Research Note: Relative bioavailability of zinc in zinc hydroxychloride for chicks.

A chick assay was conducted to determine the effects of Zn source on performance and to establish a Zn relative bioavailability value (RBV) for a new source of Zn hydroxychloride. In the assay, 8-day-old chicks were fed a Zn-deficient soy protein concentrate diet supplemented with 0, 7, and 15 mg Zn/kg from feed grade ZnSO4 monohydrate for 14 d to establish a standard response curve. The same basal diet was supplemented with 3, 7, and 10 mg Zn/kg from a new Zn hydroxychloride (SAMZn). A second source of Zn hydroxychloride (IBZn) was supplemented at 10 mg Zn/kg as a direct comparison to the highest level of SAMZn. Weight gain increased (P < 0.05) with increasing Zn level, regardless of source. Weight gain of chicks fed 7 mg Zn/kg from SAMZn was not different (P > 0.05) from chicks fed 15 mg Zn/kg from ZnSO4. Weight gain was not different (P > 0.05) when comparing the 2 sources of Zn hydroxychloride supplemented at 10 mg Zn/kg. Tibia ash Zn and total tibia Zn were increased (P < 0.05) by all Zn sources and responded linearly (P < 0.05) to Zn supplementation from ZnSO4 and SAMZn. Total tibia Zn concentration was not different (P > 0.05) for chicks fed 10 mg Zn/kg from either source of Zn hydroxychloride. Multiple linear regression of total tibia Zn on supplemental Zn intake (R2 = 0.95) resulted in a RBV of 115% for SAMZn compared with ZnSO4 (set at 100%). The RBV of SAMZn was higher (P < 0.05) than ZnSO4. In conclusion, relative bioavailability of Zn (based on tibia Zn) in Zn hydroxychloride from SAMZn was higher than feed grade ZnSO4 based on multiple regression slope-ratio analysis and was similar to that of IBZn Zn hydroxychloride based on tibia Zn responses to 10 mg/kg supplemental dietary Zn.

Determination of TMEn, standardized amino acid digestibility, phosphorus digestibility, and phosphorus bioavailability in conventional and reduced phosphorus distillers dried grains with solubles.

The TMEn, amino acid (AA) digestibility, and P availability in 2 conventional corn distillers dried grains with solubles (C-DDGS1 and 2; 0.86 to 1.14% P, DM basis) and reduced phosphorus DDGS (RP-DDGS; 0.39% P) were evaluated. The TMEn of C-DDGS1 and 2 and RP-DDGS were determined in Experiment 1 using conventional adult Leghorn roosters, while standardized AA digestibility was determined in Experiment 2 using cecectomized roosters. Apparent ileal digestibility (AID) of P at different Ca levels was determined using precision-fed (crop intubation) broiler chickens in Experiments 3 and 4. The AID and total tract retention of P in C-DDGS2 were evaluated in Experiment 5 using ad libitum-fed broilers. Phosphorus bioavailability in C-DDGS2 relative to KH2PO4 based on bone ash was determined in Experiment 6. Experiments contained 4 to 5 replicates per treatment. In Experiment 1, the TMEn of C-DDGS1 and RP-DDGS was 3,428 and 2,840 kcal/kg, respectively (DM basis). In Experiment 2, there were no differences (P > 0.05) in rooster AA digestibility values between C-DDGS1 and RP-DDGS. In Experiment 3 with precision-fed chicks, AID of P in C-DDGS1 and RP-DDGS was 81 and 59%, respectively; there was no effect (P > 0.05) of increasing dietary Ca level from 0.04 to 1.0% for C-DDGS1 or reducing Ca from 1.5 to 1.0% for RP-DDGS. The AID of P in precision-fed chicks for C-DDGS2 in Experiment 4 was 48 and 80% at 1.3 and 0.3 Ca:total P ratios, respectively (P < 0.05). In Experiment 5, AID of P in C-DDGS2 at Ca:total P ratios of 1.3 and 2.5 was 63 and 42%, respectively, in precision-fed chicks. Regression of bone ash content (mg/tibia) on supplemental P intake in Experiment 6 yielded a P bioavailability of 61% relative to KH2PO4 for C-DDGS2. In conclusion, total and digestible P content in RP-DDGS was greatly reduced compared with C-DDGS, and the digestibility and bioavailability of the P in C-DDGS was affected by type of experimental assay and dietary Ca level.

