Plasma Beta-carotene Concentrations Research Articles

Plasma concentrations of beta-carotene and vitamin A in cows with ovarian cyst.

Plasma levels of β-carotene and vitamin A in Holstein cows with ovarian cysts, raised on a feed with low β-carotene contents were determined. Feeding green forages significantly increased plasma β-carotene but had small effect on vitamin A in cows. The levels of β-carotene were significantly lower in cows with ovarian cysts than those in cows without ovarian cysts, when they were fed only straw and concentrates. The levels of vitamin A were also slightly lower in cows with ovarian cysts.

Endocrine and ovarian changes in dairy cattle fed a low β-carotene diet during an oestrus synchronisation regime

Twelve Friesian cows, 76 to 110 days calved, with blood cell counts and Compton metabolic profile values in the normal range throughout, were housed and fed a marginal diet for varying periods before being injected twice, 11 days apart, with cloprostenol. Artificial insemination was carried out 72 and 96 hours after the second injection. Plasma concentrations of progesterone, oestradiol 17 beta, luteinising hormone, follicle stimulating hormone, and beta-carotene were monitored during this regime as were uterine and ovarian changes. Progesterone profiles were followed for a further 21 days by assay of milk samples. Subsequent rectal examinations showed that five of the 12 cows conceived at controlled oestrus and another four within 52 days of this time. No correlation was observed between time of conception and condition score, metabolic profiles or haematological parameters; there was a correlation between time of conception and plasma beta-carotene concentrations and cows with lower beta-carotene values showed cyclic irregularities or appeared to have depressed steroid hormone production.