Investigation of Phenotypic Characteristics and Production potential of native Cows in Gillan.

This investigation were started in 1992 by registering records on different traits in animal research station of Guilan and were continued till 1378. In order to perform this design, from 11 towns of the province in 6 areas based on variation percent and share of each area per 10 non pregnant heifers, one bull, 200 heifers totally 20 bulls were bought and transferred to animal research station of Guilan which after taking a quarantine period, were randomly mated. At the time of cows parturition, performance of registering and recording traits were performed from birth of progeny up to the ending of the design for 5 years. In this experiment, production traits included milk yield, milk fat percent, milk fat yield (kg) and lactation period (days) at the first lactation got from morning and evening the production of studied daughters and heifers considered. Data from male and female calve produced from mating between studied heifers and bulls were used for study on the traits of body weight at the different ages and daily gain. Analyzing body weight traits was performed by analysis of variance method using SAS software package in GLM procedure. Before performing the program, all the traits were corrected according their age effect. REML method using DF-REML algorithm was used for estimating genetic and phenotypic parameters of milk traits and its components. Mean milk yield per lactation period was 223.54±353.728 kg. Milk fat yield and milk fat percent were 16.42±17.55 kg and 5.01±0.51 percent, respectively. Mean lactation period was 131.43±97.99 days. Based on obtained results, heritabilities of milk yield, milk fat percent, milk fat yield and lactation period were 0.24, 0.1, 0.37 and 0.19, respectively and genetic correlations between milk yield and milk fat percent, milk yield and milk fat yield and milk yield and lactation period were -0.29, 0.9 and 0.9, respectively. Phenotypic correlations between them were estimated -0.14, 0.9 and 0.4, respectively. There were no significant differences between the six areas for birth weight (p0.01). Mean birth weights of male and female calve were 16.69±0.74 and 15.1±0.72 kg, respectively. Mean body weights of male and female calve were 16.69±0.74 and 15.1±0.72 kg, respectively at the age of 12 months and were 261.29±7.65 and 196.81±7.3 kg, respectively at the age of 18 months. Mean daily gains in male and female were 0.536±0.030 and 0.328±0.029 kg, respectively at the ages of 12 to 18 months.