EFFECTS OF RUMEN-PROTECTED METHIONINE ON WOOL PRODUCTION AND PROTEIN TURNOVER IN MUSKOXEN (OVIBOS MOSCHATUS)

Morgan A. Robertson, Janice Rowell and Robert G. White
Large Animal Research Station, Institute of Arctic Biology, University of Alaska, Fairbanks, Fairbanks, AK 99775;

Key words: muskox, qiviut, methionine, bypass, protein, Ovibos moschatus, sulfur.

Introduction

Supplementing sheep diets with rumen protected S-AAs, particularly methionine, has been shown to cause rapid and dramatic increases in fiber growth. (Graham, 1988; Reis, 1979, 1988) Additionally, studies of the family Bovidae (eg. cattle, sheep, goats) have demonstrated that addition of S-AAs can positively influence protein turnover. (Oke et al., 1986). Thus, while sulfur-based amino acid (S-AA) supplements have been shown to enhance wool production and body protein turnover in domestic animals, similar studies have yet to be done with muskoxen. As arctic adapted ungulates, muskoxen produce the majority of their underwool, or qiviut, from May 1 to November 1 (Flood et al, 1989), their peak milk production occurs from May to August, and body protein regain takes place from August to October (White et al, 1989). Thus, animals invest in protein deposition during periods of peak and post-peak protein within their diet.

We hypothesized that adding S-AA supplements into the diets of muskoxen would increase individual qiviut yield and rates of protein deposition during the wool growth season.

Methods

In 1996-1997, we conducted two experimental trials to evaluate the effects of supplementing muskox diets with rumen protected S-AAs. In trial 1, sixteen muskoxen of mixed age and sex were used to assess the palatability of four diets and their effects on wool production, measured by clipping a known area (mg/d). Animals were sorted into groups using a stratified randomized design, and were fed either no supplement (control diet); 630 mg rumen-protected methionine (Smartamine) . BW (kg) .75 . d -1 (SA diet); 630 mg rumen-protected methionine (Mepron) . BW (kg) .75 . d -1 (MP diet); or 2.46 g fishmeal . BW (kg) .75 .d -1 (FM diet) through the wool growth season (May 1 - Nov 1).

In trial 2, we measured rates of wool production, body weight gain and body condition scores through the wool growth season (May 1 – Nov 1) for nine adult female muskoxen on a high plane (HP) or low plane (LP) nutritional regime (HP=5, LP=4). Animals received no supplement through the course of one season, and received the SA supplement described in trial 1 through another. Wool production was measured by clipping in June, August and October (mg/d), as length increment (mm/d) and as average fiber diameter (m m). Hoof growth (mm/7d) was measured as an estimate of protein synthesis in3 HP and 3 LP females.

Results

In trial 1, palatability of all four diets was high. Wool growth (mg/day) was greatest in the SA group, followed by MP, FM and the control groups. In trial 2, wool production of unsupplemented animals was significantly higher (p<0.05) in the HP group than in the LP group in August, and overall hoof growth (mm/7 day) was greater in the HP group. Supplementation of the two groups improved (p<0.05) wool production (mg/d, mm/d) in the LP group from August- December and overall hoof growth increased significantly in the LP group (p<0.05). Qiviut yield was improved (p<0.05) in the HP group in August and length improved in August through September.

Discussion

Our results indicate that addition of rumen-protected methionine positively influences qiviut production and protein synthesis in muskoxen.

Acknowledgements

The authors wish to thank the Alaska Science and Technology Foundation for providing the primary funding for this research. We would also like to acknowledge the Large Animal Research Station and the Institute of Arctic Biology for their additional support.

Literature cited

Flood, P.F., Stalker, M.J. and Rowell, J.E. (1989) The hair follicle density and seasonal shedding cycle of the muskox. Can. J. Zool. 67(5):1143-1147.

Graham, C.A. (1988) The opportunity to improve wool growth by rumen manipulation or strategic supplementation. Wool Technology and Sheep Breeding. Dec 1987/Jan 1988. 211-215.

Oke, B.O., Loerchand, S.C., Deetz, L.E. (1986) Effects of rumen protected methionine and lysine on ruminant performance and nutrient metabolism. J. Animal Sci. 62:1101-1112.

Reis, P.J. (1979) Effects of amino acids on the growth and properties of wool. In "Physiological and Environmental Limitations to Wool Growth." (Eds. J.L Black and P.J. Reis) pp 223-242 (U.N.E. Publishing Unit: Armidale, N.S.W)

Reis, P.J. (1988) Relative importance of amino acids and energy for wool growth. Proc. Nutr. Soc. Aust. 13. 122.

White, R.G., Holleman, D.F. & Tiplady, B.A. (1989) Seasonal body weight, body condition and lactational trends in muskoxen. Can J. Zool. 67: 1125-1133.

 
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