Table 3.
Effects of dietary threonine levels on production performance of breeder hens of yellow-feathered chickens.
| Variable | Thr supplementation (bold) and (total dietary content, %) | P-value2 | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 0.00 (0.38) | 0.12 (0.50) | 0.24 (0.62) | 0.36 (0.74) | 0.48 (0.86) | 0.60 (0.98) | SEM1 | Thr | L | Q | |
| Productive performance | ||||||||||
| Initial BW (kg) | 2976.3 | 2990.0 | 2975.0 | 3003.0 | 2966.3 | 2967.5 | 4.4 | 0.34 | ||
| Final body weight (kg) | 3134.7 | 3162.5 | 3159.1 | 3123.8 | 3062.7 | 3145.5 | 1.6 | 0.53 | ||
| Average daily gain (g) | 2.4 | 2.7 | 2.8 | 2.2 | 2.7 | 2.7 | 0.14 | 0.87 | ||
| Average daily egg production (g) | 41.7 | 43.0 | 41.3 | 42.0 | 41.9 | 41.3 | 0.29 | 0.60 | ||
| Average daily feed intake (g) | 125 | 125 | 125 | 125 | 125 | 125 | 0.0 | 1.00 | ||
| Feed conversion ratio | ||||||||||
| (kg feed/kg egg) | 3.12 | 3.03 | 3.16 | 3.10 | 3.11 | 3.15 | 0.02 | 0.59 | ||
| Laying performance | ||||||||||
| Laying rate (%)3 | 70.0b | 73.3a | 71.9a,b | 72.5a | 72. 4a | 70.3b | 0.33 | 0.01 | 0.001 | |
| Average egg weight (g) | 62.5 | 61.3 | 61.2 | 62.9 | 62.0 | 62.5 | 0.30 | 0.52 | ||
| Broken egg rate (%) | 3.6 | 4.3 | 3.7 | 4.3 | 4.3 | 4.0 | 0.23 | 0.92 | ||
| Unqualified egg rate (%) | 0.95 | 1.1 | 0.94 | 0.77 | 1.2 | 0.93 | 0.07 | 0.65 | ||
| Fertility and hatchability | ||||||||||
| Fertilization rate (%) | 95.7 | 96.7 | 95.6 | 95.6 | 95.7 | 95.9 | 0.44 | 0.98 | ||
| Hatchability (%) | 90.0 | 89.7 | 88.0 | 81.7 | 82.0 | 75.7 | 1.82 | 0.14 | ||
| Hatchling weight (g) | 40.5 | 40.9 | 40.2 | 40.6 | 40.6 | 41.1 | 0.16 | 0.65 | ||
1
Means within each row with different superscripts are significantly different (P < 0.05). Standard error of the mean from ANOVA (n = 6).
2
Thr = treatment effect; when significant, linear (L) and quadratic (Q) effects were tested.
3
Regression equation based on dietary threonine concentration (%); quadratic equation: Y = 60.40 + 36.9X–27.28X2; R2 = 0.26; P = 0.01. This equation yielded an optimized total dietary threonine concentration of 0.68%.