The role of beta‐carotene in cattle infertility, mastitis and milk yield: A systematic review and meta‐analysis

Abstract

AbstractThe impact of beta‐carotene on cattle fertility has been investigated in various studies; however, consensus on this issue has not been reached. In the present study, we systematically reviewed and meta‐analysed 29 publications conducted between 1984 and 2022, focusing on seven fertility measures, clinical mastitis and milk yield in cows. We did not find statistically significant results in 8 out of 11 parameters (p > .05). Statistically significant results were observed for milk yield (MD: 216.25 kg in 305 days, p = .01, CI: 50.73–381.77), pregnancy at first service (OR: 1.38 CI: 1.08–1.76, p = .01) and clinical mastitis (OR: 0.59, CI: 0.44–0.80, p = .006) in favour of beta‐carotene supplementation. The meta‐regression revealed significant effects of ‘plasma beta‐carotene levels’ on ‘service to per pregnancy’ and dose on ‘milk yield’ (p = .04 and p = 0). In binary outcomes, ‘dose × day’ and ‘plasma beta‐carotene concentration in the control group’ positively influenced pregnancy at first service (p = .02 and .03). In conclusion, given the positive point direction observed for some variables and insignificant results for others, there is a need for more studies. We note the very high heterogeneity of outcomes and suggest caution in interpreting results.