Effects of dietary sodium bicarbonate supplementation on eggshell quality and hatchability in Thai native hens

Investigation was conducted on Thai native hens to determine the effects of dietary sodium bicarbonate (NaHCO3) supplementation on egg production, egg and eggshell quality, fecal moisture content, plasma sodium, and hatchability performance. Two hundred and forty of 24 wk-old hens were used in this study. The birds were housed in individual cage and received 1 of 3 experimental diets. The 3 experimental diets were control layer diet, the control diet added with 1 percent NaHCO3, and the control diet added with 1.5 percent NaHCO3. The experiment was conducted for 24 weeks. There were no significant differences in feed consumption, egg weight, yolk weight, albumen weight, Haugh units or fecal moisture content among the three bird groups throughout the experimental period. However, the birds in the two groups having received the diet supplemented with NaHCO3 gave a significantly higher level of yolk color, shell weight, and shell thickness than the control hens transiently (P LT 0.05). Likewise, the hens received the diet added with NaHCO3 had a higher level of plasma sodium concentrations than the birds fed with control diet at 32 and 36 wk of age. A smaller, but still significant, increase in plasma pH was also observed in the fowls having consumed the diet supplemented with 1.5 percent NaHCO3 at 28 wk of age (P LT 0.05). Hatchability, viability (hatchability of fertile eggs), and body weight of the chick at hatching were not affected by the experimental diets (P GT 0.05). The results indicated that at moderate temperatures eggshell quality of Thai native hens could be improved by dietary supplementation with 1.5 percent NaHCO3. This suggested that the response was associated to bicarbonate intakes. However, the beneficial effect was transient that would be resulted from the hens having no access to feed during the dark period, irrespective of bicarbonate content, the time during which eggshell formation occurred. Hatchability and viability of chicken embryos were not evident.