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

Dietary calcium and nonphosphate phosphorus interaction influences tibiotarsus development and related gene expression of broilers from 1 to 21 days of age

The dietary needs of calcium (Ca) and phosphorus (P) are interdependent, thus accurate evaluation of Ca and P requirements of broilers to support skeleton health and optimal growth is critical. The present study was carried out to investigate the effects of dietary Ca and nonphytate P (NPP) levels and their interactions on growth performance, tibiotarsus characteristics, tibiotarsus metabolism-related enzyme and proteins, and their gene expression of broilers, so as to provide a rational recommendation for Ca and NPP levels in diet. A total of 540 one-day-old Arbor Acres male broilers were randomly allotted to 1 of 15 treatments with 6 replicate cages of 6 birds per cage for each treatment in a completely randomized design involving a 5 × 3 factorial arrangement of treatments (5 levels of Ca × 3 levels of NPP). The birds were fed the corn-soybean meal diet containing 0.60%, 0.70%, 0.80%, 0.90%, or 1.00% Ca and 0.35%, 0.40%, or 0.45% NPP for 21 d. Dietary Ca level affected (P < 0.03) the bone mineral density, bone mineral content (BMC), breaking strength, ash percentage and ash Ca contents in tibia, which showed linear (P < 0.006) responses to dietary Ca levels. Dietary NPP level affected (P < 0.05) tibia BMC, ash percentage, and FGF23 mRNA level. Broilers that received 0.40% and 0.45% NPP had higher (P < 0.04) tibia BMC and ash percentage than those that received 0.35% NPP, but no differences (P > 0.05) were found between 0.40% and 0.45% NPP. Broilers that received 0.40% NPP had higher (P = 0.02) tibia FGF23 mRNA level than those that received 0.35% NPP, but no differences (P > 0.05) were detected between 0.40% and 0.45% NPP or 0.45% and 0.35% NPP. The interactions between dietary Ca and NPP affected (P < 0.05) ADG, ALP activity, bone gal protein, FGF23 contents, and the mRNA expression levels ALP and bone gal protein in tibia of broilers. Results from the present study indicate that dietary Ca and NPP interaction influences growth, tibiotarsus development, and related gene expression of broiler chickens. Considering all the criteria, the dietary levels of 0.90% Ca and 0.45% NPP would be optimal for both growth and tibiotarsus development of broilers fed a conventional corn-soybean meal diet from 1 to 21 d of age.

The effect of bone and analytical methods on the assessment of bone mineralization response to dietary phosphorus, phytase, and vitamin D in nursery pigs

A total of 360 pigs (DNA 600 × 241, DNA; initially 11.9 ± 0.56 kg) were used in a 28-d trial to evaluate the effects of different bones and analytical methods on the assessment of bone mineralization response to dietary P, vitamin D, and phytase in nursery pigs. Pens of pigs (six pigs per pen) were randomized to six dietary treatments in a randomized complete block design with 10 pens per treatment. Dietary treatments were designed to create differences in bone mineralization and included: (1) 0.19% standardized total tract digestibility (STTD) P (deficient), (2) 0.33% STTD P (NRC [2012] requirement) using monocalcium phosphate, (3) 0.33% STTD P including 0.14% release from phytase (Ronozyme HiPhos 2700, DSM Nutritional Products, Parsippany, NJ), (4) 0.44% STTD P using monocalcium phosphate, phytase, and no vitamin D, (5) diet 4 with vitamin D (1,653 IU/kg), and (6) diet 5 with an additional 50 µg/kg of 25(OH)D3 (HyD, DSM Nutritional Products, Parsippany, NJ) estimated to provide an additional 2,000 IU/kg of vitamin D3. After 28 d on feed, eight pigs per treatment were euthanized for bone (metacarpal, 2nd rib, 10th rib, and fibula), blood, and urine analysis. The response to treatment for bone density and ash was dependent upon the bone analyzed (treatment × bone interaction for bone density, P = 0.044; non-defatted bone ash, P = 0.060; defatted bone ash, P = 0.068). Thus, the response related to dietary treatment differed depending on which bone (metacarpal, fibula, 2nd rib, or 10th rib) was measured. Pigs fed 0.19% STTD P had decreased (P < 0.05) bone density and ash (non-defatted and defatted) for all bones compared to 0.44% STTD P, with 0.33% STTD P generally intermediate or similar to 0.44% STTD P. Pigs fed 0.44% STTD P with no vitamin D had greater (P < 0.05) non-defatted fibula ash compared to all treatments other than 0.44% STTD P with added 25(OH)D3. Pigs fed diets with 0.44% STTD P had greater (P < 0.05) defatted second rib ash compared to pigs fed 0.19% STTD P or 0.33% STTD P with no phytase. In summary, bone density and ash responses varied depending on bone analyzed. Differences in bone density and ash in response to P and vitamin D were most apparent with fibulas and second ribs. There were apparent differences in the bone ash percentage between defatted and non-defatted bone. However, differences between the treatments remain consistent regardless of the analytic procedure. For histopathology, 10th ribs were more sensitive than 2nd ribs or fibulas for the detection of lesions.

