Australian barley for layers: value and opportunity

Are we talking ME or MEn when we refer to the metabolizable energy?
Why do we correct to zero nitrogen retention when production birds including laying hens and broilers are in fact retaining nitrogen in their eggs and meat?

Dr Swick, I'm talking AME not AMEn in my paper. I don't know why some people correct to zero N balance. For cereals there's not much difference between AME and AMEn. Maybe 50% N correction is justified (AMEs in your 2019 Poul Sc paper) but values for cereals very similar to AME anyway. Perhaps we should be using NE values?

Doctor Walker,
Thank you for the comments on my comments. Yes perhaps NE might be the way to go but I feel more work is necessary. We have produced prediction equations for NE based on crude protein, ether extract and either AMEn or AME (Wu et al 2019: Poult Sci 98:1222-1234). For a high protein ingredients such as SBM the predicted NE value is different if one uses the equation based on AME vs AMEn. I suppose someone needs to run an experiment formulating diets using predicted NE, measured AME and AMEn for all ingredients and determine which produces the best feed cost per kg liveweight. Preferably using a range of ingredients not just corn, soybean meal and oil.
Formulating diets using predicted NE values (based on AMEn) compared to using the original AMEn values certainly changes shadow prices of ingredients but the ingredient inclusions in the formulations do not change (using Australian ingredient costs).

The efficiency of AMEn and TMEn utilization for NE in broiler diets
A Yaghobfar
Animal Science Research Institute, I.R of Iran - Karaj, P. Box: 31585-1483,
Email: yaghobfar@yahoo.com

http://dx.doi.org/10.1590/1516-635x1801047-056. Brazilian Journal of Poultry Science. ISSN 1516-635X Jan - Mar 2016 / v.18 / n.1 / 047-056

Abstract:
The experiment was conducted to evaluate the feed intake, body weight gain, total energy (kJ), protein (g) intake, energy and protein efficiency ratio (EER, PER), net energy, and metabolic body weight, on two commercial broiler chickens (Arian and Ross 308 strains).
1- Four treatments included diets formulated based on AMEn (kJ/g) Total Amino Acid (TAA) (T1), AMEn (kJ/g) Digestible Amino Acid (T2), TMEn (kJ/g) Total Amino Acid (T3), and TMEn (kJ/g) Digestible Amino Acid (DAA) (T4) for commercial broilers chickens. The findings of the study indicated that AMEn or TMEn treatments yielded improved utilization of net energy on 42 days, but did not affect efficiency of dietary AMEn and TMEn for net energy, diet energy and protein efficiency ratio (EER, PER) in broilers. Findings indicated that NE is a better predictor of poultry feeds than AMEn or TMEn.
2- This is attributed to the fact that AMEn had significant effect on NE and efficiency of AMEn or TMEn and HI (Heat Increment) for NE value. Finally, NE is the final objective in energy evaluation of feed and feedstuffs for poultry nutrition.
Keywords: AMEn, TMEn, NE, EER, PER

In ruminant nutrition there are two values for the NE of the ingredients. One for maintenance (NEm) and the second one for body weight gain (NEg). The reason behind this is that the metabolism of the animal is more efficient at maintenance level than for production. Should it be the same for poultry?