For economical and ecological reasons, efficiency and profitability ofswine production relies heavily on the way pigs utilize key nutrients such as P,which is considered a potential pollutant of water ecosystems. Although cerealgrains and oilseed meals contain enough P to fulfill the biological needs of pigs,most of this P is tightly bound as phytate. As pigs do not have enough phytase(PHY) to cleave P from phytate, it is excreted in the feces. To prevent adeficiency, diets have traditionally been supplemented with highly availableinorganic sources of P. Today, an environmentally-friendly alternative is tosupplement diets with PHY.Growth promoting antibiotics are also used to enhance the utilization ofdietary components such as energy and N. It has been suggested that theantibiotic virginiamycin (VIR) could also improve phytate-P utilization by pigs.Eight experiments evaluated the effects of VIR and/or PHY amendmentson digestibility, retention, excretion, growth, bone characteristics, meat traits, andileal microflora populations of growing pigs fed corn–soybean meal (SBM) diets(seven experiments) or corn-SBM-rice bran diets (one experiment). Additionally,a comparison between two digestibility procedures was conducted for two of theexperiments.On average, VIR improved P digestibility and total P excretion by 5.0%,and P retention as a percent of absorption by 1.0%. Phytase amendmentsimproved P digestibility between 14 and 27%, and P retention (as a % ofabsorption) between 0.7 and 2.5%. In the growth trial, VIR supplementation wasassociated with numerical differences favoring bone mineralization and ilealphytate-utilizing bacteria populations. These observations demonstrate additionalresearch is warranted with this antibiotic under conditions of higher stress andbacterial load in the environment.According to the comparisons between digestibility methods, a single grabfecal collection was not reliable. Further, a cumulative grab collection for fivedays was not as good an option as the total collection method.It is concluded that VIR does improve P utilization in pigs fed corn-SBMdiets not supplemented with inorganic P. Similar effects, but of greatermagnitude, were confirmed for PHY-amended diets with either normal or highlevels of phytate P.

Thèse (M.Sc.)--Université Laval, 2005. / Titre de l'écran-titre (visionné le 23 février 2006). Dans le dépouillement, les chiffres 2 et 5 du symbole P2O5 sont souscrits. Bibliogr.

Four experiments were conducted to evaluate the efficacy and safety of a microbial phytase (Novo SP938) in weanling and grower pigs, and starter turkeys fed corn-soybean meal based diets. Pig and turkey BW and pen feed consumption were recorded weekly. Fecal and excreta samples were collected for determination of Ca and P digestibility. At the end of all experiments animals were slaughtered, and 10th ribs or right foot for pigs, and both middle toes for turkeys were removed for bone analysis. In pigs performance, bone measurements, and digestibilities of P and Ca increased as levels of phytase increased. Concentration of P and Ca in the feces decreased as dietary phytase increased. In turkeys, BW gain and toe ash increased as nonphytate P or phytase increased, when added to a low-P diet. Concentrations of P and Ca decreased as phytase was added to the diet. Based on nonlinear or linear equations, the average P equivalency of 500 U phytase/kg feed was .64 and .67 g of inorganic P for pigs and turkeys, respectively. There were no adverse effects of feeding 10,000 U phytase/kg feed in pigs and turkeys. Supplementation with Novo SP938 phytase was effective in improving performance, bone mineralization, P and Ca utilization, and decreasing P and Ca concentrations in the feces of pigs and excreta of young turkeys fed low-P diets, with no health effects, even at very high supplementation rates. / Master of Science

