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33rd Annual Australian Poultry Science Symposium
The following technical article is related to the event::
33rd Annual Australian Poultry Science Symposium

Endogenous Amino Acid Flows are Influenced by Age of Broiler Chickens

Published on: 12/16/2021
Author/s : M.BARUA 1, M.R. ABDOLLAHI 1, F. ZAEFARIAN 1, T.J. WESTER 1, G. CHANNARAYAPATNA 2 and V. RAVINDRAN 1 / 1 Monogastric Research Centre, School of Agriculture and Environment, Massey University, Palmerston North, 4442, New Zealand; 2 Evonik (SEA) Pte Ltd, 3 International Business Park, # 07-18 Nordic European Centre, Singapore.
During the process of digestion and absorption of ingested feed in poultry, significant losses of endogenous amino acids (EAA) occur from various digestive secretions, mucoproteins and the epithelial cells lining the gastrointestinal tract (GIT). Several factors such as the development of GIT and changes in dry matter intake (DMI) with advancing age, type of bird, method of euthanasia and ileal digesta collection may influence EAA loss. Correction for these inevitable losses is necessary to standardise amino acid (AA) digestibility values. The present study was carried out to measure the basal EAA loss in male broilers (Ross 308) at different ages (d 7, 14, 21, 28, 35 and 42), using a nitrogen-free diet (NFD). The assumption is that, since no protein is fed, all nitrogen and AA in the ileal digesta are of endogenous origin and represent the basal losses. The NFD was composed of maize starch (842 g/kg), fibre source (cellulose; 50 g/kg), soybean oil (50 g/kg) and mineral and vitamin premix (53 g/kg). Titanium dioxide (5 g/kg) was also added to the NFD as an indigestible marker. The NFD diet was fed to six replicate cages housing 14 (d 7), 12 (d 14), 10 (d 21), 8 (d 28), 8 (d 35), and 6 (d 42) birds per cage for four days prior to digesta collection. Following euthanisation by intravenous injection of sodium pentobarbitone, the digesta was collected by gentle flushing with distilled water from the lower half of the ileum. The basal EAA flow was calculated as grams per kilogram of DMI (g/kg DMI). Data were analysed by using general linear models procedure of SAS (SAS Institute, Inc., Cary, NC) with cage means as the experimental unit. Orthogonal polynomial contrasts (linear and quadratic) were used to compare the treatment means. The flow of ileal endogenous N and all AA, on a DMI basis, decreased quadratically (P < 0.05 to 0.001) as birds grew older. The values of ileal endogenous loss of N and total endogenous loss of all AA (TAA), when expressed per kg of DMI, were higher (P < 0.01) at d 7 compared to other ages. The values for ileal endogenous N and total EAA losses at d 7 were 3.60 and 12.9 g/kg DMI, respectively. In agreement with the present findings, Adedokun et al. (2007) recorded approximately two times higher total EAA loss in broilers at d 5 compared to d 15 and 21. However, the endogenous flow values for N and TAA were similar at d 14, 21, 28 and 35. The lowest endogenous loss for TAA (4.48 g/kg DMI) was determined at 42 d. When an NFD is fed, the source of EAA is largely mucoproteins (Lemme et al., 2004). Decreased mucin secretion, increased endogenous protein digestion and absorption, and increased DMI with age may account for the lower EAA secretion in older birds (Ravindran and Bryden, 1999). Current data suggest that specific age-related values for EAA loss should be used to standardise AA digestibility coefficients in broilers.
Presented at the 30th Annual Australian Poultry Science Symposium 2020. For information on the next edition, click here.

Bibliographic references

Author/s :
M. Reza Abdollahi is currently working as a Postdoctoral Research Fellow in Poultry Nutrition in Institute of Veterinary, Animal and Biomedical Sciences (IVABS), Massey University. Based on his doctoral research, Dr. Abdollahi has been awarded three prestigious awards. First, the award for best postgraduate oral presentation at the 2009 Australian Poultry Science Symposium, held in Sydney, Second, the 2010 Alltech (USA) Young Scientist Award at the Postgraduate level, and third, the award for Excellent Scientific Oral Presentation at the 15th AAAP Animal Science Congress, held in Bangkok, 2012
Ravi Ravindran graduated with a honours degree in Agricultural Science from University of Sri Lanka and subsequently Master of Science and PhD degrees in Animal Nutrition from Virginia Tech University.Prof. Ravindran is an acknowledged world leader in the areas of measurement of amino acid availability in poultry and feed enzymes, particularly microbial phytases. His work has addressed various aspects of feed evaluation, gut flora management, early nutrition and, digestion and metabolism of amino acids and minerals in poultry.
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