Effect of undegradable dietary protein levels and plane of nutrition on feed intake, water metabolism and blood-biochemical constituents in crossbred heifers

An experiment was conducted on crossbred heifers (16), 15 to 19 months old, randomly divided into 4 groups of 4 each in a 2 × 2 factorial completely randomized design. The heifers were fed 4 dietary treatments for 116 days involving 2 levels of UDP (RDP: UDP ratio of 50: 50 and 60: 40) at 2 levels of feeding (100 and 115%, NRC 1989) through concentrate mixtures to assess their effect on feed intake, weight gain, water metabolism and certain blood biochemical parameters. The concentrate mixture containing 50: 50 RDP: UDP ratio (high UDP based on cotton seed cake/ linseed cake and maize) at normal (100%) and higher plane (115%) was fed to heifers in treatment groups 1 and 3, respectively, whereas concentrate mixture 2 containing 60: 40 RDP: UDP ratio (low UDP based on mustard cake and wheat grain) at normal (100%) and higher plane (115%, NRC) was fed to heifers in treatment groups 2 and 4, respectively. The mixed fodder (green oats + oats hay) served as sole roughage to all the animals. The average daily dry matter consumption in the heifers ranged from 2.72 to 2.78 kg per 100 kg body weight and 101.25 to 104.84 g per kg W°.75 and did not differ significantly among groups. The heifers in treatment group 3 fed high UDP ration at higher plane of feeding gained highest daily body weight (0.80 kg) followed by treatment groups 4 (0.75 kg), 1 (0.67 kg) and lowest in heifers in treatment group 2 fed low UDP ration at normal plane of feeding (0.59 kg). The daily body weight gain was improved by 10.45% due to high UDP ration and 23.8% due to higher plane of feeding. The daily water intake and water excretion did not differ significantly amongst the groups. However, water loss was more in faeces and less in urine due to high UDP ration but plane of feeding had no significant effect. The blood serum concentration of total protein, albumin, globulin, cholesterol, calcium and phosphorus and activities of SGOT, SGPT and serum alkaline phosphatase did not differ significantly among the treatment groups, however, there was higher concentration of serum total protein, calcium content and SGPT activity due to high UDP ration. The higher plane of feeding also increased serum albumin and phosphorus content and SGPT activities significantly. It is concluded that feeding high UDP ration (50: 50 RDP: UDP ratio) with 115% of nutrients as recommended in NRC (1989) feeding standard under Indian condition is advantageous in improving the weight gain in crossbred heifers at later stage of growth without affecting the feed and water intakes and with normal blood biochemical constituents.