Impact of soluble fiber, feed additives to lower GIT pH
By Jinsu Hong, Courtney Sellner and Crystal Levesque Canola meal is a high protein source with good amino acid profile, however the inclusion in poultry diets has been limited due to glucosinolates (GIs) toxicity. The toxicity of glucosinolates from dietary canola coproducts can be potentially alleviated by modification of the pH of gastrointestinal tract in the monogastric animals. (Bones and Rossiter, 2006; Frandsen et al., 2019, Lee et al., 2020). Since a dietary soluble fiber source (barley), acidifier, encapsulated butyrate or lactic acid-producing probiotics can reduce pH of the gastrointestinal tract in broilers, our hypothesis was this would result in increased degradation of glucosinolates into less toxic glucosinolate degradation products. The objective of our research was to investigate the potential of feed additives that can lower GIT pH to alleviate the toxicity of glucosinolate degradation products in broiler chickens. We examined the effects of a soluble fiber source or feed additive supplementation in cold-pressed canola cake (CPCC) containing diets on growth performance, organ weights, and blood thyroid hormones, and pH of digesta of broilers. A total of 96 one-day-old broilers were assigned to six dietary treatments, consisting of eight cages with two birds each. The diets included a corn-soybean meal (SBM)-based diet and corn-SBM-CPCC 20% diets without or with barley, acidifier, encapsulated butyric acid and probiotics. Birds were fed a commercial diet for the first week and fed experimental diets for two weeks. Body weight (BW) and feed intake of broilers were measured on days 7 and 21. On day 21, all birds were euthanized to collect samples of blood, organs and digesta.
Collected blood samples were analyzed for serum concentrations of triiodothyronine (T3) and tetraiodothyronine (T4), and pH of digesta in gizzard, ileum, ceca and large intestine was measured. Broilers fed CPCC diet with butyric acid or probiotics had greater (P<0.05) growth performance than broilers fed CPCC diet. There were no significant differences in relative weights of thyroid glands and liver to BW. Supplementation of either butyric acid or probiotics in CPCC diets reduced (P<0.05) serum T3 concentration compared to CPCC diet by 34% and 21%, respectively.
Also, supplementation of butyric acid in CPCC diet showed no difference in serum T3 concentration compared to corn-SBM diet.
Dietary treatments in CPCC diets did not affect pH of digesta in gizzard and ileum, whereas supplementation of barley or acidifier decreased pH of cecal digesta compared to that of broilers fed CPCC diet by 0.5 and 0.51 pH units, respectively. In summary, dietary CPCC significantly reduced growth performance with increased serum T3 concentration due to dietary glucosinolates. Dietary CPCC increased pH of cecal digesta compared to corn-SBM diet. Dietary barley (soluble fiber source) did not affect the growth performance, whereas it decreased serum T3 level and the pH of cecal digesta in broilers fed CPCC diets. Dietary acidifier improved FCR and reduced pH of cecal digesta in broilers fed the CPCC diets. However, it did not affect serum T3 and T4 levels and relative organ weights. Dietary encapsulated butyrate improved growth performance with decreased serum T3 concentration in broilers fed CPCC diets. It had no significant influence on the relative organ weights and intestinal pH. Dietary probiotics improved the growth performance with decreased serum T3 concentration in broilers fed CPCC diets. It also decreased relative weight of heart, whereas it did not affect the pH of intestinal sections. Supplementation of encapsulated butyric acid in the 20% CPCC diet can improve growth performance of broilers by mitigating the toxic effects of dietary CPCC as evidenced by reduced serum T3 concentration.
Hong is a research associate, Sellner is an undergrate and Levesque is an associate professor, all with the Department of Animal Science, South Dakota State University.
