The cardinal Physiology of Gut Health in monogastric animals such as swine and poultry is vital. It is critical for digestive efficiency, immune status, and production levels. This system is related not only to the digestion and absorption of nutrients from feed ingredients contributing to growth and feed utilization efficiency but also to having a strategic microbiota that supports immunity and pathogen resistance, as well as metabolic support. Gut disease, for example, bacterial, viral, or parasitic infection, diet, or stress, can reduce nutrient digestion and absorption. They can also suppress the immune system and render patients more prone to disease. These are efficiency degradations and increase veterinary and husbandry costs. In addition, nutrient absorption because of deteriorated gut health can affect the environment in different ways: removal of nutrients through leaching and the release of gases (including CH₄ and NH₄). These pressures have led to a focus on the gut in animal research to improve the welfare of animals and ensure sustainable practices in animal production. Recent studies have included the use of probiotics, prebiotics, and other feed additives to enhance the positive effects of the gut microbiota. These are also intervention points to increase nutrient absorption and animal well-being, in turn sustainability. Such approaches are expected to promote a stable microbial community with less dependence on the use of antibiotics, less waste generation, and less environmental impact from animal farming. This review provides a critical evaluation of the current literature on gut health in monogastric livestock, with pigs and poultry as the principal focus. We also considered the impact of gut health on production efficiency and Environmental sustainability. Current progress in nutritional modulation of gut health for increased productivity, enhanced animal welfare, and better profitability are presented. Gut-related biological mechanisms are linked to practical nutritional strategies, and subsequently to animal welfare, production efficiency, and environmental effects, offering a coherent concept for moving from mechanism to system-level sustainability.

Fodder tree leaves (FTL) are limitless nutrient resources that provide high-quality feed, particularly during the dry season, improving animal diets, and reducing the use of concentrates in ruminant livestock farming. In order to determine the benefits of FTL, two experiments were conducted to measure the voluntary feed intake, growth performance, and nitrogen utilization of forest-type (FT) sheep fed rice straw (RS) and supplemented with either Leucaena leucocephala (LEU) or Samanea saman (SAM) or their equal combination (LS). For the growth trial (Experiment 1), 12 male FT sheep with mean initial body weight (BW) of 17.0 ± 1.0 kg (mean ± SD) were randomly assigned to one of four dietary treatments in a Completely Randomized Design. The diets were Urea-treated RS (UTS) (Control), RS + L (LEU), RS + S (SAM), and RS + 50% L + 50% S (LS). After 14 d of adjustment period, feed intakes and refusals were recorded daily, whereas BW was recorded bi-weekly for 12 wk. Four rams weighing 17.0 ± 1.0 kg BW were randomly assigned to the four treatments over a four period in a repeated (4 × 4) Latin square design to estimate the nitrogen (N) balance study (Experiment 2). Treatment diets were the same as that of Experiment 1. Dry matter intake of straw was highest (P = 0.0001) for sheep fed UTS. However, combining L with S increased (P = 0.0001) straw DM intake compared to feeding L or S alone. There was no significant difference (P > 0.05) in total feed intake between sheep offered UTS and LS, but both were significantly higher (P = 0.0001) than those offered LEU and SAM. Body weight gain (3.70 kg) and growth rate (196.15 g/d) were highest (P = 0.0001) for sheep offered LS compared to the other treatment groups. Values for N balance differed (P = 0.0001) among treatment diets. N balance for LUE and LS supplemented diets were higher than that of SAM but all were higher (P = 0.0001) than those offered UTS. Leucaena and Samanea leaves could, therefore, be utilized as supplement to poor-quality straws to improve the productivity of small ruminants especially during the long dry seasons in the tropics.

The study evaluated the effect of harvesting date on the chemical composition and in vitro gas production of the botanic fractions of Brachiaria decumbens grass. The botanic fractions (leaf, stem and whole plant) of the grass at two maturities (60 and 120 days) in a Completely Randomised Design with factorial arrangement. Samples of botanic fractions at the different harvest dates were chemically analyzed for dry matter (DM), crude protein (CP), fibre concentrations and in vitro gas production (IVGP) was measured at 3, 6, 9, 12, 24, 36, 48, 72 and 96 h to estimate the volume and rate of gas production. Short-chain volatile fatty acids, microbial protein production, in vitro organic matter digestibility, and metabolizable energy were estimated from established models. Organic matter, crude fibre, NDF, ADF and ADL increased (P<0.05) with increasing maturity whereas the reverse was so for CP and ash contents (P<0.05). Significant interactions (P<0.05) between harvest date and plant fraction were present for both ‘b’ and ‘c’ attributable to treatment effects. Potential gas production ‘b’ elicited a negative response for all plant fractions across the two harvest dates as the values decreased linearly. The rate at which the gases were produced ‘c’ also induced a negative response for the leaf and whole fraction but a positive one for the stem fraction. The nutrient composition and gas production characteristics of grasses harvested at day 60 offer a better potential as high quality forage for improved intake and digestibility. The leaf fractions performed relatively better based on the afore-mentioned methods of quality assessment at both maturity periods.