As highlighted in the accompanying article, neonatal mortality in pigs continues to be one of the greatest challenges in pig farming, especially as the move has been towards larger litters, which result in smaller sized piglets at birth. Whilst the accompanying article focuses on the role of sow management, many other factors are involved in this complex problem. Knowledge of the risk and protective factors for neonatal piglet mortality will allow for effective management that may reduce the number of piglets that die around the time of birth.
PROHEALTH conducted a large scale epidemiological study that aimed to identify mortality patterns and to establish risk factors associated with different categories of piglet perinatal mortality in pig farms. The study was done in association with the CCPA-DELTAVIT Lab., a French consulting company for animal nutrition and health. It involved data from 162 French farms (~9,000 piglets) with perinatal mortality problems, identified by either their veterinarian or farm manager. Perinatal mortality was defined as non-viable and mummified piglets, still-born piglets, and piglets born alive which died within the first 48 hours of life. In addition to the epidemiological data collected, which included the cause of the death of the piglets, the farm and sow characteristics, a subset of these farms were contacted to complete a retrospective questionnaire (58 farms agreed to participate). The questionnaire included questions related to piglet management strategies and additional variables regarding farm characteristics and sow management. The epidemiological data were expected to provide information about the risk factors, whereas the questionnaire data was expected to provide information about the protective factors that may affect piglet perinatal mortality.
The causes of piglet death were classified according to predefined definitions or protocols by veterinarians, and consisted of: 1. Non-viable piglets; 2. Starved piglets; 3. Crushed piglets; 4. Death due to early sepsis; 5. Mummified piglets; 6. Death during farrowing; 7. Other causes of death which represented the less common causes of death, i.e. <5% of the total perinatal mortality. The number of piglets and percentages under each cause of death category are in the Table below.
Categories of perinatal piglet mortality and percentage of deaths under each category
|Category||Number of piglets||Percentage|
|Death during farrowing||1785||23.0%|
Some risk factors had a similar impact on all main categories of death. Litter size did not influence the chance of death from one specific category compared to others, confirming that litter size acts as a general risk factor for all the most important categories of piglet mortality. For the six main categories of perinatal mortality, the piglets which died from a specific category tended to have more litter-mates which died from the same category of mortality. This suggests the influence of factors related to the sow, the animal keeper or the farm which impact several piglets in the litter at the same time. The total number of deaths in the litter tended to be lower for litters with mummified and non-viable piglets, than for other categories of mortality. These litters might have more deaths at the embryonic stage and therefore reduce the number of piglets at risk at birth.
Although risk factors with a common influence on the different categories of piglet mortality were identified, some of the studied risk factors had a particular impact on specific categories of perinatal mortalities, suggesting that the problem of perinatal mortality should not be considered as homogenous. Late parities increased the risk of death from early sepsis, death during farrowing and ‘other’ causes, whereas they decreased the risk of death from crushing or starvation; the latter suggesting that maternal experience acts a protective factor. Deaths during farrowing were fewer during the night than during the day, raising the possibility that daylight activities might stress the sows during the farrowing and that stillbirths may be associated with the supervision of the far-rowing itself. Non-viable piglets were fewer in summer than in other seasons, and this may relate to issues of piglet thermoregulation.
Whilst the risk factor analysis points towards factors that need to be taken into account when considering the causes of perinatal deaths in piglets, the questionnaire was expected to point toward management factors that may ameliorate piglet neonatal mortality. Such protective factors suggested by the analysis included the use of two or more heat lamps, providing a good microclimate for the neonatal piglets. Providing more frequent and diverse help to the piglets, supporting both suckling and thermoregulation, were similarly protective factors. Assisting piglets, including cross fostering, was an important protective factor mainly for certain parities, hyperprolific sows and farms with a low level of biosecurity. The total mortality percentage was not significantly different between farm types suggesting that piglet management was not the main factor that influences total piglet mortality. Sows and environment may have a bigger influence on the total piglet deaths.
Better infrastructure and sow management improved piglet survival, with a lower age of farm buildings being a significant protective factor. More modern equipment in a new housing system was associated with improved sow health and piglet survival. However, the confounding effects of sow management or stockperson skills in recently constructed buildings could not be disassociated and need to be assessed in further studies. The questionnaire study recognised limitations of small scale and the potential bias that may have been introduced by the farm selection, because of the voluntary participation of farmers. It concluded by the statement that one should ‘keep in mind that a reduction in piglet mortality can result from many factors’, consistent with the multifactorial nature of most production diseases.
Pandolfi, F., Edwards, S.A, Robert, F. and Kyriazakis, I. (2017). Risk factors associated with the different categories of piglet perinatal mortality in French farms. Preventive Veterinary Medicine 137: 1-12.
Pandolfi, F., Edwards, S.A, Robert, F. and Kyriazakis, I. (2018). Identification des profils d’élevage en fonction des différentes causes de mortinatalité. Journées Recherche Porcine, 50: 293-298.