by Dr Chet Wiernusz, nutritionist, Cobb World Technical Support Team, Highway 412 East, Siloam Springs, Arkansas 72761, USA. Other 100 80 Activity (%) 60 40 20 0 M 20 40 Pellets (%) Fig. 2. Pellet quality effects on behaviour. temperature and relative humidity extremes, immunological response and air quality. Offer at least 50-65g of feed per chickon the paper, a large volume that will be easily consumed in three to four days. If chick trays are being used, ensure at least one tray per 100 chicks. The trays must be evenly distributed throughout the house and only removed once the chicks have access to a flooded feed pan. Removal of the feed trays too early is often obvious when 14 day bodyweights are below standard. Water access is equallyimportant, but with a modern nipple system it is easily achieved. The first water consumed by the chick must be clean. Always implement a water line sanitation program during house cleanout and flush the lines just before placement. Regular water sanitation and water line cleaning can provide protection against microbial contamination and bio-film buildup. Once established in water lines,bio-films provide a place for detrimental bacteria and viruses to hide from disinfectants. Products containing 50% hydrogen peroxide, stabilised with silver nitrate, have proven to be outstanding for removing biofilms in water lines. The bird’s thermoneutral zone is defined as the ambient temperature with minimum heat production (Fig. 1). Since heat production originates from feed Continued on page 12 6080 100 Eating Resting
t a time when high feed prices are squeezing profit margins, it is surprising that many of the industry practices and management guidelines are still based more on opinion and trial and error than scientific evidence and documented solutions. With feed representing over 65% of the total production cost, managing broilers to increase the efficiency of converting feedto saleable meat is key to remaining profitable. Broiler feed conversion is dependent on dietary nutrient concentrations and environment. The energy required for broiler maintenance alone can be greater than 45% of metabolisable energy consumption. The growing environment has the greatest impact on broiler maintenance and involves factors such as effective temperature, immune status and lightingprograms. These factors are interactive and can be quantified to allow management decisions to enhance production efficiency. Decisions relating to feed and water, ambient temperature and bird activity and health are of great importance in influencing feed conversion. Various stress factors have the potential to impair performance, too, including ambient
Feed and water supply
Adequate feed andwater at placement and during the first week will ensure proper intake and minimal competition among the chicks. It is recommended to provide sufficient feeding space for the birds by covering at least 50% of the house with chick paper.
Fig. 1. The influence of ambient temperature and live bird weight on maintenance energy need (kcal/kg live weight).
265 200 135 702.06 Thermoneutral zone 24 1.38 Liveweight (kg) 0.071 20 0.042 28 Ambient temp. (˚C)
International Poultry Production — Volume 16 Number 7
Continued from page 11 intake, it is also the ambient temperature where feed conversion ratio (FCR) is optimum. Under low ambient temperature conditions, heat produced helps maintain body temperature. However, under high ambient temperatureconditions, the bird already has a higher than desired heat load, body temperature is elevated and any additional heat production to compensate for the stress further exacerbates the condition. This occurs as the birds must expend energy, usually as increased respiration, to return the elevated body temperature to normal. During heat stress the bird’s ability to dissipate heat is reduced, causing...