【环境和牛】METABOLIC AND ENVIRONMETAL HEAT 代谢热和环境热

The issue of environmental impacts on dairy production welfare has long been of interest to the industry. One environmental stressor, which has commanded considerable research attention within the past several decades, has been thermal stress. Production loss due to heat stress has been estimated at $900 million annually to U.S. dairy herd (St.Pierre et al., 2003).

业界长期以来一直关注对奶业生产的环境影响和动物福利问题。热应激是一个在过去儿十年中受到相当大研究关注的环境压力因素。美国奶牛群每年因热应激造成的生产损失估计为9亿美元（St. Pierre 等人，2003）。这种研究热应激的兴趣恰逢美国乳业从中西部地区打展到史暖和更干早的气候地区（如西南沙漠地区），也由于每头奶牛平均产量翻番，因此对热敏感度提高。温暖气候条件下牧场建筑技术的改进，为暴露在炎热气候下的动物提供了更有效的降温技术。然而，热应激仍然是奶牛的一个重要的环境压力因素。

Proper ventilation of dairy barns is vital importance. Dairy cows need a constant source of fresh and clean air to maximize their production potential. Ventilation systems in dairy barns help maintain a comfortable environment to keep cows healthy and productive Stale air harmfully affects milk production and milk quality. High moisture, manure gases, pathogens, and dust concentrations present in unventilated or poorly ventilated barns provide an adverse environment for cows.

适当的牛舍通风是至关重要的。奶牛需要持续不断的新鲜、 清洁空气来最大限度地发挥其生产潜力。奶牛场的通风系统有助于保持舒适的环境，保持奶牛健康和生产性能。污浊的全气对奶牛奶产量和奶牛奶质量有害。存在于不通风或通风恶劣的牛舍中的高水分、粪便气体、病原体和高浓度灰尘给奶牛带来了不利的环境。

Cows continuously produce heat and moisture (METABOLIC AND ENVIRONMETAL HEAT). Therefore, a ventilation system is necessary to constantly exchange warm, humid air inside the barn for cooler, drier air outside of the barn. This exchange must occur regardless of outside temperature or weather conditions. Fresh outside air is required even on a cold, windy night to reduce moisture accumulation inside the barn. Good air exchange also removes nuisance odors and manure gases that can have negative effects on animal health and performance.

奶牛不断产生热量和潮气（代谢热和环境热）。因此，通风系统必须不断地将牛舍内的温暖潮湿的空气换成牛舍外面比较凉爽、干燥的空气。无论室外温度或天气情况如何，都必须进行交换。即使在寒冷、多风的夜晚也需要新鲜的室外空气，以减少牛舍内潮气的积累。良好的空气交换还可带走那些对动物健康和性能有 负面影响的恶臭气味和粪便气体。

The articles in this series will explore the environmental impact of dairy farming and aims to provide technical advice (to Farmer and Owner, technical stalt) on practical suggestions, which could be easily monitored on how to reduce or eliminate any identified negative environmental, mechanical or technical effects of dairy farming.

本系列文章探讨了环境给奶牛养殖的影响，旨在为牧场业主、工作人员以及技术人员提供实用的技术建议，以便于大家可以很容易地看到采取哪些手段能够降低甚至消除哪些给奶牛养殖带来负面影响的环境、机械或技术问题。

PART.1

METABOLIC AND ENVIRONMETAL HEAT

代谢热和环境热

Cows generate heat internally (metabolic heat) as a result of eating and digesting feed.Like most mammals, the dairy cow needs to maintain its core body temperature within a narrow range around 39°C (between 38.6°C and 39.3°C) The core temperature fluctuates slightly throughout the day, reaching a peak in the early evening and a low early morning. Cows also lake day heelfrom the environment around them. The cycle of gaining and losing heat absorbed from the environment is on going and always operates in the context of the metabolic heat a cow is carrying at any given time.

由于进食和消化饲料，奶牛内部会产生热量（代谢热量）。像大多数泌乳动物一样，奶牛帝要将核心体温保持在 39 摄氏度左右的狭窄范围内一具体来说就是在 38.6 摄氏度到 39.3摄氏度之间！核心温度全天略有波动，在傍晚达到峰值，在早晨达到谷值。奶牛也会从周围的环境中获取热量。从环境中吸收和损失热量的循环一直在进行，与此同时，代谢热量也一直伴随着奶牛。