If you’ve arrived at this article looking for solutions to crop problems this article is unlikely to be of help.
More relevant information can be found in the two excellent articles below.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
https://www.backyardchickens.com/ar...ntion-and-treatments-of-crop-disorders.67194/
This article deals with the upper parts of a chickens digestive system and the influence that crop size and function has on the chickens ability to process feeds to ensure adequate nutrition from a given weight of feed and what influence this may have on what one feeds and the feeding regime.
An overview of the chickens digestive system from beak to intestines.
A chicken has receptors in it’s beak which give qualitative information about the object it’s pecking. Once something acceptable is found the chicken deposits the item in it’s mouth with it’s beak. While in the mouth saliva containing digestive enzymes coats the item and the tongue is used to push the item into the oesophagus where it is massaged by peristaltic contractions down into the crop.
There is some uncertainty as to whether the digestive enzymes found in the saliva can remain active in the crop.
How long foodstuffs stay in the crop depends on the foodstuff composition; animal produce taking a longer time to travel to the gizzard than vegetable matter. It is interesting to note that in one of the reference studies, pellets and mash (commercial feed) travel through the crop and the gizzard faster than foraged food stuffs when fed in isolation.
It can take four to eighteen hours for a crop to empty depending on the contents.
This may have a bearing on the morning crop tests used to assess it’s proper function if grains and animal matter is fed rather than pellets or mash, particularly in the summer months where roosting time can be as little as six hours.
It’s peristaltic contractions plus the chickens ability to adjust the orientation of the crop that feeds the contents of the crop into the proventriculus. As food is emptied from the crop, the crop adjusts in shape and size, eventually rasing the bottom of the crop closer to the height of the proventriculus opening.
True digestion starts in the proventriculus which produces hydrochloric acid and digestive enzymes. Peristaltic contractions massage the feed into the gizzard. The proventriculus starts with a fairly narrow opening which has limited flexibility (what sometimes gets considered as a crop blockage problem can be food lodged in this narrow opening) but further down the proventriculus is more elastic and this helps to accommodate partially digest food being squeezed back into the proventriculus from the muscular contractions of the gizzard.
Above the gizzard (ventriculus) is the diverticulum and this organ protects the body from foreign antigens carried in food and water from entering the gizzard and onto the intestines where the nutrients are extracted from the mulch that exits the gizzard.
The gizzard may be more easily understood as the chickens equivalent of teeth in mammals. Essentially it’s a tube surrounded by very strong muscles with a koilin layered internal wall that with the aid of ingested grit, grinds hard food particles into a mulch. The gizzard has a capacity of 5 grams to 10 grams of feed.
Pic1. Fudge proudly showing the position of her full crop.
The crop is the large bulge in front of where her wings attach to her body.
Crops come in a variety of capacities. I’ve measured a number of crops and the range I’ve found is roughly from 40 grams to 60 grams when full. It is in part the crops capacity that may have an influence on how much nutrition is available to the chicken under various feeding regimes. In the studies around 43 grams is a common average. It’s the crops state of fullness that signals the chicken to eat.
It’s the feeding regime and the crop capacity used that dictates whether the feed is stored in the crop or passes directly to the proventriculus and onto the gizzard.
Not all the feed consumed by a chicken gets stored in their crop. If feed is constantly available only a small percentage enters the crop and the chicken snacks all day (ref half hour intervals)
The faster the food travels through a chickens digestive system, including food food gathered from the crop, the more the chickens eats.
Commercial feed in both pellet and crumble form was found to travel through the chickens digestive system faster than any other feeds tested. Meat/animal flesh was found to have the slowest rate of digestion.
If feed is constantly available the chicken may store very little of it in their crop during daytime feeding; the exception being feed eaten before roosting where the chicken stores a larger quantity for night time digestion.
The chickens digestive system doesn’t rest while the chicken is roosting.
