Feed deprivation in Merino and Terminal sired lambs: (2) The metabolic response under pre-slaughter conditions and impact on meat quality and carcass yield

Title
Feed deprivation in Merino and Terminal sired lambs: (2) The metabolic response under pre-slaughter conditions and impact on meat quality and carcass yield
Publication Date
2019-07
Author(s)
Stewart, S M
McGilchrist, P
( author )
OrcID: https://orcid.org/0000-0003-3265-1134
Email: pmcgilc2@une.edu.au
UNE Id une-id:pmcgilc2
Gardner, G E
Pethick, D W
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Cambridge University Press
Place of publication
United Kingdom
DOI
10.1017/S1751731118003075
UNE publication id
une:1959.11/28966
Abstract

Under current Australian industry pre-slaughter guidelines, lambs may be off feed for up to 48 h before slaughter. The purpose of this study was to examine what proportion of circulating metabolites at slaughter are due to stress and feed deprivation and if this response differs between Merino and Terminal genotypes. In addition the effect of feed deprivation on carcass weight and meat quality was examined. Jugular blood samples were collected from 88 Merino and Terminal sired lambs at rest and at slaughter following 24, 36 and 48 h of feed deprivation and plasma analysed for glucose, lactate, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHOB). From the same carcasses hot carcass weight (HCWT) were measured as well as a suite of meat quality traits measured such as M. longissimus lumborum (loin) and M. semitendinosus pH at 24 h postmortem. Loin samples were also analysed for intramuscular fat content and Warner-Bratzer Shear Force. Merino sired lambs had a higher NEFA response compared to Terminal sired lambs at slaughter after 24, 36 and 48 h of feed deprivation, with NEFA levels up to 35% higher than previously reported in the same animals at rest in animal house conditions, whereas BHOB response to feed deprivation was not affected by sire type (P>0.05) and similar to previously reported at rest. In addition to the metabolic effects, increasing feed deprivation from 36 h was associated with a 3% reduction in HCWT and dressing percentage as well as causing increased ultimate pH in the M. semitendinosus in Merino sired lambs. Findings from this study demonstrate that Merino and Terminal sired lambs differ in their metabolic response to feed deprivation under commercial slaughter conditions. In addition, commercial feed deprivation appears to have a negative effect on ultimate pH and carcass weight and warrants further investigation.

Link
Citation
Animal, 13(7), p. 1468-1477
ISSN
1751-732X
1751-7311
Pubmed ID
30442218
Start page
1468
End page
1477

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