d。采取牛群TMR及剩料样品,进行养分分析和颗粒分级评定,计算各指标的变异系数。记录产奶量,取奶样测乳成分。多元线性回归分析养分、颗粒的变异系数与牛群生产性能的关系。结果表明：30个牛群饲喂的TMR产奶净能(NEL)和粗蛋白质(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)、微生物蛋白质(MCP)、瘤胃非降解蛋白质( RUP)、瘤胃能氮平衡( RENB)、小肠可消化粗蛋白质( DCPSI)、钙( Ca)含量分别为6.56 MJ/kg 和16.22%、35.71%、21.38%、77.84 g/kg、92.15 g/kg、14.77 g/kg、104.04 g/kg、1.43%,其中高于配方目标的指标有NDF(1.94%)、Ca(0.57%)、RUP(5.03 g/kg)、RENB (6.95 g/kg ),低于配方目标的指标有 CP (-0.36%)、ADF (-1.54%)、NEL (-0.12 MJ/kg)、MCP(-7.71 g/kg)、DCPSI(-2.12 g/kg)(正值表示提高,负值表示降低)。观测期内,RUP[(16.26±7.10)%]、MCP[(22.78±13.38)%]、RENB[(64.29±34.29)%]3种养分的变异系数大于10%,其他养分的变异系数均小于10%。长、中、短、细4类颗粒含量的变异系数分别为(15.78±9.25)%、(9.12±7.86)%、(6.00±4.00)%、(11.15±9.62)%。回归分析表明, TMR养分和颗粒度变异影响产奶量和乳成分,NEL 变异系数每升高1个百分点,产奶量下降3.662 kg/d；长颗粒变异系数每升高1个百分点,产奶量下降0.124 kg/d,乳脂率升高0.012%。结果提示,TMR饲喂泌乳奶牛摄入养分因投料不准确、加工质量不稳定、搅拌不均匀、挑食等与配方养分产生差异。 TMR加工质量稳定性影响到产奶量和乳成分,其中NEL、DCPSI、RENB的变异影响产奶量,长颗粒变异影响产奶量和乳脂率。%This experiment analyzed the reason for deviation of nutrient intake of lactating cow herds fed total mixed ration ( TMR) and the effects on production performance. Thirty cow herds with high milk yield were chosen and sampled for 5 days per herd. TMR and refusal feed samples were collected to assess nutrient com-position and particle size distribution, and the coefficients of variation ( CVs) of indexes were calculated. Milk yield was recorded, and milk sample was detected for milk composition. A multiple linear regression analysis between CVs of nutrients/particle sizes and production performance of cow herds was carried out. The results showed as follows: net energy for lactation (NEL) and the contents of crude protein (CP), NDF、ADF, mi-crobial protein ( MCP ) , ruminal undegradable protein ( RUP ) , ruminal balance of energy and nitrogen ( RENB ) , small intestinal digestible protein ( DCPSI ) and calcium ( Ca ) of TMR for 30 cow herds were 6.56 MJ/kg, 16.22%, 35.71%, 21.38%, 77.84 g/kg, 92.15 g/kg, 14.77 g/kg, 104.04 g/kg and 1.43%respectively, among which NDF (1.94%), Ca (0.57%), RUP (5.03 g/kg) and RENB (6.95 g/kg) were higher than formula target values, and CP (-0. 36%) , ADF (-1. 54%) , NEL (-0. 12MJ/kg ) , MCP (-7.71 g/kg) and DCPSI (-2.12 g/kg) were lower than formula target values ( positive value indicate in-crease, and negative value indicate decrease ) . During the observation period, CVs of RUP [ ( 16. 26 ± 7.10)%], MCP [(22.78±13.38)%], RENB [(64.29±34.29)%] were more than 10%, and those of the other nutrients were less than 10%. CVs of long, medium, short and fine particles were (15.78±9.25)%, (9.12±7.86)%, (6.00±4.00)% and (11.15±9.62)%, respectively. The regression analysis showed that var-iation of TMR nutrients and particle sizes affected milk yield and milk composition. Every 1-percentage-point increase in CV of NEL resulted in decreasing of 3.662 kg/d for milk yield. Every 1-percentage-point increase in CV of long particles resulted in decreasing of 0.124 kg/d for milk yield and increasing of 0.012% for milk fat percentage. The results indicate that the reason for difference between TMR nutrient intakes of lactating cows and formula nutrients lies in inaccurate feeding, unstable processing quality, mixing uniformity, and feed sor-ting. The stability of TMR processing quality can affect milk yield and milk composition, among which the var-iation of NEL, DCPSI and RENB affects milk yield, and that of long particles influences both milk yield and milk fat percentage.
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