Some Physical and Chemical Properties of Bovine Saliva which May Affect Rumen Digestion and Synthesis
1949; Elsevier BV; Volume: 32; Issue: 2 Linguagem: Inglês
10.3168/jds.s0022-0302(49)92019-6
ISSN1529-9066
Autores Tópico(s)Ruminant Nutrition and Digestive Physiology
ResumoThe early studies of Pavlov (25) placed great significance on the role of saliva mainly as that of a watery secretion.Although it generally is accepted that the high water content of saliva is a digestive aid as a lubricant, solvent and medium, other constituents and properties of saliva appear to be of equal importance in rumen digestion.Doubtless some of these substances and properties exert an influence on the activity of rumen flora and fauna.Scheunert and Trautmann (30) found that the water content of parotid and mandibular saliva of sheep ranged from 98.75 to 98.90 per cent and 99.0 to 99.6 per cent, respectively.The submaxillary saliva of the cow ( 19) and the parotid saliva of the buffalo (33) were found to contain 99.11 and 99.15 per cent water, respectively.The following figures were reported for the pH of saliva of several ruminant species: buffalo, 8.8 (33) ; sheep, 8.12 to 8.32 (28) ; goats, 8.2 to 8.8 (2) ; calves, 8.1 (32, 38) and 8.23 (31) ; and cattle, 8.55 to 8.90 with an average of 8.8 (10).Chrzaszez and ScheehtlSwna (10) observed ~ decrease in the pH of saliva to 7.9 during rumination.Some reducing properties and several associated constituents of saliva have been investigated by several workers.Suzuki (36) reported that human saliva generally contains less than 0.18 mg. per cent ascorbic acid, and that age and sex are without effect upon the concentration of this substance.This investigator was not able to detect ascorbic acid in oxidized form in human saliva or in the salivary glands of rabbits.The ascorbic acid content of the salivary glands was found to be progressively lower in the species of the following orders: rodentia, carnivora and ungulata (36).Suzuki (36) demonstrated an increase in the ascorbic acid content of the parotid glands of the rabbit by injecting 2 mg. of ascorbic acid per kg. of body weight or by administering pilocarpine hydrochloride; the latter substance, however, did not alter the concentration in the submaxillary glands.The investigations of Zimmet and Dubois-Ferriere (40) revealed that the concentration of aseorbic acid in children's saliva increased progressively with age.Levels of 0.04 mg. per cent for 4-year-old children, 0.11 rag.per cent for 16-year-olds, and a marked lowering of the saliva ascorbic acid level in children under febrile conditions were reported (40).These results, relative to the age effects, are contrary to those of Suzuki (36).Held et al. (14) believed 0.12 to 0.16 mg. per cent to be the normal ascorbic acid
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