Monensin, sodium bicarbonate and limestone sources in rations with high concentrated for feedlot lambs / Monensina sódica, bicarbonato de sódio e duas fontes de calcário em rações com alto teor de concentrado na terminação de cordeiros Santa Inês

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Two trials were conducted to evaluate performance, carcass characteristics, apparent digestibility and ruminal parameters in feedlot lambs fed a 90% concentrate (based on corn and soybean meal) and 10% of "coastcross" hay ration, with two sources of calcarium and sodium bicarbonate (NaHCO3), with or without monensin. Treatments were: CC = 1.3% limestone; CCF= 1.3% "Filler" Calcitic limestone; CC + BS= 1% Sodium bicarbonate + 1.3% Calcitic limestone, with or without monensin (30 mg/kg DM basis). Lambs were assigned to a complete randomized blocks with a 2x3 factorial design, according to body weight and age at beginning of the trial. In experiment 1: Forty two ram Santa Ines lambs were distributed in 7 blocks and 6 treatments, with initial average body weight of 21.2 ± 3 kg and 88 ± 5 days old. There were no differences in DMI and ADG between treatments (P >0.05), which averaged 0.955 and 0.290 kg/day, respectively. However, there was a better feed conversion (P <0.05) of the lambs fed diets containing monensin (3.32 kg DM/kg of gain) compared to diets without monensin (3.58 kg DM/kg of gain). There were no differences in carcass characteristics, which averaged 50.38%, 2.42%, 13.94 cm2 and 1.87 mm of hot carcass weight, chilling losses, longissimus muscle area and fat thickness, respectively. In experiment 2: Twenty four lambs were distributed according to the body weight in 4 blocks. They were placed in metabolism crates to evaluate apparent digestibility of the diets in total digestive tract, nitrogen metabolism and ruminal parameters (pH, total volatile fatty acids and N-NH3). Dry matter, organic matter and crude protein digestibilities were greater for treatments with CCF (P <0.05), compared to other buffers. Neutral detergent fiber digestibility was higher for treatments with the inclusion of monensin compared to treatments without monensin. There were no differences (P >0.05) in nitrogen metabolism, pH, water intake, acetate:propionate relation and butirate concentration. There was interaction between treatment CCF and monensin inclusion for N-NH3, total volatile fatty acids, acetate and propionate concentrations, which were lower when the ionophore was included in CCF treatment. There was also interaction between treatments CC + BS and monensin for total volatile fatty acid, acetate and propionate, which were in lower concentrations in the CC + BS treament without monensin. Filler" Calcitic limestone inclusion in the diet had no detrimental effect on lamb performance and carcass characteristics, but DM apparent digestibility was improved and there was a negative associative effect with monensin. Sodium bicarbonate inclusion didn´t change performance and carcass characteristics of the lambs and there was a postitive associative effect with monensin for total volatile fatty acids. In addition monensin inclusion in the diet improved feed conversion.

ASSUNTO(S)

disgestibilidade suplementos concentrados para animais. buffers ionophores confinamento animal rúmen santa ines sheep. feedlot rumen cordeiros - desempenho rações

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