Genetic variation in physiological adaptation of local, exotic and crossbred ducks to heat stress in a tropical environment

Abstract

Biotic and abiotic environmental factors significantly contribute to the well-being and performance of farm animals.
Thermal adaptation is central to livestock survival, performance and profitable enterprise most especially in hot tropical
and sub-tropical environments characterized with high environmental temperatures. Heat tolerance of 106 adult
Muscovy (Cairina moschata) (20 males and 20 females), Mule (Anas sterilis) (14 males and 12 females) and Mallard
(Anas platyrhynchos) (20 males and 20 females) ducks was investigated through physiological indices {respiratory rate
(RR), panting rate (PR), skin temperature (ST) and rectal temperature (RT)} collected at two periods {morning (7.00 –
8.30 hours) and afternoon (12.00 – 13.30 hours)}. Variance analysis revealed significant (P<0.05) effect of genotype,
period, genotype-period and genotype-sex interactions on heat tolerant indices. The higher physiological indices of
Mallard ducks as reflected in genotype, genotype-period interaction and genotype-sex interaction effects compared to
Muscovy and Mule ducks indicated physiological stress and poor thermal tolerance. Syntheses of results in this study
indicated that Muscovy and Mule ducks were genetically superior in heat tolerance and have higher adaptive capacity
to thrive better in sub-optimal hot environment.