Dietary potassium and available phosphorous on broiler growth performance, carcass characteristics, and wooden breast

Abstract

Broiler dietary potassium (K) and available phosphorous (AvP) have decreased in recent years but both ions are intimately involved in the elimination of hydrogen ions that are produced during rapid growth. It was hypothesized that the decrease of these dietary electrolytes was related to the development of myopathies, and thus increased dietary K and/or AvP would reduce the occurrence of breast myopathies. A total of 320 Ross male broiler chicks were placed into 16 pens and fed 2 diet series containing either decreasing AvP levels of 0.45, 0.40, and 0.35% in the starter, grower, and finisher diets, respectively (Decline), or a fixed AvP of 0.45% in all dietary phases (Fixed). To complete a 2 × 2 design either normal basal dietary K (K-) (0.86, 0.77, 0.68%) or added dietary K (K+) (1.01, 0.93, 0.88%) were also applied to starter, grower, and finisher diets, respectively. Blood physiology was measured at 29 and 42 d. Carcass data, wooden breast and white striping scores were measured at 35 and 43d. The K+ diets improved feed conversion ratio at 35 d (1.52vs 1.57 g: g), reduced body weight at 42 d (3524vs 3584g), reduced hemoglobin (6.83vs 7.58g/dL), and packed cell volume (20.1vs 22.3%) at 29 d, reduced ionized blood calcium (1.42vs 1.47mmol/L) at 42 d, and reduced partial pressure of blood CO2 (49.1vs 54.7mm/Hg) at 42 d relative to broilers fed basal K- diets (P < 0.05). Fixed AvP diets improved feed conversion ratio at 28 and 42 d, increased percentage breast meat (28.85vs 27.58%) and carcass water pickup (2.72vs 1.42%) at 35 d, and reduced wooden breast (2.88vs 3.69) at 43 d (P < 0.05).