Phosphorus digestibility and relative phosphorus bioavailability in two dried black soldier fly larvae meals and a defatted black soldier fly larvae meal in broiler chickens.

Two chicken assays were conducted to determine P availability, using three different approaches, for 2 black soldier fly larvae meals (BSFL 1 and 3) and one partially-defatted BSFL. Experiment 1 was conducted to determine ileal P digestibility and total tract P retention. Three experimental diets containing a BSFL as the only source of P were fed to broiler chickens from 19 to 22 days of age. Each diet contained 0.25% total dietary P. Ileal digesta and excreta were collected on day 22. Ileal digestibility of P was 87%, 75%, and 88% for BSFL 1, BSFL 3, and partially-defatted BSFL, respectively. Total tract P retention was 87%, 73%, and 85% for BSFL 1, BSFL 3, and partially-defatted BSFL, respectively. The objective of experiment 2 was to determine the relative bioavailability of P in the 3 insect meals relative to KH2PO4 using a chicken bone ash bioassay. Chickens were fed one of nine dietary treatments from 8 to 22 days of age. These diets included a P-deficient cornstarch-dextrose-SBM based diet (0.14% nonphytate P) or that diet supplemented with 0.05% or 0.10% P from KH2PO4, 7% or 14% BSFL 1, 8%, or 16% BSFL 3, and 8% or 16% partially-defatted BSFL. The slope-ratio method using multiple regression for tibia ash regressed on supplemental P intake was used to calculate the relative bioavailability of P where values for BSFL 1, BSFL 3, and partially-defatted BSFL were 54%, 51%, and 57%, respectively, relative to KH2PO4. The results of this study indicated that availability of P in BSFL based on ileal P digestibility and total tract P retention values was high, whereas relative bioavailability values for P based on tibia ash were approximately 20 to 30 percentage units lower.

Phosphorus digestibility and bioavailability in soybean meal, spray-dried plasma protein, and meat and bone meal determined using different methods.

Three experiments were conducted to determine phosphorus (P) digestibility and bioavailability using different methods. The objective of the first experiment was to determine ileal P digestibility of soybean meal (SBM), meat and bone meal (MBM), and spray-dried plasma protein (SDPP) using a precision-fed broiler chick assay. This assay involved feeding 8 g of SBM, MBM, or SDPP to broiler chicks at 21 D of age. At 6 h after feeding, ileal digesta were collected. Ileal P digestibility of SBM, MBM, and SDPP was 64, 42, and 94%, respectively. In the second experiment, ileal P digestibility and excreta P retention of SBM, SDPP, and MBM were determined using an ad libitum fed chick assay. On day 17 of age, chicks were placed on 1 of 12 dietary treatments that consisted of diets containing increasing levels of SBM, SDPP, or MBM. On day 21, ileal digesta and excreta were collected. True ileal P digestibility and true excreta P retention estimated using regression of ileal P or excreta P output on dietary P content yielded true ileal P digestibility values for SBM, SDPP, and MBM (2 diet methods for MBM) to be 83, 98, 61, and 23%, respectively. True excreta P retention values for SBM, SDPP, and MBM (2 methods) were determined to be 51, 99, 32, and 53%, respectively. The third experiment determined bioavailability of P in SBM, SDPP, and MBM relative to KH2PO4 using a chick bone ash bioassay. Dietary treatments included a P-deficient cornstarch-dextrose-SBM diet supplemented with 2 increasing levels of P from KH2PO4, SBM, SDPP, or MBM. Bioavailability of P based on tibia ash estimated using the multiple regression slope ratio method was 36, 125, and 76% for SBM, SDPP, and MBM, respectively, relative to KH2PO4. The results of this study indicated the digestibility/relative bioavailability of the P in SDPP was very high for all 3 methods, but values for SBM and MBM varied greatly among different methods.

Research Note: Phosphorus digestibility in conventional canola meal determined using different balance assays.

