Effects of different diet alternatives to replace the use of pharmacological levels of zinc on growth performance and fecal dry matter of weanling pigs

Abstract

A total of 300 weanling pigs (Line 400 × 200, DNA, Columbus, NE, initially 4.83 kg) were used in a 46-d trial to evaluate the effects of different nutritional strategies to replace pharmacological levels of Zn, provided by zinc oxide (ZnO), in nursery diets on growth performance and fecal dry matter (DM). Six treatments with 10 replicate pens per treatment and 5 pigs per pen were used. Diets consisted of: 1) Positive control (ZnO providing 3,000 mg/kg added Zn from d 0 to 7 and 2,000 mg/kg added Zn from d 8 to 25 and 21% crude protein, CP); 2) Negative control (NC; no added ZnO); 3) NC plus 1.2% Na Diformate; 4) NC with 4% coarse ground wheat bran; 5) NC but formulated to 18% CP); and 6) The combination of NC with 18% CP, 1.2% Na Diformate, and 4% coarse ground wheat bran. The diets formulated to 18% CP contained 1.2% standardized ileal digestible (SID) Lys from day 0 to 25 whereas the 21% CP diets contained 1.4% SID Lys from day 0 to 7 and 1.35% SID Lys from d 7 to 25. From d 25 to 46, all pigs were fed a common diet. From d 0 to 7, no differences in any variables were observed between treatments. From d 7 to 25, pigs fed the diet with added ZnO had greater (P < 0.01) ADG and ADFI than all other treatments. Pigs fed the diet formulated to 18% CP had decreased (P < 0.01) ADG compared with pigs fed the other diets. From d 25 to 46, no previous treatment effects on ADG or G:F were observed. Overall (day 0 to 46), pigs fed the diet with added ZnO from d 0 to 25 had greater (P < 0.01) ADG, ADFI, and final BW than pigs fed added Na Diformate, or 4% coarse ground wheat bran, or with the 18% CP diet, with pigs fed the combination of the additives intermediate. There was no evidence for differences in overall G:F. Pigs fed the NC diet had the lowest fecal DM and highest fecal scores (P < 0.05) indicating the greatest incidence of loose stools. Pigs fed added ZnO had greater fecal DM than pigs fed the NC, 4% added wheat bran, or 18% CP diets, with pigs fed the combination of additives intermediate (P < 0.01). These results suggest that adding pharmacological levels of Zn from ZnO improves nursery pig performance and increases DM content of feces when compared with pigs fed diets with either, Na Diformate, 4% course wheat bran, or 18% CP alone. However, a combination of all 3 alternatives appeared to be additive and partially restore growth performance similar to adding pharmacological levels of Zn.

Summary of methodology used in enterotoxigenic Escherichia coli (ETEC) challenge experiments in weanling pigs and quantitative assessment of observed variability

“…The ordinal nature of this data makes sample size calculation difficult, thus, fecal DM may be a more suitable response to evaluate. Despite only one ETEC challenge study using the fecal DM approach, there are other published papers in nonchallenged pigs where fecal DM analysis was conducted ( Chance et al, 2021 ; Laskoski et al, 2021 ). Because these data are quantitative, they are typically presented in a form that allows scientists to extract measures of variability and means needed for sample size calculation.…”

Nutritional strategies to reduce the impact of Escherichia coli in newly weaned pigs

“…11,14 Nevertheless, a consistent improvement in fecal dry matter has been observed when low CP diets with no ZnO are fed compared to a standard CP diet with no ZnO signifying a lesser PWD incidence. 12,15,16 In contrast to the health promoting benefits, the biggest challenge with low CP diets is the reduction in growth performance that is often observed. 15,17,18 Supplementing low CP diets with feed-grade amino acids (AA) to meet requirements can recover some losses in performance; however, reducing CP by more than 3% has resulted in conflicting responses.…”

“…12,15,16 In contrast to the health promoting benefits, the biggest challenge with low CP diets is the reduction in growth performance that is often observed. 15,17,18 Supplementing low CP diets with feed-grade amino acids (AA) to meet requirements can recover some losses in performance; however, reducing CP by more than 3% has resulted in conflicting responses. 19 It is likely that large CP reductions lead to AA deficiencies beyond the fifth limiting AA and may begin to limit indispensable AAs.…”

“…Unfortunately, supplementation with up to 9 essential AAs or indispensable AAs, such as glycine and glutamate, still did not recover growth. 15,20 In addition to low CP diets, another way to reduce the amount of lower-digestible, plant-derived protein is to replace a portion of soybean meal with highly digestible, specialty protein sources such as spray-dried blood products, fish meal, and whey protein concentrates. These ingredients can be gradually replaced with soybean meal as the pig's ability to digest plant-derived proteins becomes more developed.…”

Post-weaning diarrhea and use of feedstuffs in pigs

“…Dietary supplementation of high levels of ZnO (2,000 to 3,000 mg/kg) has been widely used as an effective approach to reducing the incidences of post-weaning diarrhea ( Laskoski et al, 2021 ). However, using a high dose of ZnO in piglet feeds has been associated with several negative effects including neutralizing the acid in the stomach because of a high ABC, being associated with post-weaning anemia, ZnO toxicity, zinc accumulation in the environment, interacting negatively with phytase, and antibiotic resistance ( Maenz et al, 1999 ; Debski, 2016 ; Burrough et al, 2019 ).…”