Heat stress of gilts around farrowing causes oxygen insufficiency in the umbilical cord and reduces piglet survival
W. Zhao,
O. Artaiz,
Y. Iqbal,
H.H. Le,
K. DiGiacomo,
B.J. Leury,
L.J. Fothergill,
J.B. Furness,
F. Liu,
M.P. Green,
B.J. Finger,
M. Navarro,
E. Roura,
D.N. D'Souza,
F.R. Dunshea,
K.J. Plush,
J.J. Cottrell
Affiliations
W. Zhao
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
O. Artaiz
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
Y. Iqbal
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
H.H. Le
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
K. DiGiacomo
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
B.J. Leury
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
L.J. Fothergill
Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia; Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
J.B. Furness
Department of Anatomy and Neuroscience, The University of Melbourne, Parkville, VIC, Australia; Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
F. Liu
Rivalea Australia Pty Ltd, Corowa, NSW, Australia
M.P. Green
School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
B.J. Finger
School of BioSciences, The University of Melbourne, Parkville, VIC, Australia
M. Navarro
Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia
E. Roura
Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, Brisbane, QLD, Australia
D.N. D'Souza
SunPork Group, Eagle Farm, QLD, Australia
F.R. Dunshea
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia; Faculty of Biological Sciences, The University of Leeds, Leeds, United Kingdom; Corresponding author at: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC 3010, Australia.
K.J. Plush
SunPork Group, Eagle Farm, QLD, Australia
J.J. Cottrell
Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, VIC, Australia
Late gestating sows are susceptible to high ambient temperatures, possibly causing farrowing complications and reducing piglet survival. This experiment aimed to quantify in the days leading up to farrowing the impact of sow heat stress (HS) on farrowing physiology and survival of the piglets. Pregnant primiparous sows (gilts) were allocated to either thermoneutral control (CON, n = 8; constant 20 °C) or cyclical HS conditions (n = 8; 0900 h to 1700 h, 30 °C; 1700 h to 0900 h, 28 °C) from d 110 of gestation until farrowing completion. Gilt respiration rate, skin temperature and rectal temperature were recorded daily, and farrowing duration was quantified by video analyses. Blood samples were collected from the piglet umbilical vein at birth. At 48 h of age, piglet growth was quantified by morphometric analyses. The thermal exposure model induced HS and respiratory alkalosis in the gilts, as indicated by increased respiration rate, rectal temperature, skin temperature (all P < 0.001), plasma cortisol (P = 0.01) and blood pH (P < 0.001). Heat-stressed gilts took longer to start expelling placentae (P = 0.003), although the active farrowing duration was not significantly different between treatments. Stillbirth rates were higher in the HS group (P < 0.001), with surviving piglets at birth having lower umbilical vein partial pressure of oxygen (P = 0.04), oxygen saturation rate (P = 0.03) and tending to have increased lactate concentrations (P = 0.07). At birth, piglet skin meconium staining scores were greater in the HS group (P = 0.022). At 48 h of age, piglets from the HS group had reduced small intestinal length (P = 0.02), reduced jejunal crypt depth (P = 0.02) and lighter absolute brain weight (P = 0.001). In contrast, piglet BW, growth rate, relative organ weight and small intestinal mucosal barrier function did not change between treatments. Collectively, these findings demonstrated gilt HS during late gestation caused farrowing complications and reduced the umbilical oxygen supply to the piglets at parturition, leading to increased risks of piglet stillbirth with implications on impaired neonatal survivability and development.
