The effects of protein source and amino acid (AA) and energy (Apparent Metabolisable Energy, AME) levels in the diets of male broilers from eight to 21 days of age on subsequent growth and blood and carcass traits were investigated at Mississippi State University.

In the paper published in Poultry Science, first-named author, X. Wang and colleagues explain that 14 Ross × Ross 708 male broiler chicks were randomly allocated to each of 80 floor pens arranged in a randomised complete block design.

Each diet contained:

• one of two dietary protein sources: high inclusion of distillers dried grains with solubles (DDGS) or high inclusion of meat and bone meal)
• one of two amino acid densities: moderate or 10 per cent higher, and
• one of two energy densities: 2,998 or 3,100kcal per kg.

Experimental diets were fed from eight to 21 days of age, and common diets from days 1 to 7 and days 21 to 55.

The higher energy density in high inclusion of meat and bone meal diets increased serum triglyceride and cholesterol levels on day 20.

The dietary inclusion of high inclusion of DDGS or lower levels of amino acid increased high-density lipoprotein cholesterol on day 20.

Feeding the high-amino acid diet decreased feed intake without affecting bodyweight gain, which resulted in a lower feed conversion ratio (FCR).

The high-energy diet lowered feed intake but increased bodyweight gain, which resulted in a lower FCR from eight to 21 days of age.

Feed intake, bodyweight gain, FCR from days 21 to 54 of age, and carcass weight at 42 and 55 days of age were unaffected by dietary treatment from eight to 21 days of age.

However, early dietary manipulation from eight to 21 days of age affected fat and meat yield at 42 and 55 days of age.

Moreover, a high-energy diet decreased feed cost per carcass weight gain from eight to 55 days of age.

Wang and colleagues concluded that high amino acid or energy densities during the grower phase – from day 8 to 21 of age – may improve growth during the grower feeding phase but may also affect meat yield during the later grow-out phases.

They added that high-energy diets from 8 to 21 days of age may save on feed costs for meat production.

Reference

Wang X, E.D. Peebles and W. Zhai. 2014. Effects of protein source and nutrient density in the diets of male broilers from 8 to 21 days of age on their subsequent growth, blood constituents, and carcass compositions. Poultry Science. 93(6):1463-1474. doi: 10.3382/ps.2013-03838

June 2014