Digestible energy intake, dry matter digestibility and mineral status of grazing New Zealand Thoroughbred yearlings.
Abstract: To measure the nutritive value of pasture in terms of digestible energy intake (DEI) and dry matter (DM) digestibility, and to determine the effect of Ca, P, Cu, Zn, and Se supplementation on growth rate and degree of physeal swelling in Thoroughbred yearlings grazed on pasture. Methods: Fourteen yearling horses were randomly allocated to 1 of 2 groups and rotationally grazed on a ryegrass/white clover pasture for 7 months. One group was supplemented daily with a mineral mix. Liveweight changes were recorded at fortnightly intervals and pasture mineral composition determined at monthly intervals. The DM intake (DMI) was determined from daily faecal DM outputs divided by the indigestible DM fraction (1 - digestible DM) determined from a digestibility study. The DEI was determined from the difference between the gross energy intake and the gross energy faecal output. The DM, gross energy content, crude protein (CP), soluble carbohydrate, acid detergent fibre (ADF), neutral detergent fibre (NDF), lipid and mineral composition of pasture offered and faeces were analysed and their digestibility or apparent absorption calculated. Results: The DM digestibility of pasture averaged 0.64 while the daily DMI and DEI of a 350 kg yearling, gaining 0.6 kg liveweight/day, averaged 6.9 kg DM/day and 78 MJ DE/day, respectively. The mineral supplement had no significant effect on the growth of yearlings grazing pasture that had a mineral composition of (g/kg DM) Na 0.17, K 32.8, Ca 3.6, P 3.4, Mg 2.1, S 3.0, and (mg/kg DM) Cu 7.9, Fe 177, Mn 83, Zn 28 and Se 0.016. Plasma Se was elevated (e.g. 40-218 microg/l) by Se supplementation while Cu supplementation had no effect on plasma and liver Cu concentrations. Physeal swelling was observed in all horses, regardless of treatment. Conclusions: Good quality ryegrass/white clover pasture that had a DE content of 11.3 MJ/kg DM and adequate mineral composition (as observed in this study, with the possible exception of Se) will provide an adequate intake of nutrients to ensure good growth in yearling horses.
Publication Date: 2005-07-21 PubMed ID: 16032212DOI: 10.1080/00480169.2002.36252Google Scholar: Lookup
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- Journal Article
Summary
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The research discusses the dietary value of pasture-fed food for young thoroughbred horses, specifically focusing on its impact on their growth and overall health. It also evaluates the effect of specific mineral supplementation.
Research Background
- The research focuses on determining the nutritional value of ryegrass/white clover pasture for thoroughbred yearlings in terms of digestible energy intake (DEI) and dry matter (DM) digestibility.
- It also investigates the impact of calcium, phosphorus, copper, zinc, and selenium supplementation on the growth rate and degree to which yearlings’ leg joints (physes) swell.
Methodology
- The study included 14 yearling thoroughbred horses, divided randomly into two groups.
- Both groups were rotationally grazed on ryegrass/white clover pasture over seven months, with one group receiving a daily mineral supplement.
- For the measurement of DM intake, scientists used faecal output, dividing it by the indigestible DM fraction, which was determined using a digestibility study.
Results and Conclusions
- The research found that the average digestibility of the pasture’s dry matter was 0.64. For a 350 kg yearling gaining 0.6 kg/day, the average daily intake was 6.9 kg of dry matter and 78 MJ of digestible energy.
- The mineral supplement didn’t significantly affect the growth of yearlings, regardless of the pasture’s mineral composition.
- Selenium supplementation was the only one found to increase plasma concentrations whilst copper supplementation had no observable effect on plasma and liver copper levels.
- All yearlings, irrespective of treatment, showed some amount of physeal swelling.
- The conclusion was that a ryegrass/white clover pasture with a DE content of 11.3 MJ/kg of dry matter and a suitable mineral composition ensures adequate nutrient intake for good growth in yearling horses, possibly excluding selenium.
Cite This Article
APA
Grace ND, Gee EK, Firth EC, Shaw HL.
(2005).
Digestible energy intake, dry matter digestibility and mineral status of grazing New Zealand Thoroughbred yearlings.
N Z Vet J, 50(2), 63-69.
https://doi.org/10.1080/00480169.2002.36252 Publication
Researcher Affiliations
- AgResearch Grasslands, Private Bag 11008, Palmerston North, New Zealand. neville.grace@agresearch.co.nz
Citations
This article has been cited 1 times.- Fitzgerald DM, Walsh DM, Sillence MN, Pollitt CC, de Laat MA. Insulin and incretin responses to grazing in insulin-dysregulated and healthy ponies. J Vet Intern Med 2019 Jan;33(1):225-232.
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