Three experiments were conducted to determine ileal P digestibility and excreta P retention values for canola meal (CM) using 3 different types of balance assays. The first experiment was an ad libitum-fed chick experiment which evaluated the effect of phytase on ileal P digestibility and excreta P retention values. Chicks were fed a P-deficient cornstarch-dextrose-45% CM basal diet (0.13% nonphytate P) as diet 1 or that diet plus 125 or 250 FTU/kg of phytase, respectively, from 8 to 21 D of age. The digestibility/retention of P was 38% and phytase linearly increased both ileal digestibility and excreta retention of P (P < 0.05). The second experiment was a precision-fed chick assay conducted to determine ileal digestibility of P in CM at 21 D. Mean ileal P digestibility was determined to be 47.5% in chicks fed 6 g and 40.0% in chicks fed 9 g of CM and the values were not significantly different. Experiment 3 was an ad libitum-fed chick assay to determine ileal P digestibility and excreta P retention for CM with and without increasing levels of dietary supplemental Ca. The chicks were fed P-deficient - dextrose - CM diets containing increasing levels of 13.5, 27, 40.5, or 54% CM, respectively, with Ca:nonphytate P ratio maintained at 2:1 in diets 1-4 and 6:1 in diets 5-8. Based on regression analysis of ileal digesta or excreta P output on dietary P concentration, digestibility/retention of P in CM was 30%. Ileal P digestibility (and to a lesser extent excreta P retention) at 21 D was reduced by increased Ca:P ratio. The results of this study indicated that the 3 balance assays yielded reasonably consistent values of 30-40% for P digestibility/retention and ileal P digestibility was greatly affected by Ca:P ratio.

Phosphorus retention in corn, spray dried plasma protein, soybean meal, meat and bone meal, and canola meal using a precision-fed rooster assay.

Four experiments were conducted to evaluate the precision-fed rooster assay for determining excreta phosphorus retention values for 5 feed ingredients in which roosters were precision-fed the ingredients and excreta were collected quantitatively for 48 h. The first rooster assay determined the effects of increasing P intakes on excreta P retention values for corn. This assay involved feeding either 20 g of corn or 20 g of corn supplemented with increasing amounts of KH2PO4 to provide total P intakes of 51 to 351 mg and non-phytate P intakes of 16 to 316 mg. The excreta P retention value for corn fed alone was 75% but decreased greatly when non-phytate P intakes were 76 mg or higher for the corn diets containing added KH2PO4. The second precision-fed rooster assay involved feeding increasing amounts of spray dried plasma protein (SDPP) (5 to 20 g) which provided non-phytate P intakes of 61 to 242 mg. Excretion of P increased and excreta P retention values decreased from 94 to 60% as SDPP intake increased from 5 to 20 g. Experiment 3 determined excreta P retention values for solvent extracted dehulled soybean meal (SBM) (24 g intake) and also the effect of increasing intakes of SDPP (5 to 10 g) and meat and bone meal (MBM) (1.5 to 10 g) on their excreta P retention values. The excreta P retention value for SBM was 41%. Excreta P retention values for SDPP again decreased as P intake increased. Excreta P retention values for MBM were low (27 to 35%) at all intakes. In Experiment 4, roosters were tube-fed 8, 16, or 24 g of canola meal and excreta P retention values varied from 23 to 35% among intake levels. The results of this study indicated that excreta P retention values often varied greatly among different levels of ingredient and non-phytate phosphorus intake and suggest that the precision-fed assay may be useful for determining bioavailability of P only if non-phytate P intakes are low. In addition, the assay may not be accurate for ingredients which contain high Ca levels such as MBM.

Phosphorus bioavailability in increased-protein, reduced-fiber canola meal, conventional canola meal, and soybean meal fed to crossbred chicks.

