Energetics, Mortality, and Body Mass Change of Breeder Chicks Subjected to Different Post-hatch Feed Dosages
Newly hatched leghorn breeder chicks (averaging 38.5 g body mass) housed in shipping containers were subjected to four limited feeding regimens 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 treatment, the chicks received an average of 2.0, 2.5, 3.0, or 3.5 g starter feed (20.5% protein and 12,754 kJ/kg ME) and twice as much Aqua-Jel® (a water supplement) (AJ) placed directly on the honeycomb bedding of the containers. Air temperature at the chick level was maintained at 29.1 ± 0.2°C. Relative humidity was 28 to 37% during the treatment and 31 to 55% during the subsequent growth period. A photoperiod 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 the 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) averaged 5.6 to 7.2 g/(kgÿh) during the light period, but 3.8 to 5.1 g/(kgÿh) during the dark period (P < 0.05). Total heat production (THP) averaged 8.3 to 9.2 W/kg during the light period and 6.0 to 6.8 W/kg during the dark period. The reduced metabolic rate in the darkness could be a useful avenue for conserving energy and, thus, body mass loss of fasting chicks during prolonged overseas shipment.
The 8-d mortality (2.4 to 3.1%) and the 5-d subsequent body mass gain (42.4 to 45.8% of the initial 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 achieve a “normal”, postshipment chick performance. Energetic responses during the 5-d subsequent growth period were similar for all the treatments. Specifically, THP averaged 21.3 W/kg during the light period and 14.9 W/kg during the dark period (P < 0.05). The corresponding MP was 23.6 g/(kgÿh) and 15.0 g/(kgÿh) (P < 0.05), respectively.
Journal Paper No. J-17221 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 3311. Funding for this study was provided in part by the U.S. Poultry and Egg Association. The experimental chicks were provided by Hy-Line International, Dallas Center, Iowa. Mention of company or product names is for presentation clarity and does not imply endorsement by the authors or Iowa State University nor exclusion of any other products that may also be suitable for the application.