MOLASSES NEURO-TOXICITY AND HIGHER VOLATILE FATTY ACIDS IN SHEEP

HAL Id: hal-00901214

https://hal.archives-ouvertes.fr/hal-00901214

Submitted on 1 Jan 1979

HAL is a multi-disciplinary open access

archive for the deposit and dissemination of

sci-entific research documents, whether they are

pub-lished or not. The documents may come from

teaching and research institutions in France or

abroad, or from public or private research centers.

L’archive ouverte pluridisciplinaire HAL, est

destinée au dépôt et à la diffusion de documents

scientifiques de niveau recherche, publiés ou non,

émanant des établissements d’enseignement et de

recherche français ou étrangers, des laboratoires

publics ou privés.

MOLASSES NEURO-TOXICITY AND HIGHER

VOLATILE FATTY ACIDS IN SHEEP

R.H. Dunlop, Lionel Bueno

To cite this version:

MOLASSES NEURO-TOXICITY

AND

HIGHER VOLATILE FATTY ACIDS

IN

SHEEP

R.H. DUNLOP L. BUENO

Department of Physio%gy, Ecole Nationale V6t6rinaire, 31076 Toulouse Cedex, France

A

_study

of the effects of diets

_containing

a

large

proportion

of molasses on the microbial fermentation in the rumen was carried out in

sheep.

The consequences of

changes

in fer-mentation acids on the function of the central nervous system was

_{investigated by}

the

per-manent control of electrical

activity

of the

cor-tex and

_sleep

_patterns. Since final molasses

contains

large

amounts of soluble sugars, the

possible

occurrence of a lactic acid fermenta-tion was also

explored.

Material and Methods.

Four female

sheep

weighing

40-45

_kg

were

prepared surgically

with a rumen cannula and with electrodes to allow continuous

recording

of the

_{electrocorticogram, electro-oculogram,}

and the

_{electromyogram}

of the

_splenius

mus-cle. Two silver screw electrodes were inserted

2 cm from the

_sagittal

suture

_through

holes

drilled in the skull so that their

tips

touched the

skrface of the cerebral cortex,

approximately

over the

sigmoid

gyrus. Two more screNs in the bones of the orbital rim allowed the

poten-tial shifts related to eye movements to be detected. Two other copper wire electrodes

were

implanted

in the

splenius

on each side to

record electrical

activity

of the neck

muscula-ture. All the wires were

_conveyed

subcuta-( *

) Present address : School of Veterinary

Stu-dies, Murdoch University, Murdoch, Western AUs-tralia.

neously

to the skin over the dorsum of the

neck and

_brought

out to a

_junction

box

fee-ding

into a multi-channel recorder

(Alvar,

Reega

VIII,

Montreuil) modified for slow

speed

(2.4 cm/min) to allow continuous 24-hour direct

_{recording. Following complete}

recovery

from the

_{surgical procedure,}

control

recor-dings

for 2

_days

and

nights

allowed

characteri-zation of the

_{electro-encephalogram}

and of the

_{sleep-waking cycles.}

Lactic acid was

mea-sured

_by

the Barker and Summerson

method,

L-lactate

by

an

_enzymatic

method,

and VFA

concentrations

by

gas

chromatography.

During

a control

_period

the animals received

hay

ad libitum distributed each

_morning

at

9:00,

and

only

100

_{g/day during}

the

_experiments

when rumen fermentation was modified

by

infusing

a

synthetic

diet via the rumen cannula for 7-10

_days.

The basal medium consisted of the

These

_ingredients

were dissolved oi

suspen-ded in water. At the start of the

experiment

the animals were

_injected

with Vitamins

A,

D,

E (Lab.

_Roger

Bellon,

Neuilly) :

2 ml = 1 x 10

6

. Vit.

A,

1.5 x

₁₀

_I

_D

₃

_,

100 E).

Molasses was added at 500 ml/41. The final diet was

_kept

in uniform

suspension

by

a

magnetic

stirrer and was

_pumped

into the

rumen via a Gilson

_Minipuls

2 pump.

The infusions were started after

healing

was

complete

and after the 48 hour control

recor-ding

period.

Continuous

_recordings

at slow

speed

allowed

_changes

in the

_sleep

_pattern or

electrical

_rhythm,

to be detected.

Daily

mixed

rumen

samples

taken at 9:00 and 16:00 were

imme-diate

_pH

measurements. The molasses

plus

basal medium infusions were delivered over a nine hour

period

during

the

_daytime.

