In the first part of this ariticle we reviewed the importance of perinatal feeding of chicks. We also discussed the morphological and physiological changes occurriying in the gastrointestinal tract before and after hatching, paying special attention to in-ovo feeding. In this second part, we present diverse strategies for feeding chicks immediately after hatch and until they reach the farm, as well as during their first week of life.
In the first part of this ariticle we reviewed the importance of perinatal feeding of chicks, as well as the morphological and physiological changes experimented in the gastrointestinal tract before and after hatching. Likewise, as a possible feeding strategy during the perinatal period, we discussed the in-ovo administration of nutrients during the last phase of embryonic development. Relevant results of experimental work were presented, reporting the effect of the injection of amino acids, carbohydrates, vitamins, probiotics, and prebiotics in fertile eggs. In this second part, we present diverse strategies for feeding chicks after hatch, from the first hours of life in the incubator until their arrival at the farm, as well as in the first days in the production facility.
In commercial incubators, newly hatched chicks remain inside the machine during a certain number of hours before being sexed, vaccinated, classified, etc. Once all the activities in the hatchery are finished, chicks are transported to the farm. Therefore, the timespan between hatch and the moment they can access feed and water can be as long as 72 hours.
In general, it is considered that chicks are able to survive on yolk sac reserves for up to 72 hours after hatch (Mitchell, 2009). However, whilst the yolk sac reseves may guarantee survival, the absence of feeding during the first hours (or days) of life negatively affects the growth and productive performance of chickens.
What is the effect of fasting time ?
De Jong et al. (2017) performed a rigorous metanalysis on data from 83 experiments, studying the effect of delayed first feeding on productive performance of chickens at different ages. The metanalysis revealed that, although chicks can compensate the growth delay derived from fasting during the first hours of life, such compensation is incomplete. Depending on the number of hours they waited to have their first meal, significant differences in body weight could still be obsered at 42 days of age (Fig. 1).
Figure 1. Effect of hours of fasting after hatch on the live weight of chickens at different age (de Jong et al., 2017). Values at the same age with different letters present statistically significant differences (p<0.001).
Similarly, the number of fasting hours after hatch significantly affected feed conversion rate (FCR) (Fig. 2) and mortality rate throughout the life of the chickens (Fig. 3).
Figure 2. Effect of fasting time after hatch on feed conversion rate (FCR) of chickens from 0 to 24 days of age (de Jong et al., 2017). Values with different letters are significantly different.
Figure 3. Effect of fasting time after hatch on mortality rate of chickens form 0 to 24 days of life (de Jong et al., 2017). Values with different leetters significant different.
Delayed access to food and water after hatch have negative effects on body weight, performance, and mortality until slaughter.
Together with the need of the earliest possible feeding, the proportion of macronutrients in the first feed is determinant for the growth throughout the life of the chicken. In this sense, the intake of protein during the first days of life will be the most important nutritional factor.
Sweenen et al. (2010) fed chicks for the first five days of life with one of three isoenergetic pre-starter diets, one low in protein, one low in fat and a third one low in carbohydrates. From day 6, all chickens received the same commercial diets until 42 days of life. The results showed that chickens that have received a pre-starter low in protein were significantly behind respect of the ones that have received pre-starter diets low in carbohydrates or fat (Figs. 4 and 5). This is explained by the fact that, during the first days after hatch, chicks are less efficient digesting proteins than fats and carbohydrates (Noy and Sklan, 1995).
Figure 4. Effect of composition of pre-starter diets on the growth of chicks from 0 to 7 days of age (Sweenen et al., 2010).
Figure 5. Effect of the composition of a pre-starter diet on the growth of chickens form 7 to 42 days of life (Sweenen et al., 2010).
The digestibility of dietary protein and amino acids is relatively low during the first 10 days of life (Fig. 6). Consequently, including highly digestible protein in pre-starter diets is crucial to secure appropriate chick growth.
