Alpha-tocopherol, selenium and polyunsaturated fatty acid concentrations in the serum and feed of spring-calving dairy heifers

Abstract

The objectives of this study were to provide baseline data for alpha-tocopherol, selenium and polyunsaturated fatty acid concentrations in the serum and feed of New Zealand dairy cattle, and to assess the likelihood that abnormal peroxide metabolism has a role in the impaired lactational and reproductive performance noted in selenium-deficient cattle. Twenty-four Friesian heifers were randomly allocated one of four winter diets consisting of hay with or without selenium supplementation, or pasture and silage with or without selenium supplementation. A winter diet consisting exclusively of hay (alpha-tocopherol concentration 19 mg/kg of dry matter) resulted in a pre-calving serum alpha-tocopherol concentration of 1.2 mg/l compared to 4.5 mg/l for pastured heifers (p<0.01). The pre-calving alpha-tocopherol concentration for the heifers fed hay fell into the range considered deficient (<2.0 mg/l), whereas heifers fed pasture and silage remained in the range considered adequate throughout the study period. Serum fatty acid concentration, and the proportion of fatty acids that were polyunsaturated, were lowest in the hay-fed heifers before calving (1.0 mg/ml, 37.1% respectively), and remained unchanged following re-introduction to pasture after calving in late July and August. Serum fatty acid concentration did not increase following the re-introduction of the heifers to pasture because of the unexpectedly low fatty acid concentration (4.8 g/kg of dry matter) of the mature winter pasture. In October, however, the proportion of fatty acids in serum that were polyunsaturated increased (50%) as did serum cy-tocopherol concentrations (greater than 13 mg/l). Mean serum selenium concentrations in the unsupplemented heifers ranged from 139 to 204 nmol/l, being lowest in October (p<0.01). Supplementation with intraruminal selenium pellets (two pellets delivering about 3 mg of selenium/day) increased serum selenium concentration and glutathione peroxidase activity (p<0.01) whereas the type of winter diet had no effect (p>0.05). These results suggest that dairy cattle wintered on hay can become Vitamin E-depleted, whereas the feeding of pasture and silage should provide adequate Vitamin E. The pasture offered following calving during July and August provided a low dietary polyunsaturated fatty acid challenge, suggesting that abnormal peroxide metabolism is unlikely to be an important mechanism in the impaired performance of selenium-deficient adult cattle which calve at this the of year.

Monitoring of vitamin E status of dry, early and mid-late lactating organic dairy cows fed conserved roughages during the indoor period and factors influencing forage vitamin E levels

“…Alpha‐tocopherol content in fresh white clover reported by Tramontano et al. (1993) and Wichtel et al. (1996) was lower than in the present study.…”

“…In accordance to the latter, our study demonstrated a significantly lower vitamin E content in white and red clover in relation to ryegrass. Alpha-tocopherol content in fresh white clover reported by Tramontano et al (1993) and Wichtel et al (1996) was lower than in the present study. Although Al-Mabruk et al (2004) found higher a-tocopherol concentrations in both red and white clover silages in comparison with grass silage, all values were lower than those found in the present study.…”

“…(2004) found higher α‐tocopherol concentrations in both red and white clover silages in comparison with grass silage, all values were lower than those found in the present study. Also the vitamin E content of grass‐white clover silage in New Zealand was lower (15 mg/kg DM) (Wichtel et al., 1996). In this study, α‐tocopherol concentrations of silage fluctuated between 72.1 and 39.3 mg/kg DM.…”

Diagnosis of the Cu and Se status of dairy cattle in New Zealand: How many samples are needed?

“…The conclusion that 5-6 samples is sufficient to diagnose Se status is consistent with published studies on the Se nutrition of cattle that have used 5-6 animals per treatment to determine changes in blood and serum Se concentrations in Se deficient cows, and the impact that various Se supplements had on Se status (e.g. Thompson et al 1981;Fraser et al 1987;Wichtel et al 1996).…”

Suplementação de selênio e vitamina E sobre a contagem de células somáticas no leite de vacas da raça Holandesa

“…Wichtel et al (1996) analisaram amostras de alimentos conservados e encontraram concentração de 19 mg vit. E/kg MS para feno e 34 mg vit.…”