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What are the limits to feed intake of broilers on bulky feeds?

Lookup NU author(s): Dr James Taylor, Dr Panagiotis Sakkas, Professor Ilias Kyriazakis



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


© 2020The view that genetic selection for carcass yield has limited the size of the gastrointestinal tract (GIT) of modern broilers has sparked concerns that their capacity to cope with energy dilution or bulk is also limited. We investigated the capacity of male Ross 308 broilers to deal with increasing levels of bulk and aimed to identify a feed bulk dimension responsible for limiting feed intake (FI). About 528 day-old broilers were allocated to 48 pens and offered a common starter feed until day 8, and 1 of 7 feeds from day 8 to 36 of age: a basal control (B), which was diluted to 3 levels (15, 30, or 45%) with either oat hulls (OH) or sugar beet pulp (SBP). Feed intake was measured daily and birds were dissected for GIT measurements at day 15, 22, and 36. Feed intake increased in birds offered OH15 (135 g/d), OH30 (140 g/d), and SBP15 (138 g/d) compared with birds offered the B feed (106 g/d; SEM 2.4). By increasing FI, birds were able to compensate for the lower energy content of their feeds. The greatest increase in FI was seen on OH30: its energy content (2,273 kcal/kg) was 26% lower than the B feed (3,081 kcal/kg). There was evidence of adaptation on the bulky feeds, as during the last week only birds on SBP45 were limited in FI and performance. The relative weights of the GIT were greater in the SBP than OH series, suggesting that the former needed to accommodate a higher bulk intake. For the OH series the increase in the relative GIT weights was confined to the gizzard and small intestine; whereas for the SBP series, the increase was extended to proventriculus and large intestine. Because only SBP45 was limiting FI, we were unable to identify a bulk dimension to be used to predict FI. Our data reject the suggestion that modern broilers have a reduced ability to cope with reductions in feed energy content.

Publication metadata

Author(s): Taylor J, Sakkas P, Kyriazakis I

Publication type: Article

Publication status: Published

Journal: Poultry Science

Year: 2021

Volume: 100

Issue: 3

Print publication date: 01/03/2021

Online publication date: 19/11/2020

Acceptance date: 09/11/2020

Date deposited: 26/07/2021

ISSN (print): 0032-5791

ISSN (electronic): 1525-3171

Publisher: Elsevier Inc.


DOI: 10.1016/j.psj.2020.11.008


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