Forty-six barrows fitted with steered ileo-cecal valve cannulas were used in four experiments to evaluate the effects of supplementing swine diets with microbial phytase or beta-mannanase on the apparent ileal (AID) and/or apparent total tract digestibility (ATTD) of amino acids, N, Ca, P, DM and energy. In Exp. 1, the addition of phytase to low CP corn-soybean meal based diets increased the AID of Ca (P < .01), P (P < .001), and all amino acids (P < .10) measured except Leu, Ser, Pro, Met, His and Tyr. In Exp. 2, the addition of microbial phytase to corn-soybean meal, corn-soybean meal-wheat middlings, or corn-soybean meal-meat and bone meal based diets resulted in increased AID of Ca and P, but had no effect (P > .1) on amino acid digestibilities. Diet type affected all digestibility measurements, but did not affect the efficacy of supplemental phytase. In Exp. 3, the addition of microbial phytase to corn-wheat-soybean meal, corn-wheat-cannola, or sorghum-corn-soybean meal based diets led to an increased ( P <.05) AID of P, Asp, Thr, Ser, Ala, Tyr, Phe, Lys and Arg. In Exp. 4, the addition of beta-mannanase to corn-soybean meal based swine diets led to an increased AID of DM and ATTD of energy. In addition, the AID of all amino acids measured were increased numerically, with many of these values approaching significance. The results of these studies demonstrate that supplementing pig diets with phytase or beta-mannanase, results in an increased digestibility of certain dietary components due to the breakdown of anti-nutritive compounds in the diet. / Ph. D.

This study was conducted to investigate the efficacy of phytase for improving the nutrient utilization for pigs and poultry. Two experiments, one with broilers and one with pigs, were conducted to compare the efficiency of transgenic microbial (Natuphosà ) and plant (Phytaseedà ) phytase for enhancing the utilization of phytate P in corn-soybean diets fed to young broilers and pigs, and to evaluate the safety of Phytaseedà phytase. Three levels of the two sources of phytase (250, 500 and 2,500 U/kg of diet) were added to a corn-soybean meal basal diet containing 0.21 and 0.26% nonphytate P, respectively, for broilers and pigs. Forty birds and thirty pigs (8 broilers and 6 pigs, one per cage, from the diet without added phytase and the diets with 500 or 2,500 U/kg phytase from both sources) were randomly selected for gross necropsy and histologic evaluation of liver, kidney and bone tissues. Adding both sources of phytase to the basal diet resulted in similar increases of BW, BW gain, feed intake, gain:feed, apparent digestibilities (retention) of DM, P and Ca, and bone measurements. Phosphorus excretion decreased as phytase addition increased. No significant abnormalities were seen in any of the broilers and pigs necropsied. In a study with pigs (n=120 and 80, respectively for grower and finisher), the effects of supplemental microbial phytase on crude protein and amino acid utilization of low protein plant-based diets was investigated. During the grower period (32 to 67 kg), diets 1, 2 and 3 contained 14, 13 and 12% crude protein and no added phytase, respectively, and diets 4 and 5 contained 12% crude protein with either 250 or 500 U of phytase/kg of diet, respectively. During the finisher period (67 to 109 kg), diets 1, 2 and 3 contained 12, 11 and 10% crude protein with no added phytase, respectively, and diets 4 and 5 contained 10% crude protein with either 250 or 500 U of phytase/kg of diet, respectively. At the end of grower phase, two pigs (1 barrow and 1 gilt) were removed from each pen; 12 of the barrows that were removed from diets 1, 3 and 5 were put in metabolism cages for total collection, and the remaining four pigs in each pen continued on test for the finisher phase. At the end of finisher phase, 12 barrows from diet 1, 3, and 5 were put in metabolism cages for total collection. Ileal contents were taken (slaughter technique) from the remaining barrows and the barrows used in metabolism cages. Daily gain increased as protein and phytase levels was added to the lowest protein level. Fecal P and Ca digestibilities improved with added phytase. Phytase addition to basal diet linearly increased ash weight in the grower phase. With the exception of proline and glycine, the digestibilities of the other amino acids were linearly increased with phytase and CP level. Nitrogen excretion was estimated to be reduced by 4.6% when phytase was added to pig diets at a level of 500 U/kg. In a study with cecectomized roosters, the main effects and interaction of phytase and non-startch polysaccharide enzymes on the nutrient utilization of barley, canola meal, rice bran and soybean meal, and canola-barley (36:64) and soybean meal-barley (27.3:72.7) were evaluated. Phytase supplementation to basal diets increased the utilization of energy, N, total amino acid and most of amino acids in barley, canola meal, and canola-barley and numerically increased energy and N utilization in rice brain, soybean meal and soybean-barley. The magnitudes of improvements in the digestibilities of lysine, arginine, cysteine, serine, and threonine were higher compared with the other amino acids. The true utilization of energy and N, and the digestibilities of total amino acid and of glycine, isoleucine, and histidine in barley quadratically increased with Ronozyme™ B. Phytase addition increased Ca retention in barley, canola and soybean meal, and the soybean meal-barley blend, and increased P retention in barley and soybean meal-barley. Addition of Ronozyme™ B to barley linearly decreased Ca retention and quadratically increased P retention. In summary, the efficiency of phytase in Phytaseed is equal to that of Natuphos for enhancing the utilization of phytate P in corn-soybean diets, and microbial phytase is effective in improving the utilization of N and amino acid in pigs and N, amino acid, and energy in poultry. / Ph. D.

