Physiological parameters in lambs during the first 30 days postpartum

The transition from a fetus, protected and nourished within the uterus in an almost parasitic state, to the free-living neonatal lamb is probably the most profound change the lamb ever has to face. The newborn becomes engaged in a series of profound metabolic and morphological changes, and the immediate postnatal period is characterized by temporary internal instability. The goal of this study was to monitor heart and respiratory rate and rectal temperature during the first month of life in the lamb, as these parameters represent valid indicators of the lamb's homeostatic response during this adaptative period. In this study, 10 clinically healthy female lambs (Comisana breed) with a mean body weight of 5.6 ± 0.7 kg were used. In each lamb, the heart and respiratory rate and rectal temperature was recorded every 3 days at the same time (09:00) for 30 days, starting at birth. One-way repeated measures analysis of variance (ANOVA) was used to determine any statistical differences between mean values of the parameters studied from the 1st to the 30th day of the observation period. The ANOVA showed a highly significant effect of time on heart and respiratory rate. The mean values recorded for the entire experimental period were 148.3 ± 22.9 beats/min (p < 0.0001) for the heart rate and 94.7 ± 33.2 breaths/min (p < 0.0001) for the respiratory rate. No significant difference was recorded in rectal temperature, with the mean value being 39.9 ± 0.4 °C. A high correlation between individual values for postnatal age (days) and heart rate (beats/min) in the 10 lambs was recorded. The results obtained in this study make a contribution to the knowledge of homeostatic, cardiorespiratory and thermoregulatory adaptations in lambs during the first 30 days of life and give useful information for the diagnosis and treatment of some neonatal diseases.