WHEAT VARIETIES AND THE ENERGY RETENTION OF BROILER CHICKENS.

Collier, Justin (1997). WHEAT VARIETIES AND THE ENERGY RETENTION OF BROILER CHICKENS. BPhil thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000f602

Abstract

There are differences in the productive performance of growing chickens fed different wheat samples, but these are not correlated with the determined metabolisable energies of the wheat samples. It is possible that metabolisable energy does not adequately describe the net energy of different wheat samples. The objectives of this experiment were to determine whether there are differences in the energy retention of broiler chickens fed 6 different wheat varieties grown in three field blocks and to assess whether these differences are correlated to differences in productive performance.

A crop growth trial at Harper Adams College produced samples of 6 different UK wheat varieties (Dean, Brigadier, Beaver, Rialto, Riband and Haven) each from three different positional blocks in the 1994 harvest. Each of the 18 wheat samples was included at 650 g/kg in a pelleted broiler food that had a calculated composition of 225 g/kg crude protein and 12.5 MJ/kg of metabolisable energy. Each diet was fed to 4 cages of broiler chickens from 7 to 21 days of age. Each cage had a floor area of 0.1 m2 and contained two birds. Metabolisable energy was determined by collecting all excreta produced during the 4 days of the feeding period and energy retention was determined by gross energy analysis of carcases.

The 18 wheat samples had similar chemical compositions with ranges of 867 to 876 g dry matter/kg, 114 to 160 g crude protein/kg dry matter, 18.3 to 19.1 MJ of gross energy/kg dry matter and specific weights of 75.9 to 78.7 kg/hl. There were no differences (P>0.05) in any of the measured variables of broiler growth or energy availability between the wheat samples grown in the three different field blocks. There were no (P>0.05) differences in AMEn between the 6 varieties, yet differences in energy retention (P<0.01) were significantly (P<0.01) correlated to the differences in food conversion ratio (P<0.05) and weight gain (P<0.05).

Although some wheat samples do vary in their ME, there are few differences in ME between Autumn sown wheat varieties produced in the UK. This experiment also showed no difference in ME between the wheat samples but that wheat variety affected the energy retention of the broilers per MJ of ME intake. The experiment indicates that there were differences in the net energy of 6 UK wheat varieties that were correlated to differences in the productive performance of broilers, but these nutritional differences were not detected by metabolisable energy determinations, digesta viscosity or determined chemical analysis of the wheat samples.