At Day 17, yolk palmitic acid concentration was lower
at 53% RH compared with that at 43 or 63% RH. Also,
percentage YSW was lower at 53% RH compared with
43 and 63% RH, and percentage YL was lower at 53%
RH compared with 63% RH in eggs from 26-wk-old hens.
In related work by Peebles et al. (2001), relative wet embryo
weight was higher in eggs incubated at 53% RH
compared with 43% RH between 17 and 19 d of incubation.
Peebles et al. (1999) previously noted that as the
embryo absorbed YL during the second week of incubation,
an associated decrease in yolk palmitic acid occurred.
It was suggested that the utilization of yolk palmitic
acid with embryonic growth during that time may
be necessary for increased embryo DM synthesis. Yolk
palmitic acid concentration was also found by Peebles
et al. (1999) to be positively correlated with percentage
embryo moisture content at 9 and 12 d of incubation;
however, Peebles et al. (2001) reported no influence of
RH on embryo moisture content. Taken together, these
data suggest that embryonic growth rate, in terms of
DM accumulation, was maximized at a 53% RH and was
concomitant with increased total yolk and yolk palmitic
acid utilization in eggs from young broiler breeders.