Effect of narasin (Skycis) or zinc bacitracin (Albac) inclusion on the growth performance and carcass characteristics of finishing pigs sent for slaughter using a 3-phase marketing strategy

Abstract

The objective of this study was to evaluate the effect of dietary inclusion of narasin or zinc bacitracin on the growth performance and carcass characteristics of finishing pigs sent for slaughter using a 3-phase marketing strategy. The study used 2,219 crossbred pigs in a randomized complete block design (blocking factor = start date) with 3 dietary treatments: 1) Control (no feed additive), 2) 15 mg/kg narasin (Skycis, Elanco Animal Health, Greenfield, IN), and 3) 28 mg/kg zinc bacitracin (Albac, Zoetis, Parsippany, NJ). Pigs were housed in single-sex pens of 25 pigs in a commercial wean-to-finish facility and there were 30 pen-replicates of each dietary treatment. All pigs were weighed as a group (i.e., pen) on d 0 (start of experimental feeding period), 77, 91, and 105 (end) of study. Pigs had ad libitum access to feed and water throughout the study period; all feed additions to the feeder were recorded. Pigs were sent for slaughter according to the following marketing strategy: 1) after 77 d on study, the heaviest 20% of each pen was sent for slaughter (Phase 1), 2) after 91 d on study, the next heaviest 48% of each pen were sent for slaughter (Phase 2), and 3) after 105 d on study, the remaining 32% of each pen was sent for slaughter (Phase 3). Pigs within each pen were selected for slaughter by visual appraisal of weight and shipped to a commercial slaughter facility where standard carcass measurements (HCW, LM depth, and backfat depth) were measured. Feeding narasin increased (P < 0.05) final live BW (1.3 kg) and overall ADG (1.1%) compared to the other treatments, which were similar (P > 0.05). Dietary treatment did not impact (P > 0.05) overall G:F. Feeding narasin increased (P < 0.05) HCW (1.4 kg) and carcass yield (0.3% units) compared to the other dietary treatments, which were similar (P > 0.05) for these traits. Overall, these results demonstrate that narasin-fed pigs had improved overall growth rate, HCW, and carcass yield compared to controls or pigs fed zinc bacitracin.

Effects of narasin or virginiamycin on growth performance and carcass characteristics of growing and finishing pigs

“…1 and 2, respectively. This is consistent with published research from Rickard et al (2017) that reported that 15 ppm of NAR increased carcass yield by 0.4 percentage units. Published commercial research on finishing pigs in a commercial environment using these two molecules is limited, especially among the studies that reported carcass data.…”

“…Past research on VIR does not indicate any effect of the antibiotic on any carcass parameter ( Castell, 1977 ). In contrast, Shircliff et al (2018) and Rickard et al (2017) reported that NAR significantly increased HCW because of greater final BW. In the studies reported herein, NAR increased carcass yield 0.5 and 0.3 percentage units versus control in Exp.…”

“…2 did not contain DDGS. Research completed in a commercial environment also using diets containing 20% DDGS reported NAR improved ADG without affecting G:F ( Rickard et al, 2017 ). The small-pen study by Kerr et al (2017) investigated the effects of NAR in diets with or without byproducts and reported similar results in performance due to NAR regardless of diet type from 23 kg through harvest.…”

“…The mechanism of action of this ionophore is to increase energy availability by altering volatile fatty acid production in the hindgut in favor of propionate, which is the most energy efficient product of fermentation ( Wuethrich et al, 1998 ). Multiple studies have shown that NAR fed at 15 ppm increases ADG ( Arentson et al, 2016 ; Knauer and Arentson, 2017 ; Rickard et al, 2017 ) and G:F ( Arentson et al, 2016 ; Fruge et al, 2016 ; Knauer and Arentson, 2017 ) compared to pigs receiving no ionophore. At the time of this research, no other studies had compared NAR to any other growth-promoting product.…”

Identification of Independent and Shared Metabolic Responses to High-Fiber and Antibiotic Treatments in Fecal Metabolome of Grow–Finish Pigs

“…The addition of bacitracin did not change weight gain, though it tended to improve feed intake in the current study. This result is not surprising, as growth performance enhancement by AGPs is more commonly observed in nursery pigs [ 10 , 44 ], and the grow–finish pigs in this study were raised through good barn hygiene. Nevertheless, the metabolic influences of bacitracin were still detected through fecal metabolomic analysis.…”