Seasonal Reproduction Shift among Three Murine Rodents in a Mediterranean Area of North-Western Africa

Abstract

The present study was conducted in order to analyze lactation performance of Friesian cattle in the local environment of Quetta, Pakistan and to evaluate non-genetic factors affecting the lactation traits. For this purpose, data on lactation performance of Holstein Friesian cows were collected from government livestock farms located at Quetta. Data obtained on calving from 608 cows during last sixteen years (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016) were analyzed. After editing the data for consistency and errors it was subjected to statistical analysis using fixed effect models. Independent variables were year of birth, season of birth, year of calving, season of calving and parity. Age of animal (linear and quadratic effects) and lactation period were fitted as co-variables. Dependent variables were lactation performance traits (lactation milk yield, dry period, etc.). The results of all traits showed that the year of calving had a highly significant (p<0.01) effect on lactation length, month of calving and parity. Lactation milk yield was significantly affected by year of calving (p<0.01) and month of calving (p<0.05) while parity had a non-significant (p˃0.05) effect. Milk yield over 305 days was significantly (p<0.05) affected by year and month of calving, while parity had a non-significant (p˃0.05) effect. Similarly, year of calving and month of calving had a highly significant (p<0.01) effect on dry period which is non-significantly (p˃0.05) affected by parity.