Evaluation of sow mortality in a large scale operation

Author(s)

Matheus Saliba Monteiro

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina Veterinária e Zootecnia (FMVZ/SBD)
• Defense date: 2022-03-31

Examining board members

Andrea Micke Moreno; Mauricio Cabral Dutra; Terezinha Knöbl

• Advisor: Andrea Micke Moreno

Abstract

There has been a steady increase in sow mortality rate over the past decade. Increased mortality of breeding sows results in substantial financial losses and raises ethical and animal welfare concerns. In spite of the rise in mortality, the literature is still scarce regarding the causes of spontaneous death of sows in large pig operation enterprises and the associated bacterial agents involved. Therefore, the present study was conducted to investigate the cause of sow mortality by performing post-mortem examination and evaluation of individual sow records from 100 sows that died spontaneously in a breeding herd with an inventory of 16,000 dams. Samples from cardiorespiratory, genitourinary, locomotor and gastrointestinal systems were collected to identify possible association between the cause of death and observed gross lesions. The samples were also subjected to microbiological examination using mass spectrometry (MALDI-TOF MS). PCR analyses were performed to identify respiratory and enteric agents. Correlation analysis was carried out using data from individual sow records, pathological findings and microbiological test results. The majority of sow deaths occurred in peripartum (53%). The peripartum increased (p<0.05) odds of death from genitourinary lesion, heart failures and prolapses. The main pathological findings were pleurisy (50%); cystitis (35%); lung edema (29%); gastric ulcers (26%); lung congestion (23%); metritis (22%); retained piglets or placentas (11%); heart failure (15%); lung consolidation (15%); pyelonephritis (14%); arthritis (11%); suppurative myositis (9%); lobe hepatic torsion (7%); uterine prolapse (6%); cervix/uterus rupture (6%); rectal prolapse (4%). Sow mortality had a multifactorial etiology, and in 70% of the deaths lesions in more than one system were observed. Furthermore, claws injuries increased (p<0.05) the odds for arthritis and suppurative myositis at the time of death. Sows with low body condition score had higher odds (p<0.05) for locomotor septic disorders. The excessive use of manual obstetric interventions increased sow deaths resulting from cervix/uterus ruptures and also increase the odds of death (p<0.05) due to metritis. The use of uterotonics and manual obstetric interventions did not (p>0.05) affect prolapses occurrence at the time of death. A positive association (p<0.05) between cystitis and pyelonephritis, indicating a possible ascending infection, was observed. Infections were mainly polymicrobial. The main microbial agents identified from septic lesion in locomotor, genitourinary and respiratory systems were: Trueperella pyogenes; Escherichia coli and Actinobacillus pleuropneumoniae, respectively. In conclusion, sows mortality had multiple risk factors and numerous bacterial agents involved. This topic warrants further studies to better elucidate sow deaths and guide the implementation of strategies to reduce mortality in breeding herds, thereby improving animal welfare and reducing financial losses. (AU)

• FAPESP's process: 19/17683-0 - Evaluation of mortality causes in swine females in intensive production system
• Grantee: Matheus Saliba Monteiro
• Support Opportunities: Scholarships in Brazil - Master