The general concern about animal welfare, especially for laying hens, is continuously increasing in consumers and farmers. This attention leads to spending time and efforts to understand if our birds are stressed or not, through many different indicators both deriving from animal observation (behavior, performance, fearfulness) and laboratory analysis (Alm et al., 2016; Rodenburg et al., 2008). Stressors (i.e. the pullet transfer commencing with the start of lay, or the huge amount of energy required at the peak of production) can negatively affect the immune status of our animals, increase the corticosterone levels, as well as birds can be more anxious and less productive. One of the aspects highly affected by stressors is the intestinal health of birds, which is at the basis of the general health of the animal: the intestinal mucosa is the first line of defense against pathogens (Figure 1). Its epithelium is composed of a monolayer in which the cells are linked one to the others by protein structures (tight junctions, TJ). Stress and inflammation disrupt the TJ and, consequently, the barrier function of the mucosa is negatively affected. This effect is strictly related to the increase in pathologies (especially bacterial infections and toxemia) as well as to the reduction in birds performance because of the reduction in nutrient absorption.
Figure 1: Intestinal mucosa. Left: healthy mucosa and physiological structure of the epithelium and the tight junctions. Right: stressors and pathologies cause the inflammation of the intestinal mucosa with the consequent disruption of its integrity and reduction in barrier function.
Galliacid®S contains a specific blend of organic acids (OA) and nature identical compounds (NIC*), molecules that are commonly used in poultry production and well known because of their antimicrobial activity against pathogens. Once ingested in the free form, OA and NIC are highly degraded before reaching the intestine, where they can be extremely useful. Galliacid®S overcome this problem through Vetagro microencapsulation technology. The lipid matrix protects the active ingredients through the anterior part of the gastrointestinal tract ensuring their slow release at the intestinal level (where the matrix will come in contact with lipase enzymes). The Gaussian distribution of the particle granulometry is specifically studied based on the gastro-intestinal transit time of poultry. Consequently, the active ingredients are uniformly released along the whole intestinal tract (Figure 2).
Figure 2: Vetagro specie-specific microencapsulation technology protects the active ingredients in the first part of the GIT and ensures their slow along the whole intestine
OA and NIC have a synergistic activity both as antimicrobials and anti-inflammatory agents at the intestinal level. As antimicrobials, their modes of action are different and complementary. The undissociated form of the OA can pass the bacterial membrane: once inside the cell, the molecule dissociates causing a reduction in the internal pH of the bacterium. At the same time, the negatively charged part of the molecule is toxic for the nucleic material of the bacterium. The result is the bacteriostatic and bactericidal activity against pathogens. On the other hand, NIC are pore-forming agents: they destroy the bacterial cell membrane integrity with a direct bactericidal activity. Once together, OA and NIC work synergistically so that we can reach the same antimicrobial effect with extremely lower concentrations of each active ingredient. For what concern their activity on the intestinal mucosa, different studies demonstrated that the combination of OA and NIC has even an anti-inflammatory effect, improving the intestinal barrier function and reducing the production of inflammatory cytokines at this level in a synergistic way. Galliacid®S contains all the ingredients together in the same beadlet so that it ensures their simultaneously release and synergistic activity on the intestinal mucosa and microflora.
One of the most frequent questions is if Galliacid®S can be used with anti-Salmonella vaccines. The live vaccines are administered to the birds per os (drinking water), to mimic the natural route of the infection and to provide powerful protection against Salmonella. Prebiotics, probiotics, and fatty acid formulations with direct anti-Salmonella activity or that block the bacterial adhesion may interfere with oral vaccination with live vaccines. Anyway, Galliacid®S active ingredients have low antimicrobial activity against Salmonella and their Minimal Inhibitory Concentration (in vitro tests) are more than 10 times higher than the application dose of the product. Moreover, in vivo there is even absorption and dilution effect, with a lower risk of anti-Salmonella direct activity. Last but not least, the final vaccination is done at least three weeks before the point of lay, so that it is not necessarily concomitant with the administration of Galliacid®S. That said, the answer to the initial question is: Galliacid®S can be used even in case of birds vaccinated against Salmonella.
For what concerns the effectiveness of Galliacid®S in vivo, the latest field trial in the UK on the laying hens has revealed significant improvements in the production metrics. These trials were conducted from Nov 2019 till Jan 2020 on six houses of laying hens with three different breeds. These six houses of hens were fed a standard UK diet supplemented with a blend of essential oils (control groups, Lohmann and Bovans brown) or the same standard diet with Galliacid®S (treated groups, Lohmann and Hyline) from week 36 to 48 of age. At this age, the animals were in full production and, for this reason, more exposed to pathogens intestinal translocation and reduced nutrient absorption. The results demonstrated that the treated groups had up to 1.9% higher HD% compared to the controls. About the eggs per hen housed (Figure 3) at the end of the trial the treated birds had 4 more eggs/HH compared to the controls. Even the egg weight (Figure 4) was higher with Galliacid®S. Before the start of the trial, the birds that will be treated with Galliacid®S laid eggs up to 1.15g lighter than the others while after 2 weeks of treatment the egg weight was comparable and then the treated groups laid eggs heavier (up to +0.68 g/egg) than the controls. The cumulative feed intake for the treated groups was on average 16 g/bird higher than the controls at the end of the trial (421 g for Galliacid®S groups VS 405 g for the control ones). 
Figure 3: Eggs/HH. The green box indicates
the duration of the trial. All animals were fed the same feed before this
period. At the end of the trial, the treated birds had 4 more eggs/HH compared
to the controls.
Figure 4: Eggs weight. The green box indicates the duration of the trial. All animals were fed the same feed before this period. Treated birds produced heavier eggs than the control after a few weeks from the start of the trial.
To summarize one of the most important things to take care of is the birds intestinal health to improve both performance and general health status. Products such as Galliacid®S may help the animals to maintain and to restore their intestinal barrier function even in case of particularly stressful periods. This specifically studied product can help to sustain birds health, performance, and welfare, ensuring persistence and longevity throughout the production cycle.
* NIC are molecules identical to the active ingredients of the essential oils but chemically produced. The synthetic production ensures their purity and the lack of contaminants (i.e. pesticide and residues).
Jim Turner B.Sc
Poultry Product Manager
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