In the modern laying hen industry, the degree of intensification and competitive pressure is increasing. Particularly, environmental changes, unstable formulation materials, frequent disease, etc. will bring sustained physiological and pathological burden to the hens. Therefore, the liver is always in an overloaded state, causing bile acid secretion to not meet the normal needs of the body.
As producers continue to pursue production efficiency, the body pressure on laying hens is increasing, and the burden on the liver which is the ‘biggest processing plant’ in the body is undoubtedly huge. Damage to the liver and gallbladder of laying hens from 38 weeks of age until elimination period is very common; the incidence rate is 60-90%, of which 50-70% of the mortality is caused by fatty liver.
Laying hen fatty liver and its harm
Fatty liver of laying hens, also known as fatty liver syndrome, is a nutritional metabolic disease which is commonly found in laying hens, especially in breeding after 38 weeks. It is mainly due to fat imbalance in liver deposition and extrahepatic transport. Firstly, anatomy will reveal a large amount of fat deposition in the abdominal cavity, especially in the abdomen, muscle and glandular stomach. Secondly, the liver is swollen, bleeding, crisp and greasy, and is easy to rupture (see Image below).
production rate, higher feed-to-egg ratio, and lower eggshell quality, such as increased non-commodity
egg rate.
Causes of fatty liver in hens
1 – Over nutrition: Mainly refers to excess energy in the feed, and it will be stored in the liver in the
form of fat.
2 – Nutritional Deficiency: When there is a deficiency of nutrients such as choline (or choline
chloride, betaine), methionine, and vitamins in the feed, there will be a problem of fat
transferring from the liver and will cause accumulation in liver cells.
3 – Less Exercise: Laying hens are kept in small areas, which greatly limits the exercise ability, thus the
energy consumption is greatly reduced, and the excess energy will be converted into fat.
4 – Hormone effects: The level of egg production is closely related to the activity of estrogen.
Estrogen can promote the synthesis and deposition of the fat in liver.
5 – Toxin effects: Aflatoxins, etc. can seriously damage the liver, and will decrease the ability of the
liver to synthesise lipoproteins and reduce the ability to transport fat out of the liver.
6 – Other factors: High levels of unsaturated fatty acids in the feed, oxidative rancidity of oils, and
decreased levels of antioxidants such as vitamins can lead to the production and accumulation
of free radicals, which will damage the liver.
Application of bile acids in layer production
toxins, metabolic toxins and other toxins from the liver through bile. In addition, bile acids can also
effectively decompose or combine with endotoxins, relieve liver burden, and keep the liver in optimal
work status. More than 95% of eggshell components are calcium carbonate.
Results from trials with bile acid supplementation
group, with 3 replicates in each group and 1000 layers in each replicate. The control group was fed a
basic diet, and the experimental group was supplemented with 60 ppm bile acids. The pre-trial period
was 7 days and the trial period was 30 days.
group was significantly increased, and the egg feed ratio and the mortality rate were significantly
decreased.
group. The control group was fed a basic diet, and the experimental group was supplemented with 60
ppm bile acids. The pre-trial period was 10 days and the trial period was 42 days.
It can be seen from Table 2 that compared with the control group, the addition of bile acids in the diet
significantly improved the egg yolk colour, eggshell hardness and eggshell colour at the 6th week and the 12th week.
Relieving the burden on the liver
improve the utilisation of fat-soluble vitamins and calcium with better performance of layers and better
quality of eggshells to bring considerable economic benefits to the layer farming industry.
