Histomorphometric analysis of the small intestine in Philippine Darag native chickens compared to slow-growing commercial broilers

Abstract

The Philippine Darag native chicken demonstrates favorable health and welfare indicatorsthat are comparable to those of slow-growing Redbro broiler chickens. Thisstudy analyzed the histomorphometric characteristics of the small intestinal segmentsin these 2 breeds over an 8-week growth period. Small intestinal sampleswere collected weekly from both breeds from week 1 to week 8. Tissues were fixedand stained with hematoxylin and eosin, and analysis was performed using ImageJto quantify villus height (VH), crypt depth (CD), villus-to-crypt ratio, epithelialthickness (ET), mucosal thickness (MT), and tunica muscularis thickness. The effectsof age and breed, as well as their correlations with body weight, relative organweight, and total feed consumption, were evaluated using a mixed-effects model,Pearson’s correlation, and multiple linear regression. Additionally, a binomial logisticregression model was applied to examine the occurrence of zigzag villi patterns. All histomorphometric parameters exhibited a significant increase with age. Redbrodisplayed earlier and more rapid intestinal development, whereas Darag demonstratedslower yet more comprehensive maturation across parameters. The zigzagvilli pattern emerged earlier in Redbro, particularly in the jejunum. The identifiedage- and breed-specific differences in small intestinal development suggest that intestinaladaptation may contribute to variations in growth performance and mayindicate potential advantages to Darag in low-input production systems. Furthermore,the significant correlations of VH, CD, ET, and MT with production indicesindicate that growth performance is influenced by a complex interaction of absorptivecapacity, intestinal health, and motility, rather than solely by villus surface area.