Changes in the suckling behaviour of beef calves at 1 month and 4 months of age and effect on cow production variables

The experiment used tri-axial accelerometers to record changes in suckling behaviour in beef calves with advancing age and also investigated the correlations between suckling behaviour, production variables and postpartum anestrous period (PPAP) of cows. Data were collected from 20 Bos taurus calves reared under pastoral conditions of northern Australia over two periods: when calves were on average1 and 4 months old. Calves suckled less frequently per 24 h at 4 months (8.2 ± 0.66 times) than at 1 month of age (9.8 ± 0.46 times, P < 0.05); however, calves had significantly longer suckling durations per bout at 4 months (9.3 ± 0.35 min) than 1 month of age (8.3 ± 0.31 min, P < 0.05). The suckling behaviour of calves had no effect on their average daily weight gain (ADWG) (P> 0.05). However, the ADWG of cows were negatively associated with suckling duration per bout (rho=-0.54, P < 0.05). Cow's PPAP was shorter when they had greater body condition score (BCS) (at 4 months of calf's age rho=-0.49, P < 0.05), greater loin eye muscle area (LEMA) (at 1 month of calf's age rho=-0.58, P < 0.05; at 4 months of calf's age rho = 0.57, P < 0.05) and greater fat depth over rib (at 1month of calf's age rho=-0.45, P < 0.05). Dams with greater fat depth over their ribs at 1 month of their calves’ age nursed their calves less frequently when they were 4 months old (rho=-0.52, P < 0.05). It is concluded that calf suckling behaviour changes with age, specifically bout length increases and suckling frequency decreases. Additionally, the calves of dams in greater body condition suckle less frequently, suggesting the dams may have greater overall reproduction efficiency.