2.2.3. Analysis of piglet condition and piglet mortality
In order not to disturb maternal behaviour during farrowing, piglet weight and rectal temperature were measured on Day 1 immediately after the farrowing was finished (mean ± SD: 3.2 ± 2.5 h after the birth of the first piglet). On Day 3 weight and rectal temperature measurements were taken at 48 h after the birth of the first piglet. In order to determine whether there was an effect of latency from the birth of the first piglet to rectal temperature measurements on piglet rectal temperature on Day 1 a PROC GENMOD test was run; rectal temperature was not significantly affected by the latency from the birth of the first piglet until the time of the measurement (Z = 1.83, NS). On Day 1, every piglet was marked (by marker pen) with a number on its back for identification on the video record. As piglet mortality was an important measure in this study, there was no human assistance provided to a piglet when it was crushed. However, to follow common practices of commercial pig farming and to avoid suffering the ethical decision was taken to humanely euthanize the piglets which were not able to survive because of body deformations, injuries and long-term starvation in large litters (N = 7). All instances of piglet mortality were noted and a macroscopic post-mortem examination was conducted to determine the cause of death. Causes of death were: stillborn (lungs sink in water on post-mortem examination), crushed (physical signs of crushing), or dead by starvation (malnourished and no milk in the stomach). The physical lesions of crushing included: bruising, lacerations, bone fractures, haemorrhages and/or injuries of internal organs. Evidence from video recordings also assisted with establishing accurate cause of death.