Wool quality traits, body conformation and liveweight measurement changes in ewe and wether lambs supplemented with Spirulina (Arthrospira platensis)

Spirulina (Arthrospira platensis) is an edible cyanobacterium rich in protein and several essential fatty acids, amino acids, vitamins and minerals. This has raised its profile as a potential supplement in lamb production. Yet, the underpinning effects of Spirulina supplementation on lamb products - wool and meat - interrelations vital to its applicability in the sheep industry is presently largely unknown. Therefore, our experimental objective was to evaluate the correlations between changes in wool quality traits, body conformation and liveweight measurements in lambs supplemented with Spirulina, as affected by sex and supplementation level. Over two consecutive years (2011-12) at the University Farm Cambridge, Tasmania, Australia, a mating ratio of 1 terminal ram to 100 Merino ewes was applied to produce approximately 1600 crossbred progeny. At 12 weeks of age, all progeny were weaned onto ryegrass pasture. At 6 months old, a total of 48 lambs was randomly selected for each feeding trial (24 per year). These were then randomly allocated into Spirulina supplementation treatment levels - CONTROL (0mL), LOW (100mL) or HIGH (200mL) - and balanced by sex - ewes and wethers. Each feeding trial continued for 9-weeks including 3-weeks of adjustment, during which Spirulina was directly supplemented daily to lambs via oral drenching as a water suspension with a 1:10 w/v ration of Spirulina (g) : Water (mL). All lambs received barley grain daily (150g) and had ad libitum access to drinking water and a basal diet of ryegrass pasture throughout the trial. Individual lamb body conformation and liveweight measurements were taken at the start and end of each feeding trial on chest girth (CG), wither height (WH), body length (BL), body condition score (BCS), and liveweight (BWT). Midside wool samples were taken and analysed for clean fleece yield (YIELD), mean fibre diameter (FD), coefficient of fibre diameter variation (CV), fibre diameter standard deviation (SD), comfort factor (CF), fibre curvature (CURV) and spinning fineness (SF). All data were transformed to changes (˜ívÆ) in wool quality traits over the feeding trial by subtracting final from initial measurements. SAS analysis for significant (P<0.05) correlations between wool quality traits, body conformation and liveweight measurements as influenced by Spirulina supplementation level and sex were investigated. It was observed in CONTROL lambs that ˜ívÆYIELD was negatively correlated with ˜ívÆBWT in wethers (-0.78) and with ˜ívÆBCS in both ewes (-0.86) and wethers (-0.91). CONTROL ewe ˜ívÆCG was positively correlated with ˜ívÆFD (0.82) and ˜ívÆSF (0.86), and negatively with ˜ívÆCF (-0.80). LOW Spirulina supplementation to ewe lambs showed no relationship between wool quality traits, body conformation and liveweight measurements (P>0.05). However, in wethers, ˜ívÆBCS and ˜ívÆCURV were negatively correlated (-0.90). In the HIGH Spirulina supplementation group, ˜ívÆYIELD was significantly correlated with ˜ívÆBL (0.86) and ˜ívÆBWT (-0.80) in wether and ewe lambs respectively. All other correlations were insignificant (P>0.05). In conclusion, this study does not only demonstrate Spirulina's potential as a nutritious lamb supplement, but the relationships and strength of the correlations between wool, body conformation and liveweight will assist in product management and serve as a tool for achieving desired wool and growth goals in sheep flocks.