Increased efficiency of wool growth and live weight gain in Merino sheep fed transgenic lupin seed containing sunflower albumin
✍ Scribed by Colin L White; Linda M Tabe; Hugh Dove; John Hamblin; Paul Young; Nathan Phillips; Romney Taylor; Suresh Gulati; John Ashes; T J V Higgins
- Publisher
- John Wiley and Sons
- Year
- 2000
- Tongue
- English
- Weight
- 116 KB
- Volume
- 81
- Category
- Article
- ISSN
- 0022-5142
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✦ Synopsis
The aim of this experiment was to assess, using sheep, the nutritive value of lupin seed transgenically modi®ed to contain sun¯ower seed albumin. Eighty Merino wether sheep of mean live weight 32.3 kg were divided into two groups and fed 796 g dry matter (DM) day À1 of a cereal hay-based diet containing 350 g kg À1 of either the transgenic or parent (unmodi®ed) lupin seed for 6 weeks. Measurements were made of wool growth and live weight gain. After 6 weeks, half the sheep in each group were selected for a urine and faeces balance study in which organic matter (OM), nitrogen (N) and urinary purine metabolites were measured. Blood samples were taken from all sheep at the beginning and end of treatment and analysed for amino acids and plasma metabolites. A comprehensive chemical analysis of the grains showed that there was little difference between them in terms of most nutritional components, but the transgenic lupin seed contained a 2.3-fold higher methionine concentration and 1.3-fold higher cysteine than did the parent. There were no signi®cant differences between grains in OM digestibility, rumen microbial protein synthesis or in sacco degradability of dry matter. Sheep fed the transgenic lupin grain had an 8% higher rate of wool growth (P 0.01) and 7% higher live weight gain (P 0.05) than sheep fed the parent grain. The sulphur (S) concentration of wool and the cysteine concentration of plasma were also higher in the sheep fed the transgenic lupin by 2.7% and 11.5% respectively (P 0.05). Plasma methionine was increased by 10%, but the differences were not statistically signi®cant (P b 0.1). Plasma urea N was lower in the sheep fed the transgenic grain than those fed the parent grain (6.5 vs 6.8 mmol l À1 , P 0.05). The results show that genetic modi®cation of a feed grain can improve its nutritive value for ruminants. The size and nature of the responses were consistent with the transgenic lupins providing more methionine to the tissues, a ®rst-limiting amino acid for sheep.