Influence of oscillating dietary protein concentration on nitrogen balance and daily weight gain in fattening male lambs

This study was conducted to investigate the effect of oscillating dietary protein concentration on nitrogen balance and daily weight gain in fattening male lambs. Oscillating crude protein in the diet and feeding it intermittently at intervals of one to several days is one of the ways to use crude protein optimally. Three diets were adjusted with 14, 12 and 16% crude protein but with the same energy. 8 male lambs were used in metabolic cages in a 4x4 Latin square design (four treatments with 2 replications). The first treatment received a diet with a crude protein level of 14% constantly. The second to fourth treatments received diets with 12 and 16% crude protein at intervals of 24, 48 and 72 hours, respectively. Nitrogen balance, feed consumption, digestibility and some rumen and blood parameters were measured. No significant difference was observed in terms of nitrogen consumption and excretion through urine or feces among the treatments. The lowest total excreted nitrogen (urine and feces) was observed in the treatment with 48-hour consumption interval (P=0.031). The retained nitrogen showed a significant increase in this treatment compared to the treatment with constant feeding (P=0.055). The experimental treatments did not show any significant difference in terms of dry matter consumption and daily weight gain. The highest digestibility of dry matter was observed in the treatment with 48-hour consumption interval (P=0.027) but, digestibility of crude protein and neutral detergent fiber did not show a significant difference between the experimental treatments. The highest rumen ammonia nitrogen and blood urea nitrogen were in the treatment with 48-hour crude protein consumption interval (P<0.05). The data indicate that the use of oscillating dietary crude protein concentration strategy in the diet of growing male lambs improves nitrogen retention and digestibility of dry matter.