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540 broilers were fed 90%, 100% or 110% of NRC arginine and methionine for 42 days. Correcting the 90% deficiency increased weight gain and improved feed conversion. Arginine also increased spleen and bursa weight and antibody responses to bronchitis and Gumboro, and methionine improved the Gumboro response.
Broilers fed 100%, 105% or 110% of recommended arginine were challenged with a mix of Eimeria species. Coccidiosis reduced weight gain and carcass yield and damaged the gut lining. Arginine at 105–110% prevented the drop in weight gain, improved feed conversion and gut villi, and 110% gave the lowest oocyst count in faeces.
Broilers were fed soy oil, soy free fatty acids or palm fat powder, with or without lysophosphatidylcholine (LPC, an emulsifier), on corn- or wheat-based diets. Soy free fatty acids gave results similar to soy oil, and LPC improved weight gain by 4.6% and feed conversion, especially with soy free fatty acids.
This review explains the immune roles of three key amino acids. Methionine supports antioxidant defence and lymphocyte growth, arginine works through nitric oxide and polyamines, and threonine is part of antibodies and gut mucus. Arginine needs for proper immunity are clearly higher than for growth alone.
150 hens aged 68 weeks received 0–2 g/kg MOS for 70 days. At 1–1.5 g/kg, MOS increased egg production and egg mass, improved protein digestibility, raised antibody titres against Newcastle and bronchitis, and reduced Salmonella and E. coli in the gut.
450 broilers were fed feed contaminated with 0–2 ppm aflatoxin B1 from day 7 to 21. Aflatoxin lowered antibody titres to Newcastle and bronchitis vaccines, raised liver enzymes, and at 1.5–2 ppm caused fatty liver and liver fibrosis.
Poorly processed soybean meal was extruded and fed to broilers. Extrusion raised the digestibility of protein and several amino acids and improved weight gain and feed conversion. With extruded meal, dietary protein could be lowered by about 9% without hurting performance.
35 Holstein calves received milk alone or milk with 15% or 30% probiotic yogurt (pH 3.8 or 4.5) until two weeks after weaning. Yogurt increased daily and total weight gain, improved feed conversion and body growth measures, and shifted white blood cells toward a healthier profile.
Zinc sulfate or zinc oxide in broiler diets was replaced by zinc-methionine at 25–100%. Zinc-methionine improved weight gain in all periods, increased breast meat and carcass yield, reduced abdominal fat, and lowered blood uric acid and triglycerides.
Broilers kept at 35 °C from day 15 to 42 ate less, grew less and had weaker immune responses. Adding chromium-methionine (500–1000 µg/kg) increased feed intake, weight gain and feed efficiency, and the benefit was larger in heat-stressed birds. 500 µg/kg also restored part of the immune response.
360 Hy-Line hens were kept at 5 or 7 birds per cage. Crowding lowered egg production, egg mass and feed intake. Chromium-methionine increased egg production and egg mass, and worked together with vitamin C to improve production and feed conversion.
In the same model of crowded cages, hens given chromium-methionine (500 or 1000 µg/kg) and vitamin C were checked for egg quality and antioxidant capacity in blood and yolk. Chromium-methionine increased antioxidant capacity in stressed hens and improved their production.
180 laying hens (55 weeks old) exposed to E. coli received 0–0.2% mannan-oligosaccharides (MOS, from yeast cell wall). At 0.1–0.15%, MOS increased egg production and egg mass and improved feed conversion, likely by changing gut bacteria and improving nutrient digestibility.
675 broilers received genistein (a soy isoflavone) at 10–320 mg/kg, antibiotics, or no additive. 20–80 mg/kg genistein improved weight gain and feed conversion, similar to antibiotics, and gave stronger immune responses. Higher doses reduced immune responses again.
720 quail of two species were fed 2800–3000 kcal/kg energy and 22–26% protein for 42 days. Higher energy and protein improved weight gain, feed conversion and carcass yield, and Japanese quail performed better than brown quail.
432 broilers were fed 90–100% of Ross protein recommendations with 100–120% threonine. After the starter period, protein could be cut by up to 10% without harming growth, and threonine up to 110% of Ross values helped make up for slower growth on low-protein diets.
540 broilers were fed three energy levels with or without choline (1000 mg/kg) or L-carnitine (100 mg/kg). Choline in particular improved feed conversion. Both additives lowered liver enzymes (ALT, AST) and oxidation markers in blood, signs of better liver health.
225 young laying hens had 25–100% of the soybean oil in their diet replaced by two commercial palm fatty acid powders. Palm fat improved Haugh unit and yolk stability against oxidation. Up to 75% of the soy oil could be replaced without harming production or egg quality.
25 Afshari lambs were fed no added fat, or 2.5–5% of either calcium salts of fatty acids or camel hump fat, for 90 days. Camel hump fat gave higher daily gain and better feed conversion than the control, and increased antibody (IgG) response.
650 broiler chicks received zinc from organic sources (zinc-methionine, zinc-proteinate) or inorganic sources (zinc sulfate, zinc oxide) at 40–120 mg/kg. Organic zinc increased feed intake, weight gain and breast and carcass yield. At 80 mg/kg, zinc-methionine gave the best antibody response to Newcastle and Gumboro vaccines.
In a 14-day trial with 650 young broilers, organic zinc raised weight gain and zinc levels in blood, bone and heart more than zinc sulfate or oxide. Compared with zinc sulfate, the relative bioavailability was 232% for zinc-methionine and 174% for zinc-proteinate.
150 hens aged 56 weeks received 0.05–0.2% MOS for 77 days. MOS lowered blood triglycerides and LDL, raised HDL, and at 0.10–0.15% improved digestibility of dry matter, protein and fat. Antibody responses were not changed in this trial.
150 laying hens were fed corn- or wheat-based diets with 0, 0.25 or 0.5% butyric acid (glyceride form). Butyric acid reduced E. coli in the gut and improved fat and mineral digestibility, with a clearer effect in wheat-based diets.
150 hens aged 56 weeks received 10–160 mg/kg genistein. Genistein did not change ovarian follicles, but at 40–80 mg/kg it increased calcium and phosphorus in the tibia bone.
550 broilers aged 21–42 days were fed 17% or 20% protein with 80–120% of NRC threonine. The 17% protein diets reduced weight gain, feed efficiency and antibody response, and even high threonine could not fully bring them back to the control level.
875 broilers received MOS at 0.05–0.25%, virginiamycin, or no additive. Birds on MOS were heavier at 21 and 42 days, and 0.10% MOS gave the best feed conversion, followed by 0.20% MOS and virginiamycin. MOS also increased gut villus height.
540 broilers were fed standard protein or 1–2 points less, with or without 0.25% citric or butyric acid. Organic acids improved antibody responses to bronchitis and Gumboro, and butyric acid improved the Newcastle response.
715 broiler chicks were fed 80–120% of the recommended arginine at two protein levels for 21 days. Low arginine and low protein reduced growth, thymus and spleen weight and the Newcastle antibody response. The arginine needed for best immunity (107% of NRC) was higher than for best growth (101%) or feed efficiency (103%).
Two inorganic (zinc sulfate, zinc oxide) and three organic (zinc acetate, zinc-methionine, zinc-lysine) sources were tested at 40, 80 and 120 mg/kg from day 1 to 42. Organic sources increased feed intake and weight gain compared with inorganic ones and improved feed conversion after the first week.
240 broilers were fed diets with or without added oil, where choline was replaced by betaine at 0, 50 or 100%. Betaine did not change feed intake, but increased dressing and breast meat percentage, reduced abdominal fat, and lowered blood triglycerides.
