One hundred eighty pregnant sows with the same breed and weight were randomly selected and allocated to 3 treatments groups designed as follow: an antibiotic-treated control (control), AMPs 0.3% (A) and AMPs 0.5% (B), respectively. The sows were fed with a commercial feed. The ELISA antibody detection method was used to detect the levels of PRRS antibodies in the test group and the control group. The results showed that: the stable ratios of PRRS antibody levels (S/P values) in test A and B groups were 80% and 88.3% respectively, which were significantly higher than 68.33% in the control group (P≤0.05). The stillbirth and mummies per litter were significantly lower than those of the control group (P≤0.05), and the number of healthy piglets per litter was significantly higher than that of control group (P≤0.05).
Table 1. The effect of AMPs on PRRS antibody titer levels in pregnant sows
The effect of AMPs on PRRs antibody levels of in pregnant sows. The proportion of the S/P value of the PRRS antibody (0≤S/P≤2) in group A accounted for 80%, group B accounted for 88.3%, and control group accounted for 68.3%. It shows that AMPs had higher stability of the PRRS antibody level than the control group, and the difference was significant (P≤0.05). And the proportion of acute infections or secondary diseases is relatively reduced. The difference between groups A and B was not significant (P>0.05).
Table 2. Reproductive performance of pregnant sows
The reproduction of pregnant sows was demonstrated as Table 2. The results showed that the total stillbirth rates of AMPs treatments decreased with increasing AMPs concentration. Both A and B groups had lower stillbirth rate (0.30 and 0.35 head, respectively) and significantly (P≤0.05) lower that of control group (0.52 head). Besides, pregnant sows fed with AMPs presented significantly lower mummy rate (0.27 and 0.17 head, respectively) than control group (0.37 head). Among the different AMPs concentration, AMPs at 0.5% exhibited lowest mortality rate (4.87%) and significantly (P≤0.05) lower than that of AMPs 0.3% (5.46%) and control (8.67%). Moreover, AMPs 0.5% exhibited higher total piglets, average piglet and healthy piglets than that of control. AMPs 0.5% possessed 636 head total piglets, 10.60 head of average piglets per litter and 10.08 head of healthy piglets per litter and even higher than AMPs 0.3% (623, 10.38 and 9.82 head, respectively) in this experiment.
Summary: In this experiment, the effect of AMPs on immune status and reproductive status of pregnant sows to PRRs vaccine. Results revealed that pregnant sows fed with AMPs exhibited significantly higher S/P values (1.42 and 1.51, respectively) than control group (1.42); while 0≤S/P≤2 (%) is higher than control (>80%). The S/P>2 (%) was lower with 20.0 and 11.7, respectively which was lower than control (31.7%). The mortality rate of piglets in AMPs was 5.46% lower than control (8.67%). Regarding reproductive as compared with control resulted in high total piglets, average piglets per litter and healthy piglets per litter. Moreover, sows fed with AMPs had lower stillbirth and mummy rate than control. In summary, AMPs could increase the titer of PRRs antibodies and reduce the outbreak in pig farm. AMPs also improved the reproduction performance of pregnant sows, reduced the number of stillbirth and mummies and increases the number of healthy piglets in litter. It is concluded that using AMPs as an alternative for antibiotics in pregnant sows may be considered.