It is apparent from studying the chickens digestive system that fermentation occurs not only in the crop but also in the lower proventriculus where less easily machinated food particles are returned from the gizzard to the proventriculus to be returned to the gizzard once sufficiently softened to provide a uniform mulch that enters the intestines.
It is also apparent that given a chickens gizzard can reduce granite particles (grit) to an indistinguishable form in the chickens faeces that too hard to digest is not an issue.
Given the efficiency of a chickens digestive system feed treatment before consumption is quite unnecessary and may in fact be detrimental considering the differing rates at which treated feed is processed by the chickens digestive system, unless the treatment such as in some commercial feeds is to encourage the chicken to eat an unnatural quantity of feed in order to supply sufficient nutrients to support the naturally unsustainable egg laying rates or physical growth of the modern high production egg and meat breeds.
The majority of the commercial feeds I’ve used recommend that a chicken be fed between 120 grams and 150 grams daily. I’ve assumed that these quantities are for high production breeds; breeds laying in excess of 280 eggs yearly in their first two years of life. I've also assumed that these feed quantities are for contained birds with no access to forage and not given supplementary “treats”.
For many backyard chicken keepers who may keep full day ranging chickens, part day ranging, confined, but fed daily treats, low egg production heritage breeds, chickens older than two years, males, juveniles, bantams, game fowl, such feed quantity recommendations have little relevance. However, many keepers attempt to provide somewhere near this daily recommended allowance irrespective of the keeping conditions and breed, age and sex of chickens.
Some keepers provide a constant supply of feed, others use a meal time feeding arrangement where the chicken gets fed a particular quantity, or is allowed to eat over a time scale. Such feeding arrangements can be found for contained chickens and chickens that have access to forage for variable amounts of time during the day.
Feeding pellets to fully confined birds on a feed always available regime.
The likelihood is the hens will over feed in confinement. It’s a calorie problem rather than a fat from the feed problem.
The gizzard may become weak. Some pellets are soft.
The hen may accumulate organ and body fat.
The hens eat out of boredom.
Feeding pellets to fully confined birds on a meal time regime.
How effective this is very dependent on crop size and whether the feed is left down until finished, or for a period of time.
Assuming a recommended feed intake of 120 grams and the hens are given 120 grams each.
A hen with a 40 gram capacity crop is going to need three meals a day to ensure her dietary requirements are met.
A hen with a larger crop at 60 gram capacity would still be 20 grams short if fed twice a day.
One meal a day is obviously not going to supply the required nutrition.
Feeding fully confined birds on a mash always available regime.
I don’t believe this is a common practice but problems are similar to those for meal time feeding
Feeding fully confined birds on a meal time mash regime.
This is what a I would feed as a mash. It’s wet enough to trowel (left), but stiff enough to make mounds.(right)
It's made with 120 grams of layers crumble and 120 grams of water. The extra 21 grams shown on the scale are the weight of the container.
The available nutrition per gram of feed has been halved.
Feed this three times a day and if the hens eat their full quota they will be getting half of the nutrition they need daily ; the other half of the total feed weight being water, assuming a 40 gram crop
A 6 mealtime feeding regime would be needed to ensure the chicken got adequately fed.
Feeding fermented grains to fully confined birds on an always available regime
The mixed grains and seeds I’ve fermented (24 hours fermenting) increased their weight by between 32grams to 40grams when drained. The grains and seeds used in the mix will have some influence on the water uptake.
Fermented feed will either ferment some more from the water uptake or dry out increasing the nutritional part to the water part, so it may be a better option than mash if feed is to be left down.
Given a feed constantly available regime, the chicken will not store feed in the crop instead passing it straight to the proventriculus one would think that once adjusted to this regime the gizzard would need to work harder and gain strength and this should have health benefits.
Feeding fermented grains to fully confined birds on a meal time regime.
There is no doubt that fermentation can increase the bioavailability of some of the feed constituents but nowhere have a I read they will compensate for roughly a third reduction in overall nutrition. That’s 80 grams daily instead of 120 grams. It would take a minimum of three mealtime feed to ensure the chicken gets the nutrition available from 120 grams of dry grain feed.
