Bashar Adham Ahmad*(1) and Wasan Jassim Al-Khazraji(2)
(1). Department of Animal Production, College of Agriculture, Diyala University, Iraq.
(2). Department of Animal Production, College of Agricultural Engineering Sciences, University of Baghdad, Iraq.
(*Corresponding author: Bashar Adham Ahmad. E-Mail: basharadh83@gmail.com).
Received: 27/02/2020 Accepted: 29/03/2020
Abstract
The research was conducted at Taj Al-Nahrain Cows Station, located in Al-Qadisiya Governorate, Diwaniya District, which is 180 km from the center of Baghdad, for the period (19/3/2018 to 20/3/2019) and molecular genetic analyzes were conducted at the laboratory of the College of Agricultural Engineering Sciences, University of Baghdad. The samples were sent to the Korean Macrogen Corporation to read the sequence of nitrogenous bases for the HSP70 gene, and the relationship between the genetic variation caused by the two mutations was examined with the traits of milk (daily milk production, total milk production, peak production, persistence of production and length of milk season) and milk components (fat ratio, non-fat solids, density, protein ratio and lactose ratio) and the heat tolerance coefficient (summer heat tolerance coefficient, autumn heat tolerance coefficient, winter heat tolerance coefficient and general heat tolerance coefficient). The results showed the presence of the first mutation (G2572T) in three genotypes (GG=26 GT=14 TT=13) and allele frequency of (G 0.62 and T 0.38), while the second mutation (G2688C) appeared in two genotypes (GG=50 GC=3) and allele frequency of (G 0.97 and C 0.03), and the first mutation (G2572T) did not show significant effect on milk production traits, but significantly affected the fat ratio, where the individuals which were carrying the mutant genotype TT were superior. While the wild genotype GG significantly surpassed the two genotypes GT and TT in non-fatty solids, density, protein ratio and lactose ratio and the autumn and winter heat tolerance coefficient and general heat tolerance coefficient. The second mutation (G2688C) had no significant effect in the all traits.
Key words: Cow Holstein, Heat tolerance coefficient, Gene HSP70.
Full paper in Arabic: PDF