Influence of different levels of calcium, non-phytate phosphorus and phytase on apparent metabolizable energy, nutrient utilization, plasma mineral concentration and digestive enzyme activities of broiler chickens

Digestible calcium equivalency of phytase and nutrient utilization of broiler chickens fed graded levels of limestone or phytase during the starter phase

The current study aimed to quantify the digestible calcium (Ca) equivalency of a new phytase (HiPhorius) in broiler chickens. A total of 1,152 male Cobb 500 broiler chickens were used in an experiment in which 8 diets consisting of graded levels of Ca supplied with limestone or graded levels of the phytase were fed. The 8 dietary treatments were based on a corn-soybean meal diet containing 5.1 g/kg of Ca and 5.1 g/kg of phosphorus (P) as negative control (NC); the NC + 1.3, 2.6, or 3.9 g/kg of Ca from limestone; and the NC + 500, 1,000, 2,000, or 4,000 FYT/kg of phytase. Birds were fed the experimental diets for 3 d (from d 7 to 10) or 14 d (from d 7 to 21) to determine apparent ileal digestibility (AID) and apparent total tract retention (ATTR) of dry matter (DM), CP, Ca, and P. In the 10-day-old birds, increasing the levels of Ca decreased the AID of P and Ca (linear, P < 0.05). Increasing the levels of phytase quadratically improved (P < 0.05) the AID of Ca and P. The AID of DM and CP in the younger birds quadratically increased (P < 0.05) as the levels of Ca increased. There were linear and quadratic effects (P < 0.05) of increasing phytase level for the AID of DM and a linear effect (P < 0.05) for the AID of CP. In the 21-day-old birds, increasing Ca levels resulted in a linear decrease (P < 0.05) in the AID of CP and P, and a quadratic decrease (P < 0.05) in the ATTR of CP. Increasing phytase levels linearly and quadratically (P < 0.05) improved the AID and ATTR of CP, P, and the ATTR of Ca. The analyzed phytase activity in the diets supplemented with phytase ranged from 1,520 to 7,661 FYT/kg. The digestible Ca equivalence for dietary phytase at 1,520 to 7,661 FYT/kg ranged from 1.55 to 2.02 g/kg in the 10-day-old birds fed for 3 d and from 0.52 to 0.64 g/kg in 21-day-old birds fed for 14 d. The results showed the reduction in Ca level that could be accommodated by phytase supplementation, which is markedly different between the younger and older birds. Feeding duration influenced the impact of phytase supplementation on Ca and P digestibility, with better efficacy of phytase observed in the 10-day-old birds fed for 3 d. Also, the results showed the extra-phosphoric effects of phytase on the utilization of other essential nutrients such as protein and Ca.

Calcium Nutrition of Broilers: Current Perspectives and Challenges

Calcium (Ca) plays an essential role in poultry nutrition as 99% of Ca is located in birds' skeletal system. However, oversupply of Ca rather than deficiency of Ca is the current concern in commercial broiler diets. Calcium is an inexpensive dietary nutrient due to the cheap and abundant availability of limestone, the major Ca source; therefore, little attention was given to the oversupply of Ca in the past. The recent shift in the use of digestible P in broiler feed formulations has necessitated a closer look at digestible Ca, as Ca and P are interrelated in their absorption and postabsorptive utilisation. In this context, data on ileal digestibility of Ca and P in ingredients has been determined. Preliminary data on the digestible Ca and digestible P requirements for the different growth stages of broilers have also recently become available. The present review focusses on these recent advances in Ca nutrition. In addition, aspects of homeostatic control mechanisms, different Ca sources and factors influencing Ca digestibility in poultry are covered.

Effects of dietary calcium and phosphorus restrictions on growth performance, intestinal morphology, nutrient retention, and tibia characteristics in broiler chickens

