Table 1 shows mean (cm), standard errors and coefficient of variation of the morphometric characteristics of the Murrah and grade Murrah she buffaloes and Murrah bulls. Coefficient of variation of the traits in Murrah she buffalo ranged from 3% (HL) to 86.3% (TW). A significant difference in the studied variables in Murrah and grade Murrah she buffaloes was observed (p<0.05), except for the TW and HW. Mean values of the studied traits were higher in Murrah than Grade Murrah. Similarly, a significant difference in the studied variables in Murrah she buffaloes and Murrah bulls was observed (p<0.05), except for the TW and CG. Horns in males were thicker than females as horn diameter was 29% higher in males. Also, horns were more tightly curved in males than females. Mean values of BL, CG, WH and TL of Murrah reported by
Dhillod et al., (2017) are in agreement to the values of our study.
Nivsarkar et al., (2000) reported lower mean values of WH and CG of Murrah as compared to our study. Mean values of WH and BL of Murrah in our study were similar to those reported by
Rezende (2017). Mean values of WH, EL and PBD of Murrah were similar to Banni buffalo
(Mishra et al., 2009); mean values of CG, HBD and TL of Murrah were higher than Banni buffalo whereas average values of HL, HW and BL were smaller. BL and WH of grade Murrah were similar to Bhadawari buffalo
(Pundir et al., 1996). Similarly, the mean values of CG, PG, HL, HW, EL, HBD, PBD and TL of grade Murrah were similar to Gojri buffalo
(Vohra et al., 2015). Our study as well as other reports indicate that a wide range of variation exists for different morphometric traits, however, extent of variation was specific to a trait.
The phenotypic correlations among various morphometric traits of Murrah and Grade Murrah she buffaloes are presented in Table 2, while those of Murrah bulls are given in Table 3. Most of the correlations between the assessed variables in Murrah she buffalo were significant and ranged from 0.16 to 0.68 except tail and horn combinations with other traits. Correlations above 0.50 were obtained for CG, PG, BL and WH (Table 2), related to animal size. Similar pattern of correlation between the assessed traits in Murrah bulls was observed, however, significant correlation values were slightly higher and ranged from 0.21 to 0.73 (Table 3). Some of the traits (ear, tail and horn) exhibited negative correlations with the other traits which were mostly non-significant. Correlation matrix indicates the degree of relationship between the two variables. Our results indicated that in Murrah she buffalo the trait CG was positively associated with PG (0.68), WH (0.50), EL (0.19) and HW (0.21). Murrah bulls showed higher positive correlations of BL with WH (0.73) followed by CG with PG (0.71), BL (0.41) and WH (0.41).
Vohra et al., (2015) showed in Gojri buffalo that WH had significantly higher correlation with BL (0.72), HL (0.50) and CG (0.50). Significantly positive associations observed among different traits suggests that indirect measure of a trait can be estimated through the estimations of other correlated trait.
Five PCs explained 67.4% of total variance of studied morphometric traits (Table 4) in Murrah she buffaloes, whereas in Grade Murrah six PCs explained 72.7% of the total variance (Table 5). The communalities found in Murrah she buffaloes ranged from 0.350 to 0.826. The communalities explain how much a particular trait contributes to explain the number of factors being considered (
Morrison, 1976). The HoD trait showed lowest commonality, indicating that it contributed little towards explaining the total accumulated variation in the factors. In Murrah bulls, 4 PCs contributed to 62% of total variance of the studied traits, while the communalities varied from 0.352 to 0.793 (Table 6). In Murrah she buffaloes (Table 4), the first principal component contributed 18.6% of total variation and was represented by high loadings for PBD, CG and PG. The second component explained 18% of the total variance with high loading of HBD, BL, WH, EL and HL. These two components explained the general body conformation. The third component explained 12.7% of variance and showed high component loadings for horn characteristics (HoL, HoD and HoC). The fourth component explained 9.9% of the variance and showed high component loadings for tail characteristics (TL and TW). The fifth component explained 8.2% of variance and showed high component loading for HW. The traits that loaded highly onto first two PCs in Murrah loaded highly together onto PC1 in grade Murrah. The pattern of loading of traits in rest of the components in grade Murrah was different from Murrah (Table 4, 5). In Murrah bulls (Table 6), the first component explained 26% of the total variance with high loadings of seven traits (HBD, PBD, CG, PG, BL, WH and HW) explaining general body conformation of the bulls.
Shahin et al., (1993) found three PCs explaining 88% of the variability while studying 13 body measurements in Egyptian buffalo bulls.
Tolenkhomba et al., (2013) evaluating 18 biometric traits of bulls of local cattle of Manipur, India, reported that 69.77% of total variation was explained by six factors.
Vohra et al., (2015), studying Gojri buffalo in India (based on 13 morphometric measurements), found four factors that explained 70.86% of the total variation.
Yakubu et al., (2009) and
Casanova et al., (2012) reported similar results in cattle. Murrah animals have distinguishable traits of horn, tail, body and forehead conformations and this knowledge is traditionally practiced by the local farmers to judge this breed. The factor loadings confirms this pattern. Our study also elucidates the structure of morphometric traits which were most useful for identification of Murrah animals. These factors could also be exploited in breeding and selection programmes to acquire highly coordinated animal bodies using fewer measurements
(Yakubu et al., 2009).
Table 7 shows the results of stepwise discriminant analysis. Based on F-values and Wilk’s lambda, eight traits were significant. These variables in the data set were found to have potential discriminatory power. CG had more discriminant power than the others traits followed by HL as indicated by their higher R
2 and F-values. In the canonical discriminant analysis, the canonical variable (CAN1) generated was significant (p<0.0001) (Table 8). Mahalanobis distance between two buffalo groups and per cent (%) of individual classified into source group are given in Table 9. The Mahalanobis distance between Murrah and grade Murrah she buffaloes was 6.92 and was highly significant (
p<0.0001). This was substantiated by the classification result. In Murrah, 92% animals were correctly assigned while the corresponding figure in grade Murrah was 97%. A very high percentage of the correct assignment of the animals in their respective classes suggests that the Murrah breed is clearly distinguishable based on its morphological characteristics. Similar results of discriminant analysis using ten morphological traits were reported by
Yakubu et al., (2010) in the study of morphometric differentiation of two Nigerian cattle breeds. The authors reported that 96.55% of Sokoto Gudali cattle were classified into their source genetic group, while 85.48% Bunaji counterparts were correctly assigned into their source population. The eight morphological variables (CG, HL, PG, HoC, HBD,TL, HoD, TW) obtained in the present study are more important and informative and could be used to assign the animals into Murrah and grade Murrah populations, thereby reducing the errors of selection in future breeding and selection programmes.