ENERGETICS, MORTALITY, AND BODY-MASS CHANGE OF BREEDER CHICKS SUBJECTED TO DIFFERENT POSTHATCH FEED DOSAGES

Newly hatched leghorn breeder chicks (averaging 38.5 g body mass) hous ed in shipping containers were subjected to four limited feeding regim ens for a three-day (3-d) period. The chicks were then raised for five days with adlibitum access to feed and nipple drinkers. For the 3-d t reatment, the chicks received an average of 2.0, 2.5, 3.0, or 3.5g sta rter feed (20.5% protein and 12,754 W/kg ME) and twice as much Aqua-Je l(R) (a water supplement) (AJ) placed directly on the honeycomb beddin g of the containers. Air temperature at the chick level was maintained at 29.1 +/- 0.2 degrees C. Relative humidity was 28 to 37% during the treatment and 31 to 55% during the subsequent growth period. A photop eriod of 12L:12D cycle was provided throughout the experimental period . The 3-d mortality rate (1.0 to 1.7%) and body mass loss (15.4 to 16. 8% initial value) showed no significant difference (P > 0.05) among th e treatments. Metabolic rate was also not significantly different (P > 0.05) among the treatments, although it was generally proportional to the level of nutrient supply. Lighting conditions had a major impact on the chick energetics. Specifically, moisture production (MP) averag ed 5.6 to 7.2 g/kg.h) during the light period but 3.8 to 5.1 g/(kg.h) during the dark period (P < 0.05). Total heat production (THP) average d 8.3 to 9.2 W/kg during the light period and 6.0 to 6.8 W/kg during t he dark period. The reduced metabolic rate in the darkness could be a useful avenue for conserving energy and, thus, body mass loss of fasti ng chicks during prolonged overseas shipment. The 8-d mortality (2.4 t o 3.1%) and the 5-d subsequent body mass gain (42.4 to 45.8% of the in itial value) of the chicks also showed no significant difference (P > 0.05) among the treatments. Thus a supply of up to 3.5 g feed and 7 g AJ per chick during 72-h post-hatch shipments seems insufficient to ac hieve a ''normal'', postshipment chick performance. Energetic response s during the 5-d subsequent growth period were similar for all the tre atments. Specifically THP averaged 21.3 W/kg during the light period a nd 14.9 W/kg during the dark period (P < 0.05). The corresponding MP w as 23.6 g/(kg.h) and 15.0 g/(kg.h) (P < 0.05), respectively.