All commercial poultry eat with reasonably good precision to balance nutrient intake with requirements. Short term, there can be some variation in feed intake related to local situations, but long-term, the mechanisms of feed intake regulation are quite precise. Matching nutrient needs with intake is an obvious inherent evolutionary necessity to ensure survival and reproduction. A bird’s da...
An excellent presentation. At what stage do you think that a laying hen would be able to self-select for calcium intake by taking oyster-shell or granular limestone from pan feeder? Would it make sense to offer such a mineral supply alongside a Pre-Lay ration, with ~2% calcium, in order to prevent any immediate shell quality issues when the first eggs are aid?
@Kevin Stickney In theory, yes. You could offer feed and oyster shell, etc., and they would balance their nutrient needs. The practical issue is that birds invariably take too much oyster shell because of its novel texture. We see this in small flocks where a calcium feeder is set up. Birds consume 8-10g/d of oyster shell and then soft shelled eggs appear because of an induced P deficiency. You could give two diets, High and Low in Ca, and they would balance themselves, but that becomes a logistics challenge. A pre-lay diet with most Ca as large particle will work, assuming it’s a mash diet.
Excess calcium is consumed by birds which are on controlled feed (feeders are empty) when grit is offered on free choice basis. Layer hens which are on full feed (feeder has feed) the hens eat as they need. They don't over consume the grit
Hi Dr. Leeson, I enjoyed reading your detailed post about feed intake, bird growth and all of the other great information you provided. As i was reading your article, i was reminded of the many lectures that you and Dr. Somers gave a few years back. Thanks for my updated course on Why Chickens Eat.
I disagree with you Steve. Generaly animals are like children. candy or soup, children chooze candy. So we give a mix with all feedstuffs they need. and give this mix in peels. So they cannot choose. I apologise for my English. Sorry.
Many thanks, Dr. Leeson, for an excellent article. I have only one comment regarding ideal temperature for layers. I agree with you that 26 degrees is ideal for layers in post-peak production but before peak production a lower temperature is desirable to stimulate them to eat more to meet adequate production and desirable body weight. I enjoyed your article immensely. Best regards
Chickens eat to get the energy and nutrients they need to survive, grow, lay eggs, and stay healthy—just like all animals. Their diet typically includes grains, seeds, insects, greens, and sometimes small animals like worm
Just remember that chickens do not have AMYLASE in their saliva. So feed digestion is not immediately as other animal species. As an adult, they love to have GRIT on their CROP and many of the stone pieces will stay for days in there. So soluble calcium will be released at different concentrations each day. Calcium grit is usually provided at molt time rather than as calcium supplement. So regulation of GRIT intake from layers would take a few days to be constant.
Dear Steve, one more article of yours that recicle knowledge and brings new information to add to our understanding. Regarding pellet and mash diets, there are differences in this main energy feed consumption regulation?
Mash vs. pellets adds another dimension to feed intake. For broilers, it’s obvious that the physical density of a pelleted feed allows for faster intake of a given quantity of feed. Pellet size likewise influences time spent feeding. Both these factors greatly impact intake and growth after about 25d at higher stocking densities, when we invariably see slowing of growth rate that is usually blamed on formulation or sub-clinical disease challenges. We can’t increase feeder space, so maximise pellet dimensions!!
Mash diets allow for some self-selection of ingredients, and so this can cause temporary shift in nutrient intake. But birds still eat to energy needs. Mash feeds work better than most of us expect, but there is always more variation in individual birds growth rate and in carcass yield of individual birds. Mash feeds, on the other han,d usually result in drier litter and better liveability, especially beyond 2.5kg live weight.
I agree that in mash feeds that the g/ bird/day decreases after day 25, but are there not ways we can get around that, by increasing density of the mash feed, particles size of feed, ingredient selection...etc?
I'm curious what you think the GMD of finisher feeds for broilers should be?
Hi Dr. Leeson, thanks for your interesting paper. In my view, there is one topic that is misunderstood: the role of taste and smell in feed intake. Evolution has kept roughly 250 genes in the chicken genome for these 2 systems. Claiming these are not well-developed is probably inaccurate. For example, chickens have a very fine taste system, including roughly several fold more taste buds in the oral cavity than humans (relative to volume). The main taste ligands are nutrients (sugars, amino/fatty acids, calcium…) or toxins / antinutritional factors all potentially powerful feed intake drivers. They involve ca 12 well-characterized taste receptors which are present in the oral cavity, gut and brain, orchestrating short-term (within meal) and mid/long-term (between meals) feed intake through the gut-brain axis. In my view, it is not possible to understand feed intake mechanisms in birds (or mammals) without understanding the taste system.
Very good observations. Chicken feed intake is regulated by 1. Requirement for maintainace 2. Requirement for Growth and productio. 3. Energy content of the feed. 4. Environment temperature 5. Texture of feed, grain/pellet size. 6. Taste, colour and smell of the feed. 7. Appetite of the birds. 8. light and visibiity which creates appetite
Thank you all for this very interesting and important topic. Feed intake is the major factor driving the growth rate of meat chickens. The modern broilers and Turkeys are more susceptible than ever to feed intake stressors, and to achieve their genetic potential, it is vital to recognize, minimize or even eliminate feed processing-related factors inducing feed intake suppression. Feed consumption can be affected by particle size and degree of grinding, feed form (mash, crumble, pellet), pellet size (diameter and length), pellet quality (percentage of intact pellets vs fines, hardness, and durability), and whole grain feeding (type of grain, barley vs wheat, inclusion rate, Introduction age, and grain hardness). An important point regarding the particle size is that the effect of particle size on the feed intake of broilers could be different in mash diets from the pelleted diets. if you are interested to know more about the feed processing and its impact on feed intake, you could have a look at the following review article from Massey University, New Zealand: Feed intake response of broilers: Impact of feed processing M.R. Abdollahi, F. Zaefarian, V. Ravindran
Fully agree, Dr. Dan Hofer. Feeder and drinker height are important observation when we get into a chicken house. Also, how much feed there is in the feeders.
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