Nutritive value of Lotus corniculatus L. containing low and medium concentrations of condensed tannins for sheep

G.C. Waghorn, A. John, W.T. Jones, I.D. Shelton

Biotechnology Division DSIR, Palmerston North

Proceedings of the New Zealand Society of Animal Production. 1987, 47: 25-30

A reduction in nitrogen degradation in the rumen of sheep fed fresh Lotus corniculatus containing 2.3-3.5% condensed tannin (CT) in dry matter has been demonstrated in two experiments. Protection from degradation appeared to favour amino acids essential (EAA) to sheep so that in the presence of 2.2% CT, 50% more EAA and 14% more non-essential amino acids essential (NEAA) reached the abomasum. Apparent absorption of EAA from the small intestine was 62% higher, and for NEAA 9% lower than in sheep fed the same diet where CT was made ineffective by ruminal infusion of polyethelene glycol. An increased absorption of EAA could explain the high nitrogen retention reported in this and previous experiments where sheep have been fed forages containing low to medium concentrations of CT.

CT did not affect digestion of carbohydrate fractions in the rumen, or over the whole digestive tract. Aspects of microbial growth, rumen pool size, fractional outflow rates and particle size of rumen digesta were determined and are discussed.

Keywords: NZSAPAB; Lotus corniculatus; condensed tannins; sheep; Amino acids; digestion

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