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.
