Effects Of Cyadox On Absorption And Deposition Of Nutrients In Swine

Quinoxalines were a group of synthetic antibacterial agents which were widely used as antibacterial growth promoters in animals. Olaquindox, Quinocetone and mequindox have been approved to use as feed additives in China. However, olaquindox and mequindox have been recently forbidden or limited to use because of their side effects, such as mutagenicity, photo-toxicity, accumulation toxicity, etc. Cyadox was a new compound of the quinoxaline-1, 4-dioxide family at the exploitation stage. The recent researches showed that cyadox can enhance the growth and FCR, improve carcass traits and meat quality in poultry, lambs and cattle with lower toxicity compared with olaquindox. Furthermore, cyadox had the advantages of quick absorption, rapid elimination, short-term residue in animal tissues and no accumulation toxicity. However, effects of cyadox on growth, absorption and retention of nutrients in swine were not clear. The research investigated the effects of cyadox on the growth performance, carcass traits and meat quality, absorption and retention of nutrients. At the meanwhile, the relationship of the growth promotion of cyadox with animal nutritional physiology, metabolic regulations, intestinal flora and its metabolites were elucidated.1. Cyadox promoted growth and deposition of nutrient in pigs In order to study the effects of cyadox on growth and retention of nutrients in pigs, one hundred Landrace×Large White crossbred barrows, weaned at 35 days of age, were randomly allotted to five treatments with five replicates. The treatments were: one control fed the basal diet without any antimicrobial, one group fed the diet containing 50 mg/kg olaquindox, and the other three groups fed the diets containing 25, 50 and 100 mg/kg cyadox, respectively. The animals at the start of the 7-day adaptation period were fed a basal diet containing no antibiotics. At the age of 42 d the piglets entered the experiment. The experiment period lasted 130 d in four phases (1, from d 0 to 40; 2, from d 41 to 68; 3, from d 69 to 95; 4, from d 96 to 130). Average daily gain (ADG), average daily feed intake (ADFI) and feed conversion ratio (FCR) were determined in each phase. At the end of each phase, five pigs were slaughtered to determine cyadox effects on carcass traits and meat quality. Longissimus muscle, liver, left femur and left tibia were sampled to analyze their chemical composition.Three doses of cyadox (25, 50 and 100 mg/kg) improved ADG and FCR by 5.4% (P＞0.05) and 10.4% (P＜0.05), 9.9% (P＞0.05) and 15.0% (P＜0.01), 24.3% (P＜0.01) and 15.8% (P＜0.01) in phase 1. ADG and FCR for pigs fed cyadox at 100 mg/kg were higher (P＜0.01) than those for pigs supplemented with 50 mg/kg olaquindox. In phase 2, 25 to 100 mg/kg cyadox improved (P＞0.05) ADG and FCR by 4.4% to 6.8% and 2.7% to 5.9%. ADG for pigs fed at cyadox at 50 and 100 mg/kg were higher (P＞0.05) than those for pigs in olaquindox. In phase 3, 25, 50 and cyadox improved ADG by 4.7% to 9.2% (P＞0.05), improved FCR by 4.0% (P＞0.05), 8.1% (P＜0.01) and 8.1% (P＜0.01), respectively. In phase 4, 25 to 100 mg/kg cyadox improved ADG and FCR by 2.9% to 6.4%, 1.8% to 8.3%, respectively. ADG and FCR for pigs fed cyadox at 25, 50 and 100 mg/kg were higher than those for pigs supplemented with 50 mg/kg olaquindox in phases 3 and 4. The results indicated that the optimum effective dose of cyadox in pigs was 50 to 100 mg/kg, the optimum supplementation period for pigs was 95 days.On d 95, inclusion of cyadox at 25, 50 and 100 mg/kg improved dressing percentage by 3.3% to 3.8% (P＞0.05), increased lean percentage by 3.4% to 8.6% (P＞0.05), enhanced longissimus muscle area (LMA) by 7.4% to 14.5% (P＞0.05), while fat percentages and backfat thickness decreased by 12.4% to 29.0%, 7.7% to 14.8%, respectively. On d 130, dressing percentage, lean percentage and LMA for pigs fed diets containing 25, 50 and 100 mg/kg cyadox increased by 4.2% to 5.2%, 2.7% to 3.1%, 17.9% to 31.4%, respectively, while fat percentages and backfat