The role of nutrition in providing optimal broiler growth and intestinal health is essential, especially during stress or disease challenge. Feed enzymes are useful for improving performance of poultry, particularly when nutrition, management, or health status is not favorable. The objective of the following experiments was to evaluate the effect of dietary phytic acid (PA) and phytase on the performance and intestinal health of birds that were vaccinated with a live coccidial oocyst vaccine. For each experiment, half of the chicks were spray-vaccinated at day-of-hatch with Coccivac®-B and grown out in floor pens with ad libitum access to diets formulated to meet Cobb nutrient recommendations. In the first experiment, birds were given one of three diets that included different levels of a PA solution to obtain dietary PA levels of 0.74, 0.87, and 1.12% for low, medium, and high PA diets, respectively. In the second experiment, two levels of PA were included to obtain dietary PA levels of 0.75 and 1.05% for low and high PA diets, respectively. In addition, phytase was added over the top to half of the diets at 1000 FTU/kg, resulting in four diets: low PA without phytase, low PA with phytase, high PA without phytase, and high PA with phytase. Live performance parameters including body weight, body weight gain, feed intake, feed conversion, and mortality were measured as well as tibia ash (experiment 2) and indicators of small intestinal health including morphology, apparent ileal amino acid digestibility (IAAD), and pH (experiment 2). The results presented here indicated that giving broilers vaccinated against coccidiosis a medium level of PA was detrimental to feed intake, body weight gain, and it induced necrotic enteritis (P ≤ 0.05). Adding phytase on top of nutritionally adequate diets did not improve performance (P ≥ 0.05), but did improve (P ≤ 0.05) apparent IAAD and morphology of the small intestine, especially in younger birds. In addition, it has been determined that important considerations in diet formulation also can include the phytate: protein as well as calcium: total phosphorus ratios, as these may critically affect how phytate impacts bird health and performance. / Ph. D.

Phosphorus (P) is an instrumental nutrient in numerous physiological processes, but can have detrimental environmental impact if fed in excess. Increased P intake in dairy cows leads to increased fecal excretion of P and a reduction in efficiency of use. Variability in P concentration or availability in feedstuffs can exacerbate P excretion. To investigate variability in P between and within feedstuffs, 170 feed samples (forages, concentrates, and by-products), were collected from across the U.S., classified by region fed, and analyzed for total P, inorganic P, and phytate. Forages contained a greater proportion of P in the inorganic form and less total P and phytate as compared to concentrates and by-products. The majority of total P (71.2, 81.8, and 81.9% of total P in forages, concentrates, and by-products, respectively) was associated with inorganic P and phytate. The enzyme phytase has been used successfully in swine and poultry nutrition, as a feed additive, to increase available P and reduce the need for supplemental inorganic P. An experiment was conducted to investigate the effect of phytase use and forage particle length, using a 2 x 2 factorial, on P availability in lactating dairy cows. Total P intake of the four diets was similar (P > 0.15). Total tract digestibility of total P tended (P < 0.10) to be reduced and total P excretion was increased (P < 0.05) with phytase supplementation. Milk fat yield, protein yield, 3.5% FCM, and ECM were increased (P < 0.05) with addition of exogenous phytase to the diet. This indicates that phytate may contain some anti-nutritional factors that reduce availability in other nutrients used for milk production. Variation in P compounds between feeds, and variation in P digestion and production performance with exogenous phytase suggests opportunity for improvement in prediction of P availability from feeds for lactating cows. / Ph. D.

