Milk yield and reproductive performance of Friesian cows under Sudan tropical conditions
Abstract. The data obtained from the dairy herd of the Arab Company for Agricultural Production and Processing (ACAPP) in a semi arid area 40 km south of Khartoum involved 337 cows with a total of 1049 records from 16 years between 1986 and 2002. The least squares means for age at first calving, calving interval, days open, lactation milk yield, daily milk yield, lactation length and dry period were 29.76±0.40 months, 433.12 ± 6.70 days, 167.79±7.08 days, 3475.53±78.89 kg, 12.29±0.28 kg, 294.10±3.62 days and 164.08 ± 6.70 days, respectively.
The analysis of variance showed that the parity number had significant (p<0.05) influences on all studied traits, while year-season of calving influenced (p<0.05) age at first calving, milk yield per lactation and daily milk yield. The sire of cow influenced (p<0.05) lactation yield, daily yield, lactation length and days open. The effects of linear and quadratic regressions of both lactation yield and daily yield on length of lactation were also highly significant (p<0.01).
Heritability estimates of age at first calving, calving interval, milk yield per lactation, daily milk yield, lactation length and dry period were generally low (0.098±0.104, 0.047±0.046, 0.130±0.042, 0.123±0.041, 0.172±0.062 and 0.044±0.031, respectively) except the heritability of days open which was 0.51±0.37.
The productivity of the herd in this study which averaged 12.3 kg/cow/day was much lower than the expected productivity of Holstein Friesian cows, which reflects the negative impact of the prevalent environment in the Sudan.
More records and economic data are required to examine the economic feasibility of raising pure Friesians under Sudan conditions.