Urinary and faecal sugar losses in growing pigs fed diets containing lactose

Abstract

Twelve castrate pigs were fed diets containing either 0, 15, 30, or 45% lactose from 50 to 120 lb live weight. Total collections of faeces and urine were made over 5-day periods at 60 lb and 110 lb live weight. Except for a single day' collection from one pig, the faeces from all pigs were of normal consistency throughout both collection periods.

A significant positive relationship was found between the amount of total reducing sugars voided in the urine and the dietary level of lactose. However, it was estimated that the maximum total quantity of reducing sugars in the urine did not exceed 1% of the lactose ingested. Lactose, galactose, and traces of glucose were found in urine samples from pigs fed lactose. Urinary samples from control animals contained traces of glucose only.

Amounts of reducing sugar in faeces samples were small and unrelated to the dietary level of lactose. The major sugar present in faeces of normal consistency was tentatively identified as the pentose sugar xylose. In the watery faeces voided by one pig on a single day appreciable quantities of glucose and galactose were detected.

These results are discussed in relation to the inferior growth performance of pigs fed diets containing high levels of lactose.