The mysterious crop milk and Miobol

How can Miobol explain the remarkable breeding results?  Why Miobol is an important supplement even during the flying season…

Background: The crop is a pouch-like thickening to the left and right halfway down the oesophagus. It stores and prepares food for digestion so that the food bolus can travel further down the oesophagus.


Above right, the crop halfway down the oesophagus.

Wave-like movements occur in the crop. The intensity, rhythm and strength of these depend on factors like hunger, nervousness and stress. These are more intense when the bird is hungry. These are completely absent when the crop is empty with the sphincter at the bottom closing ‘ waiting’ for new food.


Is artificial pigeon milk a possibility? 

Its high nutritional value has led to a variety of ongoing studies.

In recent years, the market demand for ‘meat’ pigeons has risen rapidly. Pigeons are altricial (the young need intensive parental care). This sharply constrains the production efficiency of meat pigeons, which is a severe economic disadvantage in terms of breeding. So, developing artificial alternatives to natural pigeon milk for feeding the young during the breeding period may be a good solution. 

However, the secretion of crop milk occurs via an extremely complicated physiological process. This process is typified by a permanent change – especially in the early period – in its highly complex composition. Crop milk is extremely high in protein and fat, and also contains enzymes, minerals, immune proteins and unknown growth factors. This makes it a huge challenge to develop artificial substitutes for crop milk partly due to the previous scarcity of studies on the nutritional needs of young pigeons.

We do know that the optimal nourishment of 0–7 day-old pigeons for growth performance requires a diet with a metabolic energy of 15.38 MJ/kg and 53.3% crude protein. However, giving artificial crop milk during this early growth stage resulted in unsatisfactory growth performance compared to young with a natural crop milk diet.

In the middle and late stages of growth, more grains enter the crop milk. To a certain extent, this reduces the difficulty in developing artificial crop milk. A supplementary diet containing 13.04 MJ/kg and 17.77% crude protein (approaching cereal nutritional values) could significantly boost the weight gain of 7–25 day-old squabs. However, as mentioned, their growth performance remained lower than a natural diet provided by their parents.

Breeding cylcus in pigeons

During the breeding cycle, pigeons undergo a series of behavioural and physiological adaptations during this transition period. Nutritious natural crop milk is critical for the growth and development of squabs. The young stimulate their parents to regurgitate the milk by using their peculiar flat beaks at the back of their parents’ throats. 

Pigeon milk secretion is complex and controlled by the stimulation of hormones and other factors. These cause the crop tissue to change shape dramatically such that nutrients rapidly accumulate in the (epidermal) crop wall cells. This process starts in cocks and hens a few days after breeding and before hatching. All of the surface cells on the inside of the crop wall die off and eventually, together with moisture, form crop milk.

The results of some existing studies on the composition of crop milk are not sufficiently consistent. This may be due to the diversity of feed ingested by parents and possibly the sampling methods. 

Pigeon milk is typified by high concentrations of proteins (64%) and fats (30%) and much lower concentrations of minerals (5–6%) and sugars (1–3%). In the first week of milk secretion, all components of pigeon milk are stable except the protein (and its building blocks, i.e. amino acids) which fluctuate to match the specific needs of the young pigeon day by day and hour by hour as closely as possible.

Currently, the growth performance of pigeons fed with artificial pigeon milk is not as good as when they are fed naturally. However, it is very clear that the development of artificial pigeon milk still has a bright future because of its potential benefits. 

With Miobol, Comed has already taken an important first step. The fact is, adding Miobol to natural crop milk gives noticeably better breeding results (more muscle volume, oil drops on the feathers, earlier weaning, etc.).

Our other products in the recommended breeding programme assortment also provide useful nutritious ingredients that resemble crop milk. These include Roni, Lisocur+, Curol, Fertibol, etc. It is clear that besides the nutrients present in crop milk, it contains microorganisms essential for growth and development. The crop flora (Lactobacillus, Enterococcus, Veillonella and Bifidobacterium) is intimately involved in carbohydrate metabolism, amino acid metabolism and energy metabolism. A low (acidic) pH created by microbial fermentation in the crop acts as a barrier to pathogens. 

This suggests that the microbiome in pigeon milk may play an important role in many factors, including: 

  • helping squab digestion 
  • maintaining intestinal balance (homoeostasis) of the host 
  • facilitating early (postnatal) development 
  • improving immune function 
  • metabolising energy

Pigeon milk is the only source of nutrition for squabs in their early growth period. Studies have shown that 0–3 day-old chicks only get crop milk. Thereafter, the milk is gradually mixed with grains until it is eventually replaced by feed. Moreover, when the relative grain content in pigeon milk was increased, the growth rate of squabs significantly decreased. This suggests that pigeon milk plays an irreplaceable role in rapid early growth.

Miobol was developed as a supplement to maximally meet the special need for fats and proteins.

All products in the breeding programme also take these needs into account.

Miobol also proved to be an ideal supplement for preparation and recovery during flights due to its special composition and influence on energy metabolism. 

These reasons explain why there is a strong link between the breeding and flying programmes:

  • Suitable for supporting muscle function and increasing muscle volume from hatching to fledging.
  • Supports flight performance and recovery quickly after a flight. Also for parents during breeding and certainly from the third round onwards.
  • Stimulates the growth of glossy plumage and regulates the formation of sebum.
  • Recommended in combination with Fertibol.  


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