GROWTH, BEHAVIOURAL AND REPRODUCTIVE RESPONSES OF PIGS TO WEANING AND INTERMITTENT SUCKLING REGIMES

Abstract

Early weaning of piglets is gaining attention worldwide. Although, this encourages quick rebreeding of the sow, it subjects piglets to weaning stress. However, intermittent suckling makes weaning less-stressful for piglets but the effect on behaviour and performance of piglets and the sow has not been well documented. Therefore, different weaning and intermittent suckling regimes were assessed on piglet growth, behaviour, stress response and reproductive performance of sows. Eighteen newly farrowed sows (Large white×Landrace), each with four piglets aged 1-3 days were randomly allotted to different weaning regimes: four weeks (T1), six weeks (T2) and eight weeks (T3) at 6 replicates/treatment, in a completely randomised design. In another study, sixteen newly farrowed sows, each with four piglets aged 1-3 days were randomly allotted to four treatments: S1 (Continuous suckling), S2 (4 hours separation/day), S3 (8 hours separation/day) and S4 (12 hours separation/day) at 4 replicates/treatment, during the last two weeks of the six weeks suckling period. The sow and piglets were evaluated at pre-weaning and post-weaning phases for weightchange (kg), Feed-intake (kg), Feed Conversion Ratio (FCR), stress (serum corticosterone level [ng/mL] assayed for two weeks using standard procedure), behaviour (feeding and aggression (%) which were monitored from 08:00-12:00 hours for 10 days using CCTV). The sows‟ reproductive indices (weaning-to-oestrus interval (days) and conception rate (%) were monitored. Data were analysed using descriptive statistics and ANOVA at α0.05. Weight-loss in sows in T2 (-6.25±0.33) and T1 (-5.00±1.41) were significantly lower than T3 (-10.00±1.58). The FCR of weaners in T2 (2.23±0.15) and T3 (2.22±0.10) were significantly lower than T1 (2.42±0.09). Corticosterone of weaners in T2 and T3 on day 4 (48.60±3.90 and 48.31±3.95) and day 7 (46.45±6.67and 46.96±2.36) were significantly lower than T1 (55.83±5.28 and 54.25±1.66), respectively. Feeding behaviour ranged from 41.7 (T1) to 70.3% (T3), while aggressive behaviour ranged from 0.5 (T3) to 9.2% (T1). Weaning-to-oestrus interval in sows at 7.00±1.22 (T2) and 6.00±0.71 (T1) were significantly lower than 10.00±1.58 (T3), while percentage conception ranged from 83.3 (T3) to 100.0% (T1). Piglets in S1 had significantly lower feed-intake and higher weight-gain (0.90±0.15 and 4.86±0.30) compared to S3 (2.20±0.33 and 4.17±0.15) and S4 (2.50±0.31 and 4.14±0.19), respectively. The FCR of weaners in S3 (2.83±0.16), S2 (2.87±0.22), and S4 (2.84±0.20) were significantly lower than S1 (2.99±0.26). Weight loss in sows significantly varied from -3.21±0.60 (S4) to -5.07±0.70 (S1). Corticosterone of piglets in S4 (59.43±0.66) was significantly higher than S3 (57.74±0.67), S2 (57.44±0.65) and S1 (43.86±0.76) on day 4, while corticosterone of weaners in S3 (47.02±1.47), S2 (50.16±1.53) and S4 (45.08±0.84) were significantly lower than S1 (54.66±2.08) on day 4. Feeding behaviour of weaners ranged from 8.2 (S1) to 51.5% (S4), while aggressive behaviour ranged from 0.0 (S4) to 11.8% (S1). Weaning-to-oestrus interval in sows in S3 (4.00±0.71) and S4 (4.00±0.00) were significantly lower than S1 (7.00±1.00) and S2 (6.00±0.71). Weaning at six weeks, with 8-hour daily separation in the last 14 days, improved piglets‟ post-weaning growth and sows‟ weaning-to-oestrus interval. It also reduced aggression and stress in weaned pigs.