Young Stock | DairyNZ

Target weights for your young stock should be relative to the weight that they will grow to as mature cows: 30% of mature liveweight at six months of age, and 40% at nine months; 60% of mature liveweight at 15 months (mating); 90% of mature liveweight at 22 months.

Benefits of achieving liveweight targets

Production

At a $4 payout, each additional kg of LW at 22 months between 80-90% of mature liveweight will return around $1 in the first lactation.

Reproduction

Achieving the 15 month liveweight target will help minimise the incidence of non-cycling heifers at mating.

To estimate mature liveweight for a line of heifers either:

Use the average liveweight breeding value (BV) of the line of heifers using the following equation:

Liveweight at maturity (kg) = 500 kg + (Average BV Liveweight for the line of heifers)

Weigh the 6-8 year old cows in the herd in December

Liveweight measurements taken in early lactation can underestimate mature liveweight as cows are generally at their thinnest. Liveweight measurements taken in the dry period will overestimate mature liveweight as a proportion of the weight consists of the foetus and foetal components.

The average mature liveweight of Jerseys was 407 kg, and 528 kg for Friesians in the 2004/5 LIC Sire Proving Herds.