Botanical solution in feed additive for intestinal release to control blackhead disease (Histomoniasis) in turkeys

Blackhead disease, also known as Histomoniasis, is an important poultry disease caused by Histomona meleagridis, which is a protozoa that spreads in the bird by the roundworm Heterakis gallinarum, and infects the cecum and liver. Turkeys are highly susceptible to this disease. Although mortalities in turkey flocks reach 80-100% and economic losses exceed 2 million USD/year, there are lack of approved drugs against blackhead disease. Therefore, phytogenic compounds are new and natural alternatives.

Samples were obtained by mixing Quillaja extract and different polymer combinations, commonly used in encapsulation technology, to achieve a control release in the intestinal tract. The mixture was obtained by homogenization, pH variation and spray dry. Sample (QSAP): Quillaja extract + fiber+ 1 polymer, Sample (QSBP):Quillaja extract + 2 fiber+ 1 soluble polymer, Sample (BQP): Quillaja extract + 2 fiber+ 2 complex polymer. All samples were characterized by measurement of moisture, saponin content by HPLC, solubility, saponin release kinetic and in vivo evaluation. The in vivo study was conducted at the Avian Pathology Lab (Universidad de Chile) using a total of 200 hen turkey poults. Birds were reared from 0-28 days of age in cages and randomly assigned to treatments. There were 10 cages with 20 birds/cage, and 2 cages/treatment except for Control (CON) and MED. All additives were administered via feed from day 21. On day 28, all birds except CON were individually inoculated per cloaca with ~100,000 cells/ml with H. meleagridis 14810. Body weight (BW), Feed intake (FI), and FCR was recorded. Dead birds were registered and removed for necropsy along with the assay to determine the liver and cecal lesion score using a scale of 0 to 4, with 0 being normal and 4 being the most severe. The lesion score was analyzed using Kruskal-Wallis test. One-way ANOVA and subsequent Tukey test (α=0.05) were carried out using Statgraphic software, except for body weights.

To use the same drying conditions, it was necessary to adjust the content of saponins to standardize the active compound. The moisture content was similar in all samples. There were clear differences between treatments in the saponin kinetic release and solubility, where the samples QPP and QQP had a significant lower solubility (p< 0.05). For the period 0-21 days, BW and FCR in POS, was higher than CON; 28 % increase in FCR and 2 % increase in BW. Compared with untreated/ challenged birds (POS), QSAP had a reduction (15%) in FCR and 4% increase in BWG. BWG and FCR did not differ significantly between MED and BQP. For the period 21-35 days, compared with untreated/challenged birds (POS), QSAP and BQP group had a significant increase (p< 0.05), with 9 and 13% in BW, respectively, and similar to MED. Also, compared with birds (POS), the highest reduction in FCR were observed in samples QSAP and BQP. There was a clear treatment effect on mortality. Compared with untreated/challenged turkeys (POS), BQP had a significant reduction (69%) in mortality (p-value< 0.05), followed by MED. The average cecum lesion score in BQP and QSAP was 4 and 2 times lower than in the POS group, respectively. In the liver, MED-treated birds had the lowest lesion scores followed by the BQP group, being 8 and 3.5 lower than POS.

There was a clear impact of the Histomona challenge on the performance of the bids. BQP treated groups showed promising results regarding decreased mortality and low lesion scores compared with POS and it was comparable with a natural and synthetic solution available in the market.

Key Words: Histomoniasis, turkeys, Blackhead disease, feed additives, botanical solutions.