Future Climate Change and Its Influence on Milk Production of Holstein Cattle Maintained in the Nile Delta of Egypt

Abstract

The objectives of the present study were to develop a simplified equation to estimate temperature-humidity index (THI) under the Egyptian conditions and to assess the influence of expected climate change on test-day milk yield of Holstein cattle in the Nile Delta of Egypt in the years 2025 and 2050. Data of air temperature (AT) and relative humidity (RH) throughout the period from 2000 to 2014 and of their expected corresponding values in the two years 2025 and 2050 were provided by the Central Laboratory for Agricultural Climate (CLAC). Meteorological data between the years 2000 -2014 were used to detect if there was an ascending trend in THI of Nile Delta of Egypt throughout this period. Meteorological data of the years 2025 and 2050 were used to estimate the THI of these two years relative to the year 2000 as a benchmark. Using regression technique, a new accurate and simplified equation was developed to estimate THI. The equation accounted for 99.5% of the variance of THI. The developed equation was used to predict THI in the years 2025 and 2050. A total of 109759 test-day milk yield (TDMY) records for 5546 Holstein cows located in four herds was used to establish the effect of THI on TDMY of Holstein cattle in the Delta region.Meteorological data indicated a considerable increase in THI by 13.9 % (78.8) and 17.3% (81.2) for the years of 2025 and 2050, respectively, relative to the year 2000 (69.2). Analysis of TDMY indicated a significant decrease of 0.12 kg (1.2%) for each increase of one THI unit above 74 under the current managerial practices.The study concluded that proper and prompt breeding, feeding and system modifications should be considered to counteract the expected increase in THI by the years 2025 and 2050, to restore milk production of Holstein cattle in the Nile Delta of Egypt.