This week, the Science Page answers one of your questions: Is the trend of PRRSV outbreaks recorded for the original 13 participants still related to the PRRSV outbreaks evolution monitored for all the MSHMP participants?
Key points from this week edition:
The EWMA of the original 13 participating systems is still a good representation of the overall EWMA.
Questions from participants are always welcome!
Reminder: What is the EWMA?
The Exponential Weighted Moving Average (EMWA) is a statistical method that averages data over time, continually decreasing the weight of data as it moves further back in time. An EWMA chart is particularly good at monitoring processes that drift over time and is used to detect small shifts in a trend.
In our project, EWMA is used to follow the evolution of the % of farms at risk that broke with PRRSV every week. EWMA incorporates all the weekly percentages recorded since the beginning of the project and gives less and less weight to the results as they are more removed in time. Therefore, the % of farms at risk that broke with PRRSV last week will have much more influence on the EMWA than the % of farms at risk that broke with PRRSV during the same week last year.
A longitudinal study to assess Mycoplasma hyopneumoniae natural infection in gilts
This study was conducted by Dr. Karine Takeuti under the supervision of Dr. Maria Pieters from the University of Minnesota, College of Veterinary Medicine. The objective was to sample replacement gilts from 20 days of age until the day before weaning to detect Mycoplasma hyopneumoniae . Laryngeal swabs, tested by PCR, were taken every 30 days at a Mycoplasma positive sow farm. Therefore, the animals were naturally infected.
Gilts were found positive at 110 days, no detection in piglets
11.4% of the gilts were found positive at 110 days whereas all the previous samples came back negative. Positive results peaked at 140 days when 36.4% of the samples were positive for Mycoplasma hyopneumoniae. 27.3% of the gilts got positive results twice or more during the sampling period but 18.2% of the animals remained negative for the duration of the study. All of the 220 piglets samples were also negative.
Mycoplasma hyopneumoniae causes a chronic respiratory infection in pigs and its transmission occurs mainly by direct contact and by vertical transmission (sow-to-piglet). The objective of this study was to assess the detection dynamics and persistence of M. hyopneumoniae natural infection in replacement gilts. Forty-four twenty-day-old gilts were selected from a M. hyopneumoniae positive farm and followed up to one day prior to their first weaning. Laryngeal swabs were collected every 30 days, starting at day 20, for M. hyopneumoniae detection by real-time PCR, resulting in 12 samplings. Piglets born to selected females were sampled via laryngeal swabs one day prior to weaning to evaluate sow-to-piglet transmission. The M. hyopneumoniae prevalence was estimated at each one of the 12 samplings in gilts and a multiple comparison test and Bonferroni correction were performed. Bacterial detection in gilts started at 110 days of age (doa) and a significant increase (p < 0.05) occurred at 140 doa. The M. hyopneumoniae prevalence remained above 20% from 140 to 230 doa, decreasing thereafter. However, it did not reach 0% at any sampling after 110 doa. In this study, M. hyopneumoniae was not detected in piglets sampled prior to weaning. The M. hyopneumoniae detection pattern showed that in natural infections, gilts were positive for M. hyopneumoniae for one to three months, but occasionally long-term detection may occur. Moreover, the lack of M. hyopneumoniae detection throughout the study in 18.2% of gilts indicated the existence of negative subpopulations in positive herds.
Antimicrobial resistance is an expression that everyone in swine production has heard at least once but what does it really mean? How are you as a producer or veterinarian affected?
In this column for the National Hog Farmer, Dr. Carles Vilalta explains that beyond the definition of a bacterium that is not affected by an antimicrobial, there are two different approaches to think about resistance:
One is determined by the Minimal Inhibitory Concentration or MIC, which records the minimum medicine concentration required to stop the growth of the bacteria.
The other focuses on the presence of genes enabling the bacterium to counteract the effect of the antimicrobial.
These genes are usually present in a sub-population of bacteria called mutants. The video below created by Harvard Medical School shows how these mutants can develop, adapt, and survive the highest antimicrobial concentrations. (video length < 2min)
Computer processing power keeps increasing at an alarming rate, allowing hackers to greatly increase their password cracking capabilities.
Hackers’ password cracking tools can crack weak passwords in no more than a couple of hours of execution. The same tools will take millions of years to crack a strong password.
Whenever password cracking is mentioned in this article, it should be assumed that the password is encrypted using a strong cryptographic hash algorithm such as scrypt: http://www.tarsnap.com/scrypt.html
This week, the Science Page honors Dr. Robert Morrison, the founder and leader of the Swine Health Monitoring Project.
Bob’s unique talent for creating relationships that advanced the swine industry culminated in the creation of the Swine Health Monitoring Project (SHMP), one of the initiatives that Bob carried with pride. […] As it evolved, the SHMP changed names several times but many in the industry simply refer to it as “Bob’s project”. For that reason, and to give the just recognition he deserves, we have decided to renam the project to “Dr. Bob Morrison’s SHMP” (MSHMP).