Wool growth and elemental composition

J. Lee, A.R. Bray, N.D. Grace

AgResearch, Fitzherbert Science Centre, Private Bag 11030, Palmerston North, New Zealand

Proceedings of the New Zealand Society of Animal Production. 1992, 52: 281-284

Genetic and nutritional factors that cause marked changes in wool growth influence the content (µg g-1) and rate of uptake (µg cm-2d- 1) of inorganic element into wool. When sheep fed a basal diet (L level) of chaffed ryegrass hay and crushed barley were supplemented (H level) with additional methionine (+ 1.2 gd-1), protein (+11 g N d-1) and energy (+3.9 MJME d-1), the elemental content of the wool responded [(HL)/L x 100] differentially to increases in wool growth. Dietary treatments resulted in a reduced elemental content of Ca, -13%; Fe, - 14%; K, -16% and Mg, -11% while changes in Cu, -8%; Na, -4%; P, -5%; S, +2% and Zn, +2% approached or matched the increase in wool growth.

Relative to the increases in wool growth as a result of supplementation with methionine (34%), protein (34%) and energy (16%), the uptake into wool of Cu, Na, P, S and Zn were generally greater for sheep fed additional methionine (40%, 39%, 57%, 49% and 61 respectively), while protein (27%, 32%, 22%, 39% and 29% respectively) and energy (8%, 14%, 10%, 11% and 15% respectively) supplements gave a lesser response. A group of sheep selected for increased staple strength also had increased wool growth relative to controls but no significant changes in elemental composition were observed. The possibility that the large changes in elemental concentrations may have affected fibre properties is yet to be addressed.

Keywords: NZSAPAB; Wool growth, elemental composition; elemental uptake; nutrition.

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Last Updated 25-01-1997