Serum biochemical reference ranges for lambs from birth to 1 year of age in the tropics

Abstract

The study aimed to determine the biochemical reference ranges for lambs from birth to 1 year of age in the tropics. Data were obtained from experiments performed in several institutions and commercial farms using Santa Inês, Dorper, Lacaune, Morada Nova, Bergamacia and Suffolk lambs reared under different conditions (grazing, feedlot, semi-feedlot) from 2006 to 2017. Serum energy-, protein-, mineral-, and enzyme-related metabolites were evaluated. The metabolic energy profile included data from glucose, cholesterol, triglycerides, fructosamine, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol; the metabolic protein profile included total protein, uric acid, urea, albumin, and creatinine; the metabolic mineral profile included data on calcium, phosphorus, and magnesium; and the metabolic enzymatic profile included the enzymes aspartate aminotransferase, gamma-glutamyl transferase, alkaline phosphatase, and creatine kinase. The reference ranges were estimated using confidence intervals with a 95% confidence level, and percentiles were estimated or bootstrapped nonparametrically when the data were not normally distributed. The serum biochemical reference ranges determined for lambs are strongly divergent from those established by one of the most cited books on the topic, especially considering the high serum urea and cholesterol concentrations and low levels of blood glucose observed. Therefore, the serum biochemical reference ranges for lambs from birth to 1 year of age in the tropics differ from international data, which consider adult sheep in temperate climate zones.