UNIT 10

Swine Health Management

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  Part I. Swine Management Procedures to Minimize Disease

History of development of management techniques

A. SPF (Specific Pathogen Free)

• cesarean derived piglets, removed aseptically and reared in clean environment
• free of mycoplasma, atrophic rhinitis, mange, lice, dysentery, pseudorabies and brucella

B. MEW (Medicated Early Weaned)

• remove from dam at <16 days of age
• various antibiotics administered (heavily medicated)

C. AI/AO (All-In/All-Out)

• pigs moved as groups by age; buildings, rooms or sites are cleaned between batches
• decreased spread of disease from older pigs

D. Modified MEW

• piglets vaccinated and heavily medicated prior to weaning
• raised AI/AO after weaning

E. SEW (Segregated Early Weaning)

• weaned at <16 days of age, placed in clean isolated environment
• maintain biosecurity
• AI/AO rearing

Segregated Early Weaning Swine Management

A. Theory -- pig disease agents are acquired from 3 sources

1. sows during lactation
2. environment
3. other pigs

B. Requirements

1. early weaning

• passive colostral antibodies from dam are high
• colostral antibodies protect against infection
• exposure risk to agents is low (only from dam & littermates)

2. clean environment and strict biosecurity throughout rearing

3. stable sow herd immunity to viruses and bacteria on farm

• vaccination may help stabilize sow herd
• cross fostering may spread disease if done after 1st 24 hours (if a piglet is taken from a sow with low colostral immunity and transferred to one with high levels but shedding virus, her pigs will be passively immunized but the foster pig will not and will become infected with the agent)

4. minimize age variation of pigs in groups

5. rearing all-in-all-out without exception

C. Health problems in SEW pigs

1. Anorexia & dehydration
2. Streptococcus suis
3. Staphylococcus hyicus skin infections (greasy pig disease)
4. foot & leg lameness

The Concept of SEW and the rules to make it work.

Part II. Enteric Health Concerns of Swine

As with all phases of health management in swine, biosecurity is of utmost importance in controlling enteric (diarrheal) diseases. 

• sanitation of the environment -- cleaning and disinfecting between batches of pigs
  • assure proper ventilation and temperature within the environment at pig level; avoid large temperature fluctuations
• sanitary practices of workers -- shower before entering pig facilities; wear clarn coveralls and boots; use disinfectant boot baths
• control of traffic flow -- always move from the healthiest to the sickest groups of pigs; usually this is from the youngest to the oldest groups, but that is not always true!
• avoid moving and mixing pigs
• practice an all-in/all-out management system, ideally with a 2 day down time between moving one batch of pigs out of a facility, cleaning and disinfecting, and moving a new batch into the facility
•  

Link 1 -- Neonatal Diarrhea

Link 2 -- Growing/Finishing Diarrheal Diseases

Part III. Respiratory Health in Swine

Part IV. Reproductive Health Concerns of Swine

Background Information on Reproductive Diseases

A. Reproductive problems are most easily identified by examining records, hence it is important to keep good records!

B. Timing of reproductive failure

1. Management failure

• animal cycles normally, returns to estrus in 21 days

2. Disease problem

• animal cycles normally, returns to estrus in 21 days
• mummification of fetus
• pseudopregnancy
• abortion
• weak and stillborn pigs at normal gestation

C. Reproductive problems represent 5-10% of all health problems in pigs

1. 90% are caused by management mistakes, 10% by disease

2. those caused by disease are also usually due to poor management

• poor biosecurity
• poor vaccination

3. Diagnosis - 61% of cases submitted for diagnostic workup find no causative (etiologic) agent

Breeding Herd Reproductive Problems

A. Means with which disease is transmitted from animal to animal

1. direct contact

2. aerosol (can be airborne over considerable distance)

