Coprophagia in early life tunes expression of immune genes after weaning in rabbit ileum.

Coprophagia by suckling rabbits, i.e. ingestion of feces from their mother, reduces mortality after weaning. We hypothesized that this beneficial effect of coprophagia is immune-mediated at the intestinal level. Therefore, this study investigated immune development after weaning by analyzing the ileal transcriptome at day 35 and 49 in rabbits with differential access to coprophagia in early life. Rabbit pups had access between day 1 and 15 to (i) no feces (NF) or (ii) feces from unrelated does (Foreign Feces, FF) or (iii) feces from unrelated does treated with antibiotics (FFab). 350 genes were differentially expressed between day 35 and day 49 in suckling rabbits with access to coprophagia. These genes coded for antimicrobial peptides, a mucin, cytokines and chemokines, pattern recognition receptors, proteins involved in immunoglobulin A secretion and in interferon signaling pathway. Strikingly, prevention of coprophagia or access to feces from antibiotic-treated does in early life blunted immune development between day 35 et 49 in the ileum of rabbits. Thus, coprophagia might be crucial for the maturation of intestinal immunity in rabbits and could explain why this behavior improves survival.

Thermoregulation at birth differs between piglets from two genetic lines divergent for residual feed intake.

Thermoregulation is essential to piglets' neonatal survival. This study used infrared thermography (IRT) to assess thermoregulation abilities of piglets from two lines divergent for residual feed intake (RFI). At birth, morphology (weight, length, width and circumference), vigour (respiration, mobility and vocalisation), and rectal temperature were recorded from piglets of the 11th generation of the low RFI (LRFI, more efficient; n = 34) and the high RFI (HRFI, less efficient; n = 28) lines. Infrared thermography images were taken at 8, 15, 30 and 60 min post partum. Temperatures of the ear base and tip, and of the back (i.e. shoulders to rumps) were extracted (Thermacam Researcher Pro 2.0) and analysed with linear mixed models (SAS 9.4). Piglets had different average hourly weight gain (HRFI = 7.1 ±â€¯1.3 g/h, LRFI = 3.6 ±â€¯1.3 g/h; P < 0,001) but did not differ in morphology or vigour. All temperatures increased overtime. At birth, piglets' rectal temperature was correlated with the initial temperature of the ear base and the maximum back temperature (0.37 and 0.33, respectively; P < 0.05). High residual feed intake piglets had lower ear tip temperatures than LRFI piglets at 15 (24.7 ±â€¯0.37 °C vs. 26.3 ±â€¯0.36 °C, respectively; F1, 63.5 = 9.11, P < 0.005) and 30 min post partum (26.2 ±â€¯0.47 °C vs. 27.6 ±â€¯0.44 °C, respectively; F1, 66.9 = 4.52, P < 0.05). Moreover, thermal pattern of the ear tip differed between the two genetic lines. In conclusion, IRT allowed non-invasive assessment of piglets' thermoregulation abilities and indicated an influence of genetic selection for RFI on neonatal thermoregulation abilities.