Frequently Asked Questions


1. For low dose IA, what’s the difference in number of pigs born between 1.5 billion and 3 billion IA twice? For 1.5 billion sperms IA, should make it 40 ml or 80 ml? Any difference?(For Knox)

Answer: The use of intrauterine AI with reduced numbers of sperm and volume allows similar or even improved fertility in some cases. Farrowing rates and litter sizes in some studies show no effects from 1.5 to 3 billion sperm while other studies show no differences between 2.0 billion and 3 billion, but some reductions in fertility at numbers below 2 billion. In general, the intrauterine AI (IUI) technology allows faster insemination, does not require boar exposure, and can allow 1.5 to 2 billion sperm to be inseminated in 40 to 60 mL volumes without any change in fertility compared to conventional AI  when using 2 inseminations performed during estrus in weaned sows. For farms beginning to use IUI, perhaps transition to the technology could include 2 billion sperm and if fertility data meet expectations, the number of sperm could be reduced even further to 1.5 billion. Other approaches would be to use the technology on a limited number of high fertility (parity 2 to 4) sows in good body condition with estrus expression on days 4 to 5 after weaning. Volume of inseminate helps to transport sperm and there is no effect of volume as long as 40 mL or more is used. There is no advantage to greater volumes with IUI.

2. What’s the correlation between backfat and reproductive performance?(For Knox)

Answer: Most of the information shows that animals that have lost a considerable amount of backfat, weight or body condition before breeding, (and includes lactation) are at increased risk for reproductive failure. The backfat level varies among breeds of pigs, age and parity of animals, and global location and type of housing. So an absolute measure for backfat might be a target for one breed of animal in a particular housing type, but would not be the target for another.  In gilts, classification varies considerably by genetics, location and breed. In one study, an average of 20 mm was associated with puberty at 137 kg, while while in another study, average BF thickness for 2 maternal breeds at 170 days of age was 11 mm. At time of breeding, gilts have been classified as thin (12 mm), and fat (19 mm).  For weaned sows, < 10 mm is very thin, moderate is considered 15-22 mm, and very fat > 30 mm. Again, depending upon genetics, global climate, length of lactation, and parity, weaned sows most often average between 15 and 23 mm.  In general for gilts, low levels of backfat could be associated with delayed puberty, and perhaps reduced litter size, while in weaned sows, low backfat could be associated with delayed wean to estrus and perhaps smaller litter size.


3. During lactation, more fat and other nutrients should be added to the feed. What are other nutrients, amino acid or protein? What should be the appropriate ratio of these nutrients? (For Tyler)

Answer: Attached are 2 factsheets that address the lactation question.  First, if you’re adding fat, then you need to increase all the amino acid levels to keep them in the proper AA/metabolizable energy ratio (see table 1 on the lactation pdf).  Never think of protein for pigs.  We focus on getting the right amino acids there in the right ratios.  Secondly, make sure they are also adding folic acid, choline, and biotin in their sow diets (table 6 in the VTM pdf).  Make sure they are also getting enough g/day of Ca and P.  It is dependent on daily feed intake.  There are all other kinds of additives to stimulate feed intake and most don’t work.  Best thing is to keep the sow cool and make sure she has access to good, clean water. Nipple placement and flow rate are huge factors in China.

4. Fine particle size will cause ulcer. What’s the mechanism? (For Tyler)

Answer: Fine grinding cause feed to bridge up in the bulk bins and feeders, which cause the feed pan to be empty.  This is referred to as an “out of feed” event.  If a pig is out of feed for 20 hours or more, it starts “digesting” its own stomach, causing gastric ulcers.  Therefore, fine grinding indirectly cause ulcers, but only if it causes out-of-feed events.  Most US producers will grind feed as fine as possible with it still flowing freely through bulk bins and feeders.


5. Biosafety issues: how to quickly evaluate the disinfection efficacy of swine transport vehicles? How to evaluate the disinfection efficacy of swine farms abroad? (For Gordon)

Answer: This is a very good question. Transportation is a high risk area for exposure to many pathogens including PEDV and PRRSV. A couple of recommendations for quick evaluation of transport bio-security to evaluate efficacy:
1)Set a specific protocol for transport sanitation
2)Train all staff on this protocol
3)Use an external auditor that inspects the process and audits all transport vehicles (including the cab of the truck) with visual inspection. Any vehicles that fail physical inspection are required to repeat the process.
4)Finally, submit environmental samples using Swiffer technique for PRRS and PEDV PCR to determine if virus is present after completion of process.
5)Repeat the steps above in improve the process!

6. In a PRRSV complex pig farm (where multiple PRRSV strains existed), how to choose the right PRRS vaccine? (For Gordon)

Answer: The presence of multiple PRRS strains on a farm is a challenge. You may wish to consider the following plan:
1)Repeated sampling in a very short period of time to determine the number of PRRS isolates that are in the population. The number of samples and sampling dates will be determined by farm type and number of animals.
2)Sequence the isolates to allow analysis and comparison of isolates to each other and to vaccines.
3)After a farm visit and review of production performance records and along with your herd veterinarian, determine which of the several isolates is responsible for the majority of the issues in the farm. This will take experience and knowledge of production on the farm that takes time to make “best decision”.
Remember that success may be measured by several parameters and that everyone needs to agree prior to any intervention implementation on what will be the measures to determine success or failure of any intervention.

7. Are they inter-related between PRRS and PCV as diseases causing pathogens? (For Bob)

Answer: All pathogens can work together to cause disease – that is the nature of disease complexes such as we see with respiratory disease. This is more apparent in growing pigs but can take place in the sow herd as well. Many pathogens are secondary and require a primary pathogen to set the pig up for its infection. For example, Pasteurella multocida type A requires a primary pathogen to help get it established.

8. How long we should wait before moving sows after feedback? (For Bob)

Answer: For sows that have never been exposed before, it probably takes around 3 weeks to have adequate immunity to protect their pigs.  For sows that have been exposed and are receiving feedback in an effort to boost immunity, it could be as short as a week.

9. Pigs have multiple concurrent disease, necropsy shows lungs congestion, edema, a lot pericardial and pleural effusion, what’s the next step to make the diagnosis? (For Albert)

Answer: Collect representative samples and send fresh and fixed samples to a diagnostic laboratory. Collect at least the following samples: lung, heart, lymph nodes, liver, spleen and kidney. Request histopathology on the tissues with lesions as well as tests for detection of viruses (PCRs for PRRSV, SIV, PRV, CSFV, PCV2) and bacteria (aerobic culture for most bacteria, PCRs for Mycoplasma hyopneumoniae and Mycoplasma hyorhinis). Most likely you will get positive results for several potential pathogens. The histopathological examination of fixed tissues performed by a pathologist should help understand which ones are most important in this particular case.