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A comparison between chromium‐mordanted hay and acid‐insoluble ash to determine apparent digestibility of a chaffed, molassed hay/straw mixture
Author(s) -
CUDDEFORD D.,
HUGHES DENISE
Publication year - 1990
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.1990.tb04223.x
Subject(s) - hay , straw , dry matter , zoology , chromium , chemistry , feces , agronomy , biology , ecology , organic chemistry
Summary The apparent digestibility of a molassed, chaffed grass hay/straw mixture was determined using four mature horses (mean weight 606 kg). Animals were stalled individually and kept on rubber mats. A preliminary feeding period of 18 days was followed by a 10 day collection period. Chromium‐mordanted hay was given before the first feed at 08.00 h and subsequent meals were at 12.00, 16.00 and 20.00 h. On Days 3 and 10 of the collection, all faeces were sampled over a 24 h period. In addition, throughout the 10 day collection, faecal material was sampled at 10.00 and 16.00 h. The mean (± se) chromium recovery was 96.5 per cent ± 0.76 and the hay/straw mixture contained 7 MJDE/kg dry matter and 15.1 g DCP/kg dry matter. There was no significant difference between the methods used to estimate apparent digestibility although chromium measurements consistently underestimated whilst acid‐insoluble ash consistently overestimated digestibility values. There was a large variation in faecal chromium concentration for each horse over a 24 h period compared to acid‐insoluble ash concentrations and, consequently, indirect estimates of apparent digestibility of nutrients in the equine are prone to large errors if chromium is used as a marker. If total faecal collection is impractical, acid‐insoluble ash is the preferred indirect marker for the estimation of apparent digestibility coefficients for nutrients in horses.