ABSTRACT
The COVID-19 global pandemic greatly affected pork processing plants in the United States. These pork processing plants were forced to either temporarily close or operate at reduced capacity due to the increased number of health-related employee absences. Because finishing pigs could not be timely marketed, methods to reduce growth performance were required to keep pigs from becoming too heavy at slaughter weight. Therefore, our objective was to determine the extent that reducing dietary standardized ileal digestible (SID) Lys and tryptophan-to-lysine ratio (Trp:Lys) ratio would slow finishing pig average daily gain (ADG) in a commercial setting. A total of 1,080 finishing pigs (327 × 1050, PIC; initially 32.3 kg) were used in a 119-d growth trial. Pigs were allotted by initial body weight (BW) and randomly assigned to 1 of 4 dietary treatments in a completely randomized block design with 27 pigs per pen and 10 pens per treatment. Three dietary regimes were formulated to contain either 100%, 90%, or 80% of the estimated SID Lys requirement for pigs in this facility, with a SID Trp:Lys ratio of 19%, with the exception of the last dietary phase formulated to 17% SID Trp:Lys. Seven different dietary phases were fed. The SID Lys concentrations in the 100% diets were: 1.10%, 1.01%, 0.91%, 0.83%, 0.79%, 0.71%, or 0.67% SID Lys from 32 to 40, 40 to 51, 51 to 72, 72 to 85, 85 to 98, 98 to 112, and 112 to 130 kg, respectively. A fourth regime was formulated to 80% SID Lys with a SID Trp:Lys ratio of 16% (80-16% SID Trp:Lys) throughout all phases. Overall from d 0 to 119, ADG (linear, P < 0.001), final BW (linear, P < 0.001), and gain-to-feed (G:F) decreased (linear, P = 0.087) as SID Lys decreased from 100% to 80% of the estimated requirement. Pigs fed the 80-16% SID Trp:Lys diets had an additional decrease in ADG (P < 0.05) and G:F (P < 0.10) compared with pigs fed 80% of the SID Lys requirement with the normal Trp:Lys ratio. The reduction in SID Lys (from 100% to 80%) and reduction in SID Lys and Trp:Lys ratio resulted in an 8.6 and 11.7 kg, respectively, decrease in final BW compared with pigs fed Lys and Trp at the requirement (100%). This study provides alternatives for pork producers to reduce growth rate of finishing pigs.
ABSTRACT
Feed has been shown to be a vector for viral transmission. Four experiments were conducted to: 1) determine if medium chain fatty acids (MCFA) are effective mitigants when applied to feed both pre- and post-porcine epidemic diarrhea virus (PEDV) inoculation measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR), 2) evaluate varying levels and combinations of MCFA measured by qRT-PCR, and 3) evaluate selected treatments in bioassay to determine infectivity. In exp. 1, treatments were arranged in a 2 × 2 + 1 factorial with main effects of treatment (0.3% commercial formaldehyde [CF] product, Sal CURB [Kemin Industries, Inc.; Des Moines, IA], or 1% MCFA blend (Blend) of 1:1:1 C6:C8:C10 [PMI, Arden Hills, MN]) and timing of application (pre- or post-inoculation with PEDV) plus a positive control (PC; feed inoculated with PEDV and no treatment). All combinations of treatment and timing decreased detectable PEDV compared with the PC (P < 0.05). Pre-inoculation treatment elicited decreased magnitude of PEDV detection (cycle threshold value) compared with post-inoculation (P = 0.009). Magnitude of PEDV detection was decreased for CF compared with Blend (P < 0.0001). In exp. 2, pre-inoculation treatments consisted of: 1) PC, 2) 0.3% CF, 3 to 5) 0.125% to 0.33% C6:0, 6 to 8) 0.125% to 0.33% C8:0, 9 to 11) 0.125% to 0.33% C10:0, and 12 to 15) 0.125% to 0.66% C5:0. Treating feed with 0.33% C8:0 resulted in decreased (P < 0.05) PEDV detection compared with all other treatments. Increasing concentration of each individual MCFA decreased PEDV detectability (P < 0.042). In exp. 3, pre-inoculation treatments consisted of: 1) PC, 2) 0.3% CF, 3 to 7) 0.25% to 1% Blend, 8 to 10) 0.125% to 0.33% C6:0 + C8:0, 11 to 13) 0.125% to 0.33% C6:0 + C10:0, and 14 to 16) 0.125% to 0.33% C8:0 + C10:0. Treating feed with CF, 0.5% Blend, 0.75% Blend, 1% Blend, all levels of C6:0+C8:0, 0.25% C6:0 + 0.25% C10:0, 0.33% C6:0 + 0.33% C10:0, 0.25% C8:0 + 0.25% C10:0, or 0.33% C8:0 + 0.33% C10:0 elicited decreased detection of PEDV compared with PC (P < 0.05). Increasing concentration of each MCFA combination decreased PEDV detectability (linear, P < 0.012). In exp. 4, feed was treated pre-inoculation with: 1) no treatment (PC), 2) 0.3% CF, 3) 0.5% Blend, or 4) 0.3% C8:0 and analyzed via qRT-PCR and bioassay. Adding 0.5% Blend or 0.3% C8:0 resulted in decreased PEDV compared with PC and only PC resulted in a positive bioassay. Therefore, MCFA can decrease detection of PEDV in feed. Further, inclusion of lower levels of MCFA than previously evaluated are effective against PEDV.