A. GUTIERREZ del ALAMO
H. ENTING
J. de LOS MOZOS
P. PEREZ de AYALA
Nutreco Poultry and Rabbit Research Centre
Casarrubios del Monte
Spain
An experiment with 528 non-infected and 624 malabsorption syndrome-infected Hybro G broiler chickens was carried out. Birds were housed at day-old in two separated rooms, each with 48 pens. Birds were infected from day 0 by two seeder birds in each pen, which were removed at 21 days of age. The experiment included 3 treatments: T1 was the control group in which feed without antibiotic growth promoter was provided. In T2, 0.75 g/kg of a mixture of sodium butyrate and medium chain fatty acids (MCFA) was added to the starter and grower diets. In T3 1.0 g/kg and 0.5 g/kg of this mixture were added to the starter and grower diets respectively.
The results of the experiment showed that the mixture of sodium butyrate and MCFA improved performance in both non infected and infected birds and reduced mortality in infected chickens.
Introduction
The use of antibiotic growth promoters (AGP) has been banned in the European Union from January 2006 on. Because AGP still showed an improvement in the performance of broiler chickens, alternatives were sought for these growth promoters. The positive effect of AGP on bird performance is believed to be caused by a reduction in the incidence of sub clinical infections, a reduction of growth inhibiting metabolites that are produced by the intestinal micro flora, a reduced use of nutrients by the micro flora and an increased absorption and utilisation of nutrients due to a thinner intestinal wall (Gaskins et al., 2002). Recently, it was suggested that the main effect of AGP is due to a reduction of inflammatory responses in the intestinal tract (Niewold, 2006).
Many potential alternatives for AGP have been described (Verstegen and Williams, 2002). Among these, short and medium chain fatty acids (MCFA) affect parameters that are also affected by the banned AGP (Canibe et al., 2001; Dierick et al., 2002). Short and medium chain fatty acids have been reported to have antibacterial properties (Santomá et al., 2006), with their antibacterial effect more pronounced in acid-intolerant bacteria such as Salmonella (Thompson and Hinton, 1997; Van Immerseel et al., 2004) and Campylobacter (Chaveerach et al., 2002). MCFA are digested and absorbed faster than long chain fatty acids and may be very useful when the digestion, absorption or transport of dietary fat is defective (Bach and Babayan, 1982).
An experiment was carried out to determine the effect of short and medium chain fatty acids (C6 to C12, mainly C8 and C10) on broiler chicken performance. Since Ter Huurne and Smits (1999) demonstrated that malabsorption syndrome (MAS) can be used as a model for intestinal disorders in broiler chickens, the experiment was carried out with both healthy and MAS infected birds.
Material and methods
The experiment involved in total 1152 Hybro G broiler chickens, of which 528 were placed in 48 floor pens in the control room (11 birds per pen) and 624 in 48 floor pens in an identical room that were infected with MAS (13 broilers per pen). Each pen had a floor area of 0.8 m2 and wood shavings were used as bedding material. Feed was provided ad libitum by one feeder per pen and water by 2 nipple drinkers per pen.
Birds were infected with MAS by giving 2 “seeder” birds per pen 0.5 ml of a MAS homogenate at 0 days of age. This homogenate was obtained from the intestines of an earlier flock that was infected with MAS. Before infection, the homogenate was thawed and mixed 50/50 with a phosphate buffer solution. In order to facilitate transmission of infection, plastic foil was put on top of the wood shavings during the first week in order to promote pecking of the excreta. The 2 seeder birds were removed at 21 days of age after weighing. Weight was also determined at 0 and 42 days of age. Feed intake was recorded from 0 to 21 d and from 21 to 42 d and mortality was recorded daily along with the body weight of dead birds to correct FCR for mortality.
In each room, three treatments were applied with 16 replicates per treatment. The treatments included one control treatment without the addition of any antibiotic growth promoter (treatment 1). In treatment 2, 0.75 g/kg of a mixture of sodium butyrate and medium chain fatty acids (Trouw Nutrition, Putten, The Netherlands) was added to the starter and grower diets. In treatment 3, 1.0 g/kg of this mixture was added to the starter diet and 0.5 g/kg in the grower diet. The starter diet contained diclazuril as the coccidiostat and monensin was added to the grower diet. The starter and grower diets were provided as 2 mm and 3 mm pellets respectively. The composition of the basal diets is given in Table 1.
Birds were vaccinated at day-old against Marek’s Disease and Infectious Bronchitis and at 20 days of age against Infectious Bursal Disease. A standard temperature schedule was applied, commencing at 30 °C at day-old and gradually decreasing to 20 °C at 28 days of age. Light was continuously provided during the first 3 days of age and thereafter, a light schedule of 20L:4D was applied.
Data was subjected to analysis of variance (general linear models procedure of SAS, 1997). The statistical model included treatment, room (infection) and treatment x room (infection) as factors. Significant differences between treatments were detected by a Least Significant Difference procedure (Snedecor and Cochran, 1967). Differences between treatments were considered significant at P≤0.05.
Results and discussion
The results of the experiment are summarised in Tables 2 and 3. The MAS infected chickens had a significantly lower live weight and feed intake compared to the non-infected ones. The changes in live weight and feed intake were in line with earlier experiments with MAS infected chickens (Den Hartog et al., 2005). FCR and mortality were not significantly influenced by the MAS infection.
The inclusion of the mixture of sodium butyrate and medium chain fatty acids in the feed resulted in a non significant increase in live weight at 42 days of age, while feed intake was not affected. FCR improved with inclusion of sodium butyrate and medium chain fatty acids. As compared with the control group, this difference was significant when the starter and grower feed contained 1.0 and 0.5 g/kg respectively of the mixture. These results confirm that short and medium chain fatty acids improve performance of broiler chickens and can be considered as important alternatives to AGP (Canibe et al., 2001).
No significant interactions were observed between infection and treatment for live weight, feed intake and FCR. Thus, a mixture of sodium butyrate and medium chain fatty acids improved performance of both healthy chickens and of chickens suffering from an intestinal disorder. Sodium butyrate is the principle energy source of the enterocytes (Isolauri et al., 2003) and may reduce inflammatory responses as with AGP. This might explain why healthy birds also responded to the addition of the mixture. There was an indication (P=0.074) of an interaction between infection and treatment for mortality. This was caused by a considerable decrease in mortality in the MAS infected chickens when sodium butyrate and medium chain fatty acids were included in the feed but no effect of SB and MCFA on mortality in the non-infected chickens (Table 3). This reduction of mortality in the infected birds is most likely a response to the antibacterial properties of MCFA (Chaveerach et al., 2002; Van Immerseel et al., 2004) which probably alleviated the poor health status of the infected animals. The results show that sodium butyrate and medium chain fatty acids have an additional beneficial effect when intestinal health status is impaired.
References
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From Proceedings of the “19th Australian Poultry Science Symposium”, New South Wales, Australia.
