Morphological features of half sib local Pabna calves
Linear increasing trend identified in all morphological features from birth to yearling stages for both body and head characteristics of Pabna calves in which heart girth (63.33±1.31 cm at birth and 91.83±2.18 cm at pre-weaning), wither height (84.17±0.60 cm at pre-weaning), carpal circumference (10.50±0.50 cm at birth), mouth circumference (21.33±0.33 cm at birth and 26.58 cm at pre-weaning) and head length (30.08±0.99 cm at pre-weaning) had significantly higher (
p<0.05) measurements in male calves compare to female (Table 1). These data suggested that the phenotypic features of male progeny over female at pre-weaning stages of yearling local Pabna cattle for heart girth, wither height, mouth circumference and head length could be used as selection parameters for this initial stage (data of non-significant features are not shown) but its continuation was not similar for the next measuring periods.
Similarly, the effect of calves’ birth weight deferred significantly (
p<0.05) for body length (77.25±1.54 cm at pre-weaning), heart girth (91.88±1.46 cm at pre-weaning), abdominal circumference (104.67±0.88 cm at post-weaning), wither height (83.88±1.17 cm at pre-weaning) and tail length (50.50±1.40 cm at pre-weaning) in the calves’ group having ³20 kg of birth weight compare to <20 kg (Table 2). These data indicated that birth weight of calves might had positive association with a number of morphological features at pre-weaning stage but its consequences were not continued for the following stages. Thus, birth weight might not be a useful tool for selecting future weight gain.
Correlation on growth traits of Pabna calves
Body weight of Pabna calves also showed linear fashion from birth (19.56±2.11 kg) to yearling stages (112.33±3.30 kg) including moderate correlation at first (53%) and twelfth (48%) month and weak at weaning (7%) stages (Fig 1). The study of
Das et al., (2003) and
Hoque et al., (1999) observed 16.58 and 17.9 kg birth weight, respectively, in local Pabna cattle at Baghabrighat Milk Vita areas which was comparatively lower than our findings. Another study by
Mostari et al., (2017) in local Pabna cattle known as BCB-1 cattle breed found 18.40, 50.10, 91.62, 139.40 and 194.70 kg in birth, 3
rd month, 6
th month, 9
th months and 12
th months, respectively, raised for beef production. However, the higher growth performance after weaning than our findings might be associated with special feeding regime of those local Pabna progeny. The sex and birth weight of calf had significant effects (
p<0.05) up to pre-weaning stage of calf (Table 3). These data suggested the growth rate patterns of local Pabna calves and also to provide special care through feeding management during adverse situation.
Seasonal effects on growth traits of calves
It was observed that calves birth in Winter (22.45±0.19) attained higher body weight (
p<0.001) compare to other seasons (Table 4) while similar observation observed at post weaning stage in Summer (64.85±1.84). The average daily gains (ADG) of calf showed highest (449.33±17.07 g) and lowest (261.35±12.96 g) values at first and twelfth month of birth, respectively (Table 5). In pre-weaning stage, the ADG observed highest in Winter season (471.11± 20.95 g) while at post-weaning stage in Summer (333.88±13.44 g) season (Table 6). The study of
Mostari et al., (2017) observed seasonal variation in calves’ birth and pre-weaning stage which agreed with our findings. It might be the reason of feeding regime through abundant green grass from Winter to Summer when skeletal muscle development (Shahjahan, 2015) occurred properly in early embryonic stage of fetus in the pregnant cows.