Differences in Clinicochemical Serum Parameters of Gestating Bos taurus taurus and Bos taurus indicus Cattle and Relationships With Embryo‐Fetal and Placental Weights

Differences in clinicochemical serum parameters of gestating Bos taurus taurus (taurine, Angus) and Bos taurus indicus (indicine, Brahman) cattle and the relationships of such parameters with conceptus phenotype are largely unexplored. We determined the concentrations of 21 electrolytes, metabolites and enzymes in serum of Angus and Brahman dams at early (Day 48, n = 24) and midgestation (Day 153, n = 37) and examined relationships with embryo, fetal and placental weights. At early gestation, ionised calcium (+26%), magnesium (+7%), lactate (+32%), total protein (+6%) and alanine transaminase (ALT, +39%) were significantly (p < 0.05) higher in Angus than in Brahman. At midgestation, ionised (+15%) and total calcium (+4%), magnesium (+11%), sodium (+2%), calcium/phosphorus ratio (+25%) and albumin (+5%) were higher (p < 0.05) in Angus cows. Ionised calcium, magnesium, sodium, albumin, lactate and ALT correlated positively with embryo, fetal and/or placental weights (r = 0.31-0.48, p < 0.05), while calcium/phosphorus ratio correlated negatively with Day 48 placental weight (r = -0.51, p < 0.05). Serum creatinine (+21%), glucose (+15%), triglycerides (+16%), alkaline phosphatase (ALP, +73%) and glutamate dehydrogenase (GLDH, +44%) levels were higher (p < 0.05) in Brahman at midgestation. Creatinine, glucose and ALP correlated negatively with fetal and placental weights at midgestation (r = -0.37 to -0.48, p < 0.05-0.01). Our data demonstrate genetic effects on maternal blood composition that reflect differences in maternal physiology of gestating taurine and indicine cattle which may affect conceptus growth and birthweight.