Predictability of nursings without milk ejection in domestic pigs

Up to 30% of nursings in domestic pigs do not result in the let-down of mil k (non-nutritive nursings). The motivation to nurse often seems to be simil ar in non-nutritive and nutritive nursings; the sow exposes the udder and b egins to grunt rhythmically while the piglets massage the teats intensively . The question arises, whether the behaviour of the piglets and sow is inde ed the same during nutritive and non-nutritive nursings. We investigated qu antitatively whether the latency to start teat massage, the proportion of p iglets participating in the nursing, the intensity of tear massage tin term s of snout movement frequency) by the piglets and the grunting rate by the dam differ between nutritive and non-nutritive nursings. These behavioural characteristics were compared between videotaped nutritive and non-nutritiv e nursings in 7 sows and their litters at the age of 7-8 days after farrowi ng. Teat massaging movements and sows' grunts were counted during periods o f 40 s one minute before (Period 1) and one and a half minute after the mil k ejection (Period 2) in nutritive nursings, and during the same periods, c alculated from the start of the nursing, in non-nutritive nursings. Gruntin g frequency was also assessed during 30 s before and 30 s after the start o f the udder massage. The latency to start teat massage by the piglets and t heir participation in the massage were the same in nutritive and non-nutrit ive nursings. During Period 1 rear massage intensity did not differ between nutritive and non-nutritive nursings (13.2 vs. 18.7 snout movements, paire d t-test, p = 0.23), but it did differ during period 2 (20.9 vs. 12.5, pair ed t-test, p = 0.024). The sow's grunting frequency was similar in the two types of nursings both before (0.27 grunts per second in nutritive, 0.22 in non-nutritive nursings, paired t-test, p = 0.216) and after the start of u dder massage (0.47 vs. 0.35 grunts/s, p, = 0.148). In nutritive nursings, t he grunting increased further to 0.74 grunts/s in Period I (p = 0.005), whe reas in non-nutritive nursings, it remained at 0.34 grunts/s. We conclude t hat both the sow and her litter enter non-nutritive nursings with full moti vation to accomplish a complete nursing, and it is not until the initial ma ssage is in full progress that it is revealed in the sow's grunting that th e milk ejection will fail. (C) Elsevier Science B.V. All rights reserved.