Average litter size in commercial herds has increased substantially in the past decade, resulting in large numbers of low-birth-weight (LBW) piglets.
Mortality rates are higher in piglets that weigh 2 lb. or less.
A team of Canadian researchers investigated the effects of processing LBW piglets during the first 24 hours of life vs. processing piglets at 3 days of age.
In the study, six piglets/litter from 20 litters were weighed at birth and designated as LBW (2.2 lb.) or average-birth weight (ABW greater than 2.6 lb.), and processed (tail docked and ear notched) at either 1 or 3 days of age.
Piglets were assessed for viability at birth. Those piglets incapable of standing, walking or suckling were excluded from the experiment.
During the study, piglet vocalizations were recorded and behavioral responses were observed. Piglets were observed for six hours after birth and after processing to determine if they attended nursing sessions and if they remained in close contact to their littermates.
On Day 5, blood samples were collected to determine concentrations of immunoglobulins, a measure of colostral intake and suckling success.
Piglet weights were recorded at birth and at Days 5, 14 and 21. Mortalities were recorded until weaning.
High-frequency vocalizations have been shown to be indicative of distress in piglets. In this study, both groups of weight classes produced these calls, indicating that processing is equally distressing for both LBW and ABW piglets. However, LBW piglets produced fewer calls overall, possibly reflecting lower vigor in these animals.
Regardless of age at processing, LBW male piglets had the lowest attendance at nursing time and spent the greatest amounts of time alone when nursing was not occurring.
Both male and female LBW piglets had lower concentrations of immunoglobulins than ABW piglets.
Overall, LBW piglets were 5.5 times less likely than ABW piglets to survive to weaning.
Some LBW piglets suckled less often, spent more time isolated and had a lower immune status, suggesting it may be advisable to delay processing until Day 3 for LBW piglets. This will avoid needlessly processing piglets that won’t survive the first few days of life.
The research was funded by Agriculture and Agri-Food Canada.
Researchers: Kristi Bovey and Stephanie Torrey, both of Agriculture and Agri-Food Canada at Guelph, Ontario and the University of Guelph Department of Animal and Poultry Science; Tina Widowski of the University of Guelph Department of Animal and Poultry Science; Nicolas Devillers, Martin Lessard and Chantal Farmer, all of Agriculture and Agri-Food Canada at Sherbrooke, Quebec; and Cate Dewey of the University of Guelph Department of Population Medicine.