Association of wool growth with gut metabolism and anatomy in sheep

• Genetically divergent wool production in sheep is not necessary related with gut metabolism.
• Different level of intake in sheep may improve efficiency of feed conversion into animal products.
• No interaction was detected between restricted levels of intake and divergent wool genotypes.

The hypothesis tested by this study was that sheep with divergent estimated breeding values (EBV) for fleece weight differ in gut metabolism and anatomy; regardless of the level of intake. Adult Merino wethers with contrasting EBVs for fleece weight were fed at two levels of intake in two 7-week periods in a crossover design, where wool growth, gut metabolism and anatomy of the sheep were evaluated. Regardless of the level of intake, wool genotype affected wool growth (P<0.05); however, rumen metabolism and gut anatomy did not differ between wool genotypes (P>0.05). Increases in the level of intake increased the supply of nutrients to the animal and the measured end-products of the process (wool production, live weight, methane) independent of wool genotype. The results obtained in this study indicate that differences in gut fermentation and anatomy are not a major cause of differences in wool production among sheep of different estimated genetic merit for fleece weight when fed restricted intakes.