Egg quality traits in quail breeders depend on various factors which may influence embryo survival during incubation, affecting the chicks' production and quality. The current study aimed to determine the effect of the laying period on the external and internal quality of the egg, the chemical composition of albumen, yolk, and eggshell as well as the reproductive parameters of quail breeders. A total of 450 quails (Coturnix japonica) obtained from the same hatchery, were reared in a battery cage with a sex ratio of 1 male to 3 females. All the quails were subjected to standard breeding conditions and fed a balanced laying diet. A total of 960 eggs were collected at two different periods of the laying cycle, the beginning period of the laying (BP indicating 10 weeks of quail age) and the peak period of laying (PP showing 20 weeks of quail age). At each laying period, 30 eggs were used to analyze the various parameters of egg quality, and 450 eggs were randomly selected to assess the reproductive performances. Overall, no differences in the external quality of eggs, such as egg length, egg width, and the egg shape index, were recorded between the two laying periods. Apart from albumen weight that tended to be higher at the peak laying period, the shell and the yolk weights were not affected by the period of laying. Additionally, Japanese quail tend to deposit similar proportions of shell, albumen, and yolk at the two periods of laying. Likewise, the rate of dry matter of the three egg components, shell mineral concentrations, and yolk fat concentrations did not show any noticeable variation with the laying period. The most significant effect of the laying period was related to the potential reduction in the total protein content of the albumen and the yolk of eggs laid at the peak period of laying. Finally, the laying period did not significantly affect the fertility and hatchability rate of the incubated quail eggs but slightly improved the embryonic mortality rate during the peak laying phase.

The effects of early age thermal conditioning (ETC), vinegar supplementation (VS) of drinking water, broilers' gender, and their interactions on respiratory rate, body temperature, and blood parameters (biochemical, hematological, and thyroid hormones) of broiler chickens reared under high ambient temperatures were determined. A total of 1100 1-day-old chicks were divided into four treatments: the "control" which were non-conditioned and non-supplemented; "heat-conditioned" which were exposed to 38 ± 1 °C for 24 h at 5 days of age; "vinegar supplemented" which were given drinking water supplemented with 0.2% of commercial vinegar from 28 to 49 days of age; and "combined" which were both heat conditioned and vinegar supplemented. All groups were exposed to the natural fluctuations of summer ambient temperature (average diurnal ambient temperature of about 30 ± 1 °C and average relative humidity of 58 ± 5%). ETC and broiler gender did not affect the respiratory rate or body temperature of chronic heat-exposed chickens. VS changed the body temperature across time (d35, d42, d49) (linear and quadratic effects, P < 0.05) without changing respiratory rate. Heat-conditioned chickens exhibited lower levels of glycemia (P < 0.0001) and higher hematocrit and red blood cell counts (P < 0.05). Furthermore, the greatest effects of VS, alone or associated with ETC, were the lowering of cholesterol and triglyceride blood concentrations. A significant (P < 0.05) effect of ETC, gender, and ETC×gender on T3:T4 ratio was observed. Finally, some beneficial physiological responses induced by ETC and VS, separately or in association, on chronically heat-stressed chickens were observed. However, the expected cumulative positive responses when the two treatments were combined were not evident.

Aim: This study analyzed risk factors influencing the conception rate at the first artificial insemination (CR1) in dairy cows reared in the plain of Mitidja, which is considered a major dairy region in North Algeria. Materials and Methods: A total of 1054 lactations were used in the relational study of fertility conducted using the multivariable logistic regression model using the odds ratio (OR). Results: The breeding season had a specific effect on fertility; the first service was often followed by pregnancy when performed during autumn (AUT) (OR=1.67, p<0.05) and spring (SPR) (OR=1.65, p<0.05). The chances of obtaining conception during the first service increased significantly for a waiting period (WP) (interval between calving and time to first service) of 50-100 days postpartum (DPP) (OR=1.67, p<0.05). Conclusion: From this study, it can be concluded that no specific effect was observed relative to the breed and parity. Furthermore, CR1 significantly increased after summer calving when the first services were performed during SPR and AUT and a WP after 50 DPP.

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