Agriculture Reference
In-Depth Information
4
Modelling Nutrient Utilization in Sows:
A Way Towards the Optimization of
Nutritional Supplies
J.Y. Dourmad,* J. van Milgen, A. Valancogne, S. Dubois, L. Brossard and J. Noblet
INRA, Saint-Gilles, France
Abstract
In recent years, the reproductive performance of sows has been drastically improved. Nowadays, on
many farms, with the use of hyperprolific sows, the average litter size exceeds
13
piglets at farrowing
and 11.5 at weaning. These changes in performance have had major effects on the nutritional require-
ments during both pregnancy and lactation. At the same time, from the results obtained over the past
20
years on energy, amino acid and mineral utilization in sows, it has become possible to improve the
determination of nutrient requirements (factorial approach) and the prediction of an animal's response
to nutrients supplies (modelling). The aim of this chapter is to describe how the current state of know-
ledge on sow nutrition can be included in an integrated model, as well as in a software tool, designed
for end-users, mainly nutritionists in the pig industry and students in animal nutrition. Different ex-
amples are given to illustrate how the use of such a model can help in optimizing the productivity of
sows, while considering new priorities such as the reduction of the environmental impact of pig pro-
duction, which can be achieved through a more precise adjustment of nutrient supply to requirement.
Introduction
of the problem. During gestation, sufficient
body reserves must be built to restore ad-
equate body condition and compensate for
possible nutritional deficits that may occur
in the following lactation. However, these
reserves should not be excessive in order to
avoid farrowing problems, which are typ-
ical for fat sows, or impairing feed intake
after farrowing (Dourmad, 1991). During
lactation, it is recommended to adapt daily
nutritional supplies to requirements to maxi-
mize milk production and growth of the
piglets, and to minimize the risk of repro-
ductive problems of sows after weaning.
Until recently, most attention has been paid
In mammals, the process of reproduction,
from conception to weaning, can be con-
sidered as directed to buffer the developing
progeny from nutritional distress (Oldham,
1991), involving both homeostatic and
homeorhetic controls of nutrient partitioning
(Bauman and Currie, 1980). Reproductive
problems, which may result in a reduction
in sow productivity and early culling, are
often related to extreme variations in body
reserves (Dourmad
et al
., 1994). Neverthe-
less, body reserves should be considered
more as an indicator of risk than as the cause
