Reticular groove contraction in dairy cattle following drenching with an anti-bloat solution or a combination of anti-bloat solution and NaCl.
OBJECTIVE
To determine whether the inclusion of NaCl in an antibloat drench increased the incidence of contraction of the reticular (oesophageal) groove in cattle.


METHODS
Non-lactating Friesian dairy cows aged 3-10 years (n=30) were subjected to a 13C-octanoic-acid breath test after being drenched with either an anti-bloat solution alone or a mixture of anti-bloat solution and NaCl, to determine the incidence of reticular groove contraction.


RESULTS
Drenching with an anti-bloat solution alone did not result in detectable by-pass of the reticulorumen in 27/29 cows; minor by-pass occurred in 2/29 cows. The inclusion of NaCl in the anti-bloat solution increased the incidence of reticulorumen by-pass; minor by-pass occurred in 12/30 cows and substantial by-pass was detected in 5/30 cows. The incidence of by-pass did not vary significantly with cow age.


CONCLUSIONS
Drenching with an anti-bloat solution alone did not result in significant by-pass of the reticulorumen. The inclusion of NaCl in the anti-bloat drench increased the incidence of reticulorumen by-pass. The proportion of anti-bloat/ NaCl fluid by-passed was considered to be of no practical significance to the protection from bloat afforded in the majority of animals, but may significantly decrease protection from bloat afforded by drenching in 10-15% of cows. The proportion of animals at risk within a herd may vary with their physiological state and the method and frequency (number of doses per drench) of drenching.
McLeay
L M
LM
Department of Biological Sciences, The University of Waikato, Private Bag 3105, Hamilton, New Zealand. L.McLeay@waikato.ac.nz
Waller
J E
JE
O'Connor
M B
MB
Hobson
B L
BL