Studies regarding the effect of pregnancy on circulating metabolic biomarkers of cattle have mostly focused on Bos taurus beef or dairy breeds of cattle. This study focused on Bos indicus cattle by collecting longitudinal data on grazing Brahman heifers during their first pregnancy.
Blood samples were collected from 20 pregnant heifers observed over 14 months, and sampled at five periods: pre-conception, once in each trimester of pregnancy, and post-partum. Results were compared to 18 non-pregnant heifers across the same time periods. The circulating concentration of non-esterified fatty acids (NEFA), triglycerides, cholesterol, and glucose were measured at each time point.
Before pregnancy and in the first two trimesters of pregnancy, the metabolic markers did not differ between the groups. However, glucose and NEFA levels were significantly different between pregnant and non-pregnant animals in trimester 3 (NEFA P= 3 ×10 -3; glucose P= 5 ×10 -6 ), and post-partum (NEFA P= 2 ×10 -3; glucose P= 9 ×10-5 ), with NEFA concentrations significantly higher in pregnant animals but glucose concentrations significantly lower. Triglyceride levels were significantly lower in pregnant cattle post-partum (P= 4 ×10 -3), while cholesterol was significantly lower in pregnant cattle in the third trimester (P= 6 ×10 -3).
This data suggests that the final trimester of pregnancy and the establishment of lactation is associated with changes in the metabolism of Brahman heifers indicating a higher demand on maternal metabolism. This may be due to changes in dry matter intake, microbiome composition or progesterone levels, which will be further investigated in this animal cohort. Furthering the knowledge and awareness of the impact of pregnancy and lactation on the metabolism of Brahman heifers could lead to stronger management and nutritional strategies for beef breeding cattle.