The effect of flush feeding during lactation on sow reproductive efficiency, litter size, birth weight and within litter variation

The aim of the experiment was to determine the effect of feed- and energy intake by adapting a feeding curve and change in energy source during lactation, on reproduction functions in sows and the effect on the subsequent litter. In this experiment, 252 lactating sows were randomly divided into three groups of 84 each. To remove sow variation between groups and within a treatment group, Topigs Norsvin, purebred Z-Line sows, were inseminated with pooled A-line semen, and randomly assigned to a specific treatment group. All sows were fed to the same feed intake curve until day 13 of lactation. From day 14 the sows were fed according to a specific treatment group. Group 1 (Control) received a lactation diet during lactation, following the standard feed curve (maximum level of 2kg plus 500 g per piglet). Group 2 (Ad Lib) was fed with the same lactation diet with an increase in feed level (ad lib) on day 14 to 21. Group 3 received the same lactation diet and followed the standard feed curve with a dextrose top-up (500g/day) from day 14 to day 21. There was no significant effect of group on the sow efficiency (WSI; P>0,41) and the subsequent litter’s total number born (P>0.36), although there was a trend seen of the effect of dextrose top-up on the subsequent litter’s total number born (P>0.16). The sows with a high total number born before treatment, also had a high total born after treatment (P0.1). Empty body weight loss during lactation was affected by parity (P<0.01), where younger sows lost more weight during lactation. Sows having a smaller litter size at farrowing, exhibited a greater weight loss during lactation (P<0.0001). Feed intake during the last week of lactation had a significant effect on weight loss (P<0.05). For every 1kg feed intake per day during the last week of lactation, the weight loss % decreased with 0.91%. For every 100 MJ NE increase in energy intake during the last week of lactation, the sow lost 1.15% less empty body weight loss during lactation. For every 100MJ NE increase in energy intake during the last week of lactation, results in a 0.41 increase in total number born in the following farrowing. For every 1kg increase in feed intake, the total born increased with 0.23 piglets. The subsequent average birth weight of a piglet was significantly influenced by the total number born (P<0.0001) and litter weight (P<0.0001) of the following litter. Litter weight was significantly influenced by gestation gain (P<0.0001) and the total number born (P<0.0001) of the following litter. The with-in litter variation was influenced by the parity of the sow (P