Diagnostic value of copper parameters to predict growth of suckling calves grazing native range in Argentina

Abstract

RESUMO.-[Valor diagnóstico dos parâmetros de cobre para prever o crescimento de bezerros lactantes em pastagem nativas na Argentina.] Foi realizado um estudo para predisser o valor diagnóstico de diferentes parâmetros de cobre (Cu) como indicadores de ganho mé-dio diário (ADG) na criação de bezerros. Também foram avaliados os efeitos da suplementação com Cu nas vacas no último terço da gestação. Cinco ensaios de suplementação, com um total de 300 bezerros, foram realizados. Dois grupos de 30 bezerros foram atribuídos aleatoriamente em cada proba, um grupo foi parenteralmente suplementado (SG) e o outro não foi suplementado (NSG). Os ensaios começaram quando os bezerros tinham três meses de idade e terminou ao tempo do destete. Em cada ensaio os bezerros foram pesados e mostras do sangue foi tomada para determinar as concentrações Cu no plasma, sangue total (WB), eritrócitos (RC) e hematócrito (PCV). Amostras de fígado foram colhidas em seis animais de cada grupo tanto no início quanto no final do ensaio As mães do SG receberam suplementação de Cu no último terço da gestação em dois ensaios. Quatro dos cinco ensaios apresentavam baixa ADG nos NSGs. Nesses grupos, a concentração plasmática de Cu diminuiu rapidamente antes que a baixa do ADG fossei detectada, o que ocorreu com os valores abaixo 25 μg/d. A diminuição da concentração de RC Cu foi bastante lenta. WB mostrou uma posição intermédia. PCV nos SGs foi mais elevado do que nos NSGs em todos os ensaios. A suplementação das vacas foi insuficiente para gerar um armazenamento hepático A study was conducted to evaluate the predictive diagnostic value of different copper (Cu) parameters as indicators of average daily gain (ADG) in growing calves. The effects in calves of cow Cu supplementation in the last one-third gestation period were also evaluated. Five supplementation trials, with a total of 300 calves, were carried out. Two groups of 30 calves were randomly assigned to each trial, one group was parenterally supplemented (SG) and the other was not supplemented (NSG). Trials began when calves were three-month-old and ended at weaning time. At each sampling calves were weighed and blood was taken to determine Cu concentrations in plasma, Whole Blood (WB), Red Cells (RC) and Packed Cell Volume (PCV). Liver samples from six animals of each group were taken both at the beginning and at the end of the trial. In two trials the mothers of the SG received Cu supplementation at the last one-third gestation period. Four of the five trials exhibited low ADG in the NSGs. In these groups, plasma Cu concentration decreased rapidly before low ADG was detected, which occurred with values remaining below 25μg/dl. The decrease of RC Cu concentration was considerably slow. WB showed an intermediate position. PCV in the SGs was higher than in the NSGs in all trials. Cow supplementation was insufficient to generate a liver storage able to last after calves reached the 3 months of age. These data could be useful to predict the risk of low ADG in grazing calves.

Effects of Copper and Zinc Supplementation on Weight Gain and Hematological Parameters in Pre-weaning Calves

“…In the present study, marginal Cu deficiency did not affect either daily weight gain or hematological parameters. Nevertheless, our data correlated with previous results of Cu supplementation at the SRB reporting differences in weight gain in calves with Cu levels lower than 25 μg/dL [14], which are related to severe deficiency [15]. Likewise, decreased hemoglobin concentrations and low white cell counts were found in heifers only with Cu concentrations lower than 19 μg/dL [12].…”

Effect of mineral deficiencies on the red blood cell parameters in cattle

“…na parametry hematologiczne Obniżone stężenie miedzi (Cu) jest często obserwowane w stadach bydła na całym świecie (16,18). Dostępna literatura podaje, że niedobór tego pierwiastka występuje u około 50% krów w badanych stadach (12). Przyczyny niedoboru Cu w przypadkach klinicznych są niejednokrotnie wieloczynnikowe i mogą być trudne do diagnozowania, szczególnie w początkowych stanach niedoboru, kiedy objawy kliniczne mogą być trudne do zaobserwowania (18).…”