Performance responses and indicators of gastrointestinal health in early-weaned pigs fed low-protein amino acid-supplemented diets1

Abstract

The effects of low-protein AA-supplemented diets on piglet performance, visceral organ mass, incidence of diarrhea, intestinal microbial population, and fermentation were studied in a 3-wk trial. After a 7-d adaptation period, 96 piglets (approximately 6.2 kg of initial BW) were assigned to 4 corn-wheat, soybean meal-based dietary treatments in a completely randomized design to give 6 replicate pens per treatment (n = 4 piglets per pen). The treatments were a control wheat-corn-soybean meal-based phase I diet containing 23% CP, or the same diet with CP reduced to 21%, 19%, or 17% and supplemented with crystalline AA to achieve equal standardized ileal digestible contents of Lys, Met plus Cys, Thr, and Trp in all diets. Diets were formulated to similar nutrient levels and provided ad libitum. Blood from all pigs was taken on d 0, 7, 14, and 21 for determining plasma urea N. Weekly feed intake, BW changes, and G:F were determined. On d 21, 2 pigs per pen were randomly selected and killed to determine small intestinal morphology, digesta pH and ammonia levels, and luminal microbial counts. Average daily feed intake, ADG, and G:F were not affected (P > 0.10) by reducing CP to 21%, but a reduction to 19% or 17% decreased ADFI (P < 0.001) and ADG (linear, P < 0.001; quadratic, P < 0.05) over the 3-wk study period. Reducing CP to 19% had no effect (P > 0.10) on G:F; however, this response criterion was decreased linearly (P < 0.001) over the 3-wk study period as dietary CP declined. Water usage was only numerically decreased (P > 0.10) with dietary CP reduction. Plasma urea N was decreased linearly (P < 0.01) with CP reduction. Reducing CP from 23 to 17% had a linear (P < 0.05) and cubic effect on stomach and liver weights, respectively. Although histological data showed some differences among diets, no distinct trend was evident. Ammonia N in ileal digesta was reduced linearly (P < 0.01) as dietary CP was decreased. With the exception of valeric acid, VFA levels in ileal digesta of piglets fed low-protein diets were generally lower (P < 0.05) compared with the control diet. Diet had no effect on intestinal microbial counts (P > 0.10). The results show that piglet performance may suffer when dietary CP is reduced by 4 or more percentage units from 23% and support the hypothesis that low-CP diets help maintain enteric health in pigs by lowering toxic microbial metabolites such as ammonia.

Effects of low-protein diets supplemented with indispensable amino acids on growth performance, intestinal morphology and immunological parameters in 13 to 35 kg pigs

“…PUN concentration is mostly dependent on the amounts and balance of AA (Nyachoti et al, 2006;Yue and Qiao, 2008). Previous studies have also reported that there were reductions in PUN concentration by feeding low-CP diets TLR = toll-like receptor; MyD88 = myeloid differentiation factor 88; TRAF-6 = TNF receptor-associated factor 6; NF-κB = nuclear factor kappa B; TOLLIP = toll-interacting protein; IL-1β = interleukin-1 beta.…”

“…It is well documented that reducing dietary CP level from 16% to 12%, supplemented with indispensable amino acids (IAA), could maintain similar growth performance as pigs fed control diet (Figueroa et al, 2002 andKerr et al, 2003). In addition, a moderate reduction of dietary CP level has been shown to decrease the harmful microbial metabolites in the digesta such as ammonia N (Nyachoti et al, 2006;Opapeju et al, 2008), as well as improving the villous morphology of weaned piglets (Gu and Li, 2004;Opapeju et al, 2008). In contrast, several studies have shown that pig growth performance can decrease when the dietary CP level is reduced by more than 4% , even though supplemented with IAA (Powell et al, 2011;Gloaguen et al, 2014), moreover, poor intestinal growth and morphology, reduced disaccharidase activities in small intestine were observed in pigs receiving extremely low-CP diets Yue and Qiao, 2008).…”

“…Peng, Hu, Liu, Yan, Fang, Lin, Xu, Li, Wu, Chen, Sun, Wu and Che (Figueroa et al, 2002;Nyachoti et al, 2006). Besides, reducing dietary CP level from 20.00% to 13.90% resulted in higher plasma concentrations of lysine, methionine and alanine, this response is in agreement with previous reports that the higher protein degradation of pigs occurred in pigs fed low-CP diet, thus increased the plasma concentration of some free AA .…”

Effects of dietary protein supply, weaning age and experimental enterotoxigenic Escherichia coli infection on newly weaned pigs: performance

“…Consequently, focus has been shifted to finding alternative, nonpharmaceutical, strategies for the prevention and control of PWC, such as the manipulation of dietary ingredients, to minimise substrate availability to ETEC within the distal small intestine and modification of management practices. It has been suggested that PWC is sensitive to dietary protein supply and that it may be possible to limit the extent of PWC by lowering the protein content of the diet (Prohá szka and Baron, 1980;Nyachoti et al, 2006;Wellock et al, 2006). However, Nyachoti et al (2006) and Wellock et al (2006) also noted detrimental effects on performance with a decrease in protein supply.…”

Effects of dietary threonine:lysine ratios on growth performance, blood urea nitrogen, and nitrogen balance in weaned pigs

“…It has been well accepted that the use of crystalline amino acids (AA) in low crude protein (CP) diets can reduce the nitrogen excretion in swine manure by more than 35% (Le et al 2006;Nyachoti et al 2006).…”