Effect of Supplemental β-Carotene on Incidence and Responsiveness of Ovarian Cysts to Hormone Treatment

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Abstract
Multiparous (62) and 35 primiparous Holstein cows were assigned randomly at 10 days postpartum to receive a ration with or without 300 mg .beta.-carotene/cow per day. Multparious and primiparious cows were grouped separately and group-fed complete rations once daily. Incidence of ovarian cysts (26% by rectal palpation) was not affected by .beta.-carotene feeding. Multiparous cows had greater incidence (39%) of ovarian cysts than primiparous cows (11%). Of cysts (57%) were classified follicular by rectal palpation. Progesterone concentration of milk also was used for diagnosis of type of cyst. Cows with ovarian cysts and with progesterone concentrations in milk less than 1 ng/ml were classified follicular, and those having concentrations greater than 1 ng/ml were classified luteal. As determined by milk progesterone rectal palpation was more accurate for diagnosis of luteal cysts than for diagnosis of follicular cysts. Progesterone concentrations of milk for animals with luteal and follicular cysts were 10.66 .+-. 1.29 and 0.37 .+-. 0.07 ng/ml. .beta.-Carotene did not affect respone or days to respond to treatment with human chorionic gonadotropin or gonadotropin-releasing hormone. Supplemental .beta.-carotene was not beneficial for reducing incidence of ovarian cysts in cows receiving an adequate supply of .beta.-carotene in their diet.