Practical implications:
Reducing the dietary
crude protein level

In young pigs, the occurrence and the severity of diarrhoea are more acute than at later stages. The transition from sow milk (liquid) to plant food (solid) and the limited acidification capacity of the immature digestive tracts of the piglet lead to a poor digestion of the protein fraction. Therefore, a part of the dietary CP remains undigested and a significant amount reaches the distal intestine causing the proliferation of pathogenic bacteria which are responsible for digestive disorders and so diarrhoea. This results in depressed growth and damaged health status of the herd.

Figure 1. Role of acidification in the gut of the piglet

Low CP diets, aside from a lower nitrogen contents shows a higher acidifying capacity than diets containing higher amounts of CP. An acidification of the digesta and a limitation of the amount of undigested protein in the large intestine limit pathogenic bacteria proliferation. Limiting dietary CP level helps thus to decrease the amount of undigested protein reaching the lower part of the digestive tract and to some extent to lower the pH of the digestive bolus (Figure 1).

Securing the feed by decreasing the CP level is thus a practical nutritional solution to decrease the incidence and severity of digestive disorders leading to diarrhoea problems and it had been widely implemented in Europe.

Lowering the dietary CP level should not be done at the expense of growth, since good performance in the piglet phase is shown to improve the overall growth of the pigs. Heavy piglets are more resistant to environmental changes, transition to other feed, and go on to perform better in the follow-on accommodation. Reducing the dietary CP content impacts both amino acid and energy content of the diet. It thus requires the use of an adequate nutritional system to control growth performance and carcass composition: SID amino acids and NE for swine and true digestible (TD) amino acids and ME for poultry.