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Routes of yolk utilisation in the newly-hatched chick
Insights
Newly-hatched chicks utilize yolk via the yolk sac membrane, which allows bidirectional transport to the blood and intestine. Feeding accelerates yolk utilization by increasing intestinal activity.
Area of Science:
- Animal Physiology
- Developmental Biology
- Avian Nutrition
Background:
- Yolk is a critical nutrient source for newly hatched chicks.
- Understanding yolk utilization pathways is essential for avian development and nutrition.
Purpose of the Study:
- To investigate the routes of yolk utilization in chicks post-hatching.
- To determine the permeability of the yolk sac membrane in both directions.
- To examine the transport of yolk components into the intestine.
Main Methods:
- Injecting labeled compounds (oleic acid, triolein, inulin, dextran) into the yolk and circulation.
- Monitoring the movement of labeled materials between yolk, blood, and intestine up to 72 hours post-hatch.
- Assessing the impact of feeding status on yolk utilization.
Main Results:
- The yolk sac membrane demonstrated bidirectional permeability for all tested labeled materials.
- Labeled yolk components were transported into the intestine and gizzard, with the yolk stalk serving as a transient pathway.
- Yolk utilization was more efficient in fed chicks compared to fasted chicks, linked to increased intestinal activity.
Conclusions:
- The yolk sac membrane facilitates yolk transfer to both the bloodstream and the gastrointestinal tract.
- Intestinal transport of yolk is significant in early post-hatch development, influenced by feeding status.
- Yolk stalk patency decreases by 72 hours post-hatch due to lymphoid cell accumulation.
Abstract:
1. This study was conducted to study the routes by which yolk is utilised in the chick during the initial posthatch phase. 2. Transfer from yolk to blood was examined by injecting, in the form of labelled compounds, oleic acid, triolein, inulin and dextran into the yolk; movement from yolk to blood was observed up to 72 h posthatch. 3. Transport of these molecules from blood to yolk was also observed by injecting them into the circulation and determining label in yolk. The yolk sac membrane was permcable in both directions for all labelled materials tested. 4. In the newly-hatched chick, blue dextran injected into the yolk sac could be seen moving in pulses into the intestine at irregular intervals. Transport of labelled materials from the yolk sac into the intestine was observed up to 72 h after hatching, and marker was found in the proximal small intestine and gizzard. The yolk stalk provided a pathway for transport to the intestine until lymphoid cells began to accumulate, with passage becoming partially occluded at 72 h posthatch. 5. Yolk utilisation was more rapid in fed than in fasted birds suggesting that the transport of yolk through the intestine could be increased by the greater intestinal activity found in fed chicks.