Nutritional And Physiological Effects Of Supplementation Of Glutamine And Mannan Oligosaccharides Into The High Concentrate Diet Of Finishing Steers

Many studies have shown that both glutamine (Gin) and mannan oligosaccharides (MOS) can protect the gut, enhance immunity, promote growth performance, and so on. This has been widely confirmed in monogastric animals, aquatic animals and calves. But both of them are rarely used in adult ruminant animal. Up to now, there are few reports about the roles of Gin or MOS in reducing the harmful effects of endotoxinon in cattle fed high concentrate diets. In addition, though Gin and MOS may protect rumen epithelium of steers and attenuate the adverse effects of LPS, there is no report that whether steers can select the diet which is more beneficial to the body or not. Therefore, this study was conducted to investigate:(1) Effects of dietary supplementation of Gin and MOS on serum endotoxin and acute phase protein concentrations in finishing steers.(2) Effects of dietary supplementation of Gin and MOS on nutrient digestibility and growth performance in finishing steers.(3) Effects of dietary supplementation of Gin and MOS on diet selection in finishing steers.Trial1was intended to investigate the effects of dietary addition of Gln/MOS on endotoxin and acute phase protein concentrations in finishing steers. Eighteen Simmental x Luxi crossbred finishing steers were randomly selected and evenly divided into3treatments:(1) the basal diet (control);(2) the basal diet+1%Gin;(3) the basal diet+0.2%MOS. The duration of the trial was25days. The plasma endotoxin and plasma acute protein concentrations were measured at the end of trial. The fecal endotoxin was measured from Day23to Day25. The results showed:(1) Dietary supplementation of Gin decreased the plasma and fecal lipopolysaccharide (LPS) by7.10%and12.49%, respectively, but the differences did not attain statistical significance (P>0.05). Dietary supplementation of MOS decreased the plasma and fecal LPS contents by10.43%(P<0.05) and18.35%(P<0.05), respectively.(2) Dietary supplementation of Gln did not affect the plasma concentrations of haptoglobin (Hp), serum amyloid A (SAA), and C-reactive protein (CRP)(P>0.05), but the plasma concentration of LPS binding protein (LBP) was significantly increased (P<0.01). Dietary supplementation of MOS reduced the plasma contents of Hp, SAA, CRP and LBP by95.65%(P<0.05),85.88%(P<0.05),50.63%(P<0.05) and46.80%(P>0.05), respectively. Collectively, MOS is more effective than Gln in decreasing the concentrations of LPS in plasma and feces, and the plasma acute phase proteins are affected in different manners by dietary supplementation of Gln and MOS.Trial2was intended to investigate the effects of dietary addition of Gln and MOS on nutrient digestibility, growth performance in finishing steers. Eighteen Simmental x Luxi crossbred finishing steers were randomly selected and evenly divided into3treatments:(1) the basal diet (control);(2) the basal diet+1%Gln;(3) the basal diet+0.2%MOS. The duration of the trial was25days. The average daily feed intake was measured each day during the experiment, the nutrient content in feces and diets were measured from Day21to Day25. The results showed:(1) Dietary supplementation of Gln increased average daily gain (ADG) by3.85%(P>0.05), increased average daily dry matter intake (ADMI) by3.18%(P>0.05), decreased ADMI/ADG by5.15%(P>0.05), and had no significant effect on nutrient apparent digestibility (P>0.05).(2) Dietary supplementation of MOS increased ADG by7.69%(P>0.05), increased ADMI2.62%(P>0.05), decreased ADMI/ADG by14.05%(P>0.05), and had no significant effect on nutrient apparent digestibility (P>0.05). Overall, dietary supplementation of Gln and MOS has the tendency to improve growth performance in finishing steers.Trial3was intended to investigate the effects of dietary addition of Gln/MOS on diet selection in finishing steers. Six Simmental x Luxi crossbred finishing steers were randomly selected and housed in individual tie stalls, and each of them was offered three concentrates at the same time:(1) the basal concentrate feed without adding Gln/MOS (control);(2) the basal concentrate feed+1%Gln;(3) the basal concentrate feed+0.2%MOS. Roughage was fed ad libitum. Diets were offered twice daily, and the positions of feeders were rotated each day. The duration of the trial was7days. The average daily feed intake and feeding frequency were measured each day during the experiment. The results showed:(1) The intake of the basal concentrate feed supplemented with Gln was higher than that of the control group and the basal concentrate feed supplemented with MOS (P<0.05).(2) The visit frequency of the concentrate feed supplemented with Gln was the highest and that of the concentrate feed supplemented with MOS was the lowest (P<0.01). In conclusion, based on a "nutritional wisdom" and because of the special odor of MOS, steers prefer the concentrate feed supplemented with Gln to that supplemented with MOS.