Resumo

UYARLAR, C. et al. Effects of propylene glycol and organic chromium on milk production and blood parameters in early lactation dairy cows. S. Afr. j. anim. sci. [online]. 2025, vol.55, n.4, pp.174-187. ISSN 2221-4062.  https://doi.org/10.4314/sajas.v55i4.02.

This study assessed the effects of supplementing organic chromium (Cr), alone and in combination with propylene glycol (PG), on milk yield and blood chemistry in early lactation dairy cows. Thirty multiparous Holstein cows were randomly assigned to three treatments: control (CONT), Cr (1 g Cr/day), and Cr with PG (CrPG, 1 g Cr/day plus 125 mL liquid PG/day). The study started at calving and continued for three weeks postpartum. Drenching dairy cows with Cr and PG significantly improved fertility, with a decrease in the number of days to fall pregnant and a shorter calving interval. Cows administered CrPG had lower serum concentrations of urea, non-esterified fatty acids, beta-hydroxybutyric acid, alanine aminotransferase, and aspartate aminotransferase. Serum triglyceride and very-low-density lipoprotein levels were higher in the CrPG and Cr groups from day 12 after calving onwards, whereas high-density lipoprotein concentrations were higher in the CrPG and Cr groups from day nine onwards. Insulin levels were significantly higher in the CrPG and Cr groups than in the CONT group from the day of parturition to the ninth day postpartum, whereas from the 12th day onwards, insulin levels were significantly lower in the CrPG group. Gamma-glutamyl transferase levels only showed significant variation between the treatment groups on the third day after calving. Dietary supplementation with CrPG during early lactation improved fertility parameters and positively influenced energy metabolism by reducing non-esterified fatty acid and beta-hydroxybutyric acid concentrations and increasing insulin concentrations, thus protecting the dairy cows from subclinical metabolic disorders.

Palavras-chave : cattle; Holstein; immunity; serum; transition period.

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