【分享】来庆文译 | 肉鸡增重 VS 肉鸡体温

共享精神

A fast-growing broiler produces a surprising amount of heat, roughly 10 - 15 Btu/hr per pound of body weight. To put this in perspective, a single match produces one Btu/hr of heat which means that a four pound broiler has essentially 40 to 60 matches of heat being produced within it. An eight-pound broiler would have 80 to 120 matches of heat within it, heat it must continually rid itself of in order to maintain anormal body temperature.

白羽肉鸡生长过程中会产生大量的热量，粗略计算，每磅体重的肉鸡，每小时会产生10 - 15 BTU的热量。（换算一下就相当于每公斤体重的肉鸡一小时大约产生23.2-34.9千焦的热量）从这方面比较一下，一根火柴每小时产生的热量是 1 BTU，即1.055千焦，这意味着一只4磅重的肉鸡（1.81公斤）产生了相当于40-60根火柴散发的热量。一只8磅的肉鸡会散发相当于80-120根火柴产生的热量。所以，为了维持肉鸡自己合适的体温，它必须持续不断的排除这些热量。

As a bird’s body temperature increases, feed consumption will decrease. This is because it is essentially the digestion of feed that generates the heat within a bird that can potentially lead to dangerously elevated body temperatures. So it stands to reason that a bird with an elevated body temperature will tend to reduce its consumption of the very thing, namely feed, that is causing its elevated body temperatures. After all, how likely are we to eat a big meal on a hot summer afternoon?Reduced feed consumption will, in turn, lead to lower growth rates. It’s quite simple. If we want to maximize bird performance we must create an environment where the bird can easily get rid of the excess heat it is producing.

随着鸡体温的升高，采食量会降低，饲料消耗量会减少。这是因为肉鸡采食饲料，饲料消化，使鸡体产生热量，此产生的热量可能会导致鸡体温上升到危险的地步。因此，我们有理由认为，一只体温升高的鸡往往会减少采食。 毕竟，设身处地的想一下，你会在炎热的夏日，下午吃大餐吗？ 饲料消耗量的减少反过来又会导致生长速度的下降。 很简单。如果我们想最大限度地提高肉鸡的生产性能，我们 必须创造一个凉爽的环境，让鸡群可以很容易地排除它产生的多余热量。


Figure 1. Study birds in pen

A recent field study conducted on a commercial broiler farm provided a good illustration of the relationship between body temperature and weight gain during the last week of a flock. Eight, 34-day  old-broilers from one of the houses on the farm ingested a small temperature logger that recorded their body temperatures every minute, The birds were placed in a pen within the house until the house was caught five days later (Figure 1). Birds were weighed at the beginning and end of the study (Table1). House air temperatures were measured every minute and ranged from the mid-seventies to the mid-eighties (Figure 2). Air speed was measured four feet above the pen and was found to average approximately 500 ft/min.

最近在一个商业肉鸡养殖场进行的一项田间研究很好地说明了肉鸡群在最后一周内的体温和增重之间的关系。在某鸡场的同一栋鸡舍内，给8只34日龄的鸡安装了小型温度记录仪。可以每分钟记录一次他们的体温。这八只鸡被放置在鸡舍内的一个围栏内，直到5天后出栏。在研究开始和结束时，我们都对此鸡群进行了称重（表1）。舍内的气温每 分钟测量一次，舍内温度保持在23.9-29.4之间。在围栏上方0.1米处测量风速，发现平均风速约为500英尺/分钟。即2.5m/s 米每秒左右。



The weight gain for each bird over the five-day study was determined and graphed against its average body temperature (Figure 2). Normal deep body temperature for a broiler is approximately 106oF. Average body temperature for the birds during the study ranged between 106.5oF (normal) and 108.8oF (extremely high). The two birds with average body temperatures of over 108oF did not gain weight during the study (one actually lost weight). The two birds with the lowest average body temperatures (approximately 106.5oF) had the highest weight gain  of approximately 1.3 lbs. There was no correlation between initial body weight and body temperature.This is likely due to the fact that there was a minimal difference in the initial weights among the birds.

在为期五天的研究中，研究人员记录了每只鸡的体重增加情况，并根据其平均体温绘制制成图表（图2）。一只肉鸡的正常深部体温约为106度oF.大约41.1摄氏度。在研究期间，这些肉鸡的平均体温在 41.1度（正常）和42.7（极高）之间。研究期间，这两只鸡的平均体温超过了42.2度，体重没有增加(  其中一个实际上体重减轻了）。平均体温最低的两只鸡的增重幅度最大。差不多1.3磅，0.59公斤。实验开始时的初始体重和体温之间没有相关性，这可能是因为这些鸡的初体重，差别很小。


Figure 2. Weight gain vs. avg. body temperature
图2 ，增重和平均体温之间的关系

As documented in this, as well as previous field studies, there is a significant variation in bird body temperatures within a house (Figure 3). The variation can be due to differences in location within a house, density in the vicinity of a given bird, bird size, genetics, growth rate, health status, etc. For instance, the bird with the highest body temperature was found to have a slight respiratory infection. The other bird with an average body temperature of over 108oF likely had some other health issue but anecropsy of the bird did not find any obvious health issues. The fact remains whether an elevated body temperature is due to illness or insufficient heat removal due to high ambient temperature/RH, a bird’s response will be the same; it will consume less feed, and as a result gain less weight.

