Understanding satiety in broiler breeders during rearing and application to commercial diets
Lead Research Organisation:
University of Edinburgh
Department Name: The Roslin Institute
Abstract
Project objectives are to advance our knowledge of avian appetite regulation, in terms of nutrient-gut-brain interactions, and to apply behavioural and neurobiological measures to determine whether broiler breeder satiety (and therefore welfare) can be improved using diets which are viable for use in commercial practice. Our approach will be to investigate the effect of high fibre and low protein diets on broiler breeder hunger/satiety, to investigate 4 further diets developed by Aviagen and tested in a commercial trial, and finally to investigate the nutrient-gut-brain pathway to determine which nutrients have the biggest effect on the AGRP circuit in the Arcuate nucleus, and by what mechanism does this occur?
Objective 1) Investigate the effect of high fibre and low protein diets on broiler breeder hunger/satiety. This experiment will rear birds (n=24 per treatment) to the same growth curve using four diets and compare them to a standard commercial broiler breeder diet (R) as a control. A 2x2 design will be used, with two levels of energy density/fibre (Nielsen et al 2011) and two levels of protein content (Van Emous et al 2014). Home-pen observations of behaviour (focusing on feeding, pecking and activity) will be made weekly and Foraging motivation tests carried out between 8 and 12 weeks of age. All birds will be killed at 12 weeks of age and tissues collected so that brain (arcuate nucleus: AGRP, NPY, POMC, CART) and gut measures (CCK, PYY, GLP1 and ghrelin from various gastro-intestinal tract tissues) will be made.
Objective 2) Investigate 4 further diets developed by Aviagen and tested in a commercial trial.
Aviagen carries out commercial trial work in the Netherlands, and this experiment will 'piggy back' on a current trial. The details of the diets and treatments will depend on the latest in-house research, but our intention would be to make use of n=24 birds from each of 4 diet treatments, to determine the effect on the behavioural and physiological markers of hunger/satiety already discussed.
Objective 3) Investigate the nutrient-gut-brain pathway
Our work to date in this area suggests that the AGRP circuits in the arcuate nucleus of the hypothalamus are a crucial integrative system in the control of feeding behaviour. However, little is known about how feedback from the gastro-intestinal tract affects AGRP. Depending on earlier findings and on how the student's interests develop over the course of the project, various approaches are possible. For example, using small experiments with 3 week old birds, the effect of different nutrients such as glucose vs artificial sweeteners, specific amino acids such as lysine, and free fatty acids on AGRP and on behaviour could be examined by intubation into the crop . In a similar way, feeding different types of fibre (such as soluble vs. insoluble) and different fibre ingredients will be examined. This will also aim to identify the mediators of the feedback from the different parts of the intestine to the brain.
Outcomes
We anticipate the studentship will result in increased understanding of the dietary factors which mediate satiety in chickens and appraise the ability of commercially realistic diets to improve neurochemical markers of satiety and behavioural correlates.
Objective 1) Investigate the effect of high fibre and low protein diets on broiler breeder hunger/satiety. This experiment will rear birds (n=24 per treatment) to the same growth curve using four diets and compare them to a standard commercial broiler breeder diet (R) as a control. A 2x2 design will be used, with two levels of energy density/fibre (Nielsen et al 2011) and two levels of protein content (Van Emous et al 2014). Home-pen observations of behaviour (focusing on feeding, pecking and activity) will be made weekly and Foraging motivation tests carried out between 8 and 12 weeks of age. All birds will be killed at 12 weeks of age and tissues collected so that brain (arcuate nucleus: AGRP, NPY, POMC, CART) and gut measures (CCK, PYY, GLP1 and ghrelin from various gastro-intestinal tract tissues) will be made.
Objective 2) Investigate 4 further diets developed by Aviagen and tested in a commercial trial.
Aviagen carries out commercial trial work in the Netherlands, and this experiment will 'piggy back' on a current trial. The details of the diets and treatments will depend on the latest in-house research, but our intention would be to make use of n=24 birds from each of 4 diet treatments, to determine the effect on the behavioural and physiological markers of hunger/satiety already discussed.
Objective 3) Investigate the nutrient-gut-brain pathway
Our work to date in this area suggests that the AGRP circuits in the arcuate nucleus of the hypothalamus are a crucial integrative system in the control of feeding behaviour. However, little is known about how feedback from the gastro-intestinal tract affects AGRP. Depending on earlier findings and on how the student's interests develop over the course of the project, various approaches are possible. For example, using small experiments with 3 week old birds, the effect of different nutrients such as glucose vs artificial sweeteners, specific amino acids such as lysine, and free fatty acids on AGRP and on behaviour could be examined by intubation into the crop . In a similar way, feeding different types of fibre (such as soluble vs. insoluble) and different fibre ingredients will be examined. This will also aim to identify the mediators of the feedback from the different parts of the intestine to the brain.
Outcomes
We anticipate the studentship will result in increased understanding of the dietary factors which mediate satiety in chickens and appraise the ability of commercially realistic diets to improve neurochemical markers of satiety and behavioural correlates.
Studentship Projects
| Project Reference | Relationship | Related To | Start | End | Student Name |
|---|---|---|---|---|---|
| BB/N503836/1 | 01/10/2015 | 30/06/2024 | |||
| 1734551 | Studentship | BB/N503836/1 | 01/10/2015 | 31/03/2021 | Gillian Cherrie |
| Description | The experiment consisted of 7 dietary treatments; standard (pellet and mash), decreased protein (pellet), decreased protein and energy diet (pellet), all of which were fed to a standard growth target, the decreased protein diet fed was also fed to a plus 20% growth target, there were two ad libitum treatments which were fed either the standard or decreased protein and energy diet. There were five treatment replicates with twenty-four birds per treatment, a total of one-hundred and sixty-eight female 308 broiler breeders were used. Birds were housed in groups of four or five birds, behaviour of birds (between 7-11 weeks) within the group was recorded using a video camera mounted above each pen. This footage was analysed using instantaneous scan sampling, which means that the behaviour of a bird was recorded after a pre-determined interval. For this experiment the interval was every 5 minutes over a 30 minute period, this was repeated 4 times throughout the light period. Behaviour frequency was then analysed using ANOVA, the results obtained from this indicate that; birds fed ad libitum diets spent more time non-active than all other treatments which suggests satiety, birds fed standard mash were more active than all other treatments, birds fed the standard pellet or decreased protein and energy showed more drinker directed pecking however it is unclear if this was drinking or pecking due to video quality. From this behavioural analysis it is difficult to interpret an improvement in satiety and welfare (although ad libitum fed birds were less active, there were no clear differences between the remaining dietary treatments). Further work is being carried out using the same footage but focusing on positive welfare indicators to assess if frequency and bout length of preening and dustbathing could be used as indicators of satiety. |
| Exploitation Route | Further analysis of these dietary treatments is being carried out (gene expression within the basal hypothalamus and further behavioural observations such as using positive welfare indicators) to determine if they may improve satiety. If a link between the diet and improved satiety is found this diet could be used by the commercial poultry industry to improve both satiety and welfare of broiler breeder stock. |
| Sectors | Agriculture, Food and Drink |