Summary

This proposal initiated from industry’s enquiry to investigate sup-optimal growth performance in broiler chickens offered diets with drought-stressed sorghum. With a variable climate, drought has been a constant and inevitable feature of the Australia landscape. The current drought began in NSW in mid – 2017 and it is equivalent to a major drought event on the long term historical record (100 years) according to NSW Department of Primary Industry. Consequently, this led to reduction of grain harvest and increase of grain price by more than 50% for chicken-meat producers. Sorghum has been routinely used in poultry diets in Eastern States to substitute wheat when there is a $20/MT price difference in comparison to wheat. Due to the shortage of wheat grains and its premium price this year, sorghum has been used in broiler diets with high inclusion rates (>50%). Surprisingly, growth performance in broiler chickens offered drought-stressed sorghum was depressed and the reduction of growth did not justify the price advantages in sorghum. It is also of concern the existing Near-infrared spectroscopy (NIRs) calibrations failed to detect drought-stressed sorghums as outliers, which means other anti-nutritive factors need to be identified and included in the calibration. The present project will evaluate nutrient utilisation and growth performance in broiler chickens offered sorghum grains planted under different weather conditions. Meanwhile, sorghum grains will be collected from the industry opportunistically for wet chemistry analyses and development of NIRs calibrations from 2020-2023.
A Barley trial will also be conducted.The feeding study will compromise eight dietary treatments (Table 1). Each treatment will be replicated 6 times with 18 birds per replicate. Wheat-soybean meal diets (containing both canola meal and seeds consistent with commercial practice) will be formulated to meet birds’ nutrient requirements based on breeder recommendations.

Program

Chicken Meat

Research Organisation

The University of Sydney

Objective Summary

The primary objective of this project is to identify and quantitate the anti-nutritive factors in drought-stressed sorghum and how to recover the reduction on broiler performance when these sorghums are used in diets. The specific objectives are,
1: Measure the influence of drought on nutrient profiles in sorghum, including starch content, amino acid profiles, kafirin, minerals and phenolic compounds.
2: Evaluate the influence of sorghum varieties and growing conditions on growth performance, carcass yields and nutrient utilisations in broiler chickens
3: Determine the optimal inclusion rate of drought-stressed sorghum in wheat-based broiler diets. 
4: Determine the efficacy of protease and phytase and the feasibility of reduced crude protein (CP) diets in broiler chickens offered diets based on drought-stressed sorghum.
5. Conduct a Barley Trial comprised of 8 dietary treatments and report on: 
o Growth performance
o Feed conversion ratio 
o Digesta samples taken to determine viscosity and water content.