豬只常見的一系列應激因素

發(fā)布單位:天津瑞孚農(nóng)牧科技集團有限公司

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時間：2019-12-12

應激會對豬只的免疫力產(chǎn)生負面影響，在豬只的不同生長階段，對豬只產(chǎn)生嚴重影響的應激因素并不盡相同。有豬只研究專家總結并描述了如何能夠更好地應對豬群應激問題。
應激被定義為對不良刺激（無論是生理、心理還是情感上的）的一切生物反應，無論是在體內(nèi)還是體外，它擾亂了機體的平衡（平穩(wěn)運行）。許多應激對免疫系統(tǒng)有有害的影響，可能導致一種輕微的反應（稱為亞臨床反應），通常不會立即被察覺；或者產(chǎn)生臨床反應（明顯的或急性的）很快就顯現(xiàn)出來。
應激產(chǎn)生的3個階段：①首先是一種警報反應，通常是對應激源的出現(xiàn)立即做出的反應，此時身體的防御系統(tǒng)會激活腎上腺素和非腎上腺素，這兩種激素會刺激機體做出“戰(zhàn)斗或逃跑”反應。 ②其次，通過減緩應激源的刺激，使機體協(xié)調(diào)一致，協(xié)助控制應激。 ③再次，如果身體對這些防御措施沒有反應，或者反應太慢，就會產(chǎn)生疲勞，干擾血液中的糖分，身體儲備就會被耗盡，足以導致死亡。
貫穿于豬只一生的常見應激源： ①新生兒，特別是在剛出生時， 衛(wèi)生問題/病原體（病原體是新生豬的典型應激源）、來自兄弟姐妹的競爭、寒冷、不正確的移動進食（常見的錯誤）、斷奶后的檢查。 ②生長階段，溫度變化和溫度本身一樣重要，空間不足、病原體、睡眠不足、缺乏食物和水、空間布局、充足的空氣和流通情況、興趣、以及運輸、轉欄過程中的惡劣條件。 ③分娩的母豬，分娩的難易和時長、水的充足性和溫度（特別是在炎熱的條件下）、舒適度欠缺、寄生蟲、斷奶的方法等。④妊娠期，排卵、配種、著床、圈養(yǎng)和舒適度、群體競爭（欺凌）、自動喂料槽的設計、腸道填充物/纖維、溫度、寄生蟲、水質(zhì)缺乏和質(zhì)量等。
如何控制這一切：應激檢查是絕對有必要的，①仔細觀察豬只，不要分心，找出不正常的應激誘發(fā)行為和前一次應激時發(fā)生的變化。 ②檢查所有設備（溫度計，控制器，傳感器，風扇速度，其他安全覆蓋范圍的設備），儲料器和飼料槽、水點都需要觀察，以確保豬只是舒適的。 ③對豬只管理人員進行壓力檢查，能夠起到觀察工作人員在豬只應激時是如何操作處理的。例如，母豬在接受授精時容易受到不友善的對待；在配種期間，由于有很多的事情需要在同一時間完成，工作人員的情緒很容易受到影響。他們可能需要一些幫助和調(diào)整工作負荷。

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.

文章來源：豬營養(yǎng)國際論壇
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