Relationships of some reproductive trails with milk production in Friesian cows

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]

comparative study of imported pregnancy friesian cattle and their locally born home-bred daughters under Egyptian conditions

A total of 2130 lactation records of Friesian cattle from one station of Dallah Agricultural Investment and Animal Production Company were used to compare the imported pregnant cattle with their locally born home-bred daughters under Egyptian environmental condition. The imported cattle were pregnant heifers when they arrived in Egypt. Age at calving and calving intervals of the locally born home-bred cows were significantly lower [P< 0.01] than in the imported animals in the 2nd and 3 rd lactations and in the 1st and 2nd lactations, respectively. The overall mean of calving interval was 12.80 and 13.14 months for the locally born home-bred cows and the imported animals, respectively. Lactation length, dry period and days open of the locally born home-bread cows were significantly lower [P< 0.01] than for the imported animals in the three lactations. The overall means of lactation length, dry period and days open were 294.14, 90.58 and 111.03 days for the locally born home-bred and 305.18, 100.58 and 128.80 days for the imported cows, respectively. The number of services per conception of the imported animals was significantly lower [P< 0.01] than in the locally born home-bred only in the first lactation but it was significantly lower in the locally born home-bred only in the first lactation but it was significantly lower in the locally born home-bred cows in the 2nd and 3 rd lactations compared with the imported animals. Sex ratio was significantly higher [P< 0.05] in favor of males in the imported animals [53.40%] and in favor of females in the locally born home-bred cows [54.40%]. 305-day and total milk yield of the locally born home-bred cows [4338.17 and 4658.20 Kg, respectively] were significantly higher [P< 0.01] than in the imported animals [3697.88 and 4146.80 kg, respectively] in the first lactations. The reverse trend was obtained, where the imported animals were significant higher [P< 0.01] than in the locally born home-bred cows in the 2nd and 3 rd lactations [5253.23 and 5544.34 Kg. versus 4826.22 and 5015.81 Kg, respectively]