Dietary means to improve antioxidant status in broiler chicken flocks

Woods, S.L. (2021) Dietary means to improve antioxidant status in broiler chicken flocks. Doctoral thesis, Harper Adams University.

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Abstract

Threeexperiments were carried out to investigate the effects of different sources of Selenium (Se) on antioxidant status and broiler growth performance. In thefirst study, fourdiets with different sources of Sewere fed tobroilers to investigate their effect onantioxidant status and growth performance variables. Feed intake (FI) was highest in birds fed inorganic Se (sodium selenite) (SS) and lowest in birds fed organic Se(selenised yeast) (SY) (P<0.05).Highest weight gain (WG) was in birds fed control (C)(P<0.05). All birds fed supplementary Se (irrespective of source), had highertotal hepatic Seconcentration versusC(P<0.001), and birds fed SYhad the highestSe concentration in the liver andbreast tissue(P<0.001). All birds supplemented with Se had higherSe containing enzyme glutathione peroxidase (GSH-Px)(P<0.001),indicating better oxidativestatus,but there wereno differences between theSe sources.The second study investigated the effects of three sources and two levels of Se and a C diet, when broilers were raised at two different constant temperatures (20°C (ST) and 35°C(HT)). Total antioxidant status (TAS) and GSH-Px were measured to determine oxidative status and Se levels in breast and tissue.Birds raised atHT consumed less and weighed less than those reared at ST(P≤0.05). WG was greatest in birds fed higher Selevel and raised at 20°C,but increasing Selevel decreased WGat 35°C(P<0.05).Birds fed SYhad the lowest FI, WG and higher feed conversion ratio (FCR) (P<0.05).All birds fed Se supplemented diets had higher GSH-Px versusC(P<0.001).Birds fed diets with SY had greater levels of Sein breast and liver tissue and birds fed Chad the least amount(P<0.001).The third study investigated the effectsofSe(and saturated (SF) and unsaturated fat (USF) on the oxidative status and performance of broilers rearedatconstant ST and HT.The results showed that birds reared in ST had greater FI and WGand lower FCRthan those reared at HT(P<0.001). There were interactions between temperature x Se, and highest GSH-Px was seen in birds fed Seat 20°C, and lowest GSH-Px wasin birds fed C dietsat HT(P<0.05).Results for TAS were not significant(P>0.05).Highest concentration of Se in breast tissue was in those birds fed unsaturated fat with Se (USFSe)versusthose birds fed USFC(P<0.05). Sefed birds also hadhighest Se in the liver tissue at 20 °C(P<0.05),but at HTthere was no difference in Sedeposition in the liver(P>0.05).Birds reared at ST had higher nitrogen retention (NR) versusthose raised at HT (P<0.05), and birdsfed diets withSFhad lower apparent metabolizable energy adjusted for nitrogen (AMEn)and fat retention (FR) (P<0.05 and(P<0.001)respectively.At HT, Se did not increase GSH-Px activity (P>0.05).In conclusion, these studies show thatwhen broilers are fed different sources of Se, itincreases the levels ofSe deposited in liver and breast tissue and improves theanimals’ oxidative status.These improvements were independent ofthe ambient rearing temperature of the broilers. High rearing temperaturedid not significantly affect oxidative status of thebroilers in the present studiesand this may have been related to the levels of Se in the C diet.

Item Type: Thesis (Doctoral)
Divisions: Veterinary Health and Animal Sciences (from 1.08.20)
Depositing User: Ms Kath Osborn
Date Deposited: 11 Jun 2021 14:21
Last Modified: 28 Oct 2021 03:30
URI: https://hau.repository.guildhe.ac.uk/id/eprint/17694

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