53 Evaluation of the impact of high doses of phytase and marketing strategy on performance and carcass characteristics of late finishing pigs in commercial settings

Abstract

Abstract As late finishing pigs reach market weight, space allowance per unit of body weight (BW) is reduced, which negatively impacts growth performance. Supplementing high doses of phytase results in the near complete destruction of phytic acid resulting in increased levels of lower inositol esters and inositol, which have been associated with a decreased stress response as well as having insulin-like effects. This study evaluated the impacts of high doses of phytase and two marketing strategies on growth performance and carcass characteristics of late finishing pigs. Pigs (n = 2,200; initial BW = 89.64 ± 3.08 kg) were randomly distributed to 96 pens using two commercial research barns, with 18 to 24 pigs per pen, balanced for gilts and barrows. Two phytase supplementation doses (super-dosing control of 2,250 FTU/kg and hyper-dosing at 4,500 FTU/kg) and two marketing strategies (Standard or Late) were combined to create 4 treatments in a 2×2 factorial arrangement. The first marketing event occurred at an average BW of 123.3 kg on d 22 for the Standard group and at 145.3 kg on d 44 for the Late group, marketing the heaviest 1 to 5 pigs per pen (13.2% of pigs). The second group (15.4% of pigs; BW of 147.3 and 144.8 kg for Standard and Late marketing) was marketed on d 50 and marketing of all remaining pigs occurred on d 63 for both treatments. Finisher diets contained 0.74% SID lysine, 0.60% Ca, and 0.37% available P. Regardless of the dose, phytase was given the same matrix values for nutrients and metabolizable energy. No interactions were observed between marketing strategy and phytase supplementation (P > 0.22), and no effect of phytase was observed (P > 0.09). Average BW of all pigs marketed was greater (P < 0.001) for the Late compared with the Standard marketing strategy (143.8 vs. 141.7 kg/d). Days to market was greater for Late marketing (59.7 vs. 56.8 d) as a result of the extra 22 d before the first marketing compared with the Standard strategy. Thus, average daily gain (ADG), average daily feed intake (ADFI), and gain to feed ratio were not impacted (P ≥ 0.486) by marketing treatments. Hot carcass weight (103.83 vs. 101.44 kg) and yield (78.10 vs. 77.73%) were greater (P < 0.001) for Late marketing. Fat cover was greater and percent lean was less (P < 0.05) for the Late marketing treatment, but loin depth and marbling were not different (P > 0.09). All primal cuts were heavier (P < 0.001), resulting in a total primal weight of 89.44 and 87.54 kg (P < 0.001) for Late and Standard marketing, respectively. Results suggest that delaying the first marketing improved final BW, yield, and weight of primal cuts and that supplementing phytase above super-dosing levels in late finishing pigs did not improve growth performance or carcass value, regardless of marketing strategy.