Scientific Abstract
This project was designed to determine the impacts of space allowance, marketing strategy, and the strategic application of hyper-doses of phytase (≥ 4,500 FTU/kg) on performance and carcass quality of late finishing pigs, and to further provide an analysis integrating the effects of space requirements and phytase application with feed costs, pig price, and pork produced per unit of space. In experiment 1, a total of 375 finishing pigs (94.63 ± 0.61 kg) were randomly assigned to 48 pens, with 7 to 8 pigs per pen equally balanced for gilts and barrows. Two phytase supplementation doses (control of 2,500 FTU/kg or hyper-dose of 5,000 FTU/kg) and two space allocation dimensions (adequate with 0.85 m2/pig or restricted with 0.64 m2/pig) were combined to create 4 treatments in a 2 x 2 factorial arrangement. No interactions (P > 0.10) were observed between floor space allowance and phytase supplementation. Pig body weight was determined weekly and was reduced (P < 0.008) by restriction of space. Body weight considering all pigs marketed (day 28 and day 42) was reduced (P = 0.009; 133.9 vs. 135.4) by space restriction. Average daily gain and average daily feed intake were reduced in space restricted pigs (P < 0.05), but gain:feed, back fat depth, and loin eye area were not impacted (P > 0.08). In experiment 2, the effects of hyper-dosing of phytase (control of 2,250 or hyper-dose of 4,500 FTU/kg) in late finishing pigs (2,200 pigs with 18 to 24 pigs per pen and 96 pens) on pig performance and carcass quality was evaluated when using a standard marketing program or a modified program. For the standard strategy the first marketing cut was made at 110 kg of body weight and for the modified strategy, the first cut was targeted for 130 kg of body weight, which was 22 days later. The second cut and the final marketing were the same for both marketing programs. No interactions were observed between marketing strategy and phytase supplementation and hyper-dosing of phytase did not impact any of the growth parameters measured throughout the study.
Overall, the average market weight of pigs using the modified marketing strategy was 2.15 kg higher (P < 0.001) than the market weight of pigs using the standard marketing strategy. When considering the number of pigs and days to market, no differences were observed for average daily gain (P = 0.727), average daily feed intake (P = 0.486), and gain:feed (P = 0.807). Body weight at harvest, hot carcass weight, and yield were greater (P < 0.001) for pigs in the modified marketing program. In Experiment 3, the impact of supplementing hyper-doses of phytase (4,500 FTU/kg) was evaluated compared to the standard super-dose of 2,250 FTU/kg using a total of 17,862 pigs distributed in 16 barns (8 barns per dietary treatment). Average body weight at marketing, number of days to market, total gain, average daily gain, average daily feed intake, gain:feed, carcass weight, percent lean, back fat thickness, loin depth, adjusted base price, and lean premium were not different (P > 0.230) between treatments. The results of these experiments suggest that there was no benefit in supplementing phytase above the standard level of 2,250 to 2,500 FTU/kg. Based on feed costs, carcass value, and the performance results in these experiments, housing more pigs per pen (ie, restricting space) or using a modified marketing program (ie. delaying the first marketing cut) is economically advantageous in spite of reductions in performance.
