Ontogeny of gut associated immune competence in the chick

Abstract

To accommodate the rapid transition to external nutrients, the chick's gastrointestinal tract undergoes dramatic changes within the first few days of life. These include a rapid increase in mass, villi number and length, enterocyte number, crypt depth and proliferating cells. Concomitant with the development of digestive structures and functions a rapid development of the gut associated lymphoid tissue (GALT) occurs. This lymphoid system works within and in concert with digestive tract parenchyma, however, there is little information describing the normal development and immunological function of the avian GALT in the immediate posthatch period. The purpose of this review is to summarize current knowledge on the structure and function of the avian GALT during the early post-hatch period. At hatch, the gut is poorly populated by both innate immune leukocytes and lymphocytes. The basal numbers of lymphocytes are the result of early waves migrating from the thymus and bursa of Fabricius. Further waves of lymphocyte migration occur after 4 days of life and continue intermittently with time. In concert with this pattern of lymphocyte population adaptive immunity develops. Hence, the gut of the hatchling is unprotected by adaptive immunity during the first few days of life. Protection during this critical period might be the result of maternal antibody activity or that of the innate immune system. This system appears to be functional at this time, though much work is needed to establish this possibility. Upon maturity of the immune system, most of the immunological activity within the chick GALT is concentrated in the hindgut, and specifically so in the caeca and bursa of Fabricius. Once immune responses have become established the relevant cells disseminate systemically and to other areas of the small intestines. Finally, observations on the beneficial effects of early feeding on development of gut and GALT are discussed with reference to management of hatchlings.Ontogeny of gut associated immune competence: A. Friedman et al.

Early life experiences affect the adaptive capacity of rearing hens during infectious challenges

“…Previous studies demonstrated that early feed intake (immediately after hatch) enhances the functional development of the intestines in chicks that results in increased digestibility and thereby growth (Noy et al, 2001;Friedman et al, 2003). This explains the higher BW of optimized chicks in the first 3 weeks posthatch in this study.…”

“…The functional development of the intestines as a digestive organ seems to be closely related to its development as a major lymphoid organ (Thompson et al, 1996). Previous studies showed that early feed intake has a positive effect on the development and maturation of the gut associated lymphoid tissue (GALT), which includes the cecal tonsils, bursa of Fabricius, Peyer's pathes and other lymphoid nodules, and provides both local and systemic protection in young chicks (Dibner et al, 1998;Friedman et al, 2003;Kajiwara et al, 2003). Delayed access to feed has shown to decrease bursa weight (Dibner et al, 1998) and to delay the development of T and B lymphocytes in the hindgut in the first 2 weeks of life (Bar-Shira et al, 2005).…”

GUT IMMUNITY IN BIRDS: FACTS AND REFLECTIONS (review)

“…In the authors' view, such retrograde motility of the middle intestine improves reabsorption of urine and caecal contents, and provides better absorption of cellulose degradation products and crude protein (82)(83)(84). Such reverse peristalsis between the middle part of jejunum, duodenum, and even gizzard, was observed in both newly hatched chicks and in adult chickens (85). So, it is possible that external material enters immunoactive caecal appendices, and, moreover, that antibodies may uplift from the bursal sac into the small intestine.…”

“…The colon of birds has no lymphoid follicles, but they occur in its terminal part opening into the cloacal bursa -a lymphoid organ located in proctodeal part of the cloaca and involved in primary and secondary immune responses. Mucosa and submucosa of the bursal duct contain many lymphoid follicles (85). There are single lymphoid nodes in procdeum (hindgut) and urodeum (part of cloaca near urethral orifices) (54).…”

The effect of organic diets on the performance of pullets maintained under semi-organic conditions

“…Furthermore, even if a wide range of ingredients were available, the preparation of adequate diets is difficult to achieve in commercial systems because of the limited storage available to feed compounders. Birds fed conventional diets that provide methionine at suboptimal levels have been shown to be predisposed to health-, welfare-and productionrelated problems (Friedman et al, 2003;Kidd, 2004;Klasing, 2006). Furthermore, birds cannot necessarily compensate for inadequate amino acid levels by increased food intake (Whitehead, 2002).…”