Effect of Borax and cysteamine compound on finishing sheep growth performance, nitrogen retention, serum biochemical indices and body protein motabolism

Experiment was conducted to investigate the effects of borax, cysteamine and the mixture of two compounds on growth performance, serum biochemical indices, protein turn-over and nitrogen aggradation of sheep by using isotope (15N-Gly) technique, nitrogen balance trial and serum testing. The results showed that both borax and cysteamine could increase the growth performance of sheep, especially the cysteamine and its mixture with borax, which increased average daily feed intake (P<0.05), both cysteamine and borax increased average daily weight gain (ADG) (P<0.05), however, the mixture increased average day weight gain (ADG) (P<0.01). Serum glucose content of mixture was the highest, and serum urea nitrogen (BUN) of mixture was the lowest (P<0.01), and somatostain (SS) of mixture was 56.02pg/ml, significantly lower than that of control group (71.45pg/ml) (P<0.01); The concentrations of triiodothyronine (T3) and levothyroxine (T4) of mixture were higher than that of control group (P<0.05), and the concentrations of growth hormone (GH) and insulin-like growth factors (IGF-1) were also significantly higher than those of control group (P<0.01). There was no significant difference of insulin (INS) between experiment groups and control group (P<0.05). Both mixture and borax contributed to increasing nitrogen retention, net nitrogen utilization, digestibility and biological value. Both borax and cysteamine accelerated protein degradation rate, apparent amino acid utilization rate and net amino acid utilization rate as well as biological value, body protein and oxidation rate, but the former was greater than the later. (authors)