Table 2.

Measurements of persistency in milk yield

Measurements	Author
PS1 = (EBV280 − EBV60)	Jamrozik et al. (1997)
${\text{PS}}_2=\left({\displaystyle \sum _{t=106}^{205}}EB{V}_t-{\displaystyle \sum _{t=6}^{105}}EB{V}_t\right)$	Jakobsen et al. (2002)
${\text{PS}}_3=\left({\displaystyle \sum _{t=206}^{305}}EB{V}_t-{\displaystyle \sum _{t=6}^{105}}EB{V}_t\right)$	Jakobsen et al. (2002)
${\text{PS}}_4=\left({\displaystyle \sum _{t=61}^{280}}(EB{V}_t-EB{V}_{60})\right)$	Jamrozik et al. (1997)
${\text{PS}}_5=\left({\displaystyle \sum _{t=60}^{279}}(EB{V}_t-EB{V}_{280})\right)$	Jakobsen et al. (2002)
PS6 = (EBV290 − EBV90)	Cobuci et al. (2004)
${\text{PS}}_7=\left(\frac{1}{51}{\displaystyle \sum _{t=255}^{305}}EB{V}_t-\frac{1}{21}{\displaystyle \sum _{t=50}^{70}}EB{V}_t\right)$	Kistemaker (2003)
${\text{PS}}_8=\left({\displaystyle \sum _{t=101}^{300}}EB{V}_t-200*EB{V}_{100}\right)$	Pösö (2003) cited by Kistemaker (2003)
${\text{PS}}_9=\left({\displaystyle \sum _{t=61}^{305}}EB{V}_t-245*EB{V}_{60}\right)$	De Roos et al. (2004)

EBV, estimated breeding value; PS_i, measures of persistency in milk yield.