DENTAL ERUPTION PATTERNS AND PROFILE OF DENTAL ANOMALIES IN THE NIGERIAN INDIGENOUS PIG (Sus scrofa)

Abstract

Pigs are omnivores which possess two sets of teeth, the deciduous and permanent teeth. Patterns of dental eruptions have been deployed in age estimation, while variations in dental eruption reflect the influence of genetics and the environment. Dental anomalies are noticeable deviations from the normal dental architecture. Despite the advances in dental studies in exotic pigs, there is limited information on the eruption pattern and dental anomalies of the Nigerian Indigenous Pig (NIP), which are important indices in production. This study was therefore designed to investigate the pattern of dental eruption and profile of dental anomalies in the NIP. Adult NIPs (six females, one male), with history of extensive husbandry, were obtained, housed intensively, and fed compounded feed (calcium-2.45%, crude protein-16.06%, metabolisable energy- 2,659kcal/kg) supplemented with cassava peels. The pigs were allowed to mate naturally and pregnant sows were observed till farrowing. Piglets (24 males, 27 females) and subsequent adults (12 males, 14 females) were retrieved, from the initial total of 51 piglets, for deciduous and permanent teeth eruption investigations, respectively. Deciduous tooth eruption was monitored, by oral observation, thrice weekly, from day one to 24 weeks, while permanent tooth eruption was monitored from 18 to 148 weeks. The profile of dental anomalies was assessed, using 47 macerated skulls of randomly selected pigs from the eruption studies (21 males, 26 females), that were sacrificed at various time points, between 12 and 204 weeks. Data on eruption and dental anomalies were observed and data analysed using descriptive statistics and Student’s t-test at α0.05. All piglets had eight “needle” (third incisor and canine) teeth at birth. Females had earlier onset of eruption of deciduous teeth (3.19±0.24 weeks), compared to males (3.38±0.25 weeks), while males had earlier onset of eruption of permanent teeth (20.33±0.33 weeks), compared to females (20.64±0.25 weeks). The eruption time for the third maxillary incisor, the mandibular and maxillary canines, and the fourth mandibular premolar teeth were significantly earlier in the adult males (38.00±2.07, 41.73±1.65, 42.18±1.71 and 67.29±0.42 weeks, respectively) compared to the females (47.24±1.52, 48.75±1.61, 51.50±1.04 and 69.45±0.64 weeks, respectively). Adult pigs (69.2%) did not erupt the first mandibular premolar tooth, while the deciduous mandibular incisor tooth was persistent in 42.3%. The deciduous teeth eruption sequence in the NIPs, was i3/i3→c1/c1→i1→p3→p3→i1→i2→p4→p4→p2→i2→i2, while permanent teeth eruption sequence was M1→P1→M1→I3→I3→C1→P1→C1→M2→M2→I1→I1→P3/P3→P4/P4→P2→P2→I2→I2→M3/M3. Dental anomalies were significantly higher in females (96.2%) than males (66.7%). Most of the skulls had signs of dental attrition (97.8%), stained teeth (95.7%), at least a missing tooth (65.9%) and 48.9% had at least one persistent deciduous tooth. Dental calculus, tooth fracture, dental caries and tooth rotation occurred in 74.4, 46.8, 34.0 and 21.3% of the skulls, respectively. The occurrence of needle and first molar teeth, as the first set of deciduous and permanent teeth to erupt, respectively, were established in the Nigerian indigenous pig. This is the first template for ageing in the Nigerian indigenous pigs. The preponderance of dental anomalies in the pig underscores the importance of the maintenance of dental health, for good management in this species.