Three experiments were conducted to evaluate 3 increased-protein, reduced-fiber canola meals (CM) (CMA, CMB, and Test CM), 2 conventional CM (CCM), and 2 soybean meals (SBM). For determination of P bioavailability in CM and SBM, a P-deficient cornstarch-dextrose-SBM basal diet was fed as Diet 1. The latter basal diet was then supplemented with 0.05 and 0.10% P from KH2PO4 or 12.5 and 25% of a CM or SBM. In addition, the effect of phytase enzyme on bioavailability of the P in CMA, Test CM, and one of the CCM was determined using P-deficient 45% CM-cornstarch-dextrose diets (0.11 to 0.15% non-phytate P), with a CM as the only source of dietary P. Additional diets contained 0.05 and 0.10% added P from KH2PO4 or 125 to 500 units phytase added per kg of diet. Crossbred chicks (New Hampshire X Columbian) were fed the experimental diets from 8 to 21 d post hatch in all experiments, and bioavailability of P was estimated using the slope ratio method in which tibia ash was regressed on supplemental P intake. A linear increase in tibia ash was observed as the P level increased by the addition of KH2PO4, CMA, CMB, or SBM. Based on the mean values of tibia ash in mg/tibia and tibia ash %, the mean bioavailabilities of P in the 3 increased-protein, reduced-fiber CM, 3 CCM, and 2 SBM relative to KH2PO4 were 18, 15, and 39%, respectively. A linear increase in weight gain and tibia ash was observed with addition of KH2PO4 or phytase to the P-deficient CM diets. It was estimated that 125 or 250 units/kg microbial phytase resulted in approximately 0.05 and 0.10% P being released from CM, respectively. In conclusion, the bioavailablity of the P in the new increased-protein, reduced-fiber CM was similar to that of CCM. Furthermore, phytase substantially and similarly increased the bioavailability of P in both types of CM.

Commercially available avian and mammalian whole prey diet items targeted for consumption by managed exotic and domestic pet felines: true metabolizable energy and amino acid digestibility using the precision-fed cecectomized rooster assay.

Whole prey diets are commonly used in the zoo and home setting for captive exotic and domestic cats, respectively. Despite their increase in popularity, nutrient digestibility of such diets has been poorly studied. In this study, the precision-fed cecectomized rooster assay was used to determine the protein quality and nitrogen-corrected true ME (TMEn) of 17 whole prey samples (mice [1 to 2 , 10 to 13 , 21 to 25 , 30 to 40 , and 150 to 180 d old], rats [1 to 4, 10 to 13, 21 to 25, 32 to 42, and >60 d old], rabbits [stillborn, 30 to 45 d old, and >65 d old], chicken [1 to 3 d old], and quail [1 to 3, 21 to 40, and >60 d old]) and 2 ground poultry-based products (chicken and duck). Amino acid score (AAS) and protein digestibility corrected AAS (PDCAAS) were calculated using the nutrient profile recommendations for domestic cat food as a reference value (AAFCO, 2012). Average individual indispensable AA (IAA) and total IAA (TIAA) digestibility coefficients were variable anddepended on AA (84 to 94% TIAA, 85 to 95% Arg, 87 to 96% His, 82 to 92% Ile, 84 to 94% Leu, 85 to 93% Lys, 89 to 97% Met, 83 to 94% Phe, 80 to 95% Thr, 84 to 94% Trp, and 80 to 93% Val) and sample. For a majority of the whole prey items, AA concentrations were greater than the Association of American Feed Control Officials ( AAFCO: , 2012) domestic cat nutrient profile recommendations for growth and reproduction and adult maintenance; however, some whole prey had AA concentrations below the AAFCO (2012) recommendations: Met + Cys (1.10% DM) in ground duck (1.06% DM) and taurine (Tau; 0.20% DM) in 30-to-45- and >65-d-old rabbits (0.01 and 0.10% DM, respectively), 150-to-180-d-old mice (0.18% DM), and ground duck (0.15% DM). The TMEn (3.76 to 6.44 kcal/g DM) expressed as the percent of GE (i.e., TMEn/GE) ranged from 66 to 85%, demonstrating how variable the digestibility of these items may be and justifying more research in this area. Both Met and Tau are commonly added to commercial pet foods, so supplements are readily available to address potential deficiencies and improve protein quality. A direct comparison of the ME of whole prey items by in vivo feline and rooster experiments is needed.

Phosphorus bioavailability, true metabolizable energy, and amino acid digestibilities of high protein corn distillers dried grains and dehydrated corn germ.