1. This study evaluated the effects of dietary calcium (Ca)‎ and available phosphorus (aP) restrictions on growth performance, intestinal morphology, nutrient apparent total tract retention (ATTR), and tibia characteristics.2. A total of 1296, one-day-old male Ross-308 broilers were reared for 42 d. During the ‎starter phase (1-10 d), all birds were fed a nutrient-adequate diet (C). Diets fed during the grower phase (11-24 d) included: 1. C; 2. 15% of the Ca and aP in C; 3. 30% of the Ca and aP in C. At the beginning of the finisher phase (25 d), chickens fed the C diet were divided into two subgroups including C, and C+ phytase (500 FTU/kg). Restricted treatments were divided into eight subgroups as 1. C; 2. 10% of the Ca and aP in C; 3. 20% of the Ca and aP in C; 4. 30% of the Ca and aP in C; 5. C+ phytase; 6. 10% of the Ca and aP in C+ phytase; 7. 20% of the Ca and aP in C+ phytase and 8. 30% of the Ca and aP in C+ phytase.3. On d 24 and 42, ATTR of Ca and phytate phosphorus (pP) were linearly increased by decreasing Ca and aP levels (P<0.05). Birds receiving phytase showed higher nutrient ATTR ‎compared to those fed non-phytase supplemented diets (P<0.05). Tibia Ca and P were linearly decreased at 24 d (P<0.05) and tibial ash was linearly decreased (P<0.05) at 42 d by decreasing levels of Ca and aP in finisher diets (without phytase)‎. By decreasing the levels of Ca and aP in the finisher diets (with phytase) with a 30% reduction of Ca and aP in the grower phase, tibia ash linearly decreased (P <0.05). Using 500 FTU/kg phytase improved tibia traits compared to non-phytase supplemented treatments (P<0.05).4. In general, decreasing dietary Ca and aP (up to 30%) during grower and finisher phases increased ATTR of minerals and decreased Ca, P and breaking strength (BS) of tibia without any negative effect on growth performance or intestinal morphology. Reduced dietary Ca and aP decreased tibial ash content, although 500 FTU/kg phytase improved ATTR of minerals and tibia attributes.

Phytase Supplementation Effects on Amino Acid Digestibility in Broiler Chickens are Influenced by Dietary Calcium Concentrations but not by Acid-Binding Capacity

BACKGROUND

Responses to dietary calcium (Ca) and supplemented phytase on prececal amino acid digestibility (pcAAD) in broiler chickens vary among studies. The variation may arise from the dietary acid-binding capacity (ABC) that influences the activity of enzymes in the digestive tract and from microbial activity.

OBJECTIVE

This study aimed to investigate whether the ABC influences phytase effects on pcAAD and whether microbial activity contributes to this.

METHODS

Male Ross 308 broiler chickens were provided 1 of 12 diets in 72 pens (15/pen) from day 16 of age until the end of the experiment on days 21 or 22. In a 3 × 2 × 2-factorial arrangement, the ABC was varied by replacing calcium carbonate (CaCO3) with Ca-formate or by adding formic acid to CaCO3-containing diets, and contained 5.6 or 8.2 g Ca/kg and 0 or 1500 phytase units/kg. The ileum content was collected for pcAAD measurement and microbial community composition was used to investigate whether changes in pcAAD are related to the microbiota.

RESULTS

Three-factor ANOVA showed that reducing the ABC increased pcAAD (average 1.1 percentage points) and no significant interaction of the ABC with Ca concentration and phytase supplementation including 3-way interactions. Without phytase, increasing dietary Ca concentration decreased pcAAD (average 3.1 percentage points). Phytase supplementation increased pcAAD (average 2.1 and 5.0 percentage points at low and high Ca concentrations, respectively), to reach the same level for both Ca concentrations. Microbial functional predictions pointed towards an influence of the microbiota in the crop and ileum content on amino acid concentrations, as indicated by different relative abundances of predicted genes related to amino acid biosynthesis, degradation, and metabolism.

CONCLUSIONS

Dietary Ca concentrations but not the ABC modulates the effect of supplemented phytase on pcAAD in broiler chickens. The microbiota might contribute to differences in pcAAD by changing the amino acid composition of the digesta. The extent of this effect is still unknown.

Multi-carbohydrase enzymes improve feed energy in broiler diets containing standard or low crude protein

