Short- and Long-Term Effects of Feed Form on Fast- and Slow-Growing Broilers

Three experiments were conduced to quantify the potential negative effect of fine particles (<0.5 mm diameter) in the feed on fast- and slow-growing broiler growth performance. In the first experiment, chickens were fed mash or pellets of 2.5 and 4 mm diameter between 15 and 35 d of age. During this period, fast-growing broiler fed pelleted feed had a 19% higher final BW, a 12% higher feed intake, and a 12% lower (improved) feed conversion ratio than those fed mash. Feed form had no significant effect on feed intake, BW gain, or final BW of slow-growing chickens. Feed conversion ratio, however, was 6% lower with pellet than mash. In the second and the third experiments, fast and slow-growing chickens weighed 1.2 kg at the beginning of the experiment. In the second experiment, the effects of a transition from pelleted feed to mash or a mixture between the 2 feed forms on the short-term feed intake and growth was investigated. After the transition from pellet to mash or the mixture, both fast- and slow-growing chickens adapted their feed intake in less than 10 min. The mixture between mash and pellets led to a 25% higher feed intake and an 18% lower feed conversion ratio for fast-growing chickens. There was no significant difference between mash and the mixture on slow-growing feed intake, but feed conversion ratio was 9% lower. In the third experiment, the effect of fine particles concentration in the feed on short-term growth response was measured. Increase in the concentration of fine particles in the feed linearly reduced feed intake and BW gain of both fast- and slow-growing chickens. However, the slope was 5 times greater for fast-growing chickens than for slow-growing chickens. These 3 experiments showed that fast-growing chickens are more sensitive to feed form than slow-growing chickens. Therefore, physical form of the feed can be a major limiting factor of performance.