Diet composition and nutrient balance can have a critical impact on intestinal integrity during exposure to enteric pathogens. Researchers have extensively reported benefits on nutrient availability and broiler performance as a consequence of the impact of phytase supplementation. However, the poultry industry has little information on the effects of phytase supplementation in disease settings. The objective of these studies was to evaluate phytase supplementation impact on bird performance, intestinal morphology and pH, nutrient digestibility and bone mineralization during necrotic enteritis (NE). In each experiment, Cobb 500 broilers were obtained from a commercial hatchery and housed in floor pens at the Virginia Tech Turkey Research Center. Birds were placed on used litter from a previous flock that had presented clinical signs of NE. Broilers were fed non-medicated diets formulated to meet NRC (1994) nutrient requirements, except for calcium and phosphorus. In the first experiment, birds began exhibiting clinical signs of NE on d 9, and elevated NE-associated mortality persisted until d 26. Mortality was influenced by the main effects of dietary Ca or phytase. Dietary Ca supplemented at 0.9% or 1000 FTU/kg of phytase increased mortality compared to 0.6% Ca or 0 FTU/kg phytase, respectively, from d 0 to 19. Feed intake (FI) and feed conversion (FC) were affected by Ca x P interaction. From d 0 to 19, birds fed 0.9% Ca and 0.3% available P (avP) had decreased FI and improved FC compared to birds fed 0.9% Ca and 0.45% avP, while FI and FC were similar in birds fed diets with 0.6% Ca, regardless of avP level. Calcium x P x phytase interaction influenced BW or BWG from d 0-12. In general, birds fed 0.9% Ca and 0.45% avP with phytase were heavier compared to birds fed 0.6% Ca, 0.45% avP, and phytase. Calcium at 0.9% increased gizzard (d 19) and jejunum (d 12) pH. Dietary Ca supplemented at 0.9%, avP supplemented at 0.45%, and 1,000 FTU/kg phytase significantly increased tibia ash weight compared to 0.6% Ca, 0.3% avP, and 0 FTU/kg phytase, respectively, on d 12. A 3-way interaction was observed on d 35 for tibia ash percentage; birds fed 0.9% Ca and 0.45% avP had a significant increase in tibia ash percentage, regardless of phytase supplementation. A 3-way interaction was also observed for Ca and P digestibility on d 35. Phytase supplementation significantly increased Ca digestibility regardless of Ca and P levels of the diets. In addition, diets containing 0.6% Ca and 1,000 FTU/Kg of phytase resulted in a significant increase in P digestibility, regardless of P levels. In the second experiment, birds also began exhibiting clinical signs of NE on d 9, and elevated NE-associated mortality persisted until the end of the trial (d 21). Mortality was significantly affected by an interaction between Ca source and Ca levels. Significantly higher mortality was observed when animals were fed 0.9% Ca diets formulated with calcified seaweed from d 0-21 compared to 0.6% Ca diets (regardless of Ca source). From d 0-7, birds fed 0.6% Ca in diets supplemented with phytase had heavier BW than the other treatments regardless of Ca source. From d 0-14 and 0-21, animals fed diets with calcified seaweed had significantly higher FC than animals fed diets with limestone. On d 21, the gizzard of birds fed 0.9% Ca was significantly less acidic than the gizzard of birds fed 0.6% Ca. In conclusion, reducing dietary levels of Ca associated with phytase supplementation improved bird performance and nutrient digestibility. In addition, these experiments indicate that Ca is an important dietary factor in the pathogenesis of NE. / Ph. D.

