Effect of climate change on test-day milk yield of Holstein cows maintained in the Nile Delta of Egypt

الملخص EN

To evaluate the effect of climate change on milk yield of Holstein cattle maintained in the Delta region of Egypt, meteorological data covering the period 2000-2014 were obtained from the Central Laboratory for Agricultural Climate.

Data of test-day milk yield (TDMY) comprised 109759 records, were collected from four herds (5546 Holstein cows) covering the same period of meteorological data.

The four herds represented different parts of the Delta region: west of the Delta (Dina farm, El- Behera governorate, H1 and H2), middle (El- Sharkia governorate, Sami Asaad farm, H3) and east of Delta (El- Karada farm, Kafr El-Sheikh governorate, H4).

Daily management practices were almost comparable in the four studied herds, except for the housing systems.

Preliminary analysis of meteorological data during the period (2012-2014) revealed that the air temperature increased (P<0.05) by19.8%, during June–September, and by 3.1% for all the year round, relative to the period (2000 to 2011).

Temperature humidity index (THI) showed a similar trend to air temperature, increased (P<0.05) by10.5%, during June–September, and by 2.3% for all the year round, during the same year periods.

THI values were more than the minimum threshold of heat stress (≤74), throughout the June–September, while less than this threshold during the rest of the calendar year.

TDMY decreased (P<0.05) when THI was >74.

TDMY, also decreased (P<0.05) by 6.1% in the period from 2012-2014 compared to 2000-2011.

It could be concluded that a marked change in the climate of the Delta region of Egypt expressed in the rise of THI values.

This rise started the year 2011 up to 2014.

This change negatively affects milk production as measured by TDMY.