Effect of age of calf on suckling behaviour and other behavioural activities of Zebu and crossbred calves during restricted suckling periods

The objective of this study was to investigate the effect of age of calf on the behaviour of Zebu and crossbred calves during restricted suckling (RS) periods. The behaviours of 20 Zebu and 16 crossbred calves were recorded d uring two j0-min sessions each day after milking when the calves and their dams were brought together in a group for suckling. This was made for a tim e period of 2 weeks/month for 6 months postpartum. The total suckling duration was significantly longer in Zebu calves (11.8 /- 0.19 min) compared to the crossbred calves (9.4 +/- 0.19 min), but decre ased significantly in both breeds with increasing age from I to 6 months. T he number of suckling bouts decreased from a mean of 3.8 at 1 month of age to 1.1 at 6 month (P < 0.05). The duration of each suckling bout decreased significantly from a mean of 3.5 +/- 0.15 min at 1 month of age to 1.6 +/- 0.01 min at 6 months (< 0.05). The frequency of crossbred calves cross-suck ling (3.7%) was significantly higher than that of the Zebu calves (1.9%; P < 0.05). The frequency of calves cross-suckling decreased significantly fro m 4.2% at 1 month of age to 2.3% at 6 months. The duration and number of bo uts of cross-suckling was significantly higher in the crossbred calves (dur ation 0.9 +/- 0.06 min; bouts 3, 7) than in the Zebu calves (duration 0.5 /- 0.06 min; bouts 2, 7) and decreased with increasing age of calf. The dur ation and number of bouts of inter-sucking was significantly higher in the crossbred calves (duration 0.6 i 0.07 min; bouts 1, 6) than in the Zebu cal ves (duration 0.1 +/- 0.04 min; bouts 0, 5) and decreased with increasing a ge of calf. Exploration increased in duration as the calves increased in ag e from 1 to 6 months (P < 0.05). The duration of play increased significant ly with the increase in age of calf from 1 to 6 months, and occurred mainly after nursing. (C) 2000 Elsevier Science B.V. All rights reserved.