The use of animal manures to replace commercial fertilizer has increased the economic and environmental sustainability of agriculture. However, this practice has resulted in excess P being applied to the soil in some areas. Excess P may run-off into surface water and leach in the ground, causing eutrophication. Decreasing the amount of P fed and improving the utilization of P are two possible nutritional solutions to this problem. Two experiments were conducted to investigate the effects of levels of dietary P, chemical form of P, and phytase supplementation in ruminants. For Exp. 1, 24 steers (average BW = 229 kg) were allotted to two diets containing 0.12 and 0.19% dietary P for a 112-d growth trial. The steers were individually full-fed, weighed every 14 d, and blood samples were collected every 28 d. The steers fed the 0.12% P diet had increased (P<0.02) ADG during the first 28 d, after which there were no differences. They also had higher (P<0.05) feed intake. By d 56 serum P for the 0.12% P group was lower (P<0.01), and this difference continued for the remainder of the trial. For Exp. 2, 18 wether lambs (average BW = 23 kg) were allotted to the following six diets for each of two metabolism trials: 1) a negative control diet deficient in P, 2) control diet supplemented with inorganic P, 3) control diet supplemented with phytic acid, 4) control diet supplemented with phytic acid and phytase, 5) control diet supplemented with cottonseed meal, and 6) control diet supplemented with cottonseed meal and phytase. Each metabolism trial was preceded by a 5 wk depletion phase in which the lambs were fed a low-P diet. The metabolism trials consisted of a 10 d preliminary period followed by a 10-d collection of feces and urine. On the final day ruminal fluid, blood, and saliva were collected. At the end of the second metabolism trial 10th rib bones were collected from each lamb. Absorption of P was lowest (P<0.0001) for the low-P treatment, compared to the other treatments. There was no treatment effect on saliva P. Ruminal fluid P was higher (P<0.05) for lambs receiving P supplementation. Within supplementation treatments, ruminal fluid P was higher (P<0.05) for lambs fed organic P than for those fed inorganic P. Feeding CSM resulted in higher (P<0.001) ruminal fluid P than phytic acid. The addition of phytase to the diets with organic P resulted in more (P<0.04) P in the ruminal fluid. There was a decrease (P<0.003) in serum P associated with the low-P treatment. There was no difference in bone ash or breaking strength. / Master of Science

The effects of starch and phosphorus (P) source on P partitioning and ruminal phytase activity were evaluated in eight lactating cows (113 DIM). Four cows were ruminaly cannulated. Cows were randomly assigned to treatments in a duplicated 4x4 Latin square with four, 18-d periods. Diets included dry ground corn (DG) or steam flaked corn (SF), with a no supplemental P (low P diet; 0.34% P) or supplemental purified phytic acid (PA; 0.45% P) to provide additional P from an organic source. Total collection of milk, urine, feces, and feed were sampled each period, while rumen fluid was sampled on d 18. Excretion of feces, urine, P, and N was lower in cows fed SF than in cows fed DG. Milk yield was unaffected by diet despite a lower DMI by cows fed SF. Cows fed SF tended to have a higher feed efficiency and lower milk urea nitrogen (MUN) concentration than cows fed DG. Rumen pH was unaffected by diet, but milk fat content was lower for cows fed SF. Milk yield, DMI, and feed efficiency were not affected by PA. Cows fed PA had increased P intake and excretion, but a lower milk P as a percentage of intake compared with cows fed the low P diet. An interaction of starch source and P source was observed for ruminal phytase activity. Altering dietary sources of starch and P offers opportunity to improve P availability and reduce manure nutrient excretion. / Master of Science