There is currently much ongoing research and interest for developing new processing technologies to produce corn distillers dried grains with solubles (DDGS). The current study evaluated a high protein (HP) distillers dried grains (DDG) and a dehydrated corn germ, which are products that can be produced by a modified dry milling process. Two chick experiments were conducted to determine the P bioavailability based on tibia ash. In addition, precision-fed rooster assays were conducted to determine TME(n) and amino acid digestibility. In the first chick assay, a P-deficient cornstarch-dextrose-soybean meal basal diet containing 0.10 to 0.13% nonphytate P was supplemented with 0.0, 0.05, and 0.10% P from KH(2)PO(4) or 7 and 14% conventional DDGS, HP DDG, and corn germ. In the second experiment, the P-deficient basal was supplemented with 7 and 14% conventional DDGS and 12.5 and 25% HP DDG. New Hampshire x Columbian female chicks were fed the experimental diets from 9 to 22 d posthatch, and bioavailability of P was estimated using the slope-ratio method where tibia ash was regressed on P intake. The total P content (90% DM basis) of the conventional DDGS, HP DDG, and corn germ were 0.76, 0.33, and 1.29%, respectively. Bioavailabilities of the P in conventional DDGS, HP DDG, and corn germ relative to KH(2)PO(4) were found to be 60, 56, and 25%, respectively. The TME(n) in conventional roosters was found to be significantly reduced for HP DDG and increased for the corn germ when compared with the conventional DDGS. The protein content (90% DM basis) of the HP DDG and corn germ was 33 and 14%, respectively, and the total lysine as a % of CP was approximately 2 times greater for the corn germ than for the HP DDG. Amino acid digestibilities in cecectomized roosters were consistently higher for the corn germ than for the HP DDG, which was similar to conventional DDGS.

Evaluation of the inclusion of soybean oil and soybean processing by-products to soybean meal on nutrient composition and digestibility in swine and poultry.

This experiment was designed to evaluate the effects of selected soybean (SB) processing byproducts (gums, oil, soapstock, weeds/trash) when added back to soybean meal (SBM) during processing on the resulting nutrient composition, protein quality, nutrient digestibility by swine, and true metabolizable energy (TMEn) content and standardized AA digestibility by poultry. To measure ileal DM and nutrient digestibility, pigs were surgically fitted with a T-cannula in the distal ileum. The concentration of TMEn and the standardized AA digestibility by poultry were determined using the precision fed cecectomized rooster assay. Treatments in the swine experiment included SBM with no by-products; SBM with 1% gum; SBM with 3% gum; SBM with 0.5% soapstock; SBM with 1.5% soapstock; SBM with 2% weeds/trash; SBM with a combination of 3% gum, 1.5% soapstock, and 2% weeds/trash; SBM with 5.4% soybean oil; and roasted SB. A 10 x 10 Latin square design was utilized. The experiment was conducted at the University of Illinois, Urbana-Champaign, and at The Ohio State University, Columbus. In the swine experiment, apparent ileal DM, OM, CP, and AA digestibilities were reduced (P < 0.05) when pigs consumed the combination by-product diet compared with the diet containing no by-products. Apparent ileal digestibilities of DM, CP, and total essential, total nonessential, and total AA were lower (P < 0.05) for any diet containing by-products compared with the diet with no by-products. Apparent ileal digestibilities of DM, OM, CP, and AA were lower (P < 0.05) for the roasted SB-compared with the SB oil-containing diet. In the rooster experiment, TMEn values were greater (P < 0.05) for roasted SB compared with SBM with no by-products and increased linearly as the addition of soapstock increased. Individual, total essential, total nonessential, and total AA digestibilities were lower (P < 0.05) for roosters fed roasted SB versus SBM devoid of by-products. Gums, soapstock, and weeds/trash reduce the nutritive value of the resultant meal when they are added back during processing.

Relative bioavailability of phosphorus and true amino acid digestibility by poultry as affected by soybean extraction time and use of low-phytate soybeans.

