The effect of starter soybean oil and protein level on growth performance, plasmaparameters and urinary purine derivatives of Holstein dairy calves

The aim of this experiment was to investigate the effect of starter soybean oil (SO) and crude protein (CP) level on growth performance, plasma parameters and urinary purine derivatives (UPD) of dairy calves. Forty-eighth 3-old Holstein dairy calves with initial BW of 39.8 ± 2.4 kg were used in a completely randomized design with 2 × 2 factorial arrangement. The experimental diets consisted of diet without SO and 19% CP, diet without SO and 22% CP, diet with 3% SO and 19% CP and diet with 3% SO and 22% CP. Feed intake, feces score, skeletal growth indices, plasmaparameters, liver enzymes, urinary purine derivatives and microbial protein synthesis were measured. Growth performance, plasma parameters and UPD were not influenced by interaction effect of starter diet SO and CP level. Starter diet intake, average daily gain and feed efficiency were lower in calves fed SO than those fed diets without SO (P < 0.05). The fecal score and wither height of calves fed diets containing SO were higher and lower that those fed diets without SO, respectively (P < 0.05). Plasma concentrations of glucose, beta-hydroxy butyrate and total protein were lower in calves fed SO (P < 0.05). Addition of SO to the diets decreased urinary allantoin and total UPD concentrations (P ≤ 0.05). Microbial protein synthesistended to be decreased in calves received diets containing SO compared to other groups (P=0.06). Plasma urea nitrogen concentration of calvesincreased by increasing dietary CP level (P < 0.05). According to this results, growth performance of Holstein dairy calves is not affected by interaction of SO and CP level in starter diet.