Time series analysis of first lactation traits in Phule Triveni cattle

The data pertaining to first lactation records of 356 Phule Triveni crossbred was collected from history and pedigree sheets maintained at RCDP on cattle, MPKV, Rahuri, Dist: Ahmednagar (M.S.) spread over period of 25 years (1981–2005) and were subjected to least squares analysis and time series analysis. The overall least squares means for AFC, FCI, FL300DMY and FLTMY estimated by least square analysis were 1041.63 ± 1045 days, 450.27 ± 6.40 days, 2519.35 ± 36.73 kg and 2749.20 ± 46.81 kg, respectively. The least squares analysis of variance revealed that month had non-significant influence on all the traits under study, while periods of birth and calving had highly significant effect (P < 0.01) on all the traits. In time series analysis, the exact periods for various first lactation traits were formulated. The exact periods for AFC, FCI, FL300DMY and FLTMY were 4, 6, 5 and 7 years, respectively. The overall least squares means for AFC, FCI, FL300DMY and FLTMY estimated by time series analysis were 1051.05 10.46 days, 447.75 ± 6.78 days, 2519 ± 36.73 kg and 2661.06 ± 44.84 kg, respectively. The models for different traits using these periods were compared with R² values fitting the models from least squares having an arbitrary period of 5 years duration. The indices obtained from ratio-to-trend method were comparatively consistent and hence were used for further analysis. The time series analysis indicated periodicity of data over the years. The fitted periodic functions for different traits with higher R² values revealed cyclicity of data over the period. The higher R² values in case of time series analysis indicated that more precise results could be obtained by time series analysis.