Readers' Rating:

Rate this article

Growing very heavy broilers requires a re-evaluation of nutritional management, because it is neither essential nor desirable to induce maximum early growth rate. The emphasis is on maximizing monetary return, not on maximizing growth rate. Since the major problems likely to be encountered with these birds are metabolic disorders and carcass fatness, the feeding program must be designed to ensure maximum liveability and product quality. Heavy broilers should not be considered simply conventional birds grown to older ages. Nutrition and general management strategies must start at day-of-age, rather than considering the 42-70d period as an "add-on" to a normal grow-out operation.

Acute Death Syndrome (ADS) and skeletal abnormalities are currently of major concern, although ascites will play a more important role in economics of producing heavy birds. To some extent, these problems can be controlled by lighting programs, although our preliminary studies suggest that even with such step-down programs, 8 to 10% mortality occurs in males from 42-80d of age. This "expensive" late mortality must be resolved by nutritional and management programs that allow for slower initial controlled growth, followed by steady increase in body weight to market weight. Five percent late mortality is as economically unacceptable as 10% mortality in 0-42d birds.

The main reason for conducting our study was to identify feeding strategies that reduce mortality in heavy broilers. Broilers were grown to 70d on mash vs pelleted diets, either conventional high-nutrient dense "broiler-type" or low-energy, low-protein diets aimed at slowing down growth. Each treatment was represented by four replicate pens of 30 broilers. At 70d, eight birds per pen were processed, carcass weight ascertained, and then abdominal fat and breast meat removed and weighed.

Growth characteristics and mortality are shown in Table 1. The most striking result is reduction in mortality of birds fed mash vs pellets, regardless of diet type. Feeding mash also resulted in reduced body weight. Body weight was also reduced when the single-stage low-nutrient dense mash diet was given throughout, compared with the conventional three-stage diet series. Mash-fed birds were about one week behind in growth, although mortality was only 2-6% compared to a mean of 15% for the birds fed pellets.

TABLE 1. Body weight, body weight gain and mortality of broilers fed mash or pelleted diets to 70 d
Body weight (g) Body weight gain (g) Mortality
Treatment Texture Die

²Low nutrient density.

³Adjusted for mortality.

⁴Unadjusted for mortality.

Carcass characteristics are shown in Table 3. Feeding mash resulted in a significant reduction of carcass weight, and yield of breast meat and abdominal fat. For the lower energy diets, using mash vs pellets also resulted in a significant decline in breast yield as a percentage of carcass weight.

Although mash-fed birds were about one week behind in growth, the feed cost was less, mainly due to this high livability.

The main undesirable effect of mash feeding, however, is loss of up to 1% breast meat yield which is of great commercial significance.

Readers' Rating:

Rate this article