The above are worst case scenarios, Depending on the state of the crop and the feeding regime, a hen may also utilise the capacity of the proventriculus and gizzard as storage when intermittently fed,. 10 gram capacity in the gizzard and a further 10 gram capacity in the proventriculus gives an increase of very approximately 20 grams for hens fed on an intermittent regime. In some cases this may make intermittent feeding on a twice daily regime a realistic option given a 40 gram capacity crop. Total feed consumption crop=10 grams, proventriculus=10 grams, plus any feed diverted to the crop gives a minimum of 60 grams total. Two daily feeds gives the required 120 grams for dry feed.
Free ranging and ranging chickens.
How important feed dilution is for ranging chickens is complicated. There are too many variables to take into account. However, for keepers that feed mash or fermented feeds in such keeping arrangements the water content of the feed should be considered when profiling a whole grain based feed. This study helps to illustrate the level of nutrition the hens received from foraging.
https://www.researchgate.net/publication/221973200_Whole_wheat_versus_mixed_layer_diet_as_supplementary_feed_to_layers_foraging_of_different_forage_crops
There was a performance drop from the free rangers for a few weeks, after which they performed as well if not better than the pellet fed hens.
My observations of all day ranging chickens and fully free range chickens, heritage, mixed breed and bantams suggest that these chickens which are likely to exhibit more natural feeding habits have a routine with, or without, a supply of keeper provided feed, and as the studies suggest, their foraging and eating are largely governed by the fullness of their crop. Most will eat some quantity of keeper provided feed once let out of their coops if housed. Some, depending on the time of year and the quantity of food remaining in their crop (the number of daylight hours has a major influence on morning crop states; summer nights for example may have allowed only six hours of roosting digestion time which, depending on what they consumed at last feed may not be sufficient time for their crop contents to empty) will head straight for their preferred foraging spots. Up to two hours of foraging was average, after which they headed for cover to rest and preen. Foraging chickens are unlikely to find sufficient foodstuffs to fill their crops in a two hour period unless they have been particularly lucky and found a termite mound or some other concentrated supply of food. Checking the crops of some of these ranging chickens none were filled to capacity and I assume, because their feed intake is regular over this period a proportion of what they eat doesn’t get stored in the crop and goes straight into the proventriculus and onto the gizzard.
None of these chickens would have ingested the minimum levels of protein often recommended and it is unlikely they have met the methionine requirements quoted for high production breeds. Nor did they consume anything like the 120 grams to 150 grams of supplementary feed recommended by the commercial feed manufacturers. Despite this, sickness, unless one includes injuries, was non existent and providing they avoided the numerous predators, lived to the average age for their breed and keeping conditions. They laid well shelled eggs and looked slim and healthy.
The only time I found their crops full to capacity was before roosting, so in their cases they ate sufficient to support themselves during the day without using the crop as a storage option and filled their crop before roosting as chickens fed on a meal time basis do.
This is an interesting article on one persons experience of feeding dawn to dusk ranging chickens on a limited acreage a fermented feed.
https://www.backyardchickens.com/ar...eat-tears-a-calculator-or-deep-pockets.78655/
Discussion
The majority of the studies quoted used broiler chickens and high production breeds. While the digestive system of other types of chickens will be the same, their response to different feeding regimes may not be and their nutritional requirements may be considerably less if the breed lays significantly fewer eggs.
For keepers who range for a couple of hours a day assessing the nutritional intake from forage is almost impossible given the diversity of soil conditions and vegetation possible. Most keepers will supply some form of supplementary feed to compensate for poor forage conditions and/or limited foraging time. Keepers falling into the part ranging category should also take into account nutrition reduction due to the addition of water if feeding mashes or fermented grains if they wish to ensure their chickens get a particular amount of nutrition from the supplementary commercial/supplied feed.
It seems possible that problems such as feather plucking and eating, fatty liver syndrome and other behavioural problems may not be due to what gets fed to them, but how it gets fed to them, when it comes to fully confined chickens.