The effects of increasing dietary total Ca/total P ratios on growth performance, Ca and P balance, and bone mineralization in nursery pigs fed diets supplemented with phytase

The objective of this study was to investigate the effects of increasing dietary total Ca/total P ratios on growth performance, digestibility of Ca and P, bone mineralization, and concentrations of Ca and P in urine and plasma in nursery pigs. There were six diets in a randomized complete block design, including one positive control and five diets corresponding to five total Ca/total P ratios: 0.55, 0.73, 0.90, 1.07, and 1.24 (analyzed as 0.58, 0.75, 0.93, 1.11, and 1.30). These five diets were deficient in P but supplemented with 1,000 phytase units/kg feed. Each diet was fed to six pens of eight pigs (four barrows and four gilts per pen). All diets contained 3 g/kg TiO2, and fecal samples were collected from each pen on days 5-7 of trial. At the end, one pig per pen was sacrificed to collect the right tibia and urine in the bladder. The results showed that increasing dietary Ca/P ratio to 0.93 increased gain:feed but then gain:feed decreased as the Ca/P ratio was increased to 1.30 (linear and quadratic, P < 0.05). Although average daily gain and final BW were unaffected by changing Ca/P ratio in diet, dry bone weight; weights of bone ash, Ca and P; and bone Ca/P ratio increased linearly (P < 0.001) with increasing dietary Ca/P ratio. The percent bone Ca showed a tendency to increase (P = 0.064). Increasing dietary Ca/P ratio decreased apparent total tract digestibility (ATTD) of Ca and P linearly (P < 0.05) and the concentration of digestible P linearly (P < 0.001), but increased the concentration of digestible Ca (linear and quadratic effects: P < 0.01) and the digestible Ca/P ratio (linear effect: P < 0.001). In plasma, the concentration of Ca increased both linearly (P < 0.01) and quadratically (P = 0.051), whereas the concentration of P tended (linear and quadratic, P < 0.10) to decrease with increasing dietary Ca/P ratio. Similarly, in urine, the concentration of Ca increased both linearly and quadratically (P < 0.05), whereas the concentration of P decreased linearly (P < 0.01). In conclusion, increasing the dietary Ca/P ratio reduced feed efficiency but increased bone mass and the amounts of Ca and P deposited in bone of nursery pigs fed diets supplemented with 1,000 FYT/kg phytase. The increases in bone growth led to a reduction of urinary P excretion that exceeded the decreased digestible P supplied in diet with the widening dietary Ca/P ratios.

Chemical body composition and bone growth of young pigs as affected by deficiency, adequate and excess of dietary phosphorus supply

Objective of the experiment was to study the effect of deficiency, adequate and excess dietary phosphorus supply on growth performance, retention and utilisation of phosphorus, length, mass and geometry measurements of the femur shaft, content of protein, ash, phosphorus in viscera, edible (meat and fat) and inedible (bones and skin) parts of the body in pigs ageing from 33 to 110 days. It was found that compared to animals fed according to phosphorus requirement the deficiency and excess of dietary phosphorus did not influenced o total feed intake (mean 120.6 kg) and feed conversion (mean 1.9 kg/kg gain). However phosphorus deficiency lowered total gain of the body mass (P=0.0072), diminished weight of the inedible part of the carcass (P=0.0229), decreased the content of body protein (P=0.0171), ash (P=0.0001), and phosphorus (P=0.0001). Whereas, over-supply of dietary phosphorus did not cause any change of these component. Utilisation of the total phosphorus was diminished (P=0.0001) in pigs fed diet with both excess (by 16.26%) and deficiency (by 12.28%) of the phosphorus, but excess had much lower negative impact than its’ deficiency. When available form of this element was considered over-supply still reduced (P=0.0001) its utilisation the most (by 26.58%) but deficiency made utilisation the best (7.77%). Both dietary deficiency and over-supply of the phosphorus diminished (P=0.0001) femur mass (by 25 and 11 g, respectively). Thus negative impact of phosphorus deficiency was much stronger. Moreover, phosphorus deficiency diminished (P=0.0015) bone length (by 0.5 cm), however, excess did not change this feature. Response of animals to a decrease bone mass and length due disturbances in phosphorus supply (both deficiency and excess) was the increase the vertical external diameter of the femur shaft.

