Objective:

Prove three levels of 25-hydroxycholecalciferol in broilers at a high risk of Tibial Dyschondroplasia incidence, raised under thermal neutral temperature conditions and high temperature, with an altitude of 2130 m above sea level.

Methodology:

348 Ross birds from 1 to 21 days old were used, 308 with an average weight of 43.97±1.25 g, distributed in a factorial 2x3 model, two ambient temperatures (thermal neutral and high temperature) and three levels of 25-hydroxycholecalciferol (34.5, 69 o 93.5 µg/kg of food, as the only source of vitamin D), each of them with 8 repetitions and 8 birds per experimental unit. On the 21st day of age, the final weight, the feeding conversion and mortality in each experimental unit were determined. Moreover, a tibia bone sample was taken in order to conduct a quantitative measure of the percentage of area with Tibial Dyschondroplasia.

Results:

Even though birds fed with 93.5 µg/kg of vitamin D showed lower biological results of Tibial Dyschondroplasia, the statistical evidence does not reveal a significant difference between the treatment measures (p>0.05). The final weight increased considerably (p<0.05) in the birds fed with 93.5 µg/kg25-hydroxycholecalciferol; and when the results were analyzed in the temperature factor, significant statistical differences were not observed (p>0.05).

Conclusion:

Based on the obtained results under the experimental conditions, the addition of 25-hydroxycholecalciferol per dose by 93.5 µg/kg, improved the productive response. However, there was no difference in the degree of Dyschondroplasia when the birds consumed 25-hydroxycholecalciferol in 34.5 and 93.5 µg/kg of food in 1 to 21 days old broiler chickens.

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