Influence of environmental temperature on PGF 2α-induced nest building in female pigs

Abstract

Domestic pigs build a maternal nest in the day preceding parturition. We have shown that prostaglandin F 2α (PGF 2α) induces nest building behaviour in non-pregnant pigs. The aim of this experiment was to examine the effects of different environmental temperatures on PGF 2α-induced nest building. Data were collected from 9 Large White (LW) and 10 Large Black (LB) 8–9-month-old nulliparous sows (gilts). The pigs were housed in social groups between experiments and tested individually in pens ( 1.8 m×1.8 m) containing straw, within an environmentally controlled chamber. Pigs were habituated to the testing pens (maintained at 17°C) and tested once at each of three temperatures (low, 5°C; moderate, 17°C; high, 30°C). During testing the temperature of the chamber was adjusted at 09.00 h and had reached set point by10.00 h. The pigs were injected intramuscularly with 3 ml saline at 10.30 h and 0.1 mg/kg PGF 2α (Lutalyse, Upjohn) at 11.30 h. Behaviour was scored for 1 h after treatment with saline and 1 h after treatment with PGF 2α using one/zero sampling from video recordings. Nest building behaviour (rooting, pawing and gathering straw) was induced by PGF 2α at all temperatures in both LW and LB breeds. There was a significant increase in rooting behaviours with decreasing temperature. No significant effects of temperature were found on the scores for gather or paw. The pigs spent more time lying down at the high compared to the low temperature after both saline and PGF 2α treatment. Other behaviours unrelated to nest building but induced by PGF 2α, such as scratching, were unaffected by temperature. The results show that the nest building behaviour of non-pregnant pigs can be induced by exogenous PGF 2α treatment, and that some, but not all, aspects of PGF 2α-induced nest building (rooting but not pawing or gathering) are altered by environmental temperature.