Data of 7825 Mehsana Buffaloes spread over a period of 25 years (1989-2013) were collected and analysed to examine the effect of non-genetic factors on age at first calving trait. The data were classified and coded according to different seasons; least calving season (January to June) and most calving season (July to December). The period was classified according to the year of birth as, 1994-1997 (I), 1998-2001 (II), 2002-2005 (III), 2006-2009 (IV) and 2006-2009 (V). The totals of 74 villages were grouped into following three clusters named cluster I, II and III. The data were subjected to Least-Squares Technique (Harvey, 1987) for the effects of seasons, period and clusters on AFC. Duncan’s Multiple Range Test (DMRT) was used to test the significance of differences between treatments’ means. The Overall least square means of age at first calving (AFC) was 1377.21 ± 4.50 days. Effects of season of birth, period of birth as well as clusters were highly significantly effects on age at first calving (AFC). Therefore, it is required the adjusted data first for estimates of genetic parameters in Mehsana buffaloes.
