Beta-carotene functions separately from Vitamin A as an antioxidant and can directly enhance immunity with possible reproduction and udder-health benefits.

But, to-date, beta-carotene research has had a multitude of responses with inconsistent results. The National Research Council concluded that the data were insufficient to establish a beta-carotene requirement for dairy cattle. However, they did recommend that additional dietary vitamin A be considered in certain diets.

Mary Beth de Ondarza, nutritionist with Paradox Nutrition in West Chazy, N.Y., recently conducted research on a commercial dairy operation to see if supplementing beta-carotene to cows with normally low serum beta-carotene levels (but adequate vitamin A supplementation) would affect synthesis of milk components, milk yield and reproduction.

Treated and control cows were housed in a free-stall barn in separate pens. The study was 120 days in length. Half of the cows received supplemental beta-carotene and half did not.

Results showed that milkfat percentage was higher for cows that were fed beta-carotene. Although total yield of 3.5 percent fat-corrected (FCM) milk was generally not affected by beta-carotene supplementation, early-lactation cows (0 to 100 days in milk) tended to produce more 3.5 percent FCM when supplemented with beta-carotene, and cows in their third or greater lactations produced more 3.5 percent FCM when supplemented with beta-carotene.

Overall milkfat production was unaffected by treatment. Milk true protein percentage and milk true protein production were not affected by supplementation, either.

Results also indicate a positive impact on pregnancy rates. Pregnancy rates for cows supplemented with beta-carotene were numerically higher than those that did not receive it.

Read the paper that de Ondarza presented at the Penn State Nutrition Conference.