Performance and carcass characteristics of feedlot lambs fed different levels and sources of phosphorus

Abstract

The search for more economical and sustainable nutritional strategies has encouraged the replacement of traditional mineral sources with more affordable alternatives. Phosphorus, being essential for metabolism and one of the most expensive nutrients in ruminant diets, has been the focus of several studies. This study aimed to evaluate the productive performance and carcass characteristics of feedlot lambs fed diets containing different levels and sources of phosphorus. Forty crossbred lambs (Santa Inês × Dorper), with an average initial body weight of 23.9 kg, were kept in confinement for 60 days. Four diets were used: a control diet containing 0.50% dicalcium phosphate and three diets with complexed phosphorus at levels of 0.50%, 0.20%, and 0.08%. All other ingredients were kept constant. Body weight was monitored weekly. Variables such as average daily gain, commercial carcass cuts, yield, and non-carcass components were evaluated. Final average body weights ranged from 35.31 kg (0.08% complexed phosphorus diet) to 36.98 kg (control diet), with no significant differences. Average daily gain over 60 days also showed no differences between groups, ranging from 0.206 to 0.221 kg/day. A significant difference was observed in leg weight, with the highest value in the 0.08% complexed phosphorus group (3.257 kg), as well as in cold carcass weight, which was also higher in this group (20.450 kg; P<0.05). Slaughter live weight was higher in lambs fed diets with 0.50% and 0.08% complexed phosphorus (39.933 and 41.650 kg, respectively) compared to the control (P<0.05). Differences were also observed in visceral organs such as liver (1.97% of live weight) and empty rumen (1.56%) in the diet with the lowest phosphorus inclusion (P<0.05). In conclusion, the results indicate that diets with lower levels of complexed phosphorus maintain performance, representing a viable alternative for intensive production systems.