Modern trends for modulating dry period length for holstein dairy cows based upon their parity and herd productivity

الملخص EN

The primary objectives of this research were to determine the dry period lengths, parity number and their interactions that maximize Holstein dairy productive and reproductive parameters.

For this propose 2158 dairy cow records were collected from four dairy Holstein farms.

Farms were classified into three main groups according to their milk yield performance.

Dairy farms were allocated in high (HPF), medium (MPF), and low producing farms (LPF) for milk production of 8000-10000 ; 6000-8000 and 4000-6000 kg milk per 305 day milk season, respectively.

In each farms type, dairy cows were arranged according to their day's dry length into 4 groups.

Dry period groups were short, medium, long, and very long for dry period length of < 30 ; 30-45 ; 45-60, and > 60 days, respectively.

Moreover, the dairy cows were regrouped according to their lactation parity into 3 groups, as dairy cattle were allocated into 1st ; 2nd, and 3rd groups for lactation parity of 2-3 ; 4-5, and >5 lactation parity, respectively. Obtained results revealed that: modulation of the dry period length for the high and medium producing dairy Holstein herds to be 30-45 days was recommended in order to attain high milk as well as reproduction performance.

Young cows of 2-3 lactation parity recorded high milk yield and reproductive performance especially when they dried only for 30-45 days.

However, old dairy Holstein cows of high parity number over 5 needs more than 45 days for sustaining high milk yield performance in their succeeding milking phase.

Also, long dry period phase 45-60 days might promote the high dairy performance in low producing farms.