Influence of dietary slow‐release urea on growth performance, organ development and serum biochemical parameters of mutton sheep

Abstract

Eighty Dorper × thin-tailed Han cross-bred non-castrated male lambs [mean body weight (BW), 25.87 ± 1.06 kg] were randomly allocated to one of five different concentrations of slow-release urea (urea phosphate, UP). The feed consisted of an equal amount of concentrate diet and roughage; the concentrate feed was formulated to be isoenergetic and isonitrogenic and contained 0%, 1%, 2%, 4% and 8% UP (UP0.0, UP1.0, UP2.0, UP4.0 and UP8.0, respectively) as a replacement for soya bean meal. Feed intake, BW, average daily gain (ADG), feed utilisation efficiency (FUE), absolute and relative organ weights and biochemical and histopathological parameters were measured. Feed intake, BW, ADG and FUE significantly decreased in the group receiving UP8.0 (p < 0.05), but no difference was found among the other groups (p > 0.05). Quadratic equations were developed between the UP dosage in the concentrate feed and ADG or FUE (r = 0.973 for ADG and r = 0.761 for FUE) to determine the appropriate dosage of UP given the desire to maximise either ADG or FUE, the appropriate dosage (feed concentration) was calculated as 2.01% UP to achieve the greatest ADG or 2.13% UP to achieve the best FUE. The relative weight of the liver (% BW) in the UP2.0 groups was significantly greater than that of UP0.0 (p < 0.05), and the relative weight of the intestine in the UP8.0 was significantly greater than that of UP0.0 (p < 0.05); the relative weight of the carcass, heart, spleen, lung, kidney, rumen, reticulum, omasum and abomasum did not differ among treatments (p > 0.05). The UP8.0 treatment significantly increased serum phosphorus levels (p < 0.05) and decreased the levels of alkaline phosphatase, glucose and calcium (Ca) compared with the lower UP dosage (p < 0.05). No histopathological differences were found in either hepatic tissues or renal tissues among treatments. Dietary UP as a replacement for soya bean in concentrate feeds for mutton sheep should not exceed 4%, as higher dosing may cause malnutrition and mineral disorders.

Effect of Different Slow‐Release Urea on the Production Performance, Rumen Fermentation and Blood Parameter of Angus Heifer

“…The differences in DMI, ADG and feed-to-weight ratio were not significant in the Angus steers diets supplemented with 1.3% and 3.1% of the Optigen II (Alltech, Lexington, KY) compared to the group supplemented with 1.2% of conventional urea, but ADG and feed utilization efficiency were higher in the PCU group than in the conventional urea group [16]. It has also been shown that under isoenergetic and isonitrogenous conditions, DMI, ADG and feed utilization efficiency were higher among all groups than in the control group when urea phosphate was added at no more than 4% to the concentrate supplement, which is consistent with the results of previous studies; however, when urea phosphate was added at 8% to the concentrate supplement, DMI, ADG and feed utilization efficiency of beef cattle were significantly lower than in the control group [17]. In this trial, polymer-coated urea and gelatinized starch urea were added at 2% and 2.5%, respectively, in this trial.…”

Effects of Inclusion of N-Carbamylglutamate in the Non-Protein Diet on Growth and Slaughter Performance, Meat Quality, Nitrogen Metabolism and Antioxidant of Holstein Bulls

“…Consistent with previous studies, our results found that feeding the urea diet decreased ADG and DM and CP digestibility. The intake and growth performance of lambs were reduced by adding 8% urea to the diet [ 18 ]. Supplementing the urea diet instead of the protein feed to dairy cows also decreased milk yield [ 19 ].…”

Effects of slow-release urea on in vitro rumen fermentation parameters, growth performance, nutrient digestibility and serum metabolites of beef cattle

“…Huntington, Harmon, Kristensen, Hanson, & Spears (2006) found that supplementing SRU in diet did not affect the serum urea nitrogen level of cattle. The levels of serum ALP and glucose in sheep were unaffected until the dosage of urea phosphate was higher than 4% in the concentrate feed (Ji et al, 2017). Goulart et al (2013) observed that the concentration of γ-GGT, urea, and ALB were not differed in cows after feeding SRU diet and urea diet.…”