Estimation of true phosphorus digestibility of soybean meal is affected by Ca level in broilers.
Colwayne Morris*2, Roger Davin1 , Fenglan Yan1 , Megharaja Manangi1 , David Ledoux2 , Mercedes Vazquez1 , 1Novus International Inc, Saint Charles, MO, 2University of Missouri, Columbia, MO.
Previous regression analysis estimations of true ileal P digestibility (TIPD) in SBM using a fixed Ca:total P ratio predicted values lower than apparent ileal digestibility (AIPD) values in broilers. The objective of the current study was to estimate TIPD in SBM by regression analyses, using 2 fixed Ca levels (0.35 and 0.85%), and to estimate endogenous P losses (EPL) by regression analysis and by providing P-free diets. A total of 320 Ross 308 male broiler chicks were fed a common corn-SBM based diet from d 1 to d 19. From d 19 to 22, birds were fed 8 experimental diets that consisted of 3 graded levels (20, 40 and 60%; low, medium and high, respectively) of SBM and 2 gelatin-based P-free diets containing either 0.35% or 0.85% Ca. Each treatment was fed to 8 replicate cages with 5 birds/cage. Digesta from the posterior 2/3rd of the ileum was collected on d 22. Data were analyzed by one-way ANOVA to determine statistical differences among treatments. TIPD and endogenous P loss estimates were obtained by regressing P output against dietary P content in SBM diets. TIPD of SBM with 0.85% Ca was estimated to be 59.3%, a value 19 points lower than the TIPD estimation of SBM with 0.35% Ca (78.3%). TIPD estimate values were greater than the AIPD values obtained from the SBM diets supplemented at different Ca inclusion levels. Increasing SBM level from low to medium improved AIPD at both Ca concentrations. However, increasing SBM from 40 to 60% did not further increase AIPD. As previously reported, EPL estimates were significantly affected by the methodology employed, being 341 and 48.9 mg/kg DMI using the regression approach and P-free diets, respectively. Ca level did not affect EPL (P > 0.4) in both methodologies. In summary, TIPD values from SBM were greater than AIPD values when a fixed dietary Ca level is employed, however Ca concentration has a significant impact on both TIPD and AIPD. EPL estimates vary depending on the methodology employed.
Key Words: digestibility, endogenous losses, phosphorus, soybean meal
Evaluation of egg production and egg quality factors when supplementing with Mintrex P on post prime aged egg layers.
Gregory Archer*1, Pat Welch2 , 1Texas A&M University, College Station, TX, 2Novus International, Saint Charles, MO.
Trace minerals play a critical role in enzyme activities responsible for maintaining egg shell formation which can decrease as a hen ages. The risk of a trace mineral deficiency can lead to poor egg shell quality. Broiler breeder hens supplemented with MINTREX have previously been shown to have an improvement in shell breaking strength and an increase in the total number of eggs laid per hen. The objective of this study was to determine how supplementing post prime age laying hens with Mintrex would affect egg quality and production. Dietary treatments included: control standard layer diet (CON), control diet with Mintrex added at recommended level (M1: 20 ppm Mintrex Zn, 10 ppm Mintrex Cu, 20 ppm Mintrex Mn), control diet with Mintrex added at twice the recommended level (M2: 40 ppm Mintrex Zn, 20 ppm Mintrex Cu, 40 ppm Mintrex Mn). Each treatment consisted of 24 cages with 3 hens per cage. Hens were fed each diet starting at 50 weeks of age and continuing for 180 d. Eggshell breaking strength, Eggshell puncture strength, shell thickness, haugh unit score, feed conversion was recorded monthly. Egg production and egg weights were recorded daily. No statistical differences were observed in haugh unit, shell breaking strength, shell puncture strength, or shell thickness (P > 0.05); however, between 61 and 71 weeks of age M1 (78.8%, P = 0.003) hens had a higher percentage of hens in lay than CON hens (75.0%). The M2 hens showed trend (77.2%, P = 0.08) for higher percentage of hens in lay during that time period tan CON hens. No difference in egg weights or feed conversion was observed (P > 0.05). These results indicate that supplementation of feed with Mintrex in post prime age laying hens may not improve egg quality but does improve egg production in the late lay period.
Key Words: egg quality, egg productoin, mineral, laying hen