Abstract :
The effects of permanent or random exposure to stray voltage on a water trough were
evaluated in growing–finishing Romane male lambs between the age of 13 and 19 weeks.
Ninety lambs were assigned during two 6-week experimental periods to one of three treatments,
with 30 animals in each treatment (15 per experimental period). The treatments
were permanent exposure to voltage (PERM, 3.5 V) on the water trough, random exposure
to voltage (RAND, 3.5 V, 34 h/week) and no voltage exposure for the control group
(CONT). No effects of voltage exposure were observed on production parameters: growth,
average daily gain and water intake. The stress physiology seemed to be slightly modified
with a lower plasma cortisol concentration at slaughter in PERM lambs compared to CONT
lambs (P < 0.05) and a higher adrenal medulla weight in PERM lambs compared to CONT
lambs (P < 0.05). However, no differences were observed between treatments in heart-rate,
basal plasma cortisol concentration and tyrosine hydroxylase and phenylethanolamine-Nmethyl
transferase activities. Carcass yield, temperature and the pH of the M. longissimus
dorsi were not modified by voltage exposure during rearing. In the good carcass conformation
class (R class in EUROP grading scheme), there were fewer fat carcasses (grade 4 of 5) in
the PERM and RAND compared to the CONT group (P < 0.05). In conclusion, no major effects
of voltage exposure were observed in male lambs on production, carcass parameters and
stress physiology. Stray voltage could be considered as a mild stressor in growing–finishing
lambs.
