INTRODUCTION
Two different field trials were performed in a Colombian poultry company during the end of 2017 and the beginning of 2018. This company used two premix cores (A and B), obtaining unequal results: batch using core A obtained a 6 points superior productivity index (PI) compared to batch using core B. This last group also suffered from rapid intestinal transit. 

These were reasons to perform different trials to check the effect that a natural preservative (with cimenol ring) and intestinal conditioner pronutrients could have on productive parameters in batch consuming core B, first, using these natural products “ON TOP” and after, as substitutes from chemical Antibiotic Growth Promoters (AGPs) that contained the core.

EXPERIMENTAL DESIGN
During the starter period (1-21 days), both batches used core B, until the fattening stage started, when control batch began consuming core A and treatment batch consumed core B, with the natural preservative (with cimenol ring) and natural conditioner pronutrients, both mixed with the feed at a dose of 0.5kg/T. In the first trial, both natural products were administered ON TOP and in the second one as substitutes of AGPs.

Litter, faeces and feet conditions were evaluated weekly. Necropsies were also performed to random animals to assess digestive tract status. At the end of the trial, results of productive parameters were calculated.

RESULTS
As seen in the chart (Chart 1), all productive parameters (weight, feed intake and FCR) were improved in the treated batch. Intestinal transit also improved, since it was confirmed by a better consistence of faeces, and improved litter and feet conditions.

Chart 1. FCR = Feed Conversion Rate; I.P. = Productivity index (Efficiency/FCR); Efficiency = (survival x weight x 100) / feed intake.

CONCLUSION
Inclusion of a natural preservative (with cimenol ring) and an intestinal conditioner pronutrients to the premix core B showed that it could reach or even got better results than the core A and allowed the replacement of Antibiotic Growth Promoters. These products also have as other advantages that they do not need withdrawal period, they leave no residues in birds’ tissues and do not create microbial resistance.

This natural preservative (with cimenol ring) is commercially available under the name of Alquermold Natural, and natural conditioner pronutrients as Alquernat Nebsui.