128 



Maine Agricultural Experiment Station. 1920. 



TABLE 3. 



Regression Equations of the Milk Yield for Any Age from That 

 of Any Lactation Record at Another Age. 



AGE AT WHICH EXPECTED MILK YIELD IS DESIRED. 



Age at which milk 

 yield was made 



2 years to 3 years; 3 years to 4 years 



Regression 

 Equation 



2 years to 3 years y2 



3 years to 4 years ys! Y= 



4 years to 5 years y<i: Y= 



5 years to 6 years ysl Y= 



6 years to 7 years ye Y= 



7 years to 8 years yT Y= 



8 years to 10 years ys Y= 

 10 years and above yio Y= 



=2130.0+ 

 =2391.2+ 

 =2394.4+ 

 =2456.2+ 

 =1995.3+ 

 =2570.8+ 

 =2633.1+ 



.4194y3 

 ,3427y* 

 .3219ys 

 .3018ye 

 .3955y7 

 .2927ys 

 .3105yio 



Regression 

 Equation 



Y=1515.5+.7922y 2 



=1656.2+. 5935y 4 

 =2408.3+. 4362y 5 

 =2346.6+. 4330y e 

 =2252.6+. 4790y 7 

 =2437.6+. 4433ys 

 = 868.8+. 8766y io 



4 years to 5 years 



Regression 

 Equation 



Y=1447.4+.8591y2 

 Y=2013.7+.6500ys 



Y=25"l3"i+r4855ys 



Y=3092.2 + .3652y 8 

 T==2345.0 + .5149y7 

 Y=3367.9+.3298ys 

 Y=3952.6+.2190yio 



5 years to 6 years 



Regression 

 Equation 



=1795.7+ .8968y» 

 =2082.5+.6882yi 

 =2007.2 +.6325y4 



=1624.4 +.6708y« 

 =2507.8+. 5086yT 

 =2715.2+. 4959ys 

 =2905.2+.5265yio 



Age at which milk 

 yield was made 



6 years to 7 years 



Regression 

 Equation 



7 years to 8 years 



Regression 

 Equation 



8 years to 10 years 



Regression 

 Equation 



10 years and above 



Regression 

 Equation 



2 years to 



3 years to 



4 years to 



5 years to 



6 years to 



7 years to 



8 years to 

 10 years an< 



3 years yz 



4 years y3 



5 years y4 



6 years ys 



7 years ye 



8 years y7 

 10 years ys 

 1 above yio 



=1551.7+1.0023y: 

 =2578.2 +.6500y 3 

 =1158.8+.8662y4 

 =1332.7+.7958y5 



=1960.8+. 6445y7 

 =2989.5+.4591ys 

 =2899.8+. 5053yio 



Y==1910.8+.8549y2 

 Y==2502.2+.6075y3 

 T=1435.1+.7778y4 

 Y=2165.0 + .6314y 5 

 T=1779.2+.6585ye 



Y=2720"5+r492"0ys 

 Y=3772.8+.2946yio 



Y=1710.8+.8329y2 

 Y=2036.3+.6519y3 

 Y=2500.7+.5233y4 

 Y==2087.7+.5S90y 5 

 Y=2493.0+.5019y6 

 Y==1573.3+i6720y7 



y=266o"i+"5T5"o"yio 



Y== 717.0+1. 0109yj 



Y=2539.6 + .4580ya 



Y=3711.3+.2100y* 



Y=1871.7+.5480y B 



Y=2681.7+.4147y« 



Y=3205.1+.3129yT 



Y=2271.5 + .5075ys 



As the milk production is given in pounds the second term 

 of each of these equations gives the gain in expected milk yield 

 for the given age, if one pound increase in actual production is 

 made during the test. The calculation of an expected yield is, 

 therefore a simple matter of direct substitution. 



Thus for the dairyman with a herd of cows producing an 

 amount of milk similar to this herd of Jerseys, suppose one of 

 his cows produces 5000 pounds as a two year old, what would 

 the six year old production be? In the 6 year to 7 year column 

 on line with the 2 years to 3 years is given the equation neces- 

 sary to solve the problem, Y=i55i.7-|-i.oo23 y2 . The arithmet- 

 rical computation for each step is 1.0023 x 5000=501 1.5-7-1551 -7 

 6563.2 the pounds of milk expected of the cow at six years. The 

 repetition of this process for any milk production or age gives 

 the desired probable milk yield. 



