216
A. D. BONEY
and hens (Jensen, 1968). With ewes there was no significant effect
on fertility, although those ewes fed,with seaweed meal produced lambs
which showed a significantly higher rate of growth. Increased wool
production was a further result of seaweed meal supplement. The
laxative effects of too high a supplementation with seaweed meals have
frequently been described. Experiments with very young chicks
showed that seaweed meal had similar effects to commercial grass meal
when added to rations deficient in vitamins, and evidently all the vitamin A and D requirements can be supplied from this source. Jensen
(1964) observed that the ascorbic acid content of Aswphyllum nodosum,
Fwus serratus and F. vesiculosus showed a seasonal variation, being
highest in spring, and declining through summer and autumn to the
lowest value in winter. The vitamin contents of algae have also been
described by Freudenthal(l966) and Hundin and Ericson (1966). The
importance of carotenes as precursors of vitamin A is well known, and
the carotene and carotenoid contents of marine algae have also been
studied (Haug and Larsen, 1966 ; Liaaen and Smensen, 1956).
The use of seaweed in poultry food has been extensively studied.
Thus Hnrie and Sandvik (1966) and Black (1964) reported that Laminaria hyperborea and Aswphyllum nodosum meals caused heavy water
consumption and loss in weight if used in too high a quantity, and a
rapid decrease in egg production has also been recorded. Hnrie and
Sandvik (1966) and Sunde (1966) have reported that seaweed meals
lead to an enhanced iodine content in the egg yolk. Yolk colour is also
improved.
The value of seaweed meals as sources of trace elements and vitamins
seems to be well established. There is also much evidence that the
proportions of seaweed meal mixed with other feeding stuffs must be
carefully watched, since h d u l side effects have been recorded.
Aswphyllum nodosum is extensively used as a source of seaweed meal,
and for reasons given earlier (p. 144) heavy cropping of this plant can
lead to a marked fall in the standing crop.
C. Manurial value of seaweeds
Newton (1963) has summarized data on the utilization of the large
marine algae as manure. Direct utilization and methods of composting
are practised in many coytal areas. Dried seaweed meds are marketed
by a number of firms, using in particular Ascophyllum nodosum and
Macrocystis pyrifera. Chapman (1960) quoted results of work in which
the rates of decomposition of Macrocystis, E c k h i a and Durvillea were
tested after being dug into the soil. All three were completely decomposed within 3 months, and the bulk of the Na+, K+ and C1- released
A. D. BONEY
and hens (Jensen, 1968). With ewes there was no significant effect
on fertility, although those ewes fed,with seaweed meal produced lambs
which showed a significantly higher rate of growth. Increased wool
production was a further result of seaweed meal supplement. The
laxative effects of too high a supplementation with seaweed meals have
frequently been described. Experiments with very young chicks
showed that seaweed meal had similar effects to commercial grass meal
when added to rations deficient in vitamins, and evidently all the vitamin A and D requirements can be supplied from this source. Jensen
(1964) observed that the ascorbic acid content of Aswphyllum nodosum,
Fwus serratus and F. vesiculosus showed a seasonal variation, being
highest in spring, and declining through summer and autumn to the
lowest value in winter. The vitamin contents of algae have also been
described by Freudenthal(l966) and Hundin and Ericson (1966). The
importance of carotenes as precursors of vitamin A is well known, and
the carotene and carotenoid contents of marine algae have also been
studied (Haug and Larsen, 1966 ; Liaaen and Smensen, 1956).
The use of seaweed in poultry food has been extensively studied.
Thus Hnrie and Sandvik (1966) and Black (1964) reported that Laminaria hyperborea and Aswphyllum nodosum meals caused heavy water
consumption and loss in weight if used in too high a quantity, and a
rapid decrease in egg production has also been recorded. Hnrie and
Sandvik (1966) and Sunde (1966) have reported that seaweed meals
lead to an enhanced iodine content in the egg yolk. Yolk colour is also
improved.
The value of seaweed meals as sources of trace elements and vitamins
seems to be well established. There is also much evidence that the
proportions of seaweed meal mixed with other feeding stuffs must be
carefully watched, since h d u l side effects have been recorded.
Aswphyllum nodosum is extensively used as a source of seaweed meal,
and for reasons given earlier (p. 144) heavy cropping of this plant can
lead to a marked fall in the standing crop.
C. Manurial value of seaweeds
Newton (1963) has summarized data on the utilization of the large
marine algae as manure. Direct utilization and methods of composting
are practised in many coytal areas. Dried seaweed meds are marketed
by a number of firms, using in particular Ascophyllum nodosum and
Macrocystis pyrifera. Chapman (1960) quoted results of work in which
the rates of decomposition of Macrocystis, E c k h i a and Durvillea were
tested after being dug into the soil. All three were completely decomposed within 3 months, and the bulk of the Na+, K+ and C1- released