FACTORS AFFECTING GROWTH PERFORMANCES OF SIMMENTAL, ANGUS, CHAROLAIS AND HEREFORD BEEF CROSSBRED CALVES UNDER SUB-TROPICAL ENVIRONMENT OF PAKISTAN

The present study was conducted with the objective to find out the comparative growth performance of beef crossbred calves. The data of growth performance traits were collected on the calves born during the year 2006 through year 2011. The data were analyzed using computer software SPSS (19.0). The overall mean for birth weight, weaning weight, yearling weight and eighteenth month weight were 29.03 +/- 0.24, 142.50 +/- 2.38, 186.89 +/- 3.02, 245.87 +/- 4.15 kg, respectively. The pre-weaning growth rate and post-weaning growth rate were 0.483 +/- 0.01 and 0.294 +/- 0.02 g, respectively. Year of birth was a significant source of variation for birth weight, weaning weight, yearling weight, eighteenth month weight, pre-weaning growth rate and post weaning growth rate (P <= 0.05). The highest mean birth weight (31.82+0.56 kg) was recorded for the calves born during the year 2011 and the lowest mean birth weight 26.00 +/- 0.48 kg was recorded for the calves born during the year 2009. Season of birth was a significant source of variation for birth weight, yearling weight, 18- month weight and post-weaning growth rate (P <= 0.05). The calves born during winter season had the heaviest mean birth weight (29.72 +/- 0.43 kg). Calf sex significantly affected birth weight (P <= 0.01) and weaning weight (P <= 0.05). The male calves were heavier than female calves for all traits under study. The mean birth weight and weaning weight were (29.84 +/- 0.31) and (150.14 +/- 3.82 kg) for male calves; (28.09 +/- 0.35 and 138.57 +/- 2.94 kg) for female calves respectively. Animal genetic group (sire breed) was a significant source of variation for weaning weight, pre-weaning growth rate (P <= 0.01) and yearling weight (P <= 0.05). The highest mean for weaning weight (159.22 +/- 5.39 kg) was noticed for Simmental crossbred calves followed by Angus (147.77 +/- 4.37 kg), Hereford (136.80 +/- 4.34) and Charolais (135.78 +/- 4.54 kg) crossbred calves. The Simmental crosses were heavier at weaning weight, showed better pre-weaning growth rate and yearling weight as compared to Charolais and Hereford crosses. Further crossbreeding with Simmental and Angus beef breed sires is recommended in subtropical climatic conditions of Pakistan.