APSS 2013 Proceedings - The University of Sydney

Aust. Poult. Sci. Symp. 2013.....24
Table 1 - The mean (±SE) live weight at 0, 2, 4, 5 and 6 weeks of age and the gonads weight of 6-week-old
Japanese quails.
Strain
Chick
Live weight (g)
Ovaries/
Testes
Gender 0 weeks 2 weeks 4 weeks 5 weeks 6 weeks weight
1
8.9 ± 0.07 c 72 ± 1.0 a 201 ± 1.9 bcA 243 ± 1.9 bA 280 ± 2.0 bA 8.6 ± 0.3 bc
2 9.0 ± 0.07 bc 76 ± 1.0b A 197 ± 1.9 cA 235 ± 1.9 cA 274 ± 2.0 cA 9.3 ± 0.3 b
3 Female 9.1 ± 0.07 b 74 ± 0.9b a 205 ± 1.8 abA 244 ± 1.8 bA 280 ± 1.9 bA 10.2 ± 0.3 a
4 9.0 ± 0.07 bc 76 ± 1.0b A 207 ± 1.9 aA 250 ± 1.9 aA 286 ± 2.0 aA 10.2 ± 0.3 a
5 9.4 ± 0.07 a 75 ± 1.0b a 202 ± 1.9 abcA 241 ± 1.9 bA 275 ± 2.0 cdA 8.0 ± 0.3 c
1
8.7 ± 0.08 c 70 ± 1.0 b 189 ± 2.0 bB 221 ± 2.0 cB 241 ± 2.1 bB 5.3 ± 0.34
2 8.8 ± 0.08b c 71 ± 1.0 bcB 188 ± 2.0 bB 217 ± 2.0 cB 241 ± 2.1 bB 5.5 ± 0.34
3 Male 9.3 ± 0.08 a 74 ± 1.0 a 196 ± 2.0 aB 225 ± 2.0 bB 249 ± 2.1 aB 5.2 ± 0.33
4 9.0 ± 0.08 b 71 ± 1.0 bcB 193 ± 2.0 aB 223 ± 2.0 bcB 247 ± 2.1 aB 5.6 ± 0.34
5 9.3 ± 0.08 a 73 ± 1.0 ac 195 ± 2.0 aB 227 ± 2.0 aB 247 ± 2.1 aB 5.5 ± 0.34
a-d Means without a common superscript within a gender specified column (strain body weight) differ (P0.05). However, ovary weight differed
significantly (P < 0.05) between strains, which ranged from 8.0 to 10.2 grams .
IV. DISCUSSION
The pattern of growth observed in this study is consistent with that reported for meat-type
quails selected for high body weight (Aggrey et al., 2003; Reddish, 2003; Hyankova and
Novotna 2007). In this study, significant differences in live weight (between strains) were
first observed at hatch and persisted throughout the 6-week growth period. The live weight
changes show the highest growth rate in the first 4 weeks of age, especially between 2 and 4
weeks and a reduced rate of growth thereafter although chicks kept gaining weight up to 6
weeks of age. This increase in live weight occurred mainly in females, which resulted in
females having a 20% higher live weight than males at 6 weeks of age.
The greater variability in ovary weight (CV = 58%) compared to testes weight (CV =
25%) supports the view that a considerable proportion of females would not have reached
maturity at 6 weeks of age. This corroborates other reports (Reddish, 2003; Hyankova and
Novotna 2007) that have shown that females tend to reach sexual maturity at about 7 weeks
of age.
The between gender differences in the attainment of sexual maturity and reaching
final body weight may have two major implications for the breeding flocks. i) Males attaining
sexual maturity earlier (5 weeks of age) will start mating; consequently more energy is
expended in activities associated with reproduction rather than increasing body reserves
which may be utilized in the later stages. Additionally, early attempts at mating with females
before they reach sexual maturity may mean sexual harassment and increased stress levels,
resulting in poor growth and reproductive output. Sexual harassment by males during the
mating has already been reported to lower the probability of laying fertile eggs by the females
(Persaud and Galef 2005). Moreover, where females are heavier, their dominance over males
may cause injuries to males. ii) Higher body weight differences between male and female at
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