Effect of teeth eruption on growth performance and meat quality of sheep

Two hundred and forty sheep of about 15 months of age were used in this experiment to investigate the impact of dentition category on objective and sensory meat quality. The lambs were categorised into 3 dentition classes (category 1, milk teeth; category 2, partial eruption of permanent teeth; and category 3, both permanent teeth fully erupted to the height of the central lateral milk teeth). The study was conducted on 3 farms with flocks representing the 3 genotypes that contribute to the prime lamb industry in Australia: Farm A (Merino x Merino), Farm B (first cross, Border Leicester sire x Merino ewe), and Farm C (second cross, Poll Dorset sire x Border Leicester-Merino ewe). Of the 19 meat quality attributes assessed in sheep from the 3 farms, only 1 attribute in sheep from 1 farm showed a significant deterioration in meat quality as a result of lambs progressing from dentition category 1 to 2. This was an increase in myoglobin content in lambs from Farm B (P<0.05). Many of the attributes assessed showed changes that could be considered as positive for meat quality as the lambs progressed from milk teeth to partially erupted and even to fully erupted teeth. Lambs from dentition category 3 had heavier carcass weights and higher dressing percentages compared with lambs from dentition categories 1 and 2 (P<0.05). The M. longissimus dorsi et lumborum (LD) of lambs from dentition category 3 had a lower surface lightness (L*) value, a higher myoglobin content and a lower cooking loss compared with lambs from dentition categories 1 and 2 (P<0.05). Consumer sensory assessment found the LD from lambs in dentition category 1 to have a lower acceptability score for tenderness compared with the LD from lambs in dentition category 3 (P<0.05) and a lower acceptability score for juiciness, a lower consumer rating and a lower sheep eating quality score compared with the LD from lambs in dentition categories 2 and 3 (P<0.05). The results indicate that for the range of sheep studied, meat from young sheep with partially erupted teeth is unlikely to be inferior in eating quality than the meat currently classified as lamb.