The impact of “super-dosing” phytase in pig diets on growth performance during the nursery and grow-out periods1

Abstract

Previous research indicates that “super-dosing” phytase may improve pig growth performance by improved nutrient use, although the benefits appear to be more consistent in nursery than in grow-out pigs. Therefore, two experiments were conducted to determine if performance could be improved by feeding phytase at super-dosed levels, and whether this response would be different if energy and amino acid (AA) were limiting. Experiment 1 involved 440 weaned pigs (6.27 ± 0.01 kg) in a factorial arrangement of treatments comparing the main effects of diet (positive control [PC] balanced for all nutrients vs. a negative control [NC]: 10% lower standardized ileal digestible (SID) lysine with relative reduction of all other essential AA and 1% reduced fat) and phytase levels (0 vs. 2,500 FTU Quantum Blue 5G phytase/kg). Pigs were assigned to pen according to a randomized complete block design based on body weight (BW). Feed and water were provided ad libitum across four dietary phases: 3 × 1 wk plus 1 × 2 wk. The average daily gain (ADG) and gain to feed ratio (G:F) were improved in the PC relative to the NC (P < 0.05) indicating success in formulating a diet limiting in energy and/or AA. Phytase improved ADG and G:F, regardless of diet composition (P < 0.05). Thus, super-dosing phytase improved nursery pig growth performance, irrespective of diet nutrient adequacy or deficit. Experiment 2 involved 2,200 growing pigs (36.6 ± 0.30 kg) allotted to five treatments: a balanced PC (250 FTU Quantum Blue 5G phytase/kg), an NC (PC with 15% less SID lysine and 1.5% lower net energy [NE]), and three super-dosing phytase treatments applied to the NC totaling 1,000, 1,750, and 2,500 FTU phytase/kg. Feed and water were available ad libitum. At trial completion (approximately 122 kg), the PC pigs were heavier and more efficient than the NC pigs (P < 0.05) indicating success in formulating an NC treatment. Super-dosing phytase had no effect on whole body ADG or average daily feed intake (P > 0.10) but tended to improve G:F and feed energy efficiency (P < 0.10). Super-dosing phytase improved carcass-based feed and feed energy efficiency (P < 0.05) and tended to improve ADG (P < 0.10). Supplying phytase at “super-dosed” levels—above that required to meet the phosphorus requirement—improved growth performance in nursery pigs (6 to 22 kg BW) and provided smaller benefits in grow-finish pigs (37 to 122 kg BW). The improvement during the nursery period was independent of energy and AA levels in the diet.

A Novel Corn-Expressed Phytase Improves Daily Weight Gain, Protein Efficiency Ratio and Nutrients Digestibility and Alters Fecal Microbiota in Pigs Fed with Very Low Protein Diets

“…The very low protein diet decreased the feed efficiency and growth performance of pigs, which was similar to previous studies [ 9 , 10 , 11 ]. The beneficial effects of microbial phytase as a feed additive on the growth performance of pigs fed with amino acids-deficient diets have been documented previously [ 28 , 29 ], but it is unknown whether the negative effects of low protein diets can be mitigated by using phytase produced in transgenic plants. Although both doses of CEP (i.e., 2000 and 4000 FTU/kg) showed some promising effects on certain parameters, it seems that 4000 FTU/kg CEP had added benefits.…”

“…However, there are conflicting reports on the effects of microbial phytase on the digestibility of N and amino acids in pigs [ 26 , 27 ]. Some studies have shown promising outcomes on growth performance when microbial phytase was used for pigs receiving amino acids-deficient diets [ 28 , 29 ], but some others have reported no positive effects on the growth of animals [ 30 , 31 ].…”

Supplementation of protease to low amino acid diets containing superdose level of phytase for wean-to-finish pigs: effects on performance, postweaning intestinal health and carcass characteristics

“…Consequently, phytase allows adjustments around the inclusion of inorganic macromineral sources in diet formulations. High levels of added phytase (superdosing) have been observed to enhance nutrient digestibility and pig growth performance and have been observed to be more effective during the nursery phase than the grow-finish phase ( Holloway et al, 2019 ). Proteases, another commonly used enzyme in monogastric diets, may increase the rate of hydrolysis of protein sources, increasing AA availability and reducing N excretion.…”

Increasing Doses of Bacterial Phytase (Citrobacter braakii) Improves Performance and Carcass Characteristics of Pigs in Growing and Finishing Phases

“…In the finishing phase, the pigs supplemented with 1500 and 3000 FYT (i.e., the NC15 and NC30 treatments) had higher live weights at 112 days old ( p < 0.05), as did the pigs in the PC treatment (without reductions in Ca and P). Studies conducted by Holloway et al [ 9 ] showed that phytase levels between 1000 and 2500 FYT/kg of feed improved the performance (DWG and FCR) of finishing pigs, resulting in a higher slaughter weight. The better performance in this period can be credited to the fact that progressively higher amounts of phytase in the diet increased the plasma levels of blood inositol of the animals in the finishing phase [ 15 ].…”

“…Especially related to energy, this enzyme shows a similar result compared with the exogenous carbohydrases, which improve the availability of food energy and together can potentiate this effect [ 6 ]. Commercially, there are several sources of exogenous phytase available for use in monogastric nutrition, the synthesis of which is derived from isolated yeast or bacteria [ 7 , 8 , 9 ], such as Buttiauxella spp. [ 10 , 11 , 12 ], Aspergillus niger [ 13 , 14 ], Citrobacter braakii [ 8 , 15 , 16 ] and Escherichia coli [ 16 , 17 , 18 , 19 , 20 , 21 ].…”