Changes of the erythrocyte phenotype and blood biochemistry in dairy calves during the first ten weeks of age

Abstract

BackgroundBovine erythrocytes undergo important changes in their morphology and chemical composition during the first weeks of age, which must be understood to accurately interpret hematology results in calves. The objectives of this prospective cohort study were to describe physiological changes of calf erythrocytes and to investigate mechanisms potentially causing these changes.MethodsBlood samples from 30 clinically healthy dairy calves were obtained from birth to the tenth week of age in weekly intervals. Hematological and plasma biochemical parameters as well as the mineral electrolyte content of erythrocytes were determined and followed over time. The changes of parameters characterizing the erythrocyte phenotype over time were compared to the changes of plasma and erythrocyte biochemical parameters and possible associations were investigated using correlation and stepwise regression analyses.ResultsAlthough the erythrocyte mean corpuscular volume (MCV) declined from 43.6 ± 3.7 fL to 35.6 ± 3.2 fL between the first and seventh week, the red blood cell count (RBC) increased from 7.2 ± 1.1 × 1012/L to 9.3 ± 1.0 × 1012/L until the fifth week of age. The blood hemoglobin (Hb) concentration increased from 0.96 ± 0.16 g/L to 1.16 ± 0.11 g/L in the first three weeks of age and remained at this level until the end of the study. Changes in MCV were accompanied by a decline of the erythrocyte potassium content (KERY) from 91.9 ± 13.5 to 24.6 ± 7.2 mmol/L and a concomitant increase of the erythrocyte sodium content from 45.0 ± 32.0 to 102.7 ± 26.5 mmol/L. MCV was found to be associated with KERY, the primary determinant of the intra-erythrocyte osmotic pressure from the sixth week of age and with blood hemoglobin, the primary determinant of the intra-erythrocyte oncotic pressure from the eighth week of age, when KERY, blood Hb and MCV already had reached or approached normal levels of adult cattle. The plasma iron concentration was not found to be associated to any of the studied hematological parameters.ConclusionA volume reduction of 20% in bovine neonatal erythrocytes is a physiological change occurring during the first weeks of age and is neither associated with sideropenia nor with anemia in healthy calves. The mechanism driving the observed erythrocyte volume change could not be identified. Results of the correlation and regression analyses indicate that changes in intra-erythrocyte osmotic or oncotic pressure are improbable underlying causes. Results reported here show that KERYis an unreliable indicator for the K homeostasis of the intracellular space in neonatal calves and that a decrease in MCV in early life per-se is an unreliable indicator for the development of microcytic anemia.

Effect of a single, oral administration of selenitetriglycerides, at two dose rates, on blood selenium status and haematological and biochemical parameters in Holstein-Friesian calves

“…However, administration of Se in the form of sodium selenite at dose of 2.5 mg/kg for 21 days and 0.25 mg/kg for 16 weeks induced acute and chronic selenosis in calves with significant decreased of total number of RBC and WBC as well as HGB concentration [ 23 ]. Some age-related physiological changes in the haemogram were observed in the present study, similarly to data obtained by other authors [ 20 ]. The reduction in RBC volume observed is related to the maturation of blood cells as the calves get older [ 24 , 25 ].…”

“…On the other hand, Arthur [ 19 ] explained this period by the mechanisms of selenium incorporation into erythrocytes during erythropoiesis and the time necessary for the biosynthesis of the enzyme itself. It should be noted that during the monitoring period of this study (0–14 days of age) foetal erythrocytes comprised the majority of the calves’ red cell population, being replaced by adult erythrocytes by eight to 13 weeks of age [ 20 ]. Though it should be recognised that this conversion from foetal to adult haemoglobin is a dynamic process which would have already commenced during the monitored response period of the study.…”

Fitness of calves born from in vitro-produced fresh and cryopreserved embryos

“…Our results are consistent with observations of Dillane et al ( 46 ) for Cl − , PCV, and pH (which showed a tendency), are contrary for Na + , and are not coincident for glucose, HCO , PCO 2 , AG, and K + (not affected by sex in our study). Other studies did not find differences attributable to calf sex for the above and other parameters investigated ( 76 , 90 ).…”

“…Embryo cryopreservation did not interfere with this normal adaptation to adult life. Consistent with sO 2 , PCV values decreased throughout, reflecting the physiological replacement of large fetal erythrocytes by the lower volume adult cells ( 76 ). At the end of pregnancy, the fetus responds to hypoxia with a transient higher concentration of Hb and PCV.…”

Parâmetros hematológicos de bezerros leiteiros mestiços do nascimento aos 15 dias de idade

“…Wise et al (1947) e Tennant et al (1974) reportaram que o declínio do VCM em bezerros neonatos é um processo fisiológico e conforme Jain (1993) coincide a substituição dos eritrócitos e hemoglobina fetais por células de adultos (menores). O declínio observado é consistente com observações de Golbeck et al (2019) sobre o desenvolvimento de anemia microcítica leve, que, se associada à hipocromia caracteriza deficiência de ferro, sendo esperada anemia em 20 a 30% dos bezerros.…”