Dietary ractopamine promotes growth, feed efficiency and carcass responses over a wide range of available lysine levels in finisher boars and gilts

Rikard-Bell, C. V., Pluske, J. R., van Barneveld, R. J., Mullan, B. P., Edwards, A. C., Gannon, N. J., Henman, D. J. and Dunshea, F. R. (2013) Dietary ractopamine promotes growth, feed efficiency and carcass responses over a wide range of available lysine levels in finisher boars and gilts. Animal Production Science, 53 1: 8-17. doi:10.1071/AN11351


Author Rikard-Bell, C. V.
Pluske, J. R.
van Barneveld, R. J.
Mullan, B. P.
Edwards, A. C.
Gannon, N. J.
Henman, D. J.
Dunshea, F. R.
Title Dietary ractopamine promotes growth, feed efficiency and carcass responses over a wide range of available lysine levels in finisher boars and gilts
Journal name Animal Production Science   Check publisher's open access policy
ISSN 1836-0939
1836-5787
Publication date 2013
Year available 2012
Sub-type Article (original research)
DOI 10.1071/AN11351
Volume 53
Issue 1
Start page 8
End page 17
Total pages 10
Place of publication Collingwood, VIC., Australia
Publisher C S I R O Publishing
Collection year 2013
Language eng
Formatted abstract
The aim of this study was to investigate the performance and carcass responses of finisher boars and gilts offered a range of dietary lysine levels and three levels of dietary ractopamine hydrochloride (RAC). The study involved three experiments of 90 pigs each, totalling 270 individually penned pigs in a 2 by 5 by 3 factorial design comprising two sexes (gilts, boars), five levels of dietary lysine [0.40, 0.48, 0.56, 0.64, and 0.72 g available lysine per MJ of digestible energy (DE), respectively] and three RAC dose regimes (0, 5 and 10 mg/kg) for 28 days. An outbreak of pneumonia (Actinobaccilus pleuropneumonia) at Day 26 in Experiment 1 compromised Day 28 data; however, Day 21 data was considered suitable across all three experiments. The results indicate that 0.56 g available lysine/MJ DE is sufficient to maximise average daily gain (ADG), feed conversion ratio (FCR) and carcass weight in gilts. Control boars indicated that ADG and FCR were not limited by the lysine:energy ratios fed in this study. Increasing levels of dietary lysine linearly increased ADG (P 0.001), improved FCR (P 0.001) and increased carcass weight (P ≤ 0.001). Likewise, increasing dietary RAC further improved ADG (P ≤ 0.001), FCR (P ≤ 0.002) and carcass weight (P ≤ 0.075) linearly. The critical lysine levels calculated for ADG and FCR in gilts fed diets supplemented with RAC were less than required for controls. Boars had higher critical lysine levels than gilts when supplemented with dietary RAC, and increasing dietary RAC increased critical lysine levels for ADG and FCR in gilts and boars. An interaction (P ≤ 0.016) between dietary lysine and RAC occurred for FCR, such that the response to 5 mg/kg dietary RAC diminished in diets containing 0.64 g and 0.72 g available lysine/MJ DE; however, these diets elicited a response when supplemented with 10 mg/kg RAC. Responses in ADG, FCR and carcass weight to dietary RAC were noted when dietary lysine was at or below the current recommendations for RAC diets, and it was suggested that this may have been due to reduced efficiency of lysine utilisation due to chronic disease challenge. A Sex RAC interaction (P ≤ 0.027) occurred for carcass P2, indicating the higher RAC dose reduced carcass P2 in boars but not in gilts. When formulating finisher pig diets between 60 and 90 kg liveweight, consideration of the lysine:energy requirements for boars and gilts is needed in order to maximise ADG, FCR and carcass characteristics. When supplementing pigs with dietary RAC, a wide range of lysine:energy levels maybe employed; however, this is dependent on RAC inclusion level and probably herd health
Keyword Pigs fed ractopamine
Lipid deposition
Growing pigs
Meat quality
Live weight
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published online 15 November 2012

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Agriculture and Food Sciences
Official 2013 Collection
 
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