Formaldehyde treatment of lupin seed.

Abstract

Animal Production in Australia FORMALDEHYDE TREATMENT OF LUPIN SEED J.A. FORTUNE*+, W.S. HOPKINSON*++ and J.B. MACKINTOSH* Sweet lupin seed is a valuable, high protein supplement for ruminants, but much of its protein (c. 65%) is degraded in the rumen (Hume 1974). Furthermore it is low in sulphur-containing amino acids (SAA). In this study whole lupin seed (L. angustifozius cv Uniwhite) was treated with formaldehyde in an attempt to reduce the extent of protein degradation and increase the availability of SAA for wool growth. Preliminary in vitro studies using a range of concentrations of formaldehyde r showed the optimum treatment to be 60 ml of 39% (W/V) formaldehyde in 2 2 of water per kg of whole lupin seed. The lupins were soaked for 18 hours before drying at 50�C. Eight Merino wethers, with rumen and duodenal cannulae, were fed approximately 400 g DM/day of a diet containing either treated or untreated lupin seed and oaten day (1:2) for 26 days. Rate of wool growth was measured over the last 14 days. During the last seven days we measured nitrogen (N) balance, and flow of N through the duodenum using the inert marker Cr-EDTA. TABLE 1 Utilization of dietary nitrogen and rate of wool growth by sheep fed on diets containing formaldehyde-treated (FT) or untreated lupin seed (means 2 SE) Although there was a difference in intakes of nitrogen because of an error in formulating the diets, it is apparent that formaldehyde treatment greatly increased the flow of N from the stomach without impairing overall digestion. However, in these animals most of the extra N was apparently recycled to the rumen for in both groups there was limited utilization of the N apparently absorbed. Formaldehyde treatment of lupin seed did not affect the rate of wool growth (P>O.O5). Supplementary methionine (1.5 g/d) given duodenally to sheep on the same diet containing untreated lupins increased wool growth by 22% (Hopkinson and Mackintosh unpublished results). However, formaldehyde treatment may not increase the availability of SAA, particularly when the content of these in protein is low (Barry 1976). BARRY, T.N. HUME, I.D. (1976). Proc. Nutr. Soc. == 221. 35: (1974). Aust. J. Agric. Res. 25: 155. == * Dept of Animal Science, University of W.A., Nedlands, W.A. 6009. i- Present address: Dept Agronomy, Massey University, Palmerston North, N.Z. * Present address: Kirkalocka Station, Mt Magnet, W.A. 6638. 474