Goat’s saliva is hot. Plants grazed by goats are likely to die.

Goat’s saliva is hot. 

Plants grazed by goats are likely to die.

Dr Abe V Rotor

Living with Nature School on Blog

Leo Carlo and his pet - a black goat - at home, San Vicente, Ilocos Sur

Other than direct injury, what is in the saliva of the goat that leads to the death of the plant that it feeds upon?

First of all, let’s study the eating habit of this herbivore. When feeding, it pulls and tears off at anything its teeth come in contact with. It prefers seedlings and succulent tissues. But when food is scarce it feeds on older leaves, stems and roots. Goats in town may even devour wrappers of sweets and kitchen refuse. There are cases ingested plastics can cause slow death to the animals.

I gave a pet kid to my youngest son when he was small. He would allow the animal to lick his fingers. I discovered tiny lacerations inflicted by the developing milk teeth of his pet. “Was it not painful?” I asked. Leo told me it was only after some time that he felt tingling sensation of pain. I believe that the saliva of a goat contains anesthesia, which could be the thing old people call “hot.” Is this the active principle that kills plants?

But plants have their ways of defending themselves, such as the presence of thorns (e.g., Mimosa or makahiya), high level of impregnated silica (e.g., Imperata cylindrica or cogon), and obnoxious odor or taste (e.g., Lantana or bangbangsit Ilk). There are plants that respond to injuries caused by the feeding of animals. They produce poison to discourage, if not kill, the voracious feeder.

This is a classical case. In the African Savannah a species of acacia is the favorite of browsing animals like the giraffe. When the acacia trees are threatened by overgrazing, they send signals like pheromones to warn each other, including the unaffected acacia trees, to produce higher level of tannic acid, similar to mimosin in ipil-ipil. This substance, other than being unpleasant to the taste, is extremely acrid and may cause discomfort to the feeder.

I had an experience at home when I was a farmhand which is quite similar to this case. Goats after the rice harvest are usually left stray in the field but now and then they trespass into backyards and gardens. I noticed our neighbor's goat coming over to browse on wild patani (Phaseolus lunatus). My dad simply didn't mind, to think that entire borders are covered with the viny plant. Then the goat stopped visiting us.

We went to our friendly neighbor and saw the goat, its stomach bloated as if it were in its last stage of pregnancy. Tata Melecio had to slaughter the animal. We found out that its stomach was stuffed with undigested patani leaves, and emitting the characteristic bean odor which I found in later years to be that of tannic acid.

Did the patani plant, like the acacia tree, produce "toxin" to defend itself from excessive feeding by the animal? If this is so, then nature extends to both plants and animals protective mechanisms through the production of chemical compounds that directly confront extreme threat - indeed an effective means of survival not only to the organism, more so, to the species.

But this does not adequately answer why plants bitten by goats are likely to die. I attribute this observation to the manner goats feed.  

Firstly, uprooted plants have little chance to recover especially in extreme dry season. 

Secondly, plants in general die when their biomass above the ground is severed, even if their roots remain intact. It is because the roots will subsequently starve for lack of manufactured food coming from the leaves.

Thirdly, goats prefer plants in the flowering and fruiting stages, thus depriving the plant from producing offspring, even those that reproduce vegetatively.

And lastly, in the absence of fresh feeds, goats forage on the dormant parts of plants in summer (aestivation), and in winter (hibernation), thus preventing the plants to re-emerge come growing season.

One thing I learned from that childhood experience of mine is that, raise goats in corral, or tether them securely while grazing in the field. Your plants may not have a second chance. So with your goats.~

Reference: Living with Folk Wisdom, AVRotor UST

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