Figure 6. Digestibility of lysine in chickens from 0 to 20 days of life (Batal and Parsons, 2002)
As already referred in this article, the access to feed and water immediately after hatch is of utmost importance for an optimum development of the digestive and immune system. This will lay the foundations for chicken growth and health until slaughter.
Nowadays, systems can be fit inside the hatchers to administer feed and water as the chicks hatch (Fig.7). In those systems, hatching baskets have wholes through which the chicks fall into a second basket, where there is feed available for the next 24 to 36 hours.
Figure 7. Feeding inside the hatcher (reproduced with permission from HatchTech)
With this system, chicks can begin to ingest a complete feed immediately after hatch. This first feed supplies the energy the birds need for basic maintenance. In this way, yolk nutrients, of higher nutritional value, can be used for more important purposes, such as development of the immune system and of vital organs.
Another practice on the rise, to ensure early feed intake, is the administration of hydrating gels containing a growing variety of nutrients and additives, such as vitamins or probiotics.
Figure 8. Feeding hydrating gel (reproduced with permission from Pharmsure International Ltd.).
Nowadays, new technologies allow to spray the hydrating gels, achieving a more uniform distribution of the droplets, ensuring all chicks receive the desired doses of active ingredients.
Another variety of complementary feed are gel terrines, which normally are sliced and placed inside the box, either in a container or directly on the floor of the box. They can also be administered as the chicks arrive at the farm, on paper placed on the floor, or even inside the feed troughs on top of the starter feed.
Feeding chicks immediately after hatch have an effect on their performance throughout the entire production cycle. This is of great relevance and complements the results of in-ovo feeding.
In this respect, Kornasio et al. (2011) investigated the effect of administering feed 6 hours after hatch. He observed that chicks from eggs inoculated with carbohydrates and salts at day 18 of incubation, had a significantly higher body weight at day 35, as well as higher development of breast muscle (Fig. 9). This demonstrated the complementarity between in-ovo feeding and feeding in the incubator immediately after hatch.
Figure 9. Effect of in-ovo feeding, post-hatch feeding, and their combination, on breast weight of chickens at 14 and 35 days of age (Kornasio et al., 2011).
As mentioned before, protein is the most important factor during the first hours and days of life. Therefore, feeding rations rich in highly digestible protein in the incubators will be crucial for the viability and optimal development of chicks.
Early feeding in the incubator will play a crucial role in establishing a correct immune response and in the recovery from diseases in later stages.
The establishment of a diverse and beneficial intestinal microbiota is key for the development of the immune system of birds, at local and systemic levels,.
Nakphaichit et al. (2011) suplemented the first diet (from immediately after hatch) with a probiotic. They observed an increase in the diversity of intestinal microbiota, favourig the supremacy of beneficial bacteria throughout the life of chickens (Fig. 10).
Figura 10. Effect of supplementation of chicks with a probiotic immediately after hatch, on ileal miucrobiota profile at 21 and 42 days of life (Nakphaichit y col., 2011).
The composition of a pre-starter diet (macro and micronutrients) during the first week of life will, undoubtedly, affect the subsequent growth and development of broilers.
Normally, digestibility assays of amino acids and energy balance in chickens are not performed before 21 days of life.
The digestive capacity of a chick in its first week of life is not the same as in a 21 days-old chicken. Amino acid requirements of newly hatched chicks are higher due to the intense metabolic activity accompanying the rapid tissue growth during the first days.
In this respect, the main characteristic of pre-starter rations known as “super-starter” is the inclusion of sources of highly-digestible protein, addressing the fact that protein is the first limiting factor in this phase.
A correct evaluation of the cost of using these high quality ingredients in the first life stages, as well as of the financial return at the end of the broiler cycle, are aspects that cannot be ignored.
This article was originally published in nutriNews Spanish edition as «Alimentación perinatal en pollitos. Primeras horas y días de vida».
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