Determination of the standardized ileal digestible calcium requirement of male Arbor Acres Plus broilers from hatch to day 10 post-hatch

Abstract

Arbor Acres Plus male broilers (n = 1,152) were obtained at hatch and allocated to 1 of 6 diets from hatch to d 10 post-hatch. There were 16 replicate cages per diet and 12 birds per cage. Five of the diets were formulated to contain graded concentrations of standardized ileal digestible ( SID ) Ca at 0.60, 0.50, 0.40, 0.30, or 0.20%. A sixth reference diet was formulated using total Ca coefficients for each ingredient and contained 0.96% total Ca. Available P ( avP ) was maintained at 0.48% in all 6 diets. Data were subjected to an analysis of variance and the model included diet and block. Means were separated using contrasts to determine linear or quadratic effects of SID Ca and using the Dunnett's test to compare the reference diet to all SID Ca diets. There was no effect of graded levels of SID Ca on intake or gain. Birds fed diets containing 0.60, 0.50, 0.30, or 0.20% SID Ca ate ( P < 0.05) or gained ( P < 0.05) more compared with birds fed the reference diet. Mortality corrected FCR improved (linear, P < 0.05) as the SID Ca concentration in the diet increased from 0.20 to 0.60%. Tibia ash percent was greatest in birds fed 0.50% SID Ca and lowest in birds fed 0.20% SID Ca (quadratic, P < 0.05). Tibia ash percent was lower ( P < 0.05) in birds fed diets formulated to contain 0.20% SID Ca compared with birds fed the reference diet. No other differences in tibia ash were reported. Apparent ileal digestibility (AID) or retention of P was greater ( P < 0.05) in birds fed diets formulated using SID Ca compared with birds fed the reference diet. The AID of P increased (linear, P < 0.05) as the SID Ca content in the diet decreased from 0.60 to 0.20%. The AID or retention of Ca was similar in birds fed 0.60 or 0.50% SID Ca and increased as SID Ca decreased to 0.20% (quadratic, P < 0.05). Regression equations developed using bone ash and apparent P retention estimate the SID Ca requirement of Arbor Acres Plus broilers from hatch to d 10 post-hatch was 0.53 and 0.49%, respectively. This corresponds to a SID Ca to available P ratio of 1.1 to 1.02.

Determination of the standardized ileal digestible calcium requirement of male Arbor Acres Plus broilers from day 11 to 24 post-hatch

“…From hatch to d 10 post-hatch, birds fed the diet formulated using SID Ca gained more compared with birds fed diets formulated using total Ca and this agrees with a previous study evaluating the SID Ca requirement of broilers from hatch to d 10 ( Walk et al, 2021b ). During the grower phase (d 11 to 24) there was no effect of diet or graded concentrations of SID Ca on FI or BWG.…”

“…During the grower phase (d 11 to 24) there was no effect of diet or graded concentrations of SID Ca on FI or BWG. Similar results were also reported in broilers fed graded concentrations of SID Ca from hatch to d 10 ( Walk et al, 2021b ). However, David et al (2021) reported significant decreases in broiler BWG as SID Ca content in the diet increased from 0.33 to 0.55% when broilers were fed diets formulated to contain 0.34% non-phytate P. The negative impact of increasing SID Ca was mitigated as the non-phytate P content of the diet increased from 0.34 to 0.64% ( David et al, 2021 ).…”

“…Tibia ash percent responded quadratically to graded levels of SID Ca and was greatest in birds fed 0.56 to 0.36% SID Ca and significantly lower in birds fed 0.26 or 0.16% SID Ca compared with birds fed the reference diet. Walk et al (2021b) reported significant effects of graded levels of dietary SID Ca on tibia ash percent in the absence of any impact on growth performance in broilers from hatch to d 10. These results further confirm the Ca and P requirement for skeletal development is much greater than those required for growth and this agrees with previous studies in broilers ( David et al, 2021 ; Walk et al, 2021b ) or pigs ( Gonzalez-Vega et al, 2016 ).…”

“… Walk et al (2021b) reported significant effects of graded levels of dietary SID Ca on tibia ash percent in the absence of any impact on growth performance in broilers from hatch to d 10. These results further confirm the Ca and P requirement for skeletal development is much greater than those required for growth and this agrees with previous studies in broilers ( David et al, 2021 ; Walk et al, 2021b ) or pigs ( Gonzalez-Vega et al, 2016 ). Due to the quadratic relationship between dietary SID Ca and tibia ash percent, the SID Ca requirement to maximize bone ash was estimated between 0.394 and 0.515% depending on the prediction model employed.…”

“… Walk et al (2021a) presented the mean, minimum and maximum apparent or standardized ileal digestible ( SID ) Ca coefficients for a few commonly used feed ingredients and found no significant difference in the Ca digestibility coefficients if apparent or standardized values were employed ( Walk et al, 2021a ). Therefore, the use of the mean SID Ca coefficients or previously published coefficients were used to estimate the digestible Ca requirements for broilers from hatch to d 10 ( David et al, 2021 ; Walk et al, 2021b ). Formulating diets to meet a digestible Ca requirement may help to mitigate excess total dietary Ca in the final diet in 2 ways: 1) improve our knowledge and understanding of the Ca contribution from the different feed ingredients and feed additives and 2) mitigate the over- or under-supply Ca from ingredients because we have assigned a Ca digestibility coefficient to that specific ingredient in our feed formulation system.…”