Effect of daily weight gain on age at first calving and subsequent milk yield of Holstein heifers in Egypt

Abstract EN

A total number of 1152 complete lactation records for 576 Holstein cows were collected from two commercial farms (Copenhagen and Sami Asaad farm) during the period from year 2007 to 2010 to determine the effect of average daily weight gain (ADG) from birth to conception of Holstein heifers on their age at first calving (AFC) and subsequent milk yield.

Heifers were divided into four groups (G, s) based on their ADG as 650 g / day, 775 g / day, 875 g/day and 950 g/day for G1, G2, G3 and G4, respectively.

Heifers of G4 reached the AFC 5.

3 month earlier (P < 0.

001) than those of G1.

ADG had positive effect on productive traits of the first two lactations.

Cows of G4 had a similar 305 days milk yield in the first lactation compared to G1 but, scored non-significant higher milk yield in the second one by 535 kg.

G4 had non-significant increase in milk yield / day of cow age till the end of the first lactation (MY1 / DCA) compared with G1.

Milk yield / day of cow age of G4 till the end of the second lactation (MY2 / DCA) increased (P < 0.

01) by 12.

7 % compared to G1.

Days open of G4 in the first lactation (DO1) was shorter (P < 0.

05) than that of G1 by 44 days.

This trend extended to the second lactation, however, it was insignificant.

The present results showed that productive and reproductive performance of the faster growing Holstein heifers is better than that of slower ones.

The ADG of Holstein heifers during the period from birth to conception affected significantly AFC, DO1 and MY2/DCA.

G4 calved for the first time 5.

3 months earlier, produced 535 kg more milk and had shorter days open by 67 days till the end of second lactation compared with G1.