Effects of the genetically reduced feather coverage in naked neck and featherless broilers on their performance under hot conditions

A. Cahaner*, J.A. Ajuh, M. Siegmund-Schultze, Y. Azoulay, S. Druyan, A. Valle Zárate

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

37 Citations (Scopus)

Abstract

Under hot conditions, contemporary commercial broilers do not reach their full genetic potential for growth rate, body weight (BW), or breast meat yield because dissipation of their excessively produced internal (metabolic) heat is hindered by the feathers. Therefore, it was hypothesized that heat stress can be alleviated by using the naked-neck gene (Na) or the featherless gene (sc). The study consisted of 4 experimental genetic groups (fully feathered, heterozygous naked neck, homozygous naked neck, featherless), progeny of the same double-heterozygous parents (Na/na +/sc), and commercial broilers. Birds from all 5 groups were brooded together until d 21 when one-half of the birds from each group were moved to hot conditions (constant 35°C), and the others remained under comfortable conditions (constant 25°C). Individual BW was recorded from hatch to slaughter at d 45 and 52 at 25 and 35°C, respectively, when breast meat, rear part, heart, and spleen weights were recorded. Body temperature was recorded weekly from d 14 to 42. Feather coverage significantly affected the thermoregulatory capacity of the broilers under hot conditions. With reduced feather coverage (naked-neck), and more so without any feathers (featherless), the birds at 35°C were able to minimize the elevation in body temperature. Consequently, only the featherless birds exhibited similar growth and BW under the 2 temperature treatments. The naked-neck birds at 35°C showed only a marginal advantage over their fully feathered counterparts, indicating that 20 to 40% reduction in feather coverage provided only limited tolerance to the heat stress imposed by hot conditions. Breast meat yield of the featherless birds was much greater (3.5% of BW, approximately 25% advantage) than that of their partly feathered and fully feathered counterparts and the commercial birds under hot conditions. The high breast meat yield (at both 25 and 35°C) of the featherless broilers suggests that the saved feather-building nutrients and greater oxygen-carrying capacity contribute to their greater breast meat yield. Because of these results, further research on genetically heat-tolerant broilers should focus on the featherless phenotype.

Original languageEnglish
Pages (from-to)2517-2527
Number of pages11
JournalPoultry Science
Volume87
Issue number12
DOIs
Publication statusPublished - 1 Dec 2008
Externally publishedYes

Keywords

  • Body temperature
  • Breast meat yield
  • Featherless broiler
  • Heat stress
  • Naked-neck broiler

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