This study evaluated the effect of multi-carbohydrase (MC) on energy and nitrogen (N) balance and gene expression in broilers fed diets with different crude protein (CP) contents. The study employed a 2 × 2 factorial arrangement of treatments. The factors were presence or absence of MC, and standard (SCP) or low (LCP) dietary CP concentration. A 3-phase feeding program was used, including starter (0 to 7 d), grower (8 to 17 d) and finisher (18 to 28 d) phases. The study was undertaken in closed calorimetry chambers. Each of the 4 dietary treatments was replicated 8 times in total across 2 runs, with 2 birds per replicate (n = 64). Data for energy partitioning and N balance were collected from d 25 to 28. On d 28, birds were euthanized to collect muscle and intestinal tissue samples for gene expression. The results showed that the MC increased apparent metabolizable energy (AME, P < 0.01) and net energy (NE, P < 0.05), and reduced the feed conversion ratio (FCR, P < 0.01) in all diets. The proportion of energy retained as fat per total energy retention (REf/RE) was positively correlated with feed AME and NE (r = 0.541, P < 0.01 and r = 0.665, P < 0.001, respectively), suggesting that feed energy augmented with increased fat gain. Muscle ATP synthase subunit alpha (ATP5A1W) gene expression had a positive correlation with REf/RE and feed NE (r = 0.587, P < 0.001 and r = 0.430, P < 0.05, respectively). Similarly, muscle peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1A) expression was negatively correlated with weight gain and positively correlated with FCR (r = −0.451, P < 0.05 and r = 0.359, P < 0.05, respectively). These correlations show that over-expressions of muscle genes related to energy production reduce bird performance. This study demonstrated that MC increase dietary energy utilization, regardless of dietary CP concentration. However, the energy released by the enzymes increases feed energy-to-CP ratio, meaning there is excess energy that is then deposited as body fat. This suggests that supplemental MC in broiler feeds is beneficial if diets are formulated to contain marginal energy levels.

Adverse effects on growth performance and bone development in nursery pigs fed diets marginally deficient in phosphorus with increasing calcium to available phosphorus ratios

The objective of this experiment was to evaluate the growth performance and bone mineral content (BMC) of nursery pigs in response to increasing total calcium (Ca) to available phosphorus (aP) ratios in diets containing phytase (250 FTU/kg; Natuphos E, BASF, Florham Park, NJ). A total of 480 nursery pigs (body weight (BW) = 5.7 ± 0.6 kg) with 10 pigs per pen and 7 pens per treatment (6 pens fed 2.75:1 diet) were allotted to seven treatments consisting of increasing ratios of calcium to available phosphorus (Ca:aP): 1.25, 1.50, 1.75, 2.00, 2.25, 2.50, and 2.75. From day −7 to 0, pigs were fed a common diet. They were then fed the treatment diets during two experimental phases from day 1 to 14 and 15 to 28, respectively. Available P was formulated to 0.33% and 0.27% (approximately 90% of requirement) in dietary phases 1 and 2, respectively. BW, average daily gain (ADG), average daily feed intake (ADFI), and gain-to-feed ratio (G:F) were determined. BMC of the femur was measured on day 28 on one pig per pen using dual x-ray absorptiometry. Data were analyzed as a linear mixed model using PROC MIXED (SAS, 9.3). Orthogonal polynomial contrasts were used to determine the linear and quadratic effects of increasing the Ca:aP. Over the 28-d experimental period, increasing Ca:aP resulted in a linear decrease in ADG (353, 338, 328, 304, 317, 291, and 280 g/d; P < 0.01), ADFI (539, 528, 528, 500, 533, 512, and 489 g/d; P < 0.05), and G:F (0.68, 0.66, 0.64, 0.62, 0.61, 0.59, and 0.58; P < 0.01). Increasing Ca:aP also resulted in decreased BW on days 14 and 28 (P < 0.01). The BMC of the femur decreased with increasing Ca:aP (6.2, 6.3, 5.7, 5.9, 5.5, 5.6, and 5.3 g; P < 0.05). Regression analysis explained the impact of Ca:aP as follows on ADG (ADG [g/d] = 339 − 36x; r² = 0.81), G:F (G:F = 0.61 – 0.03x; r² = 0.72), and BMC (BMC [g] = 6.4 – 0.27x; r² = 0.43), where x is the Ca:aP. In conclusion, all outcomes indicated that any level of calcium above the minimum used in this experiment impaired growth performance and skeletal development. Further research using even lower levels of dietary Ca is warranted.