thickness decreased by 7.7% to 11.5%, 7.0% to 17.8%. It is obvious that cyadox, especially at the dose of 50 and 100 mg/kg, improved carcass charateristics.Inclusion three different doses of cyadox did not affect contents of moisture, crude protein, fat and ash in porcine muscle and liver. However, moisture content in porcine muscle and liver decreased as age of pigs increased, meanwhile, contents of crude protein, fat and ash increased. Compared with control, cyadox did not affect concentration and composition of amino acid of porcine muscle, did not affect concentration and composition of fatty acid in porcine muscle and liver.The three doses of cyadox (25mg/kg, 50mg/kg, and 100mg/kg) increased the retinol content of the muscle by 33.5% (P＜0.05), 60.2% (P＜0.01) and 78.0% (P＜0.01), respectively, increased retinol content of the liver by 17.4% (P＞0.05), 20.1% (P＞0.05) and 24.0% (P＜0.05). Meanwhile, tocopherol content of the muscle and live was elevated by 6.5% (P＞0.05) and 24.4% (P＜0.05), 9.2% (P＞0.05) and 26.3% (P＜0.05), 10.2% (P＞0.05) and 29.8% (P＜0.05), respectively.The contents of calcium, magnesium, phosphorus, iron, copper, zinc and manganese in the muscle and liver ranged within the physiological limits. As for the muscle, the content of iron, the content of copper on d 40 and the content of zinc on d 68 increased, but the content of manganese was not affected. The contents of calcium (P＜0.05), magnesium (P＞0.05), iron (P＜0.05), copper (P＞0.05), zinc (P＞0.05) and manganese (P＜0.05) in the liver for pigs fed cyadox increased, but phosphorus was not affected. Cyadox significantly increased the contents calcium, iron, and manganese in the bone, did not affect the contents of copper. The content phosphorus in the bone on d 40, and the content of magnesium in the bone on d 40 and d 95 increased (P＜0.05).2. Effect of cyadox on nutrient digestibility and metabolism in the intestinal of pigsEighty Landrace×Large White crossbred barrows, weaned at 35 days of age, were randomly allotted three groups with five replicates to evaluate the effect of cyadox on nutrient digestibility, intestinal flora and nutrients metabolism. The three groups were randomly allotted to one of three diets: 1) control diet without any antimicrobial agents; 2) an olaquindox diet containing 100 mg/kg olaquindox; 3) a cyadox diet containing 100 mg/kg cyadox. The pigs were fed the control diet at the start of the 7-day adaptation. At the age of 42 d the pigs entered the experiment. The experiment period lasted four weeks. ADG and FCR were determined weekly. Five pigs per group were selected to slaughter each week to determine intestinal flora, metabolites (including pH value, moisture, microbial enzyme activity, ammonia and VFA) and small intestinal villus morphology. Faeces were collected during wk four of the experiment and used for determining nutrients digestibility.Cyadox at the dose of 100 mg/kg improved (P＜0.01) ADG by 19.4% and FCR by 20.1% while 100 mg/kg olaquindox did (P＜0.05) by 7.8% and 9.2%, respectively. ADG and FCR for pigs fed 100 mg/kg cyadox were higher (P＜0.05) than those for pigs fed 100 mg/kg olaquindox.As compared with control, the apparent digestibilities of dry matter, crude protein, ether extract, nitrogen-free extract, and digestible energy were significantly increased (P＜0.05) in the cyadox-fed pigs. The apparent digestibilities of amino acid, calcium, phosphorus, iron, copper, zinc and manganese in the cyadox-fed pigs were significantly higher (P＜0.05) than those in pigs fed control diet and olaquindox diet. It is suggested that the growth promoting effect of cyadox may be attributed to the improvement in the digestibility of dietary nutrients.Cyadox increased the height of villi in the duodenum and in the jejunum, and the ratio of villus height to its recess depth in the jejunum, whichindicated that cyadox enlarged the surface area of small intestinal villi to absorb nutrients.Cyadox significantly increased (P＜0.05) lactobacillus counts in the jejunum and ileum, but decreased coliform, enterococcus