Salinity and citriculture.
Maas, E. V.
International Citrus Congress (7th : 1992 : Acireale, Italy), Acireale, Italy, International Society of Citriculture. 3: 1290-1301.
1992
บทคัดย่อ
ABSTRACT :
Genetic variation in body temperature of broilers and its response to short-term acute (43.5 deg C for 45 min) heat stress was studied. Body temperatures before (T0) and after (T45) heat exposure were recorded and the changes in body temperature (T delta ) were calculated for 5-week-old chicks from 32 broiler sire families. The T0 data were utilized to rank the families for their relative body temperature and used to conduct a one-generation divergent family selection programme for high basal body temperature (H-BT) and low basal body temperature (L-BT). A control line was established by random selection from the non-selected fowls. There was little genetic variation in the base broiler population for body temperature, and 1 generation of selection for divergence in T0 did not result in differences. There were also no differences among lines in T45. Low realized heritability estimates of 0.09 and 0.17 were obtained for T0 in the L-BT and H-BT lines respectively. Phenotypic correlations between b
ody temperature and body weight were very low for all groups. Significant negative correlations were observed between T0 and T delta after heat exposure. T0 values fluctuated during the course of each day and between days. The adjustment of the data to eliminate this variation did not result in increased h2 estimates.