Economic Value of Pregnancy in Dairy Cattle¹

Lactation curves for first (1, thick lines) and third and greater (3+, thin lines) lactations with average persistency (lactation 1, ——; lactation 3+, ——), smaller persistency (lactation 1, – –; lactation 3+, - - -), and greater persistency (lactation 1, - - -, lactation 3+, – –).

Retention payoffs (RPO) for a nonpregnant cow (○) and a cow that became pregnant on d 61 after calving (■) by day after calving. Cows are in their first lactation with average lactation curves. Value of pregnancy is equal to the difference between the RPO of the pregnant and nonpregnant cow on the same days after calving because both RPO are greater than $0.

Value of a new pregnancy during first lactation by days after calving and relative milk yield (80%, ♢; 100%, ●; 120%, □) compared with an average lactation curve.

Value of a new pregnancy during second lactation by days after calving and relative milk yield (80%, ♢; 100%, ●; 120%, □) compared with an average lactation curve.

Value of a new pregnancy during first and second lactation by days after calving. Compared with the default inputs, persistency of lactation was greater (G, +0.025kg/d) or smaller (S,−0.025kg/d) and the probability of pregnancy was greater (g, 19.2%) or smaller (s, 12.8%). Lactation 1: Gg, ♢; Gs, ♦; Sg, ○; Ss ●. Lactation 2: Gg, □; Gs, ■; Sg, ▵; Ss, ▴).