HatchTech B.V., AG Veenendaal, the Netherlands.
Poult Sci. 2013 Aug;92(8):2145-55. doi: 10.3382/ps.2013-03006.
Previous studies have shown that RH during incubation of chicken eggs influences water loss from the egg and embryonic mortality. In those studies, eggshell temperatures (EST) were not monitored or controlled. Because RH influences the egg's heat loss through evaporation, EST might have been different between RH treatments, influencing embryonic mortality and development. To eliminate the effect of EST, in the current study eggs were incubated at an EST of 37.8°C from embryonic d (E) 0 until E18 and at a high (55 to 60%) or low (30 to 35%) RH from E2 until hatch. Embryonic mortality, hatch curve, and several chick quality characteristics (length, weight, navel quality, organ weights, and DM of the yolk free body mass and yolk) were determined on E18 and at hatch. Low RH increased egg weight loss between E0 and E18 (+3.0%) and third week embryonic mortality (+3.0% of fertile eggs) and decreased hatch of fertile eggs (-2.9% of fertile eggs) compared with high RH. Hatch duration and chick quality characteristics did not differ between RH treatments. To assess the effect of RH during incubation on posthatch performance under suboptimal conditions, hatchlings were brooded at a normal (35.0°C at d 0, decreasing to 27.0°C at d 4) or cold (27.8°C at d 0, decreasing to 25.6°C at d 4) temperature until 4 d posthatch. Incubation RH and brooding temperature significantly interacted with posthatch growth but not development. Both low and high RH × cold brooding temperature resulted in lower (-6.9 and -6.0 g, respectively) BW than high RH × normal brooding temperature at 4 d of age. The cold brooding temperature resulted in lower daily feed intake (-1.3 g/chick) than the normal brooding temperature. In conclusion, incubating eggs at a low RH compared with a high RH and maintaining the EST at 37.8°C decreased hatch of fertile eggs, but had little effect on chick quality or posthatch performance.
先前的研究表明，孵化鸡胚时的相对湿度（RH）会影响蛋内水分的损失和胚胎死亡率。在这些研究中，并未监测或控制蛋壳温度（EST）。由于 RH 通过蒸发影响蛋的热损失，因此 RH 处理之间的 EST 可能有所不同，从而影响胚胎死亡率和发育。为了消除 EST 的影响，本研究在从胚胎第 0 天（E）0 至 18 天期间，将蛋的 EST 保持在 37.8°C，然后在 E2 至孵化期间将其置于高（55 至 60%）或低（30 至 35%）RH 环境下。在 E18 天和孵化时，测定胚胎死亡率、孵化曲线和几只小鸡的质量特征（长度、体重、脐部质量、器官重量、蛋黄自由体质量和蛋黄的 DM）。与高 RH 相比，低 RH 增加了从 E0 至 E18 天的蛋重损失（+3.0%）和第三周胚胎死亡率（+3.0%的可育蛋），并降低了可育蛋的孵化率（-2.9%的可育蛋）。孵化时间和小鸡质量特征在 RH 处理之间没有差异。为了评估孵化期间 RH 对次优条件下孵化后性能的影响，将孵化出的小鸡在正常温度（第 0 天 35.0°C，第 4 天降至 27.0°C）或低温（第 0 天 27.8°C，第 4 天降至 25.6°C）下育雏，直到孵化后 4 天。孵化 RH 和育雏温度显著与孵化后生长有关，但与发育无关。低 RH 和高 RH×低温育雏温度都会导致小鸡体重降低（分别为-6.9 和-6.0g），而高 RH×正常育雏温度在 4 天时的体重较高。低温育雏温度导致的每日采食量（-1.3g/只小鸡）低于正常育雏温度。总之，与高 RH 相比，在低 RH 下孵化鸡蛋并将 EST 保持在 37.8°C 会降低可育蛋的孵化率，但对小鸡的质量或孵化后性能影响不大。
