Özet:

Effects of two dietary levels of starch and crude protein on performance of dairy cow fed low roughage level (70:30 concentrate to roughage) were investigated. Twenty eight Holstein cows were randomly assigned to one of four dietary treatments in a 2 x 2 factorial arrangement. Factors were two dietary level of starch (14% and 22%) and crude protein (15% and 18%). Wheat straw was used as sole roughage source. The study was continued 6 weeks. Dry matter intake was not affected (P>0.05) by the dietary treatments in the study. Milk and protein yield (kg/d) were higher (P<0.05) with higher dietary crude protein level at each starch level. Milk urea concentrations were affected (P<0.01) by dietary protein levels with a value being higher by high dietary protein level. Nitrogen efficiency (Milk N/N intake) was decreased by increasing dietary crude protein level in the diet (P< 0.01). In conclusion, the cows fed TMR containing low level of wheat straw responded better when dietary protein increased. But, efficiency of N use decreased and N excretion to the environment increased.

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