Relationships of some reproductive trails with milk production in Friesian cows

ABSTRACT

A total of 2528 lactation records of Friesian cows from two stations of Dallah Agricultural Investment and Animal Production Company were used to investigate the sources of variation of some reproductive traits and their relationship with milk production. The results obtained revealed that the maximum 305-day and total milk yield [5108.64 and 5497.96 kg, consequently] were obtained when the age at first calving was 36 months, while the minimum 305-day and total milk yield [4253.16 and 4760.64 kg, consequently] were obtained when age at first calving was less than 24 months. A highly significant effect of days open was found on both 305-day and total milk yield. In general, 305-day milk yield increased with increasing days open until maximum production of 4975.80 kg when the days open were 60 days. Moreover, an open period up to 90 days resulted in a higher rate of increase in milk yield compared with longer periods. Moreover, as the number of services per conception increased, the 305-day and total milk yield also increased. The preceding dry period had a highly significant effect on the following 305-day and total milk yield. Preceding dry periods of approximately 60 days were associated with the highest average milk production in the following lactation both for 305-day [5028.63 kg] and total milk yield [5246.11 kg]. In addition, the 305-day milk yield was also increased to reach its maximum [4902.00 kg] at a calving interval 11 up to 13 months. Calving intervals of less than 11 months resulted in minimum 305-day and total milk yield [4399.18 and 4411.17 kg, consequently]