3. semen

4. fomites

5. rodents

B. Agent may reach uterus in 2 ways

1. through vulva, cervix

2. through bloodstream

C. Breeding herd problems are management problems, since most can be controlled by vaccines

D. Types of diseases causing reproductive problems in swine

1. Porcine Parvovirus (PPV) - present in literally all US herds

• gilts may have passive immunity until 6 mo. of age
• must vaccine twice before breeding
• clinical expression - mummies, varying size of fetuses within a litter, delayed return to service, increased preweaning mortality

2. Porcine Respiratory and Reproductive Virus (PRRS) - 80% US herds are currently positive

3. Leptospirosis - stillborns, abortions

4. Pseudorabies Virus (PRV); scheduled to be eradicated by 2000

• vaccines are very effective
• abortions

5. Swine Influenza Virus (SIV) - recognized as reproductive problem in past 2-3 years; sows become sick

Management of the Female Pig for Maximum Reproductive Potential

Since the majority of reproduction problems (90%) are not caused by an infectious agent, it is important to carefully control the host and environmental factors.   Management of the female breeding herd can be divided into 5 components:

• Management up to the first mating
  • Selection of replacement gilts can either be home-raised or purchased; the goal being to obtain good quality and heterosis in the genetics of the animals
  • Replacement gilts should be raised with their contemporaries until about 180 days of age, at which time they should be moved to an isolation/acclimation facility and begun on a pre-breeding vaccination schedule
  • At 180-200 days of age, gilts should be stimulated to puberty (1st estrus cycle); this is done most effectively through exposure to multiple mature boars, since pheromones produced by the boars will stimulate estrus.  Good nutrition, housing, appropriate temperature control and a day length (light cycle) of at least 16 hours is important.
  • The goal is to breed the majority of gilts on their second estrus (hopefully at < 225 days of age).  No gilts should be kept for breeding beyond 3 estrus cycles, since they will most likely continue to have breeding problems in subsequent matings.
• Mating
  • If there are no problems, one should expect a conception rate of approximately 70% on the first service. 
  • It is best to breed the females twice during the estrus period to assure optimal fertilization of ova, since one cannot predict precisely when the female will ovulate and the survival time of the ova and spermatazoa are short.
  • The normal estrus cycle in the pig is 21 days in length.  Pigs are not seasonally anestrous, however, if they become anorectic during lactation in the hot summer months, they will suffer from excess protein catabolism and will not cycle properly after weaning.
  • An increase in abortions that is often observed in the fall has been linked to drops in progesterone production in the sow with a decreasing day length.
• Gestation
  • Nutrition -- Sows and gilts should be fed to maintain a moderate body condition; this usually means feed restriction during the majority of the gestation, since sows fed ad libitum will over-eat.
  • Vaccination -- Sows and gilts should be vaccinated 2 and 5 weeks prior to expected farrowing for diseases that can effect the baby pig.  This will stimulate a good colostral immunity for the offspring.
  • Housing -- Sows and gilts maintained in farrowing stalls have the highest farrowing rates.
  • Reproductive checks -- All bred sows and gilts should be checked 21 days post-breeding to see if they have returned to estrus, followed by a pregnancy check at 30-40 days post-breeding. 
  • Physiology -- Each fetus requires approximately 20 cm. of space in utero; if there are too many implanted, it will result in smaller pigs at birth and/or mummified fetuses that did not have room to grow.
• Farrowing
  • Nutrition -- Sows need approximately 4 pounds of feed for themselves, as well as an additional 1 pound of feed/nursing piglet to maintain body condition.  Do not restrict water intake.  If sows are not eating adequate amounts, cool their environment, or increase the protein levels in their diet to make up for the decreased feed consumption.
  • Housing -- All-in/All-out systems should be used in farrowing facilities.  Lighting should be set at 16 hours of light/24hours. 
• Weaning-to-Estrus Interval
  • The normal interval is 5-7 days.  It is influenced by a number of factors, such as:   litter size, body condition of sow, parity of sow, season of year, and duration of lactation.
  • Unless managed to minimize protein catabolism during lactation, sows whose pigs have been early weaned will have decreased litter size in the next gestation.

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