Effect of supplementing rumen protected methionine on growth traits and feed efficiency of weaned Holstein calves

A study was performed to investigate the effect of rumen protected methionine (RPM) on growth traits and feed efficiency of weaned Holstein calves using 40 calves in 4 experimental groups in a CRD plan with repeated measures were done. The experimental groups were included: 1) control (not given RPM after weaning at 75 days) 2) group was given RPM until 10 days 3) group that was given RPM until 20 days 4) group that was given RPM until 30 days after weaning. RPM was used in the amount of 2 g/d/calf. The studied traits included weight and average daily gain, body length and height, and calculated feed efficiency of experimental period. The results showed that the average feed and nutrient intake (protein and energy) of the third and fourth treatments at the ages of 85, 95 and 105 days were 9.79, 10.12 and 10.27% higher than the average of the first and second treatments (P<0.05). Daily weight gain and feed efficiency of these treatments were also 15.92% and 4.63% respectively (P<0.05).Treatments using methionine supplements had a higher average weight (4.16%) and a higher average height increase (8.15%) than the control (P<0.05). In conclusion, the use of coated methionine supplement in the ration of calves after weaning had a positive effect on growth performance, height measure and overall feed efficiency and it can be recommended at the mentioned level to the farmers. Key words: Body measures, Gain, Feed efficiency, Holstein calves.