Use of low-protein diets for growing pigs to reduce fecal nitrogen excretion


N.S.A. Niyazov, G.G. Cherepanov, K.S. Ostrenko

The increasing risks of environmental pollution by nitrogen of pig farms wastewater compel researchers to explore the possibility to reduce protein level in diets for growing-finishing pigs. The objective of this work was to evaluate the effect of low-protein diets balanced by the bioavailable essential amino acids, on the growth rate, efficiency of nutrient utilization and nitrogen excretion with urine and feces in growing-finishing pigs. The experiment was performed on three groups of Landras × Large White piglets, 12 piglets each, and included two periods, growing and fattening. Piglets in group I (control) were fed the complete feed with following levels of components: for growing period: crude protein and metabolizable energy - 172 g, 12.56 MJ and limiting amino acids, g/kg feed: lysine - 7.7 (true available for absorption in the intestine - 5 88), threonine - 4.83 (- 3.75), methionine 4.73 (- 3.82), and in the fattening period - 153 g, 12.34 MJ, 5.75 (- 5,08), 4.5, (- 3.49), 3.06, (- 2.47) g/kg respectively. In group II, the crude protein level was reduced to 151 g/kg in growing period and to 142 g/kg in fattening periods, and in group III - to 134 and 130 g/kg respectively. The content of true available lysine, methionine and threonine in the diets of groups II and III in both periods was adjusted to respective values in the control group by the addition of synthetic amino acids. The live weight gain during the finishing period in ?? and ???? groups was approximately the same (40.62 and 40.28 kg, 752 and 746 g, respectively); in group ?????? it was by 6.2% less than in control group. The efficiency of using feed nitrogen in group II was higher by 6% compared with group I. Nitrogen excretion in II and III groups was reduced by 24.4 and 33.8% in urine and by 20.7 ? 36.0% in feces respectively. The results of this study indicate that reducing the level of crude protein in the diet for growing-finishing pigs with the addition of synthetic essential amino acids, reduces the flow of nitrogen into the environment with urine and feces, without adversely affecting productive performance.  
 Key words: Environmental pollution by nitrogen; Growing-finishing pigs; Nitrogen of pig excreta; Low-protein diets; Supplements of essential amino acids  
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