Journal Of Tropical Biosciences
Volume No: 10|
Page No: 33
| FullText PDF
JOURNAL OF TROPICAL BIOSCIENCES 33 GENETIC AND ENVIRONMENTAL FACTORS AFFECTING GESTATION LENGTH AND CALVING INTERVAL IN FRIESIAN X BUNAJI COWS IN SAVANNAH ZONE OF NIGERIA
1-SHEHU, D. M.* AND 2-ADEYINKA, I. A.
1-DEPARTMENT OF BIOLOGICAL SCIENCES.&NBSP;AHMADU BELLO UNIVERSITY, ZARIA.
2-NATIONAL ANIMAL PRODUCTION RESEARCH INSTITUTE.&NBSP;AHMADU BELLO UNIVERSITY, SHIKA, ZARIA
Data on gestation length and calving interval for twenty five years (1984-2008) were obtained from dairy research unit of National Animal Production Research Institute (NAPRI) Ahmadu Bello University, Shika, Zaria. Effects of sex, season parity, year and sire on gestation length and calving interval in Friesian x Bunaji cows were evaluated. General linear model procedure of statistical analysis system (SAS) was used to analyze the data. Sex of calf, parity of dam, season of birth, year/period of birth and sire difference were considered as fixed effects for the evaluation of gestation length and calving interval in Friesian x Bunaji cows. The overall least square means for gestation length and calving interval were 281.21±0.24 days and 395.42±1.10 days. Sex of calf, parity of dam, season of birth and sire difference significantly (p<0.05) affect gestation length in the herd, while year/period of birth had no effect on gestation length. Sex of calf, had no significant (p>0.05) effect on calving interval. However, season of birth, parity of dam, period of calving and sire had significant (p<0.05) effect on calving interval. It can be concluded that these factors had exerted significant effects on gestation length and calving interval of Friesian x Bunaji cows in these herds. Therefore, before animals are compared these factors most be corrected or otherwise be adjusted and to improve the performance of these animals great effort should be geared towards eliminating negative impacts of season and sire selection.
Gestation length was found to be influenced significantly by sex of calf, season of birth, parity of dam and sire difference. Similarly, parity of dam, season and year or period of birth and sire significantly affected calving interval. However, year of birth and sex of calf had no significant effect. Therefore, before animals are compared these factors most be corrected or otherwise be adjusted and to improve the performance of these animals more attention should be given to factors such as management and feeding, which might be responsible for most of the phenotypic variations in the herds, in addition emphasis should be given to sire selection. These may considerably reduce calving interval and gestation length.
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