CONIFERÆ.
The only Conifer which commonly causes poisoning of live-stock is the Yew, but injury might more frequently occur were it not for the fact that Conifers generally are unpleasant to the taste, and are hence avoided by stock. Many species, however, contain Tannin, Resins and Gums, Volatile Oils, and an acrid substance which may cause inflammation of the digestive and urinary tracts, while Tanret found in the young shoots of Picea the bitter glucoside Picein (C14H18O7H2O); Kawalier and Thal found the intensely bitter glucoside Pinipicrin (C22H36O11) in Pinus sylvestris, Thuja occidentalis and Juniperus Sabina; and Kubel isolated Coniferin or Abietin (C16H22O8), a slightly bitter glucoside found in Abies excelsa, A. pectinata, Pinus strobus, Larix europæa and other conifers. It is not clear, however, whether these substances are at all poisonous. It is quite possible that if eaten in quantity the foliage of some Conifers may induce poisonous symptoms and even death in the animals concerned. It is noteworthy, however, that according to Pott the needles of Picea excelsa, Abies pectinata, Larix europæa, and Pinus sp. are, in the mountainous districts of Steiermark, Kärnten, and Tyrol, extensively fed to cattle and sheep, usually as a supplementary food, either fresh or dried and ground up—chiefly perhaps as an appetiser, and in small quantities as a dietetic; Juniperus sp. are similarly utilised in some districts. It is not known to what extent the foliage may be fed without harmful consequences, but Pott states that large quantities can cause hæmaturia and similar effects, and hence only small quantities should be used, and even so may impart a bad flavour to the milk of cows. All green needles frequently cause digestive troubles.
A case has recently (January, 1916) been reported to the author in which a Douglas Fir was cut down and a small branch about 4 ft. long was flung over into a field. Two sheep nipped off the bark and nearly died, but both vomited and recovered. The farmer reporting this experience recalls that over 30 years ago, after a gale, a lot of trees were blown down in a small plantation, and in severe weather the sheep ate the bark to such an extent that 80 of them aborted, while of the ewes which did not eat the bark none aborted, so that it would appear that the bark of Scotch Fir and Spruce was to blame for the loss.
The foliage of the Yew (see below) is well known to be dangerously poisonous to stock, and has caused many losses.
In regard to Cupressus the only cases of poisoning which have been traced are recorded in The Journal of the Board of Agriculture (October, 1905). These cases were reported as follows:—
“Two instances have recently come before the Board in which the death of cattle has been attributed to the poisonous effects of Cupressus macrocarpa and C. nootkatensis. In one case four bullocks died, and on the internal organs being forwarded by the owner to the Royal Veterinary College, Professor McFadyean reported that from the inflamed condition of the fourth stomach and from the description of the symptoms he had little doubt that the cause of death was irritant poison. Some pieces of Cupressus macrocarpa were found in their stomachs, and in default of any other explanation it was suggested that this plant might have some poisonous properties.
“In another case three heifers are stated to have suffered from irritant poison; one of them died, but the other two recovered on removal to another field. The veterinary surgeon in this case also attributed the death to a Cupressus (C. nootkatensis) growing by the side of the field.
“The Board have no information as to the poisonous properties of these two species, nor can any record be found of any similar case which would tend to confirm the suspicion that they are poisonous to cattle.”
REFERENCES.