Possible role of available phosphorus in potentiating the use of low-protein diets for broiler chicken production

Abstract

A total of 945 male Ross 308 broiler chicks were used in a growth study to explore the interaction between dietary crude protein concentration and available phosphorus. Nine experimental treatments were constructed factorially by offering low, medium, or standard protein concentrations without or with low, standard, or high available phosphorus. Diets were based on corn, wheat, and soybean meal and all nutrients other than protein/amino acids and available phosphorus were maintained at or above breeder guidelines. Additional synthetic amino acids were used in the diets with low protein concentration in attempt to maintain digestible amino acid supply. Diets were offered to 7 replicate pens of 15 chicks per pen from day 8 to 35. Growth performance was measured during the grower (day 8–24) and finisher (day 25–35) periods. On day 35 carcass composition was determined, blood was drawn for various biochemical measurements and the tibia was excised for mechanical and compositional analyses. Birds that received the low-protein diet had lower terminal body weight and higher feed conversion ratio compared with those that received diets with adequate crude protein content. However, addition of available phosphorus to the low-protein diet resulted in significant reductions in weight-corrected feed conversion that were not evident in the diet with adequate protein content. Bone architecture was only moderately influenced by dietary treatment but birds that ingested the diets containing low and medium protein concentrations had relatively heavier abdominal fat pad weight. Blood biochemistry, especially ammonia, uric acid, and phosphorus, was influenced by both dietary protein and available phosphorus and trends suggested that both axes are involved in protein accretion and catabolism. It can be concluded that performance losses associated with feeding low protein diets to broiler chickens may be partially restored by additional available phosphorus. The implications for use of exogenous enzymes such as protease and phytase and protein nutrition per se warrants further examination.

Dietary Energy and Protein Levels During the Prelay Period on Production Performance, Egg Quality, Expression of Genes in Hypothalamus-Pituitary-Ovary Axis, and Bone Parameters in Aged Laying Hens

“…In this study, we observed increased serum P level in 16.5% CP diet. This result was consistent with the observation in broilers by Cowieson et al (2020) , who reported that serum P was decreased by low-protein diet, which is speculated to be a result of reduced dietary P level in low-protein diet. In the present study, the experimental diets had the same amount of P, and hence, the effect of dietary protein level on P metabolism needs to be investigated further.…”

Bone Measurements of Arginine Deficient Broilers Growing under Warm Temperatures

“…In the current study, lower serum K levels in birds fed the RP diet might be attributed to the lower inclusion of soybean meal in the RP compared to the SP diet, as soybean meal is a rich source of K. The analysed mineral levels in the mixed feed confirm a lower K level for RP diets compared to SP diets in the current study. Cowieson et al (2020) observed increased plasma Ca level as dietary CP level decreased (from 21.5% and 19.5% to 17.5% and 15.5% in grower and finisher phases, respectively). The present study results were in line with those previously documented in the literature.…”

“…However, there were not many reports investigating the effects of feeding reduced-protein diets on bone morphology, strength, and mineralisation in birds during heat stress. Available data have shown that reducing dietary protein levels could increase serum Ca, Na, and Zn levels but decrease tibia Mn and Cu levels in broilers raised under standard conditions (Cowieson et al, 2020). Bone quality is one of the most important indicators to evaluate the broiler's health and welfare (Brickett et al, 2007).…”

Supplemental protease with phytase and xylanase and cereal grain source affected nutrient digestibility and performance of broilers

“…Thus, further research is warranted into bird performance response to protease in diets with low, but comparatively less extreme, amino acid concentrations. Moreover, Cowieson et al (2020) stated that supplementation of synthetic amino acids or enzymes alone cannot counteract the multiple issues associated with feeding low-protein diets to broiler chickens. For example, they observed improved FCR in low-protein diets as a consequence of increasing dietary available phosphorus level.…”