Superdosing phytase fed to mature boars improves semen concentration and reproductive efficiency

Abstract Text: Phytate has been shown to be an anti-nutrient and that superdosing phytase breaks down phytate improving nutrient utilization and finisher pig performance, but little work has been done in mature reproductive pigs. The objective of this trial was to determine if feeding phytase (Quantum® Blue) at superdose levels (2000 FTU/kg) could enhance reproductive performance in mature boars. Thirty boars (PIC280) were randomly assigned to one of two dietary treatments: control (CON, n=15) with 500 FTU/g phytase or test (PHY) with 2000 FTU/g phytase (PHY, n =15). All boars were fed a common diet (2.25 kg/d) that contained 500 FTU/kg of phytase to release 0.15% AVP and 0.16% Ca. A top-dress (250 g/d) was then added with phytase or without phytase (placebo) to give the two final treatments (500 FTU/kg; CON and 2000 FTU/kg PHY).  The dietary treatments were fed for 12 wk. For all boars, semen was collected weekly and evaluated for volume, concentration, and morphological abnormalities.  A CASA system was used to evaluate motility, progressive motility, and mobility parameters of the sperm cells.  An extended semen sample was retained at the stud and evaluated for motility using the CASA for 7 days.  Every 4 wk, an extended semen sample was shipped and analyzed at an external lab 1d post collection for further assessment of semen quality; including additional morphological assessments, CASA motility, mobility estimations, and membrane integrity assays using flow cytometry at 0, 4, 8, and 12 wk. Phytase superdosing increased sperm cell concentration in the ejaculates (74.58x10⁹ CON vs 82.86x10⁹ PHY, P=0.0006) without negatively effecting semen quality parameters at the time of collection. The percentage of live sperm cells 1d post collection did not differ by treatment (CON = 72.01 ±0.56, PHY = 70.81 ±0.57, P=0.13).  All semen samples shipped on wk 8 and 12 of the study had a reduction in the percentage of live sperm cells (P<0.0001), an increase in distal midpiece reflex (DMR), tail abnormalities (P<0.0001), and reduced motility (P<0.0001) compared to weeks 0 and 4. The PHY boars had increased DMR (11.2±1.1% PHY vs 6.9±1.1% CON) and reduced motility (70.1±1.4% PHY  vs 74.2±1.4% CON) 1d post collection (p=0.0065 and p=0.0406, respectively), however, this was not seen at the time of collection.  Over the course of the 12 wk study, boars fed phytase at 2000 FTU/kg had increased sperm cell concentration by 11% per ejaculate without negatively effecting semen quality or motility at collection.

Keywords: Boars, Phytase, Reproduction