Characteristics and Factors Affecting Lactation Curves in Dairy Cows in the Gezira ( Sudan)

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Ali, T.I.
Abdelraheem, M.A.
Elimam, M.E.
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Faculty of Agriculture, University of Khartoum, Shambat, Sudan
The Wood gamma function was used to describe the first three lactations in 180 Kenana and Butana breeds and their 50% crosses with exotic dairy breeds, mainly Friesians, in Elneshasheba dairy farm in Wad Medani (Sudan), from 1971 to 1989 .The percentage of atypical curves was 33, and was higher in local breeds, especially Kenana (43.9), and in the first two lactations. Breed, parity, age at first calving, sire and season x year interaction significantly (P< 0.05) affected most lactation curve traits. Crossbred cows exceeded local breeds in most traits, and milk yield increased with age. The first two lactations were more persistent, and peak lactation was observed in 6.44-12.43 weeks after calving. The correlations between different traits are described, and heritabilities were 0.12,0.09,0.32, 0.23,0.043 and 0.18 for initial yield, increasing slopes, decreasing slopes, total yield, average yield and persistency, respectively.
Page(s): 8 (2), 133-143,18 Ref