Most of the studies used as references for this article are in broad agreement on the basic issue and that is how one feeds chickens has a major influence on what the chicken directs to which part of the digestion. It is also interesting to speculate whether a foraging chicken considers forage as feed, constantly available, and adjust their eating habits accordingly, or whether fed supplementary feeding (meal times) is viewed as feed to be diverted to the crop and forage treated in another manner. I couldn’t find any studies that dealt with the speed of transition from one regime to another.
I hope the reader will take away two pieces of knowledge from this article; the fact that the chickens digestive system is adaptive and the water content in mashes and ferments tend to reduce the nutrition per gram fed.
Required Reading
https://www.sciencedirect.com/science/article/pii/S1056617119303939
References.
Peristalsis
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/peristalsis
Free range feeding study.
https://www.researchgate.net/publication/221973200_Whole_wheat_versus_mixed_layer_diet_as_supplementary_feed_to_layers_foraging_of_different_forage_crops
Crop Volume study.
https://www.sciencedirect.com/scien...?ref=pdf_download&fr=RR-2&rr=850e3aa68dcb6558
Digestion General.
https://www.researchgate.net/figure...ak-gathers-food-the-bifurcated_fig1_321799440
How fast a chickens digests.
https://www.sciencedirect.com/science/article/pii/S0032579119501456
About the diverticulum.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1167709/pdf/janat00125-0184.pdf
What nutrition chickens need.
https://nap.nationalacademies.org/c...rements-of-poultry-ninth-revised-edition-1994
What got found in free ranging chickens crops.
https://www.sciencedirect.com/science/article/pii/S0032579119429106
Comparison between freerange chickens fed whole wheat as supplement instead of layer feed.
https://www.sciencedirect.com/science/article/pii/S0032579119429106
Can A Chick Balance Its Ration. E. M. Funk.
Nutrient requirements.
https://nap.nationalacademies.org/c...rements-of-poultry-ninth-revised-edition-1994
More relevant information can be found in the two excellent articles below.
https://www.backyardchickens.com/ar...w-to-know-which-one-youre-dealing-with.73607/
https://www.backyardchickens.com/ar...ntion-and-treatments-of-crop-disorders.67194/
This article deals with the upper parts of a chickens digestive system and the influence that crop size and function has on the chickens ability to process feeds to ensure adequate nutrition from a given weight of feed and what influence this may have on what one feeds and the feeding regime.
An overview of the chickens digestive system from beak to intestines.
A chicken has receptors in it’s beak which give qualitative information about the object it’s pecking. Once something acceptable is found the chicken deposits the item in it’s mouth with it’s beak. While in the mouth saliva containing digestive enzymes coats the item and the tongue is used to push the item into the oesophagus where it is massaged by peristaltic contractions down into the crop.
There is some uncertainty as to whether the digestive enzymes found in the saliva can remain active in the crop.
How long foodstuffs stay in the crop depends on the foodstuff composition; animal produce taking a longer time to travel to the gizzard than vegetable matter. It is interesting to note that in one of the reference studies, pellets and mash (commercial feed) travel through the crop and the gizzard faster than foraged food stuffs when fed in isolation.
It can take four to eighteen hours for a crop to empty depending on the contents.
This may have a bearing on the morning crop tests used to assess it’s proper function if grains and animal matter is fed rather than pellets or mash, particularly in the summer months where roosting time can be as little as six hours.
It’s peristaltic contractions plus the chickens ability to adjust the orientation of the crop that feeds the contents of the crop into the proventriculus. As food is emptied from the crop, the crop adjusts in shape and size, eventually rasing the bottom of the crop closer to the height of the proventriculus opening.
True digestion starts in the proventriculus which produces hydrochloric acid and digestive enzymes. Peristaltic contractions massage the feed into the gizzard. The proventriculus starts with a fairly narrow opening which has limited flexibility (what sometimes gets considered as a crop blockage problem can be food lodged in this narrow opening) but further down the proventriculus is more elastic and this helps to accommodate partially digest food being squeezed back into the proventriculus from the muscular contractions of the gizzard.
