The effect of β-carotene on the fertility of dairy heifers receiving maize silage
| Autor: | J. D. Edwards-Webb, M. J. Ducker, Glenys A. Bloomfield, N. H. Yarrow |
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| Rok vydání: | 1984 |
| Předmět: | |
| Zdroj: | Animal Science. 39:9-16 |
| ISSN: | 1748-748X 1357-7298 |
| DOI: | 10.1017/s0003356100027550 |
| Popis: | One hundred and sixty Friesian heifers were divided into four groups on the basis of live weight and age. All four groups received a production ration of 15 kg maize silage, 0·5 kg straw and either 1·5 or 0·5 kg concentrates according to their mean live weight. This ration supplied only 38 mg (3-carotene per animal per day.Two groups of heifers received a daily supplement of 300 mg β-carotene per head. The other two groups acted as controls and received a daily supplement of 60 000 i.u. vitamin A (18 mg retinol). All heifers received an adequate supply of vitamin A.Supplementation with 300 mg β-carotene per day significantly increased mean plasma concentrations from 3·52 mg/1 at housing to 5·58 mg/1 at first insemination (P < 0·001). Mean plasma concentrations in the control heifers declined from 3·31 mg/1 at housing to 2·42 mg/1 at first insemination and to 2·13 mg/1 50 days later. Of the 40 smaller controls half had concentrations below 1·00 mg/1 50 days after first insemination.Supplementation with β-carotene did not affect reproductive performance or growth rate in heifers receiving a ration based upon maize silage. |
| Databáze: | OpenAIRE |
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