CLINICAL CHEMISTRY OF GRAIN-FED CATTLE.: I. A PRELIMINARY STUDY OF A BASIC BIOMEDICAL PROFILE

Abstract

In a preliminary study, 12 Hereford range cattle were fed in a feedlot for 105 days and 14-point biomedical profiles were prepared regularly at short intervals for the week prior to and during the feeding period to provide a clinical chemical view of the effects of the regimen upon cattle. The animals were fed for a week on local hay and then adapted to the grain diet (90% steam-rolled barley, 5% beet pulp, 5% of a commercial supplement containing 32% protein) by introducing the diet at 1.0 kg feed/100 kg body weight and increasing the ration 0.45 kg/head per 2 days. The hay ration was progressively reduced at the same time so that from the 8th day onward the animals were eating 0.9 kg/head per day and the grain diet ad libitum. Plasma cholesterol, Ca++, Cl−, bilirubin, creatinine, protein, phosphate, alkaline phosphatase, lactate dehydrogenase, glutamic oxaloacetic transaminase, urea nitrogen, glucose, Na+, and K+ were estimated at close intervals to provide linear biomedical profiles. Although no changes were observed that could be classified as pathological either from the clinical chemistry or post-mortem examination, significant changes were observed in the levels of some parameters and in most parameters the variance was significantly higher during the first 40 days of the feeding period. The changes observed would indicate that metabolic adaptation requires at least 40 days following the start of grain feeding in contrast to dietary adaptation, which is generally considered complete 2 days after the animals are eating the grain diet ad libitum.