Above the gizzard (ventriculus) is the diverticulum and this organ protects the body from foreign antigens carried in food and water from entering the gizzard and onto the intestines where the nutrients are extracted from the mulch that exits the gizzard.
The gizzard may be more easily understood as the chickens equivalent of teeth in mammals. Essentially it’s a tube surrounded by very strong muscles with a koilin layered internal wall that with the aid of ingested grit, grinds hard food particles into a mulch. The gizzard has a capacity of 5 grams to 10 grams of feed.
Pic1. Fudge proudly showing the position of her full crop.
The crop is the large bulge in front of where her wings attach to her body.
Crops come in a variety of capacities. I’ve measured a number of crops and the range I’ve found is roughly from 40 grams to 60 grams when full. It is in part the crops capacity that may have an influence on how much nutrition is available to the chicken under various feeding regimes. In the studies around 43 grams is a common average. It’s the crops state of fullness that signals the chicken to eat.
It’s the feeding regime and the crop capacity used that dictates whether the feed is stored in the crop or passes directly to the proventriculus and onto the gizzard.
Not all the feed consumed by a chicken gets stored in their crop. If feed is constantly available only a small percentage enters the crop and the chicken snacks all day (ref half hour intervals)
The faster the food travels through a chickens digestive system, including food food gathered from the crop, the more the chickens eats.
Commercial feed in both pellet and crumble form was found to travel through the chickens digestive system faster than any other feeds tested. Meat/animal flesh was found to have the slowest rate of digestion.
If feed is constantly available the chicken may store very little of it in their crop during daytime feeding; the exception being feed eaten before roosting where the chicken stores a larger quantity for night time digestion.
The chickens digestive system doesn’t rest while the chicken is roosting.
It is apparent from studying the chickens digestive system that fermentation occurs not only in the crop but also in the lower proventriculus where less easily machinated food particles are returned from the gizzard to the proventriculus to be returned to the gizzard once sufficiently softened to provide a uniform mulch that enters the intestines.
It is also apparent that given a chickens gizzard can reduce granite particles (grit) to an indistinguishable form in the chickens faeces that too hard to digest is not an issue.
Given the efficiency of a chickens digestive system feed treatment before consumption is quite unnecessary and may in fact be detrimental considering the differing rates at which treated feed is processed by the chickens digestive system, unless the treatment such as in some commercial feeds is to encourage the chicken to eat an unnatural quantity of feed in order to supply sufficient nutrients to support the naturally unsustainable egg laying rates or physical growth of the modern high production egg and meat breeds.
The majority of the commercial feeds I’ve used recommend that a chicken be fed between 120 grams and 150 grams daily. I’ve assumed that these quantities are for high production breeds; breeds laying in excess of 280 eggs yearly in their first two years of life. I've also assumed that these feed quantities are for contained birds with no access to forage and not given supplementary “treats”.
For many backyard chicken keepers who may keep full day ranging chickens, part day ranging, confined, but fed daily treats, low egg production heritage breeds, chickens older than two years, males, juveniles, bantams, game fowl, such feed quantity recommendations have little relevance. However, many keepers attempt to provide somewhere near this daily recommended allowance irrespective of the keeping conditions and breed, age and sex of chickens.
Some keepers provide a constant supply of feed, others use a meal time feeding arrangement where the chicken gets fed a particular quantity, or is allowed to eat over a time scale. Such feeding arrangements can be found for contained chickens and chickens that have access to forage for variable amounts of time during the day.
Feeding pellets to fully confined birds on a feed always available regime.
The likelihood is the hens will over feed in confinement. It’s a calorie problem rather than a fat from the feed problem.
The gizzard may become weak. Some pellets are soft.
The hen may accumulate organ and body fat.
The hens eat out of boredom.
Feeding pellets to fully confined birds on a meal time regime.
