STILLBORN OR STILL ALIVE?
This month nutricle is the last of our series of nutricles on nutritional strategies on sows. Today, we will cover the prevention of stillbirths. Stillbirth is the term given to the birth of a piglet which is found dead within the membranes after farrowing is complete. The pig may have died prior to farrowing, died during the process of birth, or died after birth but without clearing the membranes. If stillbirths exceed 5% of total born, we must look for improvement in order to avoid negative effect on the economical viability of the operations.
Stillbirths can be the result of infectious pathologen like PRRS, Parvovirosis or Leptospirosis. It can be affected as well mycotoxicosis due to contamination of the diets namely by zearalenone. A special attention should be given in limiting for sow diets around farrowing the ingredients that could carry mycotoxins contamination (DDGS, rice bran,…)
The main cause of stillbirth is triggered by a too long process of farrowing. But after few hours of farrowing, the risk that piglets die in the process is increasing.
The cause of these long farrowing can come from several causes:
Predisposing factors
The incidence of still birth increases in older parity sows, over weight sows, pure breed sows and some sows or boars have a genetic factor which increases the risk and frequency of still births.
Stillbirths are increasing with the age of the sows. The stillbirth rate starts to become critical when sows reach their 4-6 parities.
Management practices should be put in place to ensure high risk sows are closely monitored, body condition is well managed and intervention strategies are correctly applied. It is important to record in the management software (cf Pig’Up) and monitor carefully the prevalence of stillbirths for each sow and cull the ones that present high incidence to maintain an acceptable average through the herd.
Constipation
Constipation can represent a major obstacle to piglet’s passage and expulsion. As explained in previous nutricles, constipation is the result of a decrease of digestive transit due to a drastic reduction to fibre daily intake. The sow eats less and she eats diets with lower fibre contents. To maintain an acceptable transit, it is important to keep an intake of at least 4kg / day to be distributed into 3 meals with a diet containing at least 14-16% of NDF / kg. Standard sow lactation diets in Asia are rather around 10-12% NDF which is insufficient to maintain acceptable transit. That can be the cause of high incidence of stillbirths. To add 2 to 3 points of NDF in a lactating diets without reducing energy and protein contents, you need to incorporate 2 to 3% of a very concentrated source of fibre (87% NDF) to restore the level of transit required for the farrowing process (without mentioning the negative consequences of constipation on enterotoxaemia and its effect on MMA, colostrum and milk production).
Uterus muscle tonicity
The farrowing process is a very demanding exercise requiring an optimal supply of key nutrients as sodium, potassium, calcium, magnesium, and vitamin D which are important for strong muscle contractions. Feeding a high amount of feed (e.g. 4kg/day) for the two days prior to farrowing has been shown to reduce the duration of farrowing, as well as improve colostrum quality and piglet survivability (Quesnel & Farmer 2019). This positive effect may be partially related to the increase intake of these nutrients required for strong contractions.
The timing of the last meal prior to farrowing also influences the duration of farrowing and therefore the incidence of stillbirths. When the time between meal and farrowing exceeds 3 hours, the farrowing duration increases. Increasing feeding frequency or adopting self-feeders may be another way to reduce still births.
Energy is as well a major nutrient to fuel the farrowing exercise. Without sufficient energy during the 5 hours that will take the process. Sugar (100gm/sow/day) can be applied during the few days prior to farrowing to enhance the hormone signals but it is not an optimal source of energy to fuel the farrowing process itself. The property of highly digestible sugar is to trigger a quick increase of glycemia after the meal followed by a drop. It will not last long enough. The fermentation of fiber in the colon fermentation at the opposite will take time to happen, will result in increasing levels of short chain fatty acids (SCFA). These SCFA (e.g. acetate, butyrate, propionate) will pass into the circulating blood and will provide a sustained energy source for the sows all along the farrowing process. This helps to avoid farrowing fatigue.
Chromium is an important insulin regulator and therefore can be useful to enhance the hormone changes that occur around farrowing. It is recommended that sow premixes contain at least 400ppb of chromium.
NB: All figure above have been published in 2019 by Takele Feyera, University of Denmark