Modelling and optimizing of calcium and non-phytate phosphorus requirements of male broiler chickens from 1 to 21 days of age using response surface methodology

The skeleton is the main site of P and Ca deposition; therefore, accurate estimation of Ca and P requirements is necessary to maintaining health and optimum performance of broiler chickens. A response surface methodology (RSM) using a central composite design (CCD) was used for evaluating and optimizing of Ca and non-phytate P (NPP) requirements of broiler chickens for optimal performance, ileal nutrient digestibility and bone mineralization from 1 to 21 days of age. A total of 750 one-day-old male broiler chickens (Ross 308) were randomly distributed into 50 cages including 9 treatments, each replicated 5 times (except central treatment with 10 replicates) and 15 birds in each cage by CCD. The dietary Ca levels of 4.3, 5.6, 8.6, 11.7 and 13.0 g/kg and NPP of 2.5, 2.9, 4.0, 5.0 and 5.4 g/kg were used for nine treatments of CCD. The results indicated that the linear and quadratic effects of NPP, quadratic effects of Ca and Ca × NPP were significant for average weight gain (AWG, P < 0.05), average feed intake (AFI, P < 0.05), feed conversion ratio (FCR, P < 0.05) and Ca and P apparent ileal digestibility (AID, P < 0.05); however, the linear effect of Ca was significant only for FCR (P < 0.05). On the other hand, tibia and toe ash were affected by NPP (linear and quadratic, P < 0.01) and Ca (quadratic, P < 0.01). The second-order polynomial regression model was significant for AWG (R2 = 0.93, P < 0.001), AFI (R2 = 0.88, P < 0.001), FCR (R2 = 0.78, P < 0.001), AID of Ca (R2 = 0.78, P < 0.001) and P (R2 = 0.88, P < 0.001), tibia ash (R2 = 0.86, P < 0.001) and toe ash (R2 = 0.85, P < 0.001). The multi-objective optimization indicated that broiler chickens from 1 to 21 days of age need 7.03 and 4.47 g/kg of Ca and NPP, respectively, to achieve optimal AWG, FCR, tibia and toe ash. However, the dietary Ca and NPP levels can be reduced to 6.57 and 3.95 g/kg with a slight negative impact on performance and bone mineralization, respectively. In conclusion, the findings indicate that using multi-objective optimization model such as RSM provides more information regarding optimum Ca and NPP requirements of broiler chickens, considering the complex interaction between these two minerals. While the NPP levels are in line with current recommended requirements, Ca levels are considerably lower and suggest that current recommended Ca requirements may be in excess of the needs of the broiler.

Influence of the concentration of dietary digestible calcium on growth performance, bone mineralization, plasma calcium, and abundance of genes involved in intestinal absorption of calcium in pigs from 11 to 22 kg fed diets with different concentrations of digestible phosphorus

BACKGROUND

A 21-day experiment was conducted to test the hypothesis that Ca requirements to maximize growth performance expressed as the standardized total tract digestible (STTD) Ca to STTD P ratio is less than 1.40:1. The second hypothesis was that increasing dietary Ca increases plasma Ca concentration and downregulates abundance of genes related to Ca absorption (TRPV6, S100G, and ATP2B1) in the duodenum, and tight junction proteins (OCLN, CLDN1, and ZO1) in the duodenum and ileum.

METHODS

Twenty corn-soybean meal diets were formulated using a 4 × 5 factorial design with diets containing 0.16%, 0.33%, 0.42%, or 0.50% STTD P, and 0.14%, 0.29%, 0.44%, 0.59%, or 0.74% STTD Ca. Six hundred and forty pigs (initial weight: 11.1 ± 1.4 kg) were allotted to 20 diets and 5 blocks in a randomized complete block design. On day 21, weights of pigs and feed left in feeders were recorded and blood, duodenal tissue, ileal mucosa, and the right femur were collected from 1 pig per pen. Abundance of mRNA was determined in duodenal and ileal tissue via quantitative RT-PCR. Data were analyzed using a response surface model.

RESULTS

The predicted maximum ADG (614 g), G:F (0.65), and bone ash (11.68 g) was obtained at STTD Ca:STTD P ratios of 1.39:1, 1.25:1, and 1.66:1, respectively, when STTD P was provided at the requirement (0.33%). If dietary STTD P was below the requirement, increasing dietary Ca resulted in reduced (P < 0.05) ADG and G:F. However, if dietary STTD P was above the requirement, negative effects (P < 0.05) on ADG and G:F of increasing STTD Ca were observed only if dietary STTD Ca exceeded 0.6%. Plasma Ca concentration was positively affected by STTD Ca over the range studied (quadratic, P < 0.01) and negatively affected by increasing STTD P (linear, P < 0.01). There was a linear negative effect (P < 0.05) of STTD Ca on the abundance of S100G, TRPV6, OCLN, and ZO1 in duodenum, and CLDN and ZO1 in ileum.