How effective this is very dependent on crop size and whether the feed is left down until finished, or for a period of time.
Assuming a recommended feed intake of 120 grams and the hens are given 120 grams each.
A hen with a 40 gram capacity crop is going to need three meals a day to ensure her dietary requirements are met.
A hen with a larger crop at 60 gram capacity would still be 20 grams short if fed twice a day.
One meal a day is obviously not going to supply the required nutrition.
Feeding fully confined birds on a mash always available regime.
I don’t believe this is a common practice but problems are similar to those for meal time feeding
Feeding fully confined birds on a meal time mash regime.
This is what a I would feed as a mash. It’s wet enough to trowel (left), but stiff enough to make mounds.(right)
It's made with 120 grams of layers crumble and 120 grams of water. The extra 21 grams shown on the scale are the weight of the container.
The available nutrition per gram of feed has been halved.
Feed this three times a day and if the hens eat their full quota they will be getting half of the nutrition they need daily ; the other half of the total feed weight being water, assuming a 40 gram crop
A 6 mealtime feeding regime would be needed to ensure the chicken got adequately fed.
Feeding fermented grains to fully confined birds on an always available regime
The mixed grains and seeds I’ve fermented (24 hours fermenting) increased their weight by between 32grams to 40grams when drained. The grains and seeds used in the mix will have some influence on the water uptake.
Fermented feed will either ferment some more from the water uptake or dry out increasing the nutritional part to the water part, so it may be a better option than mash if feed is to be left down.
Given a feed constantly available regime, the chicken will not store feed in the crop instead passing it straight to the proventriculus one would think that once adjusted to this regime the gizzard would need to work harder and gain strength and this should have health benefits.
Feeding fermented grains to fully confined birds on a meal time regime.
There is no doubt that fermentation can increase the bioavailability of some of the feed constituents but nowhere have a I read they will compensate for roughly a third reduction in overall nutrition. That’s 80 grams daily instead of 120 grams. It would take a minimum of three mealtime feed to ensure the chicken gets the nutrition available from 120 grams of dry grain feed.
The above are worst case scenarios, Depending on the state of the crop and the feeding regime, a hen may also utilise the capacity of the proventriculus and gizzard as storage when intermittently fed,. 10 gram capacity in the gizzard and a further 10 gram capacity in the proventriculus gives an increase of very approximately 20 grams for hens fed on an intermittent regime. In some cases this may make intermittent feeding on a twice daily regime a realistic option given a 40 gram capacity crop. Total feed consumption crop=10 grams, proventriculus=10 grams, plus any feed diverted to the crop gives a minimum of 60 grams total. Two daily feeds gives the required 120 grams for dry feed.
Free ranging and ranging chickens.
How important feed dilution is for ranging chickens is complicated. There are too many variables to take into account. However, for keepers that feed mash or fermented feeds in such keeping arrangements the water content of the feed should be considered when profiling a whole grain based feed. This study helps to illustrate the level of nutrition the hens received from foraging.
https://www.researchgate.net/publication/221973200_Whole_wheat_versus_mixed_layer_diet_as_supplementary_feed_to_layers_foraging_of_different_forage_crops
There was a performance drop from the free rangers for a few weeks, after which they performed as well if not better than the pellet fed hens.
My observations of all day ranging chickens and fully free range chickens, heritage, mixed breed and bantams suggest that these chickens which are likely to exhibit more natural feeding habits have a routine with, or without, a supply of keeper provided feed, and as the studies suggest, their foraging and eating are largely governed by the fullness of their crop. Most will eat some quantity of keeper provided feed once let out of their coops if housed. Some, depending on the time of year and the quantity of food remaining in their crop (the number of daylight hours has a major influence on morning crop states; summer nights for example may have allowed only six hours of roosting digestion time which, depending on what they consumed at last feed may not be sufficient time for their crop contents to empty) will head straight for their preferred foraging spots. Up to two hours of foraging was average, after which they headed for cover to rest and preen. Foraging chickens are unlikely to find sufficient foodstuffs to fill their crops in a two hour period unless they have been particularly lucky and found a termite mound or some other concentrated supply of food. Checking the crops of some of these ranging chickens none were filled to capacity and I assume, because their feed intake is regular over this period a proportion of what they eat doesn’t get stored in the crop and goes straight into the proventriculus and onto the gizzard.
