Nowadays, modern layers are able to achieve extremely high performances. For instance, they are capable of producing 366 eggs at 80 weeks and 437 eggs at 95 weeks with an average egg size of 63.1g. To reach this level of performance, one key to success is to achieve a successful 18-week pullet rearing period.
For their first 18 weeks of life, pullets are raised in a facility under environmentally and nutritionally controlled conditions. The objective is to achieve the specific physiological development required to start laying. Amongst the objectives, attaining pullet body weight objectives at 3, 6, 12 and 18 weeks are critical. For instance, it is established that higher performing flocks of layers have higher 18 week body weight relative to lower performing ones. The young layer’s immune system is also maturing during this phase and vaccination plays an important role. In fact, certain diseases are too widespread or difficult to eradicate and require a routine vaccination programme. The role of the vaccine is to prevent a specific disease by triggering the immune system to produce antibodies that will then combat the pathogen. An example of a vaccination programme is illustrated in Table 1 below.
From a growth point of view, these numerous and successive vaccinations are an additional challenge. In fact when a pullet undergoes stress, its feed intake is often affected and in the case of vaccination, it can be depressed by up to 25%. In addition a frequently forgotten aspect is the metabolic cost of immunity. When a pullet is vaccinated, both the acquired (antibodies production) and the innate immune systems (inflammatory response) are stimulated and nutrients (energy and amino acids) are required. The inflammation being the costliest in nutritional resources, it is important to limit its over activation following vaccination to avoid a drop of performance.
To ensure that a pullet reaches body weight objectives, different strategies are possible. First one can increase nutrient density in the diet at an early stage. A second strategy is to improve feed particle size: particles within 1 – 3 mm with a minimum amount of fines. Third and last one can improve pullet vaccination response. The first two strategies are focused on the nutritional and physical form of the feed. The third strategy is focused on the animal itself. It targets key metabolisms to limit growth impairment while improving the production of antibodies.
Different published studies concerning various animal species have highlighted the interest of supplementing low dose phytonutrients to modulate animal immune systems. Amongst the identified micro-ingredients, two of them have confirmed their efficiency and a positive synergy has been demonstrated when they are used in combination. The first, curcuminoids (contained in turmeric oleoresin) has been used for centuries in Indian and Chinese medicine. It improves and speeds up the antigens recognition by the host and therefore enhances antibodies production. The second, capsaicinoids (contained in chilli pepper oleoresin) is known to exert a strong anti-inflammatory activity. This ingredient has repeatedly demonstrated its ability to limit both local and global inflammatory response (Lee et al., 2010).
Being irritants and difficult to handle, these two ingredients have to be micro-encapsulated with an adequate matrix in order to create an additive that can be used in animal feeds.
The interest of the addition of such additives made of both turmeric and chilli pepper oleoresins (XTRACT Nature) in feed and as a supplement to a vaccination programme, was first evaluated by the USDA (United State Department of Agriculture) Animal Parasitic Diseases Laboratory in 2011 for broilers. Results demonstrated a boosting effect of the cocci-vaccination and an increase in the pool of antibodies produced.
In a recent trial performed in South East Asia, the efficacy of XTRACT Nature has been tested in Newcastle disease vaccinated pullets. This trial lasted 12 weeks and the objective was to confirm the efficiency of the additive. Two buildings were selected in a commercial farm with 5,000 pullets/building. Pullets were from Dekalb white genetic. From day 9 onward, they received the same commercial diet, XTRACT Nature at 100g/ton being the only difference between the two groups.
According to the farm vaccination programme, all pullets were vaccinated against Newcastle Disease (ND) at 19 days of age. At day 32, three pullets per treatment were necropsied and at day 46 (27 days post vaccination), the blood of 20 pullets per treatment was sampled and analysed by ELISA for Newcastle antibody titres. The trial timeframe is illustrated in the Figure 1 below.
At the necropsy (day 32), signs of inflammation were identified in the trachea of the pullet from the control group. This inflammation is most probably due to a response of the innate immune system to the vaccine. Pullet receiving the product revealed lower inflammation status.
Serum ELISA analysis for Newcastle antibody titres revealed that pullets supplemented with the standardised phyto-molecule additive had a marked increase of Newcastle titres (11,712 vs. 7,282) together with a lower coefficient of variation (55% vs. 71%) compared to the control. In other words, pullets receiving the product had higher protective levels and a more uniform flock protection against Newcastle disease (see Figures 2 and 3 and Table 2).
Last but not least, pullet body weight was measured at the end of the trial (12 weeks of age). Pullets having taken XTRACT Nature had higher body weight (945.4 g/pullet) than pullets of the negative control (914.4 g/pullet). When fed with the product, pullets achieved 98.8% of their growth potential in comparison to the application of the control diet, with 95.5% of their potential. In this context, a standardised phyto-molecule additive demonstrated its ability to modulate the animal immune system. It enables the pullet to better cope with the vaccination with effects such as reduction of inflammation and improvement of antibody response. Overall it leads to better pullet flock protection and better growth performance.
References available upon request.