Antimicrobial promotion of pig growth is associated with tissue-specific remodeling of bile acid signature and signaling

The spread of bacterial resistance to antimicrobials (AMA) have intensified efforts to discontinue the non-therapeutic use of AMA in animal production. Finding alternatives to AMA, however, is currently encumbered by the obscure mechanism that underlies their growth-promoting action. In this report, we demonstrate that combinations of antibiotics and zinc oxide at doses commonly used for stimulating growth or preventing post-weaning enteritis in pigs converge in promoting microbial production of bile acids (BA) in the intestine. This leads to tissue-specific modifications in the proportion of BA, thereby amplifying BA signaling in intestine, liver, and white adipose tissue (WAT). Activation of BA-regulated pathways ultimately reinforces the intestinal protection against bacterial infection and pathological secretion of fluids and electrolytes, attenuates inflammation in colon and WAT, alters protein and lipid metabolism in liver, and increases the circulating levels of the hormone FGF19. Conceivably, these alterations could spare nutrients for growth and improve the metabolic efficiency of AMA-treated animals. This work provides evidence that BA act as signaling molecules that mediate host physiological, metabolic, and immune responses to the AMA-induced alterations in gut microbial metabolism, eventually permitting the growth-promoting action of AMA. Consequently, BA emerge as a promising target for developing efficacious alternatives to AMA

Influence of Dietary Flavours on Sheep Feeding Behaviour and Nutrient Digestibility

The aim of the present study was to assess whether the feeding pattern displayed by sheep exposed to a monotonous ration is modified when the same ration is presented in a diversity of flavours and if such diversity influences nutrient intake and digestibility. Twelve commercial crossbred wether lambs were assigned to two groups. Six lambs/period (three lambs/group.period) were housed in metabolic crates during two successive periods. One group of lambs (Diversity, D) was fed simultaneously an unflavoured ration of alfalfa, barley, beet pulp and urea (55 : 35 : 9 : 1) and the same ration supplemented (0.2%) with one of the following two flavours: (1) sweet, and (2) umami. The other group (Monotony, M) received only the unflavoured ration. All animals were fed their respective rations ad libitum from 0800 hours to 1600 hours for 26 days in each period. Day 19 was used for assessing the lamb feeding pattern every 30 min for 8 h, and the last 6 days of the period were used for estimating in vivofood digestibility. Lambs in D tended to ingest more acid detergent fibre (ADF; P = 0.10) and to have a lower crude protein digestibility (P = 0.08) than did lambs in M. Nevertheless, average daily DM intake did not differ between treatments (P = 0.22) and lambs in M and D digested the same amount of DM, neutral detergent fibre, ADF and N (P \u3e 0.10). Flavour diversity did not affect N retained, N retained/N consumed, or ruminal pH 1 h after feeding (P \u3e 0.10). Lambs in D showed greater intakes than did those in M during 30 (P = 0.006), 60 (P = 0.02), 90 (P = 0.02), 120 (P = 0.04) and 180 min (P = 0.07) after offering the rations. Results suggest that changes in eating behaviour occurred only during the first part of the feeding period, leading to slight changes in ADF intake and crude protein digestibility, which did not impact nutrient utilisation

Interactions between mild nutrient imbalance and taste preferences in young ruminants

Thirty-two crossbred lambs (BW = 31.2 ± 4.7 kg; 16 females, 16 males) housed in individual pens were used to investigate the relationship between nutrient supply and taste preferences in ruminants. Experiment 1 determined whether an imbalanced CP supply would alter preferences for feeds containing flavors designed to elicit either umami (U) or a mixture (1/3:1/3:1/3) of umami, sweet, and bitter (M) tastes. Lambs were randomly allocated to either a low (LP; 10.9% CP) or a high (HP; 20.4% CP) CP diet for 21 d. Afterward, lambs were presented during 21 d with a choice of the same LP or HP diet unflavored (LPC or HPC, respectively) or flavored (0.1% as fed) with U (LPU or HPU, respectively) or M (LPM or HPM). Experiment 2 determined the influence of CP status on preference for dietary CP, bitter taste, and sweet taste elicited by sucrose or a noncaloric sweetener. In test 1, sixteen lambs previously fed LP or HP for 42 d in Exp. 1 could choose between the HP and LP diets. In test 2, the remaining 16 lambs from Exp. 1 were offered a choice between unflavored LP or HP diets or the same diets flavored (0.066% as fed) with a bitter flavor. In test 3, the 16 lambs from test 1 were offered a choice between an unflavored diet (LP or HP) and the same diet flavored with sucrose (0.2%) or a noncaloric sweetener (0.066%). In Exp. 1, when offered a choice, all lambs showed a preference (P \u3c 0.05) for the unflavored diet except for LP lambs, who clearly preferred (P\u3c 0.05) LPU (72% of total DMI) over LPC. However, preference for LPU progressively decreased (P \u3c 0.05) as time of exposure to the choice increased. In Exp. 2 (test 1), lambs previously fed LP progressively increased (P \u3c 0.05) total DMI when presented with LP and HP, whereas consumption was constant for lambs previously fed HP and offered a choice of LP and HP diets. At the onset of test 2, lambs fed LP progressively reduced (P \u3c 0.05) preference for the bitter flavor from 53 to 34%. In test 3, lambs previously fed LP diets consumed less (P \u3c 0.05) sweetener- than sucrose-supplemented diet, whereas lambs previously offered HP diets consumed more sweetener- than sucrose-supplemented diet. In summary, protein-restricted lambs were able to differentiate and increase consumption of U-flavored feeds. However, this increase disappeared over time. These results indicate that lambs are able to sense dietary CP content and modulate short-term consumption of flavored feeds based on their nutrient requirements

A comparative review of the flow of nitrogen fractions at the omasal canal and duodenum of dairy cows

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Antimicrobial promotion of pig growth is associated with tissue-specific remodeling of bile acid signature and signaling

The spread of bacterial resistance to antimicrobials (AMA) have intensified efforts to discontinue the non-therapeutic use of AMA in animal production. Finding alternatives to AMA, however, is currently encumbered by the obscure mechanism that underlies their growth-promoting action. In this report, we demonstrate that combinations of antibiotics and zinc oxide at doses commonly used for stimulating growth or preventing post-weaning enteritis in pigs converge in promoting microbial production of bile acids (BA) in the intestine. This leads to tissue-specific modifications in the proportion of BA, thereby amplifying BA signaling in intestine, liver, and white adipose tissue (WAT). Activation of BA-regulated pathways ultimately reinforces the intestinal protection against bacterial infection and pathological secretion of fluids and electrolytes, attenuates inflammation in colon and WAT, alters protein and lipid metabolism in liver, and increases the circulating levels of the hormone FGF19. Conceivably, these alterations could spare nutrients for growth and improve the metabolic efficiency of AMA-treated animals. This work provides evidence that BA act as signaling molecules that mediate host physiological, metabolic, and immune responses to the AMA-induced alterations in gut microbial metabolism, eventually permitting the growth-promoting action of AMA. Consequently, BA emerge as a promising target for developing efficacious alternatives to AMA