Ten

_days

after the end of molasses intraruminal

infu-sion,

the

_following

solutions were infused

intrevenosly

for 30 min. in each animal at two

day

intervals : normal (solution I) or iso

(solu-tion II)

butyric

(70 mM/1) and valeric (30 mM/I) acids at

_pH

=

6.8,

DL-lactic (100 _{mM/1) at}

_pH

= 5.8 _{(solution 111). Direct}

high speed

(14.2 cm/min) ECoG were recorded

_during

the

infu-sing

period

and

_prolonged

for 40-50 min. after it ended.

Results

a) Effects of molasses added to the rumen

contents.

The

repeated daily

infusions of the molasses diet

_initially

induced a

_change

to a

gram-positive

microflora and the death of protozoa

in the rumen within 48

hours,

accompanied by

the accumulation of lactic acid in the

_ingesta,

peaking

at about 72 hours with a mean unit fall in the

_pH

values (table 2). This

phase

was

accompanied

by

a

_profound

reduction in total

VFAs. It was followed

_by

a decline in lactic

acid and restoration of VFAs with a marked

shift towards the

_higher

acids and a 0.5 unit

pH

increase.

Remarkably

high

concentrations of

butyric,

valeric and

_caproic

acids were observed after 6

days

(table 2). Two types of sickness were

manifest in each animal :

indigestion

with

severe

_diarrhea,

_tachycardia

and weakness

during

the lactic fermentation followed

by

recovery then a

relapse

with

depression

and

incoordination in the second

phase.

One of

the four animals died

_during

the latter stage

and infusions of molasses were

_stopped

on

the 8 th

_day

on the three other animals. Normal ECoG

_activity

_{presented phases}

of

synchronized high voltage

slow

signals

with

persistent

muscle tone

_{corresponding}

to

NREM

_sleep

and low

_voltage

fast

_signals

asso-ciated with neck muscle

activity

(when awake) or

rapid

eye movements and the absence of

muscle tone (in REM

_sleep).

After 3

days

on molasses, we noticed the

transient presence of abnormal ECoG

activity

consisting

of

high

voltage (300-400

pV)

and

low

frequency

(0.5-3 Hz)

signals occurring

in 10-30 sec

_periods

during

the « awake »

period.

This «

spindle

» activity

increased

daily

from

5-7 min on the 4th

day

to 136 + 28 min on the

7th

_day

with a decrease (43 % of total

daily

sleep

(fig.

11. ).

b) lntravenous infusion of

higher

VFAs

buty-rate and valerate.

A 30-min intravenous infusion of 100

mmo-les of

mixed,

normal or

_isobutyrate

(70

mmo-les) and valerate (30 mmoles) at

pH

=

6.8,

gave rise in 5 to 10 min to bursts of

_high

ampli-tude waves with a maximum

_hourly

presence of 125 sec,

occurring

later for iso acids.

Howe-cer, a similar intravenous infusion of DL-lactic acid (100

mM, pH

= 5.8) did _not

produce

_any

spindle

activity.

It is concluded that

moderately high

levels

of molasses intake

_{by sheep}

may

trigger

a

lac-tic acid fermentation with

proliferation

of

gram-positive

bacteria in the rumen. This

phase

may be followed

by

a further transition

to a _type of fermentation characterized

by

unusually

high

concentrations of the

higher

volatile

fatty acids,

particularly butyric,

valeric

and

_caproic.

This

study

has shown that these acids are

toxic for the central nervous system, in

excess,

give

rise to short bursts of

synchroni-zed

_{high amplitude epileptiform}

slow waves on the

_{electrocorticogram}

accompanied by

behavioural

depression.

These

_findings

may have some

_bearing

on

the clinical

_syndrome

of molasses

_toxicity

encountered in cattle fed

high

levels of

molas-ses (Losada and Preston _1973, Verdura et

Zamora 1970).

_High

concentrations of

buty-rate in the rumenofluid of cattle affected

by

aci-dosis from excessive

_ingestion

of sugar beet

topq have been

_{reported previously}

(Dirksen

1970). Similar

changes

in ruminal

_butyrate

concentration were observed in

_high

molasses diets

_(Marty

and Preston 1970).

References

DIRKSEN G., 1970. Acidosis. /n A.T. Phillipson (Ed.), Physio%gy of _Digestion and Metabolism in the

Ruminant, Oriel Press, Newcastle, pp. 612-625.

LOSADA H., PRESTON T.R., 1973 : Molasses toxicity and cerebrocortical necrosis <CCN). Cuban J. agric. Sci., 7, 169-173.

MARTY R.J., PRESTON T.R., 1970 : Molar proportions of short chain fatty acids (VFA) produced in the

rumen of cattle given high-molasses diet. Rev. cubana Cienc. agric. (Eng. Ed.), 4, 183-189.