A few years ago I regularly weigh taped all my calves every 2 weeks.. Some would grow in spurts, and some had very steady growth.. One heifer in particular was VERY steady, so I plugged it all into Excel and got a formula which I use to compare the weight of all other calves...

Calves tend to put on more weight in the first month than the 5th if the feeding regime is similar, so I came up with this

-0.002 * Age^2 + 3 * Age + BW

Basically is says that they start off gaining 3 lbs a day, and every day they gain .002 lbs less, so that at 200 days they're gaining 2.6 lbs

This yields what I consider about my minimum requirements for a replacement heifer.. 600 lbs @205 days

Here's what it works out to.. week by week with an 80 lb birthweight

7 100.902

14 121.608

21 142.118

28 162.432

35 182.55

42 202.472

49 222.198

56 241.728

63 261.062

70 280.2

77 299.142

84 317.888

91 336.438

98 354.792

105 372.95

112 390.912

119 408.678

126 426.248

133 443.622

140 460.8

147 477.782

154 494.568

161 511.158

168 527.552

175 543.75

182 559.752

189 575.558

196 591.168

203 606.582

210 621.8

217 636.822