and yeast counts. Similarly, cyadox significantly reduced the activity of urease, nitrated reducase and azoreducase in the jejunum and ileum with decreasing the content of ammonia, acetate acid, butyric acid and total of VFA. The results showed that the growth promoting effect of cyadox may be attributed to intestinal bacterial suppression, reduction of microbial enzyme activity and microbial metabolites.3. Effect of cyadox on serum concentrations of nutrients in pigsIn order to study the effects of cyadox on serum concentration of nutrients in pigs, sixty Landrace×Large White crossbred barrows, weaned at 35 days of age, were randomly allotted to five treatments. The treatments included one control fed the basal diet without any antimicrobial, one group fed the diet containing 50 mg/kg olaquindox, and the other three groups fed the diets containing 25, 50 and 100 mg/kg cyadox, respectively. The animals at the start of the 7-day adaptation period were fed a basal diet containing no antibiotics. At the age of 42 d the piglets entered the experiment. The experiment period lasted sixteen weeks. Growth performance data and serum were collected every four weeks. Serum free amino acid, free fatty acid, retinol, tocopherol and mineral concentrations were determined.During the first four weeks, 25, 50 and 100 mg/kg cyadox improved ADG by 18.1% (P＜0.05), 33.3% (P＜0.01) and 34.3% (P＜0.01), increased FCR by 7.9%, 24.0% and 34.3%, respectively. Smilarly, ADG and FCR for pigs fed cyadox at 50 and 100 mg/kg were higher (P＜0.05) than those of pigs fed 50 mg/kg olaquindox. From weeks 5 to 8, 25 to 100 mg/kg cyadox improved (P＞0.05) ADG by 2.9% to 7.7%, and FCR by 2.0% to 7.1%. From weeks 9 to 12, 25 to 100 mg/kg cyadox improved (P＞0.05) ADG by 4.2% to 6.8%, and FCR by 6.0% to 8.2%. From weeks 13 to 16, 25 to 100 mg/kg cyadox improved (P＞0.05) ADG and FCR by 1.3% to 2.4%, and 0.5% to 1.3%. Over the entire experimental period, pigs given 50 and 100 mg/kg cyadox diets showed the greatest ADG and the best food efficiency among the five diets. The results indicated that the optimum effective dose of cyadox in pigs was 50 to 100 mg/kg, the optimum supplementation period for pigs was 12 weeks. Cyadox increased most of free fatty acids and amino acids in serum, whereas urea and ammonia decreased. These results showed that cyadox promoted the rate of muscle protein synthesis and retention of protein, increased utilization of protein and amino acid.In pig feds 25 to 100 mg/kg cyadox diets, the concentrations of serum retinol increased by 12.3% to 153.2% (P＜0.05) while serum tocopherol concentrations increased by 20.4% to 122.9% (P＜0.05). The contents of sodium, potassium, calcium, magnesium, phosphorus, iron, copper, zinc and manganese in the serum ranged within the physiological limits. Increases in the concentrations of serum potassium in olaquindox and three cyadox group were found only in week 12 and week 16.In conclusion, cyadox increased ADG and FCR, improved carcass characteristics, increased deposition of protein, retinol and tocopherol. Cyadox increased absorption and digestibility of nutrients, but suppressed intestinal bacterial, reduced activities of microbial enzymes and production of microbial metabolites, we systemically investigated the growth promoting of cyadox, and effects cyadox on the nutrients digestibility, nutrients concentrations in the porcine serum and tissues. The effect of cyadox on absorption, utilization and deposition of nutrients in pigs were elucidated. It was confirmed the optimum application dose and duration in swine. The results provided the scientific guidance and technical project for reasonable application of cyadox. Lucubrating of the effects of cyadox on intestinal flora, bacterial enzymes and its metabolites gave a comprehensive explanation for the relationship of growth promotion of cyadox with intestinal flora and nutrient metabolism. The effects of cyadox on the concentrations of amino acids, fatty acids vitamins and minerals in the blood and animal tissues were roundly evaluated.