凯发平台

猪只常见的一系列应激因素

发布单位:凯发平台

查看次数：7301

时间：2019-12-12

应激会对猪只的免疫力产生负面影响，在猪只的不同生长阶段，对猪只产生严重影响的应激因素并不尽相同。有猪只研究专家总结并描述了如何能够更好地应对猪群应激问题。
应激被定义为对不良刺激（无论是生理、心理还是情感上的）的一切生物反应，无论是在体内还是体外，它扰乱了机体的平衡（平稳运行）。许多应激对免疫系统有有害的影响，可能导致一种轻微的反应（称为亚临床反应），通常不会立即被察觉；或者产生临床反应（明显的或急性的）很快就显现出来。
应激产生的3个阶段：①首先是一种警报反应，通常是对应激源的出现立即做出的反应，此时身体的防御系统会激活肾上腺素和非肾上腺素，这两种激素会刺激机体做出“战斗或逃跑”反应。 ②其次，通过减缓应激源的刺激，使机体协调一致，协助控制应激。 ③再次，如果身体对这些防御措施没有反应，或者反应太慢，就会产生疲劳，干扰血液中的糖分，身体储备就会被耗尽，足以导致死亡。
贯穿于猪只一生的常见应激源： ①新生儿，特别是在刚出生时， 卫生问题/病原体（病原体是新生猪的典型应激源）、来自兄弟姐妹的竞争、寒冷、不正确的移动进食（常见的错误）、断奶后的检查。 ②生长阶段，温度变化和温度本身一样重要，空间不足、病原体、睡眠不足、缺乏食物和水、空间布局、充足的空气和流通情况、兴趣、以及运输、转栏过程中的恶劣条件。 ③分娩的母猪，分娩的难易和时长、水的充足性和温度（特别是在炎热的条件下）、舒适度欠缺、寄生虫、断奶的方法等。④妊娠期，排卵、配种、着床、圈养和舒适度、群体竞争（欺凌）、自动喂料槽的设计、肠道填充物/纤维、温度、寄生虫、水质缺乏和质量等。
如何控制这一切：应激检查是绝对有必要的，①仔细观察猪只，不要分心，找出不正常的应激诱发行为和前一次应激时发生的变化。 ②检查所有设备（温度计，控制器，传感器，风扇速度，其他安全覆盖范围的设备），储料器和饲料槽、水点都需要观察，以确保猪只是舒适的。 ③对猪只管理人员进行压力检查，能够起到观察工作人员在猪只应激时是如何操作处理的。例如，母猪在接受授精时容易受到不友善的对待；在配种期间，由于有很多的事情需要在同一时间完成，工作人员的情绪很容易受到影响。他们可能需要一些帮助和调整工作负荷。

A long list of common stress factors for pigs
Stress can have a negative impact on the immunity in pigs – and which type of stress affects them most depends on the age of the animal. Pig management expert John Gadd sums them up – and describes how to be better prepared to keep the stress away from the herd.
Stress is defined as any biological reaction to an adverse stimulus, physical mental or emotional, which disturbs the homoeostasis (‘smooth running’) of the body, be it internally or externally. Many stressors have a harmful effect on immunity, resulting in either a minor reaction (called subclinical) and usually not normally immediately noticeable, or a clinical (obvious or acute) one which is only too quickly apparent.
In farming language – 3 stages
1. First an alarm response, usually immediate, to the appearance of a stressor where the body’s defences activate the hormones adrenaline and no-adrenaline which stimulate the ‘fight or flight’ reaction. Digestion stops, heartrate increases and appetite goes – all profit-zappers!
When handled properly, even on their way to slaughter, the pigs’ stress levels can be kept low. Photo: Ronald Hissink
2. Next the body tries to get itself together by slowing down what can be considered its ‘fast-running engine’ so as to assist in controlling the stressor, the two debilitating hormones, which are partially replaced by useful corticosteroids which take the pressure off growth restriction by adjusting digestion, and slowing the functions of the sex organs especially at ovulation and implantation. But in doing this, so as to give the body some ‘breathing space’, so to speak, they reduce the number of white blood cells which fight disease, so the immune status may be damaged and productivity is worsened.
3. Thirdly, should the body not, or be too slow to respond to these defence measures, exhaustion sets in which interferes with the sugar in the blood (the source of the engine’s fuel) and body reserves can become depleted enough to result in death.
Common stressors throughout a pig’s life
The neonate
? Recovery from the unavoidable stresses of being born, especially the last to do so, thus needing special attention;
? Cleanliness/pathogens;
? Competition from siblings;
? Cold;
? Thirst;
? Inappropriate creep feed (a common error); and
? The ‘post-weaning check’.
Pathogens are a typical stressor for neonatal pigs. Illustration: Shutterstock
The grow-out stage
? Temperature variation is as important as temperature itself, which is why regular supervision of all equipment affecting the pig’s ambient (surrounding) temperature is essential; it can rapidly go wrong;
? Lack of enough space;
? Pathogens;
? Lack of adequate sleep;
? Lack of food and water;
? Growing pigs especially get fractious and anxious if regular attention is missing;
? Bad ventilation – air placement is as important as adequacy;
? Failure in keeping them interested/occupied; and finally
? Bad conditions during transport, handling and lairage.
The farrowing sow
? Ease and length of farrowing;
? Water adequacy and temperature especially in hot conditions;
? Lack of comfort;
? Parasites; and
? Method of weaning.
Gestation
? Ovulation;
? Service;
? Implantation;
? Confinement and comfort;
? Competition (bullying) in groups;
? Design of automatic feeding pens;
? Gut fill/fibre;
? Temperature;
? Legs and floors;
? Parasites;
? Insufficient or bad quality water.

文章来源：猪营养国际论坛
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