Influence of lupins and canola supplements on plasma amino acids, wool fibre diameter and liveweight in genetically divergent first cross Merino lambs

This study hypothesised that there is a positive correlation between plasma amino acids and wool quality parameters of 40 first cross Merino weaner lambs sired by five genetically divergent rams supplemented with canola meal and cracked lupins at 1% or 2% of body weight feeding level for 60 days. Results demonstrated that supplement type significantly (P<0.001) influenced liveweight as canola-fed lambs were heavier (40kg) than their lupin-fed counterparts (37kg), but wool yield, daily wool growth, fibre diameter, and body condition score were unaffected by either supplement or level of supplementation. Supplement type significantly (P<0.05) influenced the levels of plasma histidine, tryptophan, glutamic acid, threonine, arginine and lysine. There were moderate but highly significant positive correlations (P<0.01) between plasma histidine with liveweight (0.43), and fibre diameter (0.35), while lysine was strongly correlated with wool growth (0.37). Sire breed differences were non-significant (P>0.05), but the interaction between sire breed and supplement type had a significant effect on body condition score of the lambs (P<0.05). Significant interactions between type and level of supplementation (P<0.05) led to a decrease in wool fibre diameter. Lamb gender was a significant source of variation for only plasma arginine (P<0.05). In conclusion, level of supplementation had no significant effect on wool and growth parameters, thus enabling farmers to decrease the cost of feeding by supplementing at only 1% instead of 2% of body weight. For fat lamb production, supplementing with canola is advisable for higher bodyweight gain, whereas for wool production, either canola or lupins (whichever is cheaper) can be used to minimise feed costs. Crossbred sheep producers supplementing lambs with canola will increase plasma histidine with subsequent increase in liveweight and body condition, but at the expense of finer wool because of its positive correlation with fibre diameter. However, wool growth is expected with an increase in the level of plasma lysine.