How can gilts be vaccinated properly and thoroughly?

1. Development and importance of good immunity in gilts

After a pig receives its first vaccine injection, corresponding antibodies will be produced after a certain period of time. At this point, the antibody titer is low and the duration of maintenance is short, and it does not yet have the ability to resist pathogen invasion, but it lays the foundation for establishing effective immunity later, so this immunization is called basic immunization. If the same vaccine is administered again within a certain period afterward, it can induce a recall response of memory cells produced after the first vaccination, which can rapidly produce antibodies with high titer and relatively long duration in a short time. Only then can it achieve the ability to resist the corresponding pathogen, and this immunization is called booster immunization. However, after a period of time, the antibody titer will gradually decline until it disappears, so a second, third, and multiple regular booster immunizations are needed. Each time, memory cells can be stimulated to make antibodies rise rapidly, keeping the antibody titer at an appropriate level. The success of booster immunization is built on the basis of basic immunization, so without basic immunization, there can be no booster immunization.

The vaccination of gilts has a special position of linking the past and the future. Pig farms need to supplement gilts by as much as 40% each year. For first-parity sows entering the reproductive period, the proportion of mummified fetuses and stillbirths in the first litter is the largest, and the acute death and disease incidence of the piglets produced are the highest. These are all closely related to the immune status of gilts. Therefore, the immunity of gilts is the most important among the immunity of the pig herd.

2. Major diseases against which gilts should be immunized and the schedule

The vaccination of gilts should, on the basis of nursery pig immunization, focus on the prevention of virulent infectious diseases and reproductive disorder diseases.

2.1. Classical swine fever: on the basis of one immunization each at 25-35 days of age and 60-70 days of age during the nursery period, vaccinate once each at 4 months of age and 25 days before mating with classical swine fever vaccine. Use 5 doses of classical swine fever cell vaccine each time, or 1-2 doses of classical swine fever tissue vaccine. Do not use the "classical swine fever, swine erysipelas, swine pasteurellosis" triple vaccine, so as to avoid the disastrous result of classical swine fever immunization failure.

2.2. Swine foot-and-mouth disease: on the basis of immunization already carried out at 40-45 days of age in piglets, vaccinate once each at 100 days of age and 25 days before mating. A bivalent inactivated concentrated vaccine against foot-and-mouth disease type O and Asia I should be used, according to the instructions.

2.3. Porcine pseudorabies: on the basis of one vaccination at weaning, vaccinate once each at 70 days of age and 20 days before mating, and use an inactivated vaccine. Gene-deleted live vaccines may be used only on positive farms.

2.4. Porcine parvovirus disease: vaccinate once each with an inactivated vaccine at 50 days and 30 days before mating.

2.5. Porcine Japanese encephalitis: in April, gilts should be vaccinated once 30 days before mating, and either attenuated vaccine or inactivated vaccine may be used.

2.6. Porcine reproductive and respiratory syndrome: use an inactivated vaccine for one vaccination at 5 months of age, and another vaccination 14 days later. Live vaccines must not be used, because there is a risk of introducing new strains.

2.7. Swine streptococcosis: in areas where the disease commonly occurs or in summer and autumn, vaccinate pigs weighing more than 20 kg, and vaccinate once again two weeks later. Serotype group C or type II vaccines should be selected according to the local epidemic situation, and bivalent vaccines may also be used. In general areas, vaccination may be omitted.

2.8. Swine enzootic pneumonia: use an inactivated vaccine for intramuscular injection at 5-7 days of age, give a booster vaccination once again 2 weeks later, and vaccinate once more 1-2 months before mating.

2.9. Porcine transmissible gastroenteritis and epidemic diarrhea: in areas with severe outbreaks, in order to provide newborn piglets with high-titer maternal antibodies and effectively protect the piglets produced, gilts may be fed "infectious material" at 5-7 months of age, such as minced diseased pig small intestine, intestinal contents, and feces, once for 1-2 days each time, once every two weeks, for a total of 2-3 times. The protective antibodies obtained from "infectious material" are highly targeted, have high titers, and last a long time, providing very good immune protection. When using "infectious material", it should be limited to a certain range, and disinfection should be done afterward to prevent the spread of infection.

3. Precautions

3.1. Gilts include replacement boars and replacement sows. Never omit the boars.

3.2. There are many types and brands of vaccines for preventing the same disease. Before use, the respective instructions should be read in detail, and if there are any doubts, technical consultation must be sought.

3.3. The recommended immunization times may be moved forward or delayed within a range of 7 days. On the same day, two inactivated vaccines or one inactivated vaccine and another attenuated vaccine may be administered, but vaccination with two attenuated vaccines on the same day should be avoided.

3.4. Within 7 days before and after vaccination with bacterial attenuated vaccines such as those for swine streptococcosis and enzootic pneumonia, the use of sensitive antibacterial drugs should be avoided.

3.5. The immune status of nursery pigs should be clearly investigated so that the immunization schedule for gilts can be appropriately adjusted.

3.6. For purchased gilts, their true vaccination types and times should be understood as much as possible so that necessary vaccinations can be supplemented. Also, several healthy old sows from the farm should be placed in the nursery house and exercise yard to be raised together for a period of time, so that the purchased pigs become infected with and adapt to the farm's microbial flora and develop corresponding immunity.

3.7. There are many factors that cause insufficient immune antibody titers, and they are not easy to detect, so at 6-7 months of age, testing of immune antibody levels for major diseases should be carried out, and remedial measures should be taken promptly for those found to have insufficient antibody titers.