Effect of dietary supplementation of copper and phosphorus on nutrient utilization and growth in crossbred heifers

Growing crossbred heifers (16) of 12 to 16 months age with an average body weight 155 kg were divided into 4 groups of 4 animals each in a 2 x 2 factorial completely randomized design. Heifers of 4 groups were provided 4 respective feed mixtures/dietary treatments, viz, control group 1, without copper and phosphorus supplementation, (treatment 1); group 2, copper supplemented (treatment 2); group 3, phosphorus supplemented (treatment 3); and group 4, copper and phosphorus supplemented (treatment 4). Feed (mineral) mixture containing copper sulphate to supply copper and dicalcium phosphate to supply phosphorus were supplemented as top dressed after offering the concentrate mixture to the heifers as per the requirement along with ad lib. mixed fodder (green oats + oats hay). Feeding trial lasted for 90 days. Average total dry matter intake, dry matter intake per 100 kg body weight and per kg metabolic body weight, average daily TDN and DCP intakes per 100 kg body weight and per kg metabolic body size and digestibility coefficient of different nutrients did not differ significantly amongst different groups of heifers. There was also no significant effect of copper and phosphorus supplementation on these parameters, however, numerically the values were increased due to interaction of copper and phosphorus in the heifers of group 4. The crossbred heifers in group 2 fed ration supplemented with copper gained highest body weight (56.84 kg). The average daily body weight gain was 552.8, 631.5, 551.9 and 567.1 g in heifers of groups 1, 2, 3 and 4, respectively, and did not differ significantly amongst the different groups. The heifers supplemented with copper gained numerically 8.5% higher weight but interaction effect of Cu and P was not significant. It was concluded that under farm condition and existing feeding practices, dietary supplementation of copper and also phosphorus is essential for improvement in the growth and nutrient utilization.