Morphological characterization of indigenous and crossbred pigs in rural and peri-urban areas of southwestern Nigeria

Abstract

We sought to determine morphological descrip- tors of Nigerian indigenous pigs (NIP) and cross- bred pigs (CBP) based on relationships among live weight (LW) and a suite of 18 morphometric measurements plus the number of teats. We sampled four locations in southwestern Nigeria and obtained data for a total of 120 NIP and CBP. More female pigs (61.7%) than males (38.3%) were sampled, and they had a mean live weight of 19.9 ± 6.10 kg (range 9 - 32 kg) and 20.1 ± 6.08 kg (range 8 - 37 kg), respec- tively. The NIP had a longer snout, wider head and longer erect ears than CBP (P < 0.0001). Morphological variables that were highly correlated with LW included neck circumference (NC), breast height (BH), rump height (RH), body length (BL), interorbital width (IW), paunch girth (PG), hearth girth (HG), tail length (TL) and length of snout (LS) with Spearman correlation coefficients (R2) of 0.97, 0.92, 0.96, 0.97, 0.91, 0.97, 0.97, 0.90, and 0.93, respectively (all P < 0.0001). Teat number for NIP ranged from 5 to 14 while the CBP had a range of 10 to 16 teats. For male NIP, HG and TL best-fit in the model for body weight prediction (LW = −25.71 + 0.43 HG + 2.21 TL; R2 = 0.93; P < 0.0001), while HG and IW had the best-fit for the female NIP (LW = −28.27 + 0.50 HG + 2.22 IW; R2 = 0.96; P < 0.0001). Models for male and female CBP were LW = −8.89 + 0.32 RH + 0.34 BL (R2 = 0.84; P < 0.0001) and LW = −13.01 + 0.44 RH+0.27 BL (R2 = 0.94; P < 0.0001), respectively. Thus, for these populations of pigs, LS and TN differentiated NIP from CBP, because the NIP consistently re-corded longer LS and les- ser TN.