Effects of Chronic Hydrochloric and Lactic Acid Administrations on Food Intake, Blood Acid‐base Balance and Bone Composition of the Rat

Abstract

In experiment 1, weanling rats were given, for 7 weeks, a commercial rat diet supplemented with hydrochloric acid at levels up to 560 mmol.kg-1 dry matter. The supplement increased water intake but did not significantly affect food intake, live-weight gain, blood haemoglobin and haematocrit values or acid-base balance. In experiment 2, adult rats were given, for 9 weeks, a commercial rat diet supplemented with hydrochloric acid at levels up to 1250 mmol.kg-1 dry matter. Food intake and liveweight gain were not affected by hydrochloric acid concentration up to 625 mmol but at 938 and 1250 mmol.kg-they were considerably reduced and there was 100% mortality of the rats. In experiment 3, weanling rats were given, for 12 weeks, a commercial rat diet supplemented with hydrochloric or lactic acid each at 300, 600 and 900 mmol.kg' I dry matter. Lactic acid at the three levels and hydrochloric acid at the two lower levels did not affect food intake or liveweight gain and had only a slight effect on blood acid-base balance. At a dietary concentration of 900 mmol.kg-' dry matter, hydrochloric acid decreased food intake, induced a mild degree of metabolic acidosis and resulted in 30 % mortality of the rats. In the three experiments, the acid treatments did not directly affect the length or composition of the femur of the rats.A method of preservation of green fodder as silage for ruminants, by acidifying with strong mineral acids, was developed by Virtanen [1933]. This process, known as the AIV treatment, has been used also for the preservation of fish and fish offal as fish silage for use as animal feeds [Petersen, 1953;Tatterson 1976]. While it is generally recommended that these products should be neutralized before feeding, there is little experimental evidence on whether or not it is necessary to do so. The physiological effects of mineral acid loading has been studied on many species, e.g. in rats [Barzel and Jowsey, 1969;Janicki 1970;Newell and Beauchere 1975], in dogs [Schwartz, 0rning and Porter, 1957], in pigs [Scott and McIntosh, 1975] and in sheep [Braithwaite, 1972]. A common feature with all the species is that blood pH and plasma bicarbonate content may be reduced, accompanied by a decrease in urine pH and an increase in urinary excretion of ammonia and calcium. Evidence was obtained by Barzel and Jowsey [1969] that the increased excretion of urinary calcium was accompanied by a loss of bone tissue resulting from an increase in bone resorption, but this was not confirmed by Newell and Beauchere [1975].With sheep, it has been shown that supplementation of a grass meal diet with sulphuric or hydrochloric acid decreased voluntary food intake [L'Estrange

Diet, evolution and aging

“…Mobilization of bone base persists, and the bone minerals (calcium and phosphorus) accompanying that base continue to be wasted in the urine, without compensatory increases in intestinal absorption [60]. With chronicity of the acidosis, bone mineral content and bone mass progressively decline [61,62] and osteoporosis develops [61,63,64].…”

“…Release of bone mineral by osteoclasts is accompanied by osteoclastic degradation of bone matrix [50,61,63,64]. In chronic acid loading studies in humans, urinary hydroxyproline excretion increases [46,51], and serum osteocalcin levels decrease [46], suggesting that matrix resorption increased and formation decreased.…”

Re‐evaluation of hydrochloric acid (E 507), potassium chloride (E 508), calcium chloride (E 509) and magnesium chloride (E 511) as food additives

“…In experiment 2, approximately 1‐year‐old rats (strain not specified) (4 males/4 females per group, initial weight about 350 g) were given a commercial diet alone (control) or a diet supplemented with hydrochloric acid at concentrations of 312 mmol/kg, 625 mmol/kg, 937 mmol/kg or 1 250 mmol/kg dry matter for 9 weeks (equivalent to 569, 1,139, 1,708 or 2,279 mg/kg bw per day as hydrochloric acid) (Upton and Lestrange, ). The two highest concentrations (937 and 1,250 mmol/kg dry matter) resulted in 100% mortality of the rats, with an average survival time of 51.3 and 19.1 days, respectively.…”

“…In experiment 3, weanling rats (strain not specified) (6 males/4 female per group, initial weight of approximately 60 g) were given a commercial rat diet alone (control) or supplemented with hydrochloric acid at 300 mmol/kg, 600 mmol/kg and 900 mmol/kg dry matter for 12 weeks (equivalent to 984, 1,969 and 2,953 mg/kg bw per day as hydrochloric acid) (Upton and Lestrange, ). At 900 mmol hydrochloric acid/kg dry matter statistically significant decreased feed intake, a mild degree of metabolic acidosis and 30% mortality (3 animals died) were reported.…”

“…In a series of experiments, the effects of supplementing hydrochloric acid in the diet of rats (strain not specified) were investigated (Upton and Lestrange, ). In experiment 1, weanling rats (4 males/4 females per group, initial weight about 60 g) were given a commercial rat diet alone (control group) or supplemented with hydrochloric acid at levels of 280 mmol/kg, 420 mmol/kg or 560 mmol/kg dry matter for 7 weeks (equivalent to 1,225, 1,838 or 2,450 mg/kg bw per day as hydrochloric acid).…”