Estimating dry matter digestibility and intake in wapiti ( Cervus elaphus canadensis) using the double n-alkane ratio technique

• Published in: Small ruminant research 2000-04, Vol.36 (1), p.57-62
• Main Authors: Gedir, J.V, Hudson, R.J
• Format: Article
• Language: English
• Subjects: Controlled-release device; Digestibility; Intake; n-Alkanes; Wapiti
• ISSN: 0921-4488; 1879-0941
• DOI: 10.1016/S0921-4488(99)00114-5

We estimated dry matter digestibility and intake (DMI) in wapiti hinds using the double n-alkane method. We also assessed intra-ruminal controlled-release devices (CRD) for administering n-alkane markers C 32 and C 36. Nine wapiti hinds were offered alfalfa-based compounded diet for ad libitum consumption and actual DMI was measured daily (mean: 9.2 ± 1.6 kg DM/day). The DMI estimate for C 33:C 32 (9.4 ± 1.6 kg DM/day, +2%) was slightly more accurate ( P > 0.05) than that for C 31:C 32 (9.8 ± 1.8 kg DM/day, +6%), whereas C 31:C 32 was slightly more precise ( P > 0.05) than C 33:C 32 in predicting intake (C 31:C 32 — R 2 = 0.84; C 33:C 32 — R 2 = 0.71). Feed digestibility, estimated using dosed C 36, was 63%. Level of intake did not significantly affect n-alkane marker excretion rate, feed digestibility, nor n-alkane fecal recovery ( P > 0.05). This offers the advantage of concurrent use of the same CRD for predicting DMI in animals over a range of intakes. The manufacturer’s in vitro release rate (58.5 mg/day) was slightly higher than estimates of C 32 (52 ± 6) ( P < 0.01) and C 36 (50 ± 6) ( P > 0.05) based on fecal output. There was more variation among days than among animals in excretion rates of C 32, but not C 36. The double n-alkane ratio technique provides reliable assessment of DMI in wapiti feeding on alfalfa-cubes and may prove useful for determining intake of free-ranging ruminants. Furthermore, CRD eliminate daily dosing, thus minimizing disturbance of normal grazing patterns.