The consumption of milk without restrictions does not guarantee the production success of the piglet after its weaning

In previous studies we have seen that in hyperprolific sows with 28-day lactations, the piglets with a higher liveweight (LW) when weaned are the ones that have more difficulties to start to eat feed after weaning. In fact, these piglets are related with the most productive teats, even when a good fostering program is carried out. The piglets associated with the least productive teats, with a lower LW at weaning, normally have a higher growth rate after weaning, even reaching those piglets with a higher initial LW. This higher growth rate would be associated with a better adaptation and efficiency when eating the prestarter feed, due to a previous contact with the feed during lactation (Solà-Oriol, 2011).

This higher growth during the nursery period can have important implications throughout the production life of the pig, but with no doubt, the performance during the nursery period is marked by a series of factors that condition the animals since they are born and during lactation.

In this article we put forward a practical case of the evolution of growth of the pig from birth until 100 days of age (end of the growing period) with regard to the position held by the pigs on the udder and to the feed consumption during the lactation, that are factors that can affect the productivity of the fattening pig.

In order to do this, 37 sows and their 377 piglets were used, standardizing the litters so they had 10-11 piglets, following a standard fostering program (equalizing with respect to the number and the size). After the fostering process, the position where each piglet suckled was recorded (1st, 2nd or 3rd third of the udder at 5 and 10 days before the weaning), as well as the start of the feed consumption (creep-feed) during the lactation (measured by means of the appearance of Cr₂O₃ in feces at 18, 21 and 25 days of age). During lactation, feed marked with Cr₂O₃ was given ad libitum to all the litters from day 10th of age. The same “creep-feeding” feed was offered to the selected piglets during the first day after weaning followed by prestarter feed until the 14th day postweaning, starter feed until the end of the nursery period (35 days postweaning: 60 days of age) and prefattening feed (from the 60th to the 100th day of life). The LW at weaning, at the end of the nursery period, and at the end of the growing period (28, 60 and 100 days of life) was recorded.

After the fosterings, the piglets with a higher LW at birth got hold of the teats located at the first (LW_birth = 1.72 kg) and the second third of the udder (LW_birth = 1.65kg), with the piglets with a lower average LW relegated to the rear area of the udder (LW_birth = 1.48 kg). This difference in the LW was maintained until weaning, and the piglets that suckled from the first and the second third of the udder still had a higher LW at 28 days of age than the piglets that suckled from the rear area of the udder (P < 0.05). Anyhow, we could see that these differences were lost at the end of the nursery period and during the first part of the fattening period (P > 0.10, figure 1).

Figure 1. Evolution of the LW from birth until the end of the growing period (100 days of age) according to the position on the udder during the lactation.

At the same time we were able to see that the initiation to the "creep-feed" consumption was early and gradual for the piglets that were on the rear part of the udder: they presented a higher percentage of animals that consumed feed at 18, 21 and 25 days of age (Table 1). Although these percentages were at the same level, just before weaning, than that of the piglets that suckled from other positions, the piglets with a lower weight maybe had the need to consume feed before due to the fact that they suckled teats that were less productive, stopping being strict milk consumers, and this would explain a better adaptation to the weaning, just as it has been seen in previous studies. Nevertheless, the potential represented by a higher LW at birth, from the point of view of the hierarchy within the litter after the fosterings, as well as for being able to select a good position on the udder, is lost with time because the differences are only maintained until the end of the nursery period.

Table 1. Percentage of piglets that were consumers of “creep-feed” (offered from the 10th day of age) at 18, 21 and 25 days of age according to the position held on the udder during the lactation.

These results confirm that the current handling strategy in the pig farms allows a "natural" equalization along the growth stage once the critical phases of the productive life of the pig have been overcome. Nevertheless, it is not less true that we attend a loss of preweaning growth potential in the case of the heavier piglets (more than 60% of the animals > 1.6 kg LW), because, especially in big and centralized production structures, the dragging of this potential would be able to reduce the age at slaughter, being able to obtain a higher profit from the fattening stage premises.

Once more, the need for starting a solid feed consumption before weaning in 28-day lactations, independently of the LW category of the piglet is confirmed. The handling of the litters with the aim of guaranteeing the contact of all the piglets with solid feed during the lactation could be a tool to avoid the loss of productive potential of the biggest piglets, contributing to a lower wearing out of the sow.