Agriculture Reference
In-Depth Information
2. Early gestation feeding and management for
optimal reproductive performance
P. Langendijk
South Australian Research and Development Institute, J.S. Daivies Building, Roseworthy
Campus, Roseworthy, SA 5371, Australia;
pieter.langendijk@nutreco.com
Abstract
During the first three to five days post-mating, progesterone secreting capacity of luteal
tissue is still limited and an increase in feed intake during this period reduces systemic
progesterone. Limited feeding in this period may therefore increase progesterone
supply to the uterus and hence improve the uterine environment in preparation for
implantation, thus increasing embryo survival. Before implantation energy and protein
supply to the embryos are not likely to be limiting and embryo survival is mainly a
result of individual embryo development and variation between embryos, the latter
causing relatively retarded embryos to perish. Specific nutrients that may promote pre-
implantation blastocyst development are identified in this chapter, yet they still need
to be studied
in vivo
. As of approximately one week after conception, maximum luteal
capacity is attained and at this stage the ovarian-uterine transfer of progesterone probably
overcomes any reduction in systemic progesterone caused by a higher feed intake. A
high feed intake at this stage results in more luteal tissue, and also directly increases
progesterone secretion through insulin and IGF pathways and, as of day 12, through
increased luteinising hormone. During this period of established luteal capacity, a higher
feed allowance probably promotes embryo survival and supports the maintenance of
pregnancy. This is especially true in situations that increase the risk of unsuccessful
pregnancies, such as group-housing and seasonal infertility. After implantation, uterine
space becomes limiting and, in turn, the supply of energy and protein likely becomes a
limiting factor. Specific nutrients such as arginine promote placental vascularisation and
therefore support embryo survival at this early stage.
Keywords:
nutrition, embryo survival, gestation, progesterone
2.1
Introduction
The first month of gestation in pigs is critical to the success of pregnancy because it is in
this period that pregnancy is either established successfully or, in the case of insufficient
interaction between the conceptuses and the uterus, is not maintained. It is also in this
period that the potential litter size is set, being determined by the number of embryos
that survive, which is in turn affected by management strategies. This chapter deals with
the influence of management on the establishment of pregnancy and the survival of
embryos, with a focus on nutrition. The aim of the chapter is to describe the complexity
