Sows that are both gestating and lactating during a six-week lactation period should be fed on a high feeding level. A low feeding level results in a higher loss of weight and backfat thickness of the sows and in less live born piglets in the next litter. This was shown in research that was conducted within Feed4Foodure by Wageningen UR on Swine Innovation Centre Sterksel.
In 2013 a literature review was performed on the feeding of lactating sows with an extended lactation and insemination during lactation. The literature review showed that there is little information about the feeding of sows that are both gestating and lactating during an extended lactation. For milk production a high feeding level is important. However, a high feeding level may decrease embryonic survival.
Therefore, in 2014 the effect of feeding level during the last 8 days of a six-week lactation in which the sows were both gestating and lactating was studied. The effects on weight and backfat thickness, performance of the piglets and the number of live born and stillborn piglets in the next parity were studied. On day 27 of lactation intermittent suckling started to induce lactational oestrus. During a period of 6 days, sows and piglets were separated for 10 hours per day. 90% of the sows showed oestrus within 6 days after the start of intermittent suckling and were inseminated. After insemination, intermittent suckling was no longer applied and sows remained with their piglets till weaning on day 42 after farrowing. From day 34 till day 42 sows were fed on a high (6.5 kg feed per sow per day) or a low (4.0 kg feed per sow per day) feeding level.
Weight loss and backfat loss during the last 8 days of the six-week lactation was higher in the sows on the low feeding level than in the sows on the high feeding level. It seems that the milk production of the sows stays at a high level during the last 8 days of the six-week lactation and that a low feeding level in this period does not reduce milk production of the sows but increases the weight and backfat loss of the sows.