Viability of Iberian x Meishan F2 newborn pigs. I. Analysis of physiological and vitality variables.

Eight physiological and vitality variables related to the first minutes of the life of Iberian x Meishan F2 piglets were analyzed. Variables included rectal temperature, arterial oxygen saturation, heart rate (all were monitored at birth and 60 min later), time to reach the udder, and time to the first colostrum intake. Litter effect within boar, a random source of variation, influenced all variables, whereas the random boar effect was not significant for heart rate and arterial oxygen saturation at birth and the time to reach the udder. Birth weight influenced rectal temperature at birth (P < 0.01) and 60 min later (P < 0.001), arterial oxygen saturation 1 h after birth (P < 0.05), heart rate 1 h after birth (P < 0.001), time to reach the udder (P < 0.05), and time to the first suckle (P < 0.01), whereas viability score influenced rectal temperatures (at birth and 60 min later; P < 0.001), and time to reach the udder (P < 0.001) and to suckle (P < 0.001). Finally, the order of birth showed significant effects for rectal temperature 1 h after birth (P < 0.001) and time to first colostrum intake (P < 0.001). Correlation coefficients between physiological variables were generally low, with the exception of the ones for rectal temperature 1 h after birth and arterial oxygen saturation 1 h after birth (0.38; P < 0.001), and for rectal temperature at birth and rectal temperature 1 h after birth (0.34; P < 0.001). Times to reach the udder and to suckle were highly correlated (0.67; P < 0.001) and also were moderately and negatively correlated with rectal temperature 1 h after birth (-0.36 and -0.38 respectively; P < 0.001). Heart rates at birth and 1 h later, as well as arterial oxygen saturation at birth and 1 h later, were not correlated, showing that the values at birth do not necessarily provide information about the physiological status of the pig 1 h after birth. The recording of physiological variables, birth weight, and viability score may be useful to identify weak piglets quickly and to establish palliative measures.