Abstract:
Proc. Aust. Soc. Anim. Prod. (1974) 10; 394 UTILIZATION OF FERMENTATION PRODUCTS IN THE BABY PIG ANNE WHITTAKERS, P.D. CRANWELL and G.W. JOHNSTON* The baby pig reared under conventional conditions has, by 48h of age, an established gastric microflora (Smith and Jones 1963) capable of producing significant quantities of lactic acid (Cranwell, Noakes and Hill 1968). As both the D(-) and L(+) isomers of lactic acid are produced in equal quantities (Cranwell, unpublished data) and since it has been demonstrated that the D(-) isomer is not readily utilized by other mammalian species (Cori and Cori 1929; Drury and Wick 1965) a serious loss in energy may result. The purpose of our work is to investigate the utilization of lactic acid isomers by the baby pig. Four castrated litter mates, obtained from a minimal disease piggery, were reared in metabolism cages in a controlled temperature room (27OC). The diet of reconstituted whole milk (20% DM) with vitamin and mineral additives, was fed at 1.67 x l@J.DE/Kg metabolic live weight in two feeds/d. At7 weeks of age the daily pattern of lactic acid excretion in the urine was determined. Total lactic acid was determined by the method of Pryce (1969), L(+) lactic acid by an enzymic method (Beohringer Corp. (London) Ltd) and D(-) lactic acid calculated by difference. At 8 and 9 weeks of age three of the pigs were given racemic lactic acid at approximately 90 meq/l (lo-15 g/pig) in the morning feed and the fourth pig was used as a control. Urinary lactic acid increased only during the first 24h following lactic acid .feeding (Table 1). During the 1st 24h 65075% of the lactic acid excreted was the D(-) isomer but this was only 4.9% of the D(-) lactic acid fed. This is considerably less than that reported by Cori and Cori (1929) for rats and may indicate that D(-) lactic acid is utilized more readily by the pig. Our experiment did not take into account unabsorbed lactic acid and that metabolized in the gut. TABLE 1 Lactic acid concentration of urine (mg/lOOml/24h) from four pigs - Further experiments have been conducted to study the uptake and metabolism of the two isomers by measuring radioactivity in blood, tissues and urine following injection of either 14C labelled sodium L(+) and D(-) lactate into the small intestine of anaesthetized pigs. Determination of total radioactivity in blood (Laurencot and Hempstead 1971) indicates that there is no difference in the rate of uptake of the two isomers from the gut. Blood radioactivity reaches a maximum within 40-50 min and accounts for 5-8% of that injected. The residual radioactivity in the gastrointestinal tract is also to be determined. REFERENCES CORI, C.F. and CORI, G.T. (1929). J. biol. Chem. 81: 389. CRANWELL, P.D., NOAKES, D.E. and HILL, K.J. (1968)7roc. Nutr. Soc. 27: 26A DRURY, D.R. and WICK, A.N. (1965). Ann. N.Y. Acad. Sci. 119:1061. LAURENCOT, H.J. and HEMPSTEAD, J.L., (1971). 'Organic ScEillators and Liquid Liquid Scintillation Counting' (ed. Horrocks D.L. and Peng C.I.) Academic Press: New York). PRYCE, J.D. (1969) Analyst, Lond. 94: 1151 SMITH, H.W. and JONES, (1963). J.Path. Bact. 86: 387 &chool of Agriculture, La Trobe University, Bundoora, Victoria, 3083. This work is supported in part by a grant from the Australian Pig Industry Research Committee. 394