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An experiment was conducted to investigate the effect of relative humidity (RH) at chronic temperature on growth performance, glucose consumption, and mitochondrial adenosine triphosphate (ATP) production of broilers. A total of 180 28-day-old Arbor Acres broilers (half males and half females) were randomly allocated to three treatments, each containing six replicates of 10 birds per treatment, using a completely randomized design. Birds were reared at 35, 60 or 85% RH at 32°C for 15 days (temperature increased by 3°C every 3 days from 20 to 32°C within 15 days: 20−23−26−29−32°C). RH affected (P

The responses of soil total respiration (Rs) and its components (soil autotrophic respiration (Ra) and heterotrophic respiration (Rh)) to nitrogen (N) deposition have been widely evaluated in non-saline-alkaline grasslands. However, their responses to N addition under drought and wet conditions, especially in saline-alkaline grasslands, remain unclear. A two-factorial experiment involving N addition and precipitation changes (decreased or increased 50% precipitation relative to ambient) was conducted in a saline-alkaline grassland of Northern China, while soil respiration was measured in different treatment plots during two growing seasons (2018, 2019). Results showed that the addition of N or changes in precipitation alone had no significant effect on Rs, Ra or Rh in both years because root productivity and soil microbial biomass were not affected. However, N addition with increased precipitation synergistically augmented seasonal mean Rs and Ra by 25.7% and 46.8% in 2018, and by 42.4% and 89.3% in 2019, respectively, owing to the increase in plant productivity. The variation in Ra primarily contributed to variation in Rs, and the effect size of N addition on Rs and Ra were increased with precipitation. In addition, a structural equation model showed that the response of soil respiration to N addition and precipitation changes was regulated by soil salinization, in which the Ra was regulated by soil based cations while Rh was controlled by soil pH values. Our study highlights that N addition with increased precipitation preferentially affects plants rather than microorganisms, and that Rh was not sensitive to N addition and precipitation changes in saline-alkaline grassland.

In order to measure the real-time variations in body temperature with increasing ambient temperature (AT) at different relative humidity (RH) levels, 60 Jinghong laying hens (35-wk-old) were raised in 3 controlled climate chambers (10 cages with 2 birds per chamber). The RH was fixed at one of 3 levels comprising 35, 50, or 85%, and the AT was increased gradually by 1 degree per 0.5 h from 18 to 35°C in the 3 chambers. The core temperature (CT) and surface temperature (ST) of the hens, as well as the AT in the 3 chambers were recorded at 3 min intervals using mini temperature data loggers. The data were analyzed with a broken-line model to determine the inflection point temperature (IPT, the certain AT above which the body temperature of the hens started to change). The experiment was repeated 3 times on 3 d. The IPTs of the laying hens were 23.89 and 25.46°C based on ST and CT at 50% RH, respectively, which indicated that the upper critical temperature of the thermoneutral zone of hens may be a specific temperature between 23.89°C and 25.46°C. The IPTs of the laying hens were 24.11 and 25.20°C based on ST and CT at RH 35%, respectively, and 21.93 and 24.45°C at RH 85%. The RH significantly affected the IPT of ST (P0.001). The IPTs were higher at 35 and 50% RH than that at 85% RH (P0.05). The coefficients of variation for the IPTs between individual hens were 2.96 to 4.51, and coefficients of variation for the IPTs for the same bird measured on 3 d were 0.69 to 1.59, thereby indicating that this method for estimating the IPTs of hens is stable and repeatable, although more samples are needed. In conclusion, our results indicate that analyzing the real-time variation in body temperature with increasing AT is a reliable method for estimating the IPT to provide an important reference for regulating the temperature in poultry houses.