NITROGEN-BALANCE IN GROWING PIGS AT VARIOUS PROTEIN AND AMINO-ACIDS LEVELS

The nitrogen balance was assessed in the metabolic experiment with eig ht pigs of higher genotype (Seghers Hybrid) of average weight of 43 kg in four balance periods with four levels of crude protein and amino a cids using the isoenergetic mixtures. The average nitrogen and lysine intakes in groups I to IV were 36.0, 37.6, 40.2 and 42.4, and 10.4, 12 .6, 14.3 and 15.7 g per animal and day, respectively. Nitrogen digesti bility amounted to 81.38, 82.46, 83.07 and 83.84% in this sequence. Fr om the nitrogen ingested, 46.36, 50.83, 51.29 and 54.23% were deposite d. The differences in values between groups I and IV were significant in both cases (P < 0.05). Pigs in experimental groups I to IV deposite d 104.2, 119.4, 128.8 and 143.7 g of crude protein daily, the differen ce between the values in groups I and IV was significant (P < 0.05) (T ab. V). All pigs ingested in average 18.3 MJ of metabolizable energy p er anima! arid day. The obtained results give evidence for the ability of pigs of the genotype employed to deposit a comparatively large amo unt of crude protein daily although the crude protein and lysine intak e did not reach the maximum level of crude protein retention in the bo dy. An increased ingestion of lysine affected positively not only the level of crude protein deposition but their digestibility as well.