正如本文以及之前的田间研究一样，同一个鸡舍内鸡的体温存在显著变化（图3）。这种差异可能是由于鸡在鸡舍内的位置  、不同区域附近鸡的密度、鸡群的大小、遗传、生长速度 、健康状况等方面的不同。例如，体温最高的那只鸡被发现有轻微的呼吸道感染。另一只鸡的平均体温超过42.2度 的可能还有其他一些健康问题，但对这只鸡的尸检没有发现任何明显的健康问题。事实仍然是，无论鸡体温升高是由于疾病，还是由于高温高湿引起的鸡体多余热量无法去除，鸡群的反应将是相同的；它会减少采食，这就导致了鸡群增重不理想。或者料比过高。



一天内鸡的体温变化。

The objective of managing the environment during hot weather is quite simple, to make sure we remove enough heat from the birds through the use of air speed and evaporative cooling that birds don’t have to reduce their consumption of feed to limit their heat production. If a bird has to try to lower its body temperature, performance will suffer. They will pant,which will tend to make feed conversion rates worse and/or back off of feed, which will lower their growth rates. The greater the amount of heat we pull from the birds, the more likely they will have a stable body temperature and continue to eat the feed required to maximize weight gain and overall performance.

在炎热的高温高湿的天气下，鸡舍环境管理的目标非常简单，通过风速和湿帘降温来带走鸡舍和鸡群产生的多余热量，这样鸡群就不必通过减少采食来限制自身的热量产生。如果一只鸡必须努力尝试降低其体温，其生产性能一定就会受到影响。它们会张开大口，热喘，不吃饲料，这将会降低饲料转化率，增加料比，影响生长速度。我们从鸡体中带走的多余热量越多，鸡越有可能保持稳定的体温，并将继续吃料，以最大限度的增重和提高生产性能。

Do we have to be concerned about potentially over cooling market-age birds during summertime? In most cases, no. A market-age bird has much greater ability to limit its heat loss than to increase its heat loss. For instance, a bird can dramatically lower its heat loss by simply fluffing its feathers. The trapped air between the feathers increases their insulation value, which lowers bird heat loss even with high levels of air moving across the bodies. Birds can sit closer together or pull their wings closer to their bodies, further lowering their potential heat loss.When compared to a bird’s primary method of ridding itself of excess heat, panting, these heat conservation efforts require very little effort from the birds. As a result, it is far safer with market-age birds to maximize air movement over them 24/7 than, for  instance, turning a few fans off at night for fear of“chilling” the birds.

在炎热的夏季，我们会担心临近出栏的肉鸡受凉吗？在大多数情况下，不会担心。接近出栏的大鸡，自身保温的能力比它散热的能力大的多，举个例子，鸡只只需把羽毛收紧就能显著减少热量流失。困在羽毛之间的空气增加了热阻，即使有风速，空气流过鸡体，鸡群可以靠得更近，或者把翅膀拉得离身体更近，从而进一步降低它们潜在的热量损失。 与鸡散热的主要方式,喘息相比，这些保温方法，对鸡的要求很低。因此，对于临近出栏的鸡群，全天候24小时，最大限度地增加空气流动，比在晚上因为害怕鸡群受凉，关掉一些风机要安全得多。

Though this field study was limited in scope, and further trials need to be conducted, it does reinforce a basic hot weather bird management principle: The more a heat a producer can remove from their birds, the better they will perform. The best way for producers to remove excess heat from their birds during hot weather is through wind speed. The greater the wind speed in a house, the greater the heat removed from the birds, the lower the birds’ body temperatures will be, the more feed they will eat, andthe more weight they will gain.

虽然这一田间研究的范围有限，还需要进行进一步的试验 , 但它确实印证了一个基本的炎热天气鸡群管理原则：鸡场管理者从鸡群身上去除的多余热量越多，它们的表现就越好 。在炎热的天气里，管理者移除鸡群多余热量的最好方法是通过风速。鸡舍的风速越大，从鸡群带走的热量就越多，鸡群的体温就越低，它们吃的食物就越多，增加的体重就越重。料比也会很低。鸡群生产性能大大提高。

来源：一个养鸡人的财富自由之旅

DF蓝天白云

谢谢分享！

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黄哥（黄瑞强）

非常好

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