The role of the crop in poultry production

Abstract

The importance of the crop is often underestimated in poultry production. In addition to storing ingested feed, it also can impact nutrient digestion by digesta softening and the initial activity of feed (endogenous and exogenous) and microbial enzymes. The crop represents the first major defence against poultry pathogens and zoonotic organisms with well established adaptive and innate immune function, and a lactobacilli dominated microbiota capable of reducing the passage of these organisms further along the digestive tract. However, the potential to improve bird productivity and health, as well as affect meat and egg safety, are influenced by the nature of the diet, and in particular feed entry and extended presence in the crop. This is required to promote lactobacilli fermentation, the production of lactic acid and other volatile fatty acids, and the lowering of crop pH. Management practices such as meal feeding and the use of lighting programs with extended dark periods encourage crop utilisation. Further, the use of feed additives such as prebiotics and probiotics may enhance crop function, which in turn contributes to well-being of the entire digestive tract. A healthy and functional crop, along with other segments of digestive tract, has increased importance in an era of reduced antibiotic use in poultry feeds.

The length of the feed restriction period affects eating behavior, growth performance, and the development of the proximal part of the gastrointestinal tract of young broilers

“…Crop digesta pH depends, at least in part, on the fermentation capability of the microbial population and the concomitant increase in organic fatty acid production in this organ. The fermentation activity of the crop is expected to increase with age ( Classen et al., 2016 ), and consequently, the pH of the crop might decrease with age, which is in agreement with the results reported herein.…”

“…Longer retention times of the digesta in the crop are associated with more nutrients available for fermentation and with an increase in the activity of the microbiota present in this organ ( Svihus et al., 2013 , Classen et al., 2016 ). Consequently, a reduction in crop pH was expected as the length of the fasting period increased.…”

“…As per European Union guidelines, a minimum of 6-h darkness per day is mandatory after 7 D of age ( Council Directive 2007/43/EC ). It is assumed that FI is reduced during the dark period ( Buyse et al., 1993 ), and therefore, intermittent light programs are associated with FR practices ( Classen et al., 2016 ). Fasting procedures based on manipulating the light program are easier to implement and manage than physical restriction of the access to feed.…”

Phytate Degradation, Transcellular Mineral Transporters, and Mineral Utilization by Two Strains of Laying Hens as Affected by Dietary Phosphorus and Calcium

“…However, phytase activity in the crop content was identical to that of the small intestine of laying hens aged 47 weeks when measured per gram of digesta [ 26 , 27 ]. Possibly, the relatively short retention time in the crop when feed is offered for ad libitum consumption [ 28 , 29 ] leads to an insignificant degradation of InsP 6 .…”

Synthetic and Crystalline Amino Acids: Alternatives to Soybean Meal in Chicken-Meat Production

“…This possibility was investigated, where it was found that providing birds with daily physical access to feed for intervals of 12, 16, and 20 h did not influence lysine HCl utilisation in broiler chickens [134]. The basis for this appears to lie in the capacity of birds to 'crop-up' via anticipatory feeding and retention of digesta in the crop [135]. Instructively, reducing feeding frequencies from 20 h to 16 and 12 h influenced the relative crop weights (p < 0.001), with increases from 3.8 g/kg to 5.5 and 7.7 g/kg [134].…”