The live weight of the piglets weaned at 28 days: a decisive factor for a good post-weaning adaptation?

The performance decrease suffered by weaned piglets is one of the most worrying factors on the swine farms. Although part of the investigation in this area is focused on stimulating feed consumption after weaning, reducing in this way the unproductive period and the appearance of diarrhoeas, at the field level the controversy goes on about if a better start for the piglets is due (leaving aside the health matters) mainly to the live weight of the piglet at weaning, to the previous consumption of feed during the lactation (“creep feeding”) or even to the management strategies related with the feeding of the piglet during the lactation.

The work of Bruininx et al. (2001) revealed that the lighter piglets at weaning started to eat before and in a higher percentage than the heavier piglets. Later, Pluske et al. (2007), in a work in which they studied the production performance after weaning according to the previous behaviour during the lactation period, observed that most of the piglets that did not consume feed during the lactation showed a growth drop immediately after weaning, whilst the piglets classified as feed consumers (the ones relegated to the rear part of the udder) showed a better growth at 14 days after weaning.

In hyperprolific sows with 28-day lactations, this situation is aggravated even more, because even assuming a good fostering program, there is a great competition for the teats. The live weight range obtained in piglets with 28-day lactations goes from 4 to 10 kg. In this article we explain a case study about the response in terms of growth of the piglets at weaning according to their live weight (LW) category at the end of the lactation period.

From a total of 1,940 ( and ) piglets coming from 6 consecutive weaning batches (Figure 1a) 1,440 piglets were chosen (LW = 7.5 ± 0.32 kg; once the W₁₀ < LW < W₉₀ were excluded). The chosen piglets were classified in 4 weight categories (Q1 = 6.2 kg, Q2 = 7.0 kg, Q3 = 8.0 kg, and Q4 = 8.9 kg, from the lower to the higher weights; Figure 1b) that were distributed randomly within the nursery barn (6 pens with 10 animals for each weight category and weaning batch). During the lactation period creep-feed was offered to all the litters from the 10th day of life. The same “creep-feeding” feed was offered to the chosen piglets during the first post-weaning day followed by pre-starter feed until the 14th post-weaning day. The start of feed consumption was monitored at 2 days post-weaning, and the LW and the feed consumption at 7 and 14 days post-weaning for the determination of the ADFI, the ADG and the FCR.

Figure 1. Distribution of the LW of the piglets at the end of the lactation period during 6 consecutive weaning batches (A), and initial classification and evolution of the LW along the pre-starter stage (B).

Although no differences were seen with respect to the beginning of feed consumption at 2 days post-weaning (P > 0.10), after a week the piglets in the Q1 group grew more than those in the Q2 and Q4 groups (P < 0.002; Figure 2b), showing a similar feed consumption to that in the group of animals with a higher weight (Figure 2a). On the second week after weaning (7-14 days), the piglets in the Q4 group did not show a higher growth with respect to those in the Q1 group, although the animals with the highest LW showed a higher feed intake. Along all the pre-starter stage (0-14 days after weaning), the piglets in the Q1 group showed a similar growth and feed consumption (P > 0.05) with respect to those in the Q4 group, with a decrease in the initial LW difference on the 14th post-weaning day. Nevertheless, the Q2 group (initial LW: 7.02 kg) had always a lower feed consumption and weight gain, and the Q1 group reached the Q2 group at the 14th post-weaning day with respect to the LW.

Figure 2. Evolution of the average daily feed intake (ADFI) (A) and the average daily weight gain (ADG) along the pre-starter stage (B).

The highest growth rate seen in the piglets with the lowest LW at weaning (Q1; LW = 6.21 kg), matching even those piglets with the highest initial LW (Q4, PV = 8.87 kg), could be explained by a better adaptation to the pre-starter feed, related to a significant feed intake during lactation and to a lower growth and a more moderate feed consumption by the heaviest piglets, that could be related with a lack of a previous contact of the piglets with solid feed, probably as a consequence of having consumed more milk from the sow.

These results confirm the need for starting the solid feed consumption before weaning in 28-day lactations. It would also be necessary to study litter management strategies with the aim of guaranteeing the contact of all the piglets with solid feed during the lactation in order to reduce the performance loss of these piglets at weaning.