Abstract

This study aimed to determine the effect of rosemary (Rosmarinus officinalis) essential oil (REO) in lamb fattening diets on blood, rumen parameters, fattening performance and meat quality. Thirty Norduz male lambs weaned at 4 months of age with average body weight 22.0 ± 4.41 kg were used. Lambs were divided into three groups: no rosemary oil (control, R0), with 250 mg/kg DM (R250) and with 500 mg/kg DM (R500) rosemary oil added to the basal ration, and fed for 70 d. The daily feed intake of the R500 lambs (1.63 kg) was lower than other groups (1.70 kg) (p = .01). Rosemary oil did not change the density of methane-producing bacteria in the rumen fluid. Rumen pH was 6.31 in R250 lambs, while it was 6.16 in control (p < .04). The proportion of propionic acid (PA) increased in R250 (26.5 molar%) and R500 (26.0 molar%) lambs compared to control lambs (22.7 molar%) (p < .001). Serum glucose levels increased with REO dose (p < .01) and serum IGF-1 levels were significantly higher in R250 lambs (p < .001). The dose rates of REO used in fattening lambs had limited effect on fattening performance, carcase and meat quality. The results showed that although it does not affect the final live weight, the negative effect of REO on feed intake at 500 mg/kg was considered as a limiting factor and 250 mg/kg dose of REO may have positive effects on ruminal fermentation. Hence, it may be beneficial to try doses lower than 500 mg in further studies.

• Highlights

• Rosemary oil may improve rumen pH and the propionic acid (PA) concentration at 250 mg of REO/kg DM of the diet.

• Serum IGF-1 levels were significantly increased with 250 mg/kg dose of REO.

• Feed intake and feed conversion ratio were negatively affected by REO at 500 mg/kg DM.

• Lambs supplemented with 500 mg REO/kg DM in the diet had the lowest CLA.

• The effect of rosemary oil on slaughter-carcase characteristics and meat quality was limited.

摘要

本研究旨在确定迷迭香 ( Rosmarinus officinalis ) 精油 (REO) 在羊肉育肥日粮中对血液、瘤胃参数、育肥性能和肉质的影响。使用了 30 只 4 月龄断奶的 Norduz 雄性羔羊，平均体重为 22.0 ± 4.41 kg。羔羊被分为三组：无迷迭香油（对照，R0）、250 mg/kg DM（R250）和500 mg/kg DM（R500）迷迭香油添加到基础日粮中，饲喂70天。R500 羔羊的日采食量（1.63 公斤）低于其他组（1.70 公斤）（p  = .01）。迷迭香油没有改变瘤胃液中产甲烷细菌的密度。R250 羔羊的瘤胃 pH 值为 6.31，而对照组为 6.16（p < .04）。与对照羔羊 (22.7 摩尔%) 相比，R250 (26.5 摩尔%) 和 R500 (26.0 摩尔%) 羔羊中丙酸 (PA) 的比例增加 ( p  < .001)。 R250 羔羊的血清葡萄糖水平随着 REO 剂量的增加而增加 