Table 2.
Growth curve parameters of the two forms of Gompertz model (G1 and G2) estimated on the males and females of Bianca di Saluzzo and Bionda Piemontese chicken breeds.
| Item | Bianca di Saluzzo | Bionda Piemontese | SEM | p | ||||
|---|---|---|---|---|---|---|---|---|
| Females (n = 46) |
Males (n = 47) |
Females (n = 54) |
Males (n = 54) |
B | S | B × S | ||
| Model G1 | ||||||||
| BWa | 2184 a | 3074 b | 201 c | 2745 d | 55 | *** | *** | n.s. |
| b | 3.32 a | 3.55 b | 2.99 c | 3.25 a | 0.05 | *** | *** | n.s. |
| k | 0.014 ab | 0.014 b | 0.016 c | 0.015 ac | 0.000 | *** | n.s. | n.s. |
| BWip | 803 a | 1131 b | 740 c | 1010 d | 20 | *** | *** | n.s. |
| Tip | 86.0 a | 95.6 b | 71.6 c | 79.6 d | 1.9 | *** | *** | n.s. |
| BWs | 1647 a | 2188 b | 1634 a | 2177 b | 32 | n.s. | *** | n.s. |
| MGR | 11.3 a | 15.0 b | 11.2 a | 15.0 b | 0.3 | n.s. | *** | n.s. |
| Dm | 0.76 a | 0.72 b | 0.82 c | 0.79 c | 0.01 | ** | * | n.s. |
| r² | 0.99 | 0.991 | 0.99 | 0.99 | - | - | - | - |
| AIC | 196 | 199 | 196 | 200 | - | - | - | - |
| Model G2 | ||||||||
| BWa | 2508 a | 3383 b | 2193 c | 2819 d | 83 | *** | *** | n.s. |
| λ | 14.35 a | 20.63 b | 7.47 c | 12.58 a | 1.02 | *** | *** | n.s. |
| μ | 11.84 a | 15.83 b | 11.78 a | 15.65 b | 0.26 | n.s. | *** | n.s. |
| BWip | 922 a | 1244 b | 807 c | 1037 d | 30 | *** | *** | n.s. |
| Tip | 94.1 a | 101.4 b | 77.5 c | 81.0 c | 2.4 | *** | * | n.s. |
| BWs | 1748 a | 2302 b | 1718 a | 2225 b | 36 | n.s. | *** | n.s. |
| Dm | 0.72 a | 0.69 a | 0.80 b | 0.79 b | 0.01 | ** | n.s. | n.s. |
| r² | 0.97 | 0.99 | 0.98 | 0.99 | - | - | - | - |
| AIC | 206 | 201 | 197 | 200 | - | - | - | - |
SEM: standard error of mean; values within a row with no common superscript letter (a, b, c, d) differ at p < 0.05 (Waller–Duncan test) between breed and sex. Breed (B), Sex (S), and Breed × Sex (B × S): fixed effects on BW (model LM1); not significant (n.s.) p > 0.05, * p < 0.05, ** p < 0.01, *** p < 0.001. BWa: asymptotic body weight (g); b: shape parameter; k: coefficient of relative growth; Wip: body weight at inflection point (g); Tip: age at inflection point (d); BWs: body weight at the age of 180 d (g); MGR: maximum growth rate at inflection point (g/d); Dm (degree of maturity): BWs/BWa; λ: lag time (d); μ: absolute growth rate at inflection point (g/d); r2: (adjusted) goodness of fit criteria of the model; AIC: Akaike information criterion.