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Lipid and energy metabolism in chicks affected by dwarfism (dw) and Naked-neck (Na)
Insights
Dwarf chicks (dw) exhibit reduced weight gain and increased carcass lipid accumulation due to enhanced lipogenesis and lower energy expenditure. The naked-neck (Na) gene also increases lipogenesis, with gene interactions affecting thermoregulation in cool environments.
Area of Science:
- Animal genetics
- Metabolic physiology
- Poultry science
Background:
- The sex-linked dwarf (dw) gene affects growth and metabolism in chickens.
- The autosomal naked-neck (Na) gene influences thermoregulation and energy expenditure.
Purpose of the Study:
- To investigate the metabolic effects of the sex-linked dwarf (dw) gene and the autosomal naked-neck (Na) gene in chickens.
- To examine the interaction between dw and Na genes on growth, lipid metabolism, and thermoregulation.
Main Methods:
- Sister pairs of dwarf (dw) and non-dwarf (Dw+) chicks were reared to 5 weeks of age.
- Chicks were identified using the fast feathering (k) gene marker.
- Lipid metabolism was assessed using 14C-labeled acetate incorporation and carcass analysis.
Main Results:
- Dwarf chicks showed a 27% reduction in weight gain, decreased body temperature, and increased carcass lipid content.
- Increased lipogenesis and decreased energy expenditure contributed to lipid accumulation in dwarf chicks.
- The Na gene also increased lipogenesis, and interactions between dw and Na genes affected thermoregulation under cool conditions.
Conclusions:
- The dw gene significantly impacts growth and lipid metabolism by increasing lipogenesis and reducing energy expenditure.
- The Na gene influences lipogenesis and thermoregulation, with potential interactions with the dw gene affecting metabolic flexibility.
- These findings provide insights into the genetic control of metabolism and thermoregulation in poultry.
Abstract:
In two experiments, sister pairs of chicks, one dwarf (dw) and one nondwarf (Dw+), were reared in individual cages to 5 weeks of age. Chicks carrying the sex-linked recessive dw gene were identified at hatching by the closely linked fast feathering gene (k). The dwarf chicks showed a 27% reduction in weight gain, a reduced body temperature, increased carcass content of lipid, and increased lipid 14C activity from injected 14C-labeled acetate. The augmented accumulation of carcass lipid in the dwarf chicks was shown to be a result of increased lipogenesis and decreased energy expenditure. An autosomal dominant gene for naked-neck (Na), present in half of the pairs of chicks, also caused increased lipogenesis. Naked-neck birds showed increased energy expenditure in a cool environment and perhaps a greater flexibility of body temperature regulation. An interaction between the dw and Na genes was apparent under cool environmental conditions and may have been due to a suppression by the dw gene of the Na gene's effect on thermoregulation, possibly by slowing down lipid degradation.