CONCLUSIONS

The STTD Ca:STTD P ratio needed to maximize growth performance of 11- to 25-kg pigs is less than 1.40:1, if P is at the estimated requirement. Increasing dietary Ca reduces transcellular absorption of Ca and increases paracellular absorption of Ca.

Response of broiler chickens to diets containing different levels of sodium with or without microbial phytase supplementation

Phytate induced excessive mineral excretion through poultry litter leads to poor performance and environmental pollution. Exogenous microbial phytase supplementation to poultry diets reduce the environmental excretion of nutrient and improve bird’s performance. However, excessive dietary sodium (Na) level may hinder the phytase-mediated phytate hydrolysis and negate the beneficial effects of phytase. Therefore, this experiment was conducted to investigate the effects of different concentration dietary Na on phytase activity and subsequent impact on broiler performance, bone mineralisation and nutrient utilisation. In this study, six experimental diets, consisting of three different levels of Na (1.5, 2.5, or 3.5 g/kg) and two levels of microbial phytase (0 or 500 U/kg) were formulated by using 3 × 2 factorial design. The six experimental diets were offered to 360 day-old Ross 306 male chicks for 35 days, where, each experimental diet consisted of 6 replicates groups with 10 birds. Along with growth performance, nutrient utilization, intestinal enzyme activity, dry matter (DM) content of litter and mineral status in bone were analysed. Dietary Na and phytase had no effect on bode weight gain and feed intake. Birds on the low Na diet showed higher (p < 0.05) feed conversion ratio (FCR) than the mid-Na diets. High dietary Na adversely affected (p < 0.001) excreta DM content. Phytase supplementation to the high-Na diet increased (p < 0.01) the litter ammonia content. High dietary Na with phytase supplementation improved (Na × phytase, p < 0.05) the AME value and ileal digestibility of Ca and Mg. The total tract retention of Ca, P, and Mg was reduced with high Na diet, which was counteracted by phytase supplementation (Na × phytase, p < 0.001). The diets containing mid-level of Na improved (p < 0.001) the function of Na-K-ATPase and Mg-ATPase in the jejunum. The overall results indicate that high dietary Na did not affect phytase activity but influenced the nutrient utilization of birds, which was not reflected in bird overall performance.

The effects of calcium source and concentration on performance, bone mineralisation and serum traits in male broiler chickens from 1 to 21 days of age

In total, 840 1-day-old male broiler chickens (Ross 308) were used to evaluate the effects of seven dietary calcium (Ca) concentrations (4.0, 5.5, 7.0, 8.5, 10.0, 11.5 and 13.0 g/kg, at a fixed concentration of 4.0 g/kg of non-phytate phosphorus) and two calcium sources (oyster shell and limestone) on broiler chicken Ca requirements for optimal growth rate and bone mineralisation from 1 to 21 days of age. All chickens were randomly distributed into 14 treatment groups (seven treatments of each Ca source), each being replicated four times, with 15 birds per each replicate. Results indicated that Ca source and Ca source × Ca concentration interaction had no significant (P &gt; 0.05) effects on birds average feed intake, but increasing Ca concentration to &gt;8.5 g/kg significantly deteriorated average feed intake. Average weight gain and feed conversion ratio were significantly influenced by Ca source × Ca concentration interaction, whereby high concentrations of Ca from oyster shell resulted in a poorer performance for both criteria than did those from limestone. Serum Ca, P and total protein were not affected by Ca source. However, increasing Ca concentrations had adverse effects on serum P concentration (P &lt; 0.05). Toe ash, tibia ash and phosphorus concentrations at 21 days were not influenced by Ca source, but were depressed as dietary Ca concentration increased (P &lt; 0.05). A broken-line regression analysis indicated that the Ca requirements to optimise average weight gain and tibia ash when limestone was used as a Ca source were 5.54 and 6.58 g/kg of diet respectively, and 5.80 and 6.43 g/kg of diet respectively, when oyster shell was used. In conclusion, the results indicated that Ca concentration, more than Ca source, has a significant influence on broiler chicken performance and bone mineralisation, all of which deteriorate when the dietary Ca concentration exceeds 8.5 g/kg at the constant available-phosphorus concentration of 4.0 g/kg.