Use of fixed calcium to phosphorus ratios in experimental diets may create bias in phytase efficacy responses in swine

The objective of this study was to investigate the effects of two dietary total Ca/P ratios on available P release by phytase, measured using growth performance and bone mineralization with 528 barrows and gilts according to a randomized complete block design. Three were 11 diets in a factorial of 2 by 4 plus 3, including 3 reference diets consisting of 0.25% (control), 0.70%, or 1.15% monocalcium phosphate (MCP) and 8 diets from combining 4 phytase doses (500, 1,000, 2,000, and 3,000 FYT/kg) with 0.25% MCP and 2 dietary Ca/P ratios (1.05 and 1.20). Each diet was fed to 6 pens of 8 pigs. All diets contained 3 g/kg TiO₂, and fecal samples were collected from each pen on d 13–15 of trial. At the end of trial, one pig per pen was sacrificed to collect a tibia and urine in the bladder. The results showed that MCP improved growth performance linearly (P < 0.01), whereas both a linear and quadratic response was observed with the addition of phytase. The MCP increased the percent bone ash and weights of bone ash, Ca, and P linearly (P < 0.01). At both Ca/P ratios, increasing supplementation of phytase increased the percent bone ash and weights of bone ash, Ca, and P both linearly and quadratically (P < 0.05). Both MCP and phytase significantly increased digestibility of Ca and P as well as digestible Ca and P in diets and reduced the digestible Ca/P ratio. The dietary Ca/P ratio of 1.20 resulted in poorer feed utilization efficiency, more digestible Ca, greater percent bone ash, Ca, and P and heavier weights of bone Ca and P than the ratio of 1.05 (P < 0.05). The ratio of 1.20 elicited numerically higher available P release values from phytase, with percent bone ash and bone P weight as the response variables, but significantly lower values with gain:feed. The urinary concentration of Ca increased linearly (P < 0.01) with increasing digestible Ca/P ratios whilst urinary concentration of P decreased quadratically (P < 0.01). In conclusion, fixing the same total Ca/total P ratio in diets supplemented with increasing phytase dosing created an imbalance of digestible Ca and P, which could have an adverse effect on bone mineralization and thus compromise the phytase efficacy relative to mineral P.

Growth Performance, Nutrient Digestibility, Blood Profiles, and Gut Integrity of Growing Pigs Fed Pickled Fish Residue with Decreased Salt Content

This study investigated the growth performance, nutrient digestibility, blood profiles and gut integrity of growing pigs, in response to an increase in pickled freshwater fish residue (PFR) intake following a decrease in salt content. Ninety-six crossbred growing pigs [(Landrace × Large White) × Duroc] with a body weight of 23.65 ± 0.24 kg were randomly assigned to one of four treatments (6 pens/treatment, 4 pigs/pen) in a randomized complete block design. The treatments included: a corn-soybean meal based diet without PFR inclusion (CON) or with PFR addition at 5 (PFR5), 10 (PFR10), and 15% (PFR15), respectively. Desalting via soaking and stirring caused a positive reduction in the salt present on the surface of PFR. Over the 42-day feeding period, an increased level of PFR quadratically increased gain:feed ratio such that gain:feed ratio for PFR10 was greater than that for CON (p < 0.05). Pigs fed PFR10 had greater crude protein digestibility, and lower aspartate aminotransferase and crypt depth than those fed the CON diet (p < 0.05). The linear improvements in crude protein and ether extract digestibility, duodenal villus height, and villus:crypt ratio were observed as the PFR content increased (p < 0.05). However, there were no significant effects on average daily feed intake, dry matter and ash digestibility, blood metabolites (total Ca, P, creatinine, and alkaline phosphatase). Altogether, up to 10% PFR can be included in corn-soybean meal diet without impairing protein digestibility and hepatic enzyme alteration. In fact, administering PFR with lower salt content to growing pigs ultimately promotes their growth performance and gut integrity.