Are you able to change the date you get the turkeys? If so, here is a chart on growth from Meyer Hatchery. Last year ours dressed out from 18-25 lbs. at 17 weeks. From the chart you'd probably want to move your hatch date up a week or two to be sure you make that weight. Adding scratch at the end will reduce the protein content of their feed and will slow the growth a bit.
Use the chart below to estimate when to purchase your turkeys based on the weight you would like them to reach. Keep in mind, you will lose 15-20% of the live weight at the time of processing. Due to conditions beyond our control, we can not guarantee these exact results. It is merely meant to be a guide for your reference.
Live
Weight
Cumulative
Feed
in
pounds
in
pounds
Age in Weeks Toms Hens Toms Hens
2 0.88 0.79 1.18 1.06
4 2.81 2.37 4.38 3.59
6 6.15 5.04 10.30 8.14
8 10.57 8.37 19.10 14.62
10 15.68 12.07 30.51 22.88
12 21.18 15.85 44.29 32.62
14 26.84 19.55 60.17 43.67
16 32.46 23.00 77.85 55.77
18 37.96 26.12 97.39 68.79
20 43.27 28.90 118.79 82.73
22 48.39 X 142.22 X
24 53.38 X 167.83 X
Source: Ag Forte