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Effect of urea supplementation on performance and safety in diets of Dorper crossbred sheep
Author(s) -
Wang B.,
Ma T.,
Deng K.D.,
Jiang C.G.,
Diao Q.Y.
Publication year - 2016
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/jpn.12417
Subject(s) - urea , crossbreed , zoology , dry matter , body weight , biology , feed conversion ratio , endocrinology , biochemistry
Summary This study was conducted to evaluate the efficacy and safety of dietary urea in sheep rations having a 50:50 concentrate:roughage ratio. Sixty‐four Dorper × thin‐tailed Han crossbred ram lambs with an average body weight of 30.8 (±0.02) kg were randomly divided into four groups of 16 sheep each, and each group was fed one of the following diets: a basal diet ( CON ), or CON supplemented with 0.5% (0.5 UTM ), 1.5% (1.5 UTM ) or 2.5% (2.5 UTM ) urea. Growth performance, carcass characteristics, non‐carcass offals, meat quality and peptic tissue lesions were assayed. The average daily weight gains for CON , 0.5 UTM , 1.5 UTM and 2.5 UTM were 216, 218, 200 and 170 g, respectively, with the CON and 0.5 UTM groups higher than 2.5 UTM group (p < 0.05). Sheep from the 2.5 UTM treatment had a significantly lower dry matter intake (1.29 kg/day) than those from the CON and 0.5 UTM treatments (1.42 and 1.43 kg/day, p < 0.05), and the feed conversion ratio in the 2.5 UTM group was the highest (p < 0.05). Carcass characteristics, including shrunk body weight, empty body weight, hot carcass weight, dress percentage, and the absolute or relative weight (% body weight) of heart, liver, spleen, lung and kidney, were not altered by the treatments (p > 0.05). The muscular pH of 2.5 UTM was higher than that of CON (5.68 vs. 5.52, p < 0.05), and shear force in 0.5 UTM was lower compared with CON and 2.5 UTM (p < 0.05). The anatomical structure lesions in kidneys became more serious with the increasing dietary urea concentrations, with the 2.5 UTM animals showing the most severe lesions compared with CON animals. Therefore, supplementary urea as a non‐protein nitrogen source for sheep should not exceed 1.5% of ration having a 50:50 concentrate:roughage ratio to ensure efficacy and safety.