The objectives of this study were to determine if lengthening the time that soybeans (SB) spend in the extractor during preparation of soybean meal (SBM) results in increased relative bioavailability of phosphorus without negatively impacting true amino acid digestibilities, and to compare those modified SBM with that produced from a low-phytate SB. Three SBM were prepared under uniform conditions with the exception of the length of time SB spent in the extractor [45 min (300 rpm), 60 min (225 rpm), or 90 min (150 rpm)]. A SBM prepared from low-phytate SB was obtained for comparison. Relative phosphorus bioavailability in chicks and true amino acid digestibilities by cecectomized roosters were determined. Increasing the length of time that SB spent in the extractor from 45 to 90 min resulted in lower phytate phosphorus and increased phosphorus bioavailability from 34 to 56%. However, this increase came at the expense of available lysine status, with the SBM extracted for 90 min containing less total lysine and less digestible lysine than the SBM extracted for 45 min (traditional extraction time). Phosphorus bioavailability from SBM prepared from low-phytate SB was 1.5 times higher than for SBM extracted for 45 min. Increasing the length of time that SB spend in the extractor led to an increase in bioavailable phosphorus but a decrease in bioavailable lysine, potentially negating the positive effect on phosphorus.

Hy-Line W-36 and Hy-Line W-98 laying hens respond similarly to dietary phosphorus levels.

Two experiments were conducted to determine if 2 laying hen strains, Hy-Line W-36 and Hy-Line W-98, would respond similarly to being fed corn-soybean meal diets (17% CP and 3.8% Ca) deficient in nonphytate P (NPP). In experiment 1, 3 diets with varying NPP levels (0.10, 0.14, and 0.45%) were fed to 6 replicate groups of 12 hens of each Hy-Line strain from 20 to 50 wk of age. Body weight, egg weight, egg mass, feed intake, and NPP intake were higher for W-98 hens compared with W-36 hens throughout the 30-wk period. The 0.10% NPP dietary treatment was terminated for both strains at 35 wk of age due to similar low egg production. Within each strain, there was no significant difference in egg production performance for hens fed 0.14% NPP compared with hens fed 0.45% NPP. In experiment 2,3 diets with varying levels of NPP (0.10, 0.13, and 0.45%) were fed to 5 replicate groups of 12 hens of each Hy-Line strain from 95 to 112 wk of age. The 0.10% NPP treatment rapidly and severely depressed egg production and was terminated at 99 wk of age for both strains. In addition, egg production and egg mass were depressed similarly in both strains fed 0.13% NPP. In conclusion, this research indicates that Hy-Line W-36 and Hy-Line W-98 hens responded similarly to dietary NPP deficiency, suggesting that both strains have similar NPP requirements.

Effect of supplementing selenium yeast in diets of laying hens on egg selenium content.

An 8-wk experiment was conducted using 90 Hy-Line W-98 hens (26 wk of age) to evaluate the use of organic Se from Se yeast as an Se source for laying hens. At 22 wk of age, the hens were placed on a low Se corn-soybean meal pretest diet for 4 wk. At the end of the pretest period, hens were placed on 1 of 3 experimental treatments; the low Se diet without supplementation (basal diet), basal diet with 0.3 ppm of Se added from sodium selenite, or basal diet with 0.3 ppm of Se added from Se yeast. Diets contained 0.11, 0.38, and 0.34 ppm Se for basal, basal plus sodium selenite, and basal plus Se yeast diets, respectively. The experimental diets were each fed to 10 replicate groups of 3 hens for 8 wk (26 to 34 wk of age). Selenium levels in eggs (mg/kg of whole egg) were analyzed at 0, 4, and 8 wk. Egg Se contents at 0 wk were similar among treatments. Eggs from hens fed the 2 Se-fortified diets had higher (P < 0.01) Se concentrations than did eggs from hens fed the low Se diet at 4 and 8 wk. The Se yeast diet also yielded levels of egg Se that were significantly higher (P < 0.01) than those from the sodium selenite diet at 4 and 8 wk. The Se yeast resulted in a 4.8-fold increase in egg Se concentration compared with a 2.8-fold increase for the sodium selenite diet over the unsupplemented diet at 8 wk (0.065, 0.182, and 0.311 ppm for the control, sodium selenite, and Se yeast diets, respectively). There were no differences in egg production, egg weight, feed intake, or mortality among treatments. Results of this study indicate that use of Se yeast in laying hens diets is very effective for increasing the Se content of eggs.