RESEARCH ▶▶▶
Effects of stocking density on the production parameters of broiler chickens
BY DR SALAH H. ESMAIL, PHD
Feed intake and conversion A reduction of feed intake in response to increasing stocking density is often reported to be the result of feed restriction. The heat stress resulting from the increased temperature in- side the litter and in between the birds with higher stocking densities, along with the increased level of ammonia, is also a factor contributing to reduced feed intake even though the feeder space per bird is kept constant. The reduced feed in- take may result in better feed conversion when stocking den- sity increases, but in many cases, feed conversion may not be affected and may even be worse.
Growth rate There is a general tendency towards reduced growth rates with higher stocking densities not only because of the re- duced feed intake under such conditions, but also because of the loss of feed energy as a result of immunological respons- es and other body adjustments. The reduced growth rate may further be attributed to the disruption in the gut micro-flora which help in digestion, absorption of nutrients, and im- provement of intestinal microarchitecture. The critical value, however, varies between the experiments. When the stocking density increased from 18.4 to 28.6 kg/m² there was no de- pression of growth rates, but when the stocking density was raised to about 32 kg/m² or more, the slaughter weight was significantly lower. In many cases, however, this problem has been alleviated by increasing ventilation rates.
Carcass quality High stocking density has negative effects on the length, width, and depth as well as the mass of the breast meat, which is reduced by about 12 grams in each bird. It also af- fects the length of tubular bones, the development and roundness of the breast, and the development of the hind extremities. These effects were confirmed in both sexes, but were more pronounced in males compared to females, indi- cating a significant effect of sex on the conformity of broiler carcasses reared under different stocking densities. The qual- ity of broiler carcasses is also diminished because of
▶ ALL ABOUT FEED | Volume 28, No. 8, 2020 35
High stocking density is one of the most important stress factors affecting production and yield in poultry farming. It causes reduced feed consumption, lowere growth rates and poor-quality carcasses. Besides, high stocking density may be associated with a surge in airborne pathogens.
deformed and broken legs. The reduced physical activity of broilers and the mechanical injuries at high stocking densi- ties are considered to be key factors contributing to this problem and the insufficient development and maturity of the skeleton in general.
Litter quality The high stocking density also affects the microbial profile of the litter, particularly in the case where the litter material is not sufficiently dry and friable. In one study, the mold count ((105) increased from 0.6 to 1.3 in the litter at stocking rates of 10 and 17 chickens/m², respectively. Inhalation of a greater amount of toxins produced in the heavily contaminated litter resulted in numerous productivity problems. it reduced the levels of lipase, amylase, trypsin, and chymotrypsin enzymes, which leads to insufficient digestion and absorption of
Heat stress and increased levels of ammonia caused by high stocking density can contribute to reduced feed intake.
PHOTOS: LEX SALVERDA
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