Vol. 8, Issue 9 (2019)

Author(s):
AJ Shankare Gowda, TG Honnappa, CS Nagaraju, M Devaraj and A Krishnaswamy

Abstract:
The gestation length is genetically determined trait, which can be modified by maternal, foetal and environmental factors. A study was conducted in an organized dairy farm where five years data from 1996 to 2000 was used up and subjected to statistical analysis. It was found that the over all least squares mean gestation was estimated as 269.58±1.34 days with Coefficient of Variation of 11.02 per cent. The least squares mean of gestation length for first, second, third, fourth, fifth, sixth and seventh parity cow was estimated to be 270.34±2.05, 267.58±2.47, 268.88±4.62, 274.52±2.12, 264.78±7.58, 272.78±5.56, and 284.00±3.00 days, respectively with a Coefficient of Variation of 11.23, 10.64, 13.66, 5.00, 13.85, 6.12 and 1.83 per cent, respectively. The first parity cows had relatively shorter gestation period than cows in later parity. However, the difference between parity was being nonsignificant. The least squares mean for gestation length were 269.31± 3.20, 270.82± 2.30, 270.66± 2.12 and 264.41± 4.06 days for winter, summer, south west monsoon and north east monsoon seasons, respectively. Animals calving in summer and south west monsoon had slightly longer gestation period than animals calving in other seasons. However, the variations in the mean gestation period between the four seasons of the year were found to be nonsignificant. Further, the mean gestation length did not vary significantly between the sexes of the calves born. The values being 277.57 ± 0.74 days with a Coefficient of Variation of 3.91 per cent and 276.64± 0.74 days with a CV of 4.04 per cent for dams carrying male and female calves, respectively. Out of 440 calves born, 212 were males and 288 were females. The male to female ratios was 48.18: 51.82. The chi squares analysis revealed nonsignificant variation in the sex ratio (P<0.05).