Prediction and comparison of nitrogen excretions in dairy and beef cattle
2006
Choumei, Y.(Kyoto Univ. (Japan)) | ; Terada, F. | ; Hirooka, H.
The objectives of this study were to analyze how the nitrogen intake (dry mater intake or dietary crude protein content) affects the nitrogen excretion compare nitrogen excretions in dairy and beef cattle. In addition, an attempt was made to develop general equations for predicting nitrogen excretion in both dairy and beef cattle. The relationships between nitrogen intake and excretion were investigated using experimental data from 95 Holstein cows, 45 Holstein steers and 23 Japanese Black steers and literature values from 33 published papers. The result showed that lactating cows less excreted urinary nitrogen than steers. Fitting by linear equations and exponential equations from pooled data gave positive relationships between nitrogen intake and excretions in feces and urine. Although there was a large difference for nitrogen excretion in urine between lactating cows and steers at the same nitrogen intake level, the difference disappeared when compared at the same nitrogen output level in urine plus milk. The fecal nitrogen excretion was related with dry mater intake rather than nitrogen intake.
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