Estimation of Genetic and Non Genetic Parameters for Pure Friesian Cattle in the Sudan

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Date
2015-06-23
Authors
Ihlam Ibrahim, Eid
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Publisher
UOFK
Abstract
Data of 281 purebred Friesian cattle imported from Netherlands and 74 homebred Friesian cows collected from Dairy Land Farm at Tiba El Hassanab was used in this research. The traits studied were age at first calving, calving interval, gestation period, number of services per conception, total milk yield, daily milk yield and lactation length. The average age at first calving for imported and homebred cows, respectively were 24.91±2.43 and 26.50±2.84 months, 274.21±5.57 and 273.3 ±4.03 days for gestation period, 3.92±2.77 and 2.3±1. 7 for number of services per conception, 468.90±116.32 and 445.4±92.81 days for calving interval, 5533.14±1546.03kg and 3784.2±l095.2kg for total milk yield, 15.10±318 and 11.00±2.42 kg for daily milk yield and I 376.74±15.89 and 349.0±86.19 for lactation length. The parity number had a significant (P<0.05) effect on number of services per conception. Also age at first calving had a significant (P<0.05) effect on milk yield per lactation and daily milk yield (P<0.01). Year of calving had a significant (P<0.05) effect on daily milk yield, number of services per conception and calving interval (P<0.001). Place of birth had a highly significant (P<0.001) effect on total and daily milk yield and a significant (P<0.01) effect on age at first calving. Repeatability estimates for all the studied traits ranged from low (0.09) to medium (0.42). Estimates for gestation period, number of services per conception, calving interval, total milk yield, daily milk yield and lactation length were 0.170±0.045, 0.090±0.044, 0.121±0.044, 0361±0.047, 0.420±0.061 and 0.094±0.044, respectively. On the other hand, heritability estimated by paternal half sib method ranged from 0.003±0.078 for lactation length and 0.1901±0.140 for age at first calving. Whereas, estimates calculated by daughter dam regression were 0.710±0.456, 0.320±0.168, 0.106±0.120, 0.100±0.150, 10.174±0.136 and 0.055±0.224 for age at first calving, gestation period, number of services per conception, total milk yield, daily milk yield and lactation length, respectively. Age at first calving was negatively correlated with the other traits except for number of services per conception and daily milk yield. Whereas, number of services per conception exhibited positive phenotypic correlation with all the traits studied. Total milk yield was positively correlated with daily milk yield and lactation length. Concerning genetic correlation, gestation period was positively correlated with daily milk yield and lactation length, whereas, genetic correlation among other traits was either inestimable or overestimated.
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Keywords
Estimation, Genetic,Genetic Parameters,Pure Friesian Cattle,Sudan
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