Managing large litters: Selected measures of performance in 10 intermediate nurse sows and welfare of foster piglets.

• One sow did not allow foster piglets to suckle within 24 h. • Milk yield dropped for four of the nine sows who accepted the foster piglets. • Latency to the first milk ejection for foster piglets ranged from 1 to 8 h. • Foster piglets had lower growth, more competition and longer nursing intervals. • Sow nutritional status was not compromised - dietary protein appeared oversupplied. Selection for increased litter size has led to the use of so-called nurse sows in several European countries. A nurse sow receives new piglets after having weaned her own. Nurse sows are often made in two-steps. In the two-step strategy, new-born piglets are given to a sow 4–7 days into lactation. Her 4–7 days old piglets are given to a so-called intermediate sow 21 days into lactation whose piglets are weaned at day 21. The use of nurse sows has been associated with welfare problems caused by an extended length of crating and/or by the disturbance of the nursing pattern by moving and mixing of foster piglets. The aim of this study was to investigate growth and welfare indicators (latency to suckle after transfer, teat fighting, snout- and knee abrasions) of ten foster litters at the intermediate sow and to compare these with the sows' own litter at the same age as well as to compare the sows' milk production, nutritional status and fat mobilisation in the period where she nursed her own piglets compared to the foster piglets. One of the ten sows did not accept the foster litter. The results on the remaining 9 litters showed reduced growth, increased teat fighting and missing milk letdown for the foster piglets compared to the sows' own litter at the same age (P < 0.05) and more udder abrasions on the sows after transfer (P < 0.05). There were signs of milk intake being insufficient (i.e. lower growth rate of foster piglets) as the foster piglets experienced longer nursing intervals (P < 0.05) and four of the sows' milk yield dropped considerably after transfer. The sows' nutritional status did not seem to be compromised but the study indicated an oversupply of dietary protein after becoming nurse sows. In conclusion, there were signs of impaired welfare and growth of foster piglets reared by intermediate nurse sows and indications of a mismatch between sow milk yield and piglet milk removal. [ABSTRACT FROM AUTHOR]