None of these chickens would have ingested the minimum levels of protein often recommended and it is unlikely they have met the methionine requirements quoted for high production breeds. Nor did they consume anything like the 120 grams to 150 grams of supplementary feed recommended by the commercial feed manufacturers. Despite this, sickness, unless one includes injuries, was non existent and providing they avoided the numerous predators, lived to the average age for their breed and keeping conditions. They laid well shelled eggs and looked slim and healthy.
The only time I found their crops full to capacity was before roosting, so in their cases they ate sufficient to support themselves during the day without using the crop as a storage option and filled their crop before roosting as chickens fed on a meal time basis do.
This is an interesting article on one persons experience of feeding dawn to dusk ranging chickens on a limited acreage a fermented feed.
https://www.backyardchickens.com/ar...eat-tears-a-calculator-or-deep-pockets.78655/
Discussion
The majority of the studies quoted used broiler chickens and high production breeds. While the digestive system of other types of chickens will be the same, their response to different feeding regimes may not be and their nutritional requirements may be considerably less if the breed lays significantly fewer eggs.
For keepers who range for a couple of hours a day assessing the nutritional intake from forage is almost impossible given the diversity of soil conditions and vegetation possible. Most keepers will supply some form of supplementary feed to compensate for poor forage conditions and/or limited foraging time. Keepers falling into the part ranging category should also take into account nutrition reduction due to the addition of water if feeding mashes or fermented grains if they wish to ensure their chickens get a particular amount of nutrition from the supplementary commercial/supplied feed.
It seems possible that problems such as feather plucking and eating, fatty liver syndrome and other behavioural problems may not be due to what gets fed to them, but how it gets fed to them, when it comes to fully confined chickens.
Most of the studies used as references for this article are in broad agreement on the basic issue and that is how one feeds chickens has a major influence on what the chicken directs to which part of the digestion. It is also interesting to speculate whether a foraging chicken considers forage as feed, constantly available, and adjust their eating habits accordingly, or whether fed supplementary feeding (meal times) is viewed as feed to be diverted to the crop and forage treated in another manner. I couldn’t find any studies that dealt with the speed of transition from one regime to another.
I hope the reader will take away two pieces of knowledge from this article; the fact that the chickens digestive system is adaptive and the water content in mashes and ferments tend to reduce the nutrition per gram fed.
Required Reading
https://www.sciencedirect.com/science/article/pii/S1056617119303939
References.
Peristalsis
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/peristalsis
Free range feeding study.
https://www.researchgate.net/publication/221973200_Whole_wheat_versus_mixed_layer_diet_as_supplementary_feed_to_layers_foraging_of_different_forage_crops
Crop Volume study.
https://www.sciencedirect.com/scien...?ref=pdf_download&fr=RR-2&rr=850e3aa68dcb6558
Digestion General.
https://www.researchgate.net/figure...ak-gathers-food-the-bifurcated_fig1_321799440
How fast a chickens digests.
https://www.sciencedirect.com/science/article/pii/S0032579119501456
About the diverticulum.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1167709/pdf/janat00125-0184.pdf
What nutrition chickens need.
https://nap.nationalacademies.org/c...rements-of-poultry-ninth-revised-edition-1994
What got found in free ranging chickens crops.
https://www.sciencedirect.com/science/article/pii/S0032579119429106
Comparison between freerange chickens fed whole wheat as supplement instead of layer feed.
https://www.sciencedirect.com/science/article/pii/S0032579119429106
Can A Chick Balance Its Ration. E. M. Funk.
Nutrient requirements.
https://nap.nationalacademies.org/c...rements-of-poultry-ninth-revised-edition-1994
