Effect of organic sources of minerals on fat-corrected milk yield of dairy cows in confinement

This study evaluated the effects of organic and inorganic sources of minerals in diets for mid-lactation dairy cows on milk yield and composition, intake and total apparent digestibility of dry matter and nutrients, blood parameters, microbial protein synthesis, and energy and protein balances. Twenty Holstein cows averaging 146.83±67.34 days in milk and weighing 625.30±80.37 kg were used. The experimental design was a crossover. Diets were composed of corn silage (50%), ground grain corn, and soybean meal, differing with regard to the sources of trace minerals, plus an organic and inorganic mix. The organic mineral source increased milk fat and fat-corrected milk yield without changing milk yield, intake, or total apparent digestibility. Blood parameters, microbial protein synthesis, and energy and protein balances were not affected by the sources of minerals. Organic sources of minerals improve milk fat yield without affecting other parameters.

本研究评估了泌乳中期奶牛日粮中有机与无机矿物质源对产奶量及乳成分、干物质（dry matter）与营养物质采食量及总表观消化率、血液指标、微生物蛋白质合成，以及能量与蛋白质平衡的影响。本试验选取20头荷斯坦奶牛，其平均泌乳天数为146.83±67.34天，平均体重为625.30±80.37 kg。试验采用交叉试验设计。基础日粮由50%玉米青贮、粉碎玉米及豆粕构成，以微量矿物质源作为差异变量，并设置有机-无机混合矿物质源组。研究表明，有机矿物质源可提升乳脂产量与脂肪校正奶产量，但对总产奶量、采食量及总表观消化率无显著影响。血液指标、微生物蛋白质合成及能量与蛋白质平衡均不受矿物质源的影响。综上，有机矿物质源可在不影响其他试验参数的前提下提升乳脂产量。