English

Abstract

The purpose of this study was to analyze milk producing traits, correlation between milk production and parities of Chinese Jersey cattle, and to make accurate prediction. For this purpose, samples for this study were taken from a large-scale breeding farm of Chinese Jersey cattle and chemically and statistically analyzed. The results of ANOVA and LSD showed that milk yield, protein percentage, somatic cell, urea nitrogen and other lactating traits of Jersey cattle of different parities were significantly different. LSD results explored that milk fat percentage decreased gradually, as the parity increased from second to third parity, while there was no difference in milk fat percentage in third and fourth parity. Similarly, protein percentage in milk was highest in second parity and then it decreased in third parity and lowest protein percentage was observed in fourth parity. Results of coefficient of variation explored that milk yield, protein and somatic cells reached the maximum value at parity 2, and the coefficient of variation of milk fat percentage and urea nitrogen reached the maximum value at parity 4. There was a significant negative correlation between milk yield and milk fat percentage, protein percentage, somatic cell and urea nitrogen in all parities. There was a positive correlation between milk fat percentage and protein percentage, somatic cell and urea nitrogen. There was a positive correlation between the protein rate and somatic cells, which was significant only at the 1st and 4th parity. There was a significant positive correlation between urea nitrogen and somatic cells at parity 1, and a negative correlation at parity 2, 3 and 4. Results of realistic estimates of achievable prediction accuracy of lactating traits showed that the amplitude of realistic estimate of prediction of milk yield, milk fat percentage, protein percentage, somatic cell and urea nitrogen in four parities were -0.65%-23.41%, -3.23%-3.92%, -3.19%-2.94%, -44.43%-29.81% and -7.83% ~ 3.97%, respectively. Based on results it is concluded that a complex correlation between the lactating traits of Jersey cattle exist and parities can significantly affect milk yield, milk protein, somatic cells and urea nitrogen of Chinese Jersey cattle