University of Khartoum

Factors Affecting Reproductive and Productive Performance of Crossbred Dairy Cattle in the Sudan

Factors Affecting Reproductive and Productive Performance of Crossbred Dairy Cattle in the Sudan

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Title: Factors Affecting Reproductive and Productive Performance of Crossbred Dairy Cattle in the Sudan
Author: Abd EL Aziz Ahmed Fadl EL Moula, Salim
Abstract: This study was conducted to investigate the factors that influence the reproductive, productive traits and the components of the lactation curve of crossbred dairy cows at the University of Khartoum Farm. The study covered the period from 1973-1992; data from 94 grade dairy cows of known pedigree were collected and subjected to statistical analysis using the computer program (SAS, 1987). Gamma function method1 (Wood, 1967) was employed to describe the lactation curve. The results revealed that lactation number exerted a significant effect on calving interval (P<0.0l), service period (P<0.0l) and NSPC (P<0.0l). The productive traits that showed variability among parities included milk yield per lactation (P<0.0l), mean daily milk yield (P<0.0l) and dry period (P<0.0l). On the other hand, the initial yield (a- parameter), decreasing slope (c-parameter), peak yield and degree of persistency of yield were significantly (P<0.0l) affected by the order of lactations. Percentage total foreign blood and sire breed introduced variation on the productive traits namely, milk yield per lactation (P<0.0l), mean daily milk yield (P<0.0l), lactation length (P<0.05) and dry period (P<0.0l). The components of lactation curve that were affected by percentage total foreign blood and sire breed were a-parameter (P<0.05), c-parameter (P<0.0l), persistency of yield (p<0.0l), peak yield (p<0.0l) and week of peak (p<0.0l). Season, period of calving and their interaction had a significant effect on age at first calving (p<0.0l), calving interval (p<0.0l), service period (P<0.0l) and NSPC (P<0.0l). Among the productive traits studied, mean daily milk yield was found to be affected by period of calving (P<0.0l). However, both factors introduced variation in lactation length (P<0.0l). Meanwhile, week to attain peak yield was affected by season of calving (P<0.05). Degree of persistency, a- and c-parameters and maximum yield were affected by period of calving (P<0.0l), while week of peak yield effected variation among periods of calving (P<0.05). The study also investigated the relationship among the components of lactation curves.
URI: http://khartoumspace.uofk.edu/handle/123456789/14108
Date: 2015-06-22


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