Juliane Kuhl, Jörg E. Aurich, Manuela Wulf, A. Hurtienne, Florian J. Schweigert, Christine Aurich

• In this study, effects of oral beta-carotene supplementation to mares (beta-carotene group: 1000 mg/day, n = 15; control group: n = 15) from 2 weeks before foaling until 6 weeks thereafter on concentrations of beta-carotene, vitamin A and a-tocopherol in plasma, colostrum and milk and plasma of their foals were determined. In addition, effects on fertility were studied. Beta-carotene concentrations increased in plasma and colostrum of beta-carotene-supplemented mares compared to control mares (p < 0.05). In mares of both groups, beta-carotene concentrations were higher in colostrum than in milk (p < 0.05). In foals, beta-carotene concentrations increased with colostrum uptake and were higher in foals born to supplemented mares (p < 0.05; control group: 0.0003 +/- 0.0002 mu g/ml on day 0, 0.008 +/- 0.0023 mu g/ml on day 1; beta-carotene group: 0.0005 +/- 0.0003 mu g/ml on day 0, 0.048 +/- 0.018 mu g/ml on day 1). Concentrations of vitamin A and a-tocopherol were higher in colostrum than in milk (p < 0.05) but did not differ betweenIn this study, effects of oral beta-carotene supplementation to mares (beta-carotene group: 1000 mg/day, n = 15; control group: n = 15) from 2 weeks before foaling until 6 weeks thereafter on concentrations of beta-carotene, vitamin A and a-tocopherol in plasma, colostrum and milk and plasma of their foals were determined. In addition, effects on fertility were studied. Beta-carotene concentrations increased in plasma and colostrum of beta-carotene-supplemented mares compared to control mares (p < 0.05). In mares of both groups, beta-carotene concentrations were higher in colostrum than in milk (p < 0.05). In foals, beta-carotene concentrations increased with colostrum uptake and were higher in foals born to supplemented mares (p < 0.05; control group: 0.0003 +/- 0.0002 mu g/ml on day 0, 0.008 +/- 0.0023 mu g/ml on day 1; beta-carotene group: 0.0005 +/- 0.0003 mu g/ml on day 0, 0.048 +/- 0.018 mu g/ml on day 1). Concentrations of vitamin A and a-tocopherol were higher in colostrum than in milk (p < 0.05) but did not differ between groups. Concentration of a-tocopherol in plasma of mares decreased over time and in foals, increased markedly within 4 days after birth. All but one mare (control group) showed oestrus within 2 weeks post-partum. Occurrence of oestrus did not differ between groups. More mares of the control group (7/7 vs. 5/12 in the beta-carotene group) became pregnant after being bred in first post-partum oestrus (p < 0.05). In conclusion, beta-carotene supplementation to mares increased beta-carotene concentrations in plasma, colostrum and milk of mares and plasma of their foals but had no positive effects on fertility.…