by ANDREW BOURNE, broiler specialist – World Technical Support, Cobb-Vantress Correct litter and ambient temperatures are vital to ensure chick activity. Pre-heating is important and begins at least 24 to 48 hours prior to placement, even during summer and in tropical countries. This will ensure the litter temperature is at least 32°C (90°F), with the air and internal structures adequately heated at placement. Failure to achieve this target will reduce activity and lower feed consumption, so the grower will lose the opportunity to quadruple day-old chick weight in the first week. A newly hatched chick cannot control its own body temperature until fully thermo-competent at 14 days old. Their core temperature ranges between 40 to 41°C (104–106°F), increasing to 41–42°C (106–108°F) by 5 days of age. A core temperature above 41°C (106°F) post hatch will lead to panting and below 39.5°C (103°F) reduced activity and low feed consumption. Remember to always measure a chick’s core temperature when it is completely dry post hatch. A yolk sac contains 1–2 grams of moisture, with two parts fat and one part protein. If early feed consumption is limited, the chick will use both fat and protein in the yolk for energy leaving inadequate protein levels for optimum growth. Always use bird behavior as an important guide to gauge comfort levels. Comfortable chicks breathe through their nostrils and will only lose 1–2g of moisture in the first 24 hours. A chick that pants can lose as much as 5–10 grams of moisture in the first 24 hours. Dry bulb temperature, air movement and relative humidity are linked. An increase in relative humidity will reduce moisture loss but can also reduce the chicks heat loss capabilities, so correct temperature & RH is vital (a lower RH% requires a higher dry bulb temperature). Furthermore, chicks are very sensitive to air movement until they are fully feathered at 25 days of age. See the following temperature guide: As illustrated in the temperature guide, chicks from smaller eggs (younger breeder flocks) require higher brooding temperatures, about 1°C more for the first fourteen days. If humidity is less than the guide, increase temperature 0.5 to 1°C (1°F). If humidity is greater than above, reduce house temperature by 0.5 to 1°C (1°F) for the 1st 14 days. Careful consideration of the five essentials driving early feed consumption and growth will ensure the grower captures the maximum potential of the least cost advantage provided by the Cobb500.