Mineral status, metabolism and performance of dairy heifers receiving a combined trace element bolus and out-wintered on perennial ryegrass, kale or fodder beet

Norton Atkins*, Emma Bleach, Sandy Mackenzie, PR Hargreaves, Liam Sinclair

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The effects of a cobalt (Co), copper (Cu), selenium (Se), and iodine (I) trace-mineral ruminal bolus on the mineral status and performance of out-wintered, pregnant dairy heifers was investigated. Nine commercial farms grazing pasture (G), kale (K), or fodder beet (F) were used (n=3 per forage), with forty heifers on each farm randomly allocated to not receive (B-) or receive (B+) two combined mineral boluses. Mean plasma Co concentrations were 0.021 and 0.041 μmol/L in B- and B+ respectively (p < 0.001), with serum vitamin B12 also higher in heifers receiving B+ than B- (p < 0.001). Mean plasma Se concentration was 0.50 and 0.82 μmol/L in B- and B+ respectively, with heifers that received B+ also having a higher (p < 0.05) mean blood GSH-Px concentration (30 and 76 U/mL haematocrit in B- and B+ respectively). Providing a mineral bolus did not affect plasma Cu concentration in heifers receiving G or F (p <0.05), but was higher in KB+ compared to KB- (p < 0.05) at the middle and end of the out-wintering period. Heifers receiving KB- also had a lower haemoglobin and red blood cell count, but a higher mean corpuscular volume than KB+ at the end of the out-wintering period. Animals receiving B- had a higher plasma thyroxine concentration (p < 0.05). Neither the bolus nor forage type affected body weight (p > 0.05), however condition score was higher (p < 0.05) in B+ at the end of the study. It is concluded that the provision of a trace mineral bolus increased plasma concentrations of the minerals supplied, with the greatest benefits in animals grazing kale, but these increases were not translated into improved performance.
Original languageEnglish
Article number103865
JournalLivestock Science
Volume231
Early online date11 Nov 2019
DOIs
Publication statusPrint publication - Jan 2020

Keywords

  • Brassica
  • Dairy heifer
  • Forages
  • Minerals
  • Vitamin B
  • Wintering

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