Beta-carotene concentration in dairy feeds and the effect of beta-carotene supplement on conception of cross-bred dairy cows
1997
Warinda Lumchuan(Chiang Mai University, Chiang Mai (Thailand). Faculty of Agriculture. Department of Animal Science) | Boonlom Cheva-Isarakul(Chiang Mai University, Chiang Mai (Thailand). Faculty of Agriculture. Department of Animal Science) | Nucha Simasatitkul(Chiang Mai University, Chiang Mai (Thailand). Faculty of Agriculture. Department of Animal Science) | Somkid Promma(National Dairy Center, Chiang Mai (Thailand))
Five kinds of fresh grasses and legumes as well as other common dairy feeds were analyesed beta-carotene content. The concentration in mg/kg DM were : Napier (Pennisetum purpureum) = 20.48, Ruzi grass (Brachiaria ruziziensis) = 40.40, Parn grass (Brachiaria mutica) = 110.78, Hamata (Stylosanthes hamata) = 61.14 and Leucaena leaves (Leucaena leucocephala) = 110.78, Hamata (Stylosanthes hamata) = 61.14 and Leucaena leaves (Leucaena leucocephala) = 160.99. The content in grass silage, corn silage, grass hay, urea treated rice straw, concentrate feed and ground corn was 15.39, 27.32, 1.76, 0.20, 0.74 and 2.14 mg/kg DM respectively. In addition the natural sources of beta-carotene were studied. Dry leucaena leaves was better than oven dryed carrots while commercial leucaena leaves meal was the worst (116.51 vs. 55.6 and 18.9 mg/kg DM, respectively). It was also found that wet season forages had higher beta-carotene content than those harvested in dry season. Drying methods had an effect as well. Twenty cross-bred dairy cows (75 percent HF blood) were alternately assigned to two groups at 2 weeks prior to predicted calving date. The first group was unsupplemented while the second group was daily supplemented with 100 mg of beta-carotene per head until calving. In the post calving period, they were further supplemented daily with 20 mg of beta-carotene per kilogram of milk in addition to 100 mg for maintenance. Supplementation period was 25.13 weeks. Plasma samples were withdrawn from jugular vein of each cow three times, at i. e. 2 weeks pre-cavling, calving and 3 months post calving. It was found that plasma beta-carotene concentration of supplemented cows at 3 months post-calving period was higher than the unsupplemented cows (5.7 vs 3.18 micro g/ml, P LT 0.05). In addition the beta-carotene supplementation decreased day open (94.56 vs 140.13, P LT 0.025) and tended to decrease conception services (1.44 vs 1.62). The result seemed to indicate the rold of beta-carotene on the improvement of reproduction performances.
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