Effect of hot environment on cell surface differentiation antigens of porcine peripheral lymphocytes from sows and litters

The effects of floor heating on body temperature, water consumption, stress response and immune competence around parturition in loose-housed sows

The aim of the present study was to study whether floor heating from 12h after onset of nest building until 48 h after birth of the first piglet had any effect on measures related to body temperature, water consumption, stress response and immune competence in loose-housed sows (n=23). In conclusion, the present results indicate that floor heating for a limited period around parturition did not compromise physiological and immunological parameters, water intake and body temperature in loose-housed sows. The water intake peaked the day before parturition and the body temperature peaked on the day of parturition. A cortisol peak at parturition, a transient rise in the number of leucocytes and neutrophils and a transient reduction in the number of lymphocytes, erythrocytes and in the PCV value were observed. Around and after parturition some non-specific immunological variables seemed to be stimulated while others seemed to be compromised.

Interactions between environmental temperature and porcine growth hormone (pGH) treatment in neonatal pigs

Age-dependent interactions between environmental temperature and porcine growth hormone (pGH) treatment on the function of the somatotrophic axis were evaluated in the neonatal pig. At 3 d of age, 40 Landrace x Yorkshire x Duroc piglets received intraperitoneal implants containing either recombinant pGH (0.5 mg/d; n = 20) or vehicle (control; n = 20). Piglets were maintained at either a low (21 degrees C, 50% relative humidity; n = 20) or high (32 degrees C, 50% relative humidity; n = 20) temperature. At 4 and 6 wk of age, 5 pGH-treated and 5 control piglets from each thermal group were sacrificed for tissue collection. Blood samples were collected at the time of sacrifice and analyzed for serum concentrations of GH, insulin-like growth factor 1 (IGF-1), and IGF-2. Liver RNA was analyzed for mRNAs specific for the GH receptor, IGF-1, IGF-2, and IGF binding protein 3. There was no effect of pGH treatment (P = 0.4) on average daily gain; however, both age (P = 0.002) and temperature (P = 0.001) had an effect on average daily gain such that those animals maintained at a low temperature and those sacrificed at 6 wk had greater average daily gains. Serum concentration of GH was elevated (P = 0.003) by pGH treatment and was lowest in the 6-wk-old group (P = 0.008). Serum concentration of IGF-1 was elevated (P = 0.007) by pGH treatment and increased with age (P = 0.01). Liver GH receptor mRNA was unaffected (P > 0.5) by pGH treatment, but was greater in the 6-wk-old group (P < 0.0001) and in piglets maintained at the high temperature (P = 0.04). IGF-1 mRNA was enhanced by pGH treatment (P = 0.0003) and by exposure to the high temperature (P = 0.04), but did not differ (P > 0.5) between age groups. IGF-2 mRNA was greater (P = 0.0009) in the 4-wk-old group and in piglets maintained at the high temperature (P = 0.007), but was unaffected (P = 0.5) by pGH treatment. IGF binding protein 3 mRNA increased with age (P = 0.0004) and was stimulated by pGH treatment in the 6-wk-old group (P = 0.034). The relatively lower level of GH receptor and IGF mRNAs in conjunction with greater growth in the cold environment suggests that somatotrophic gene expression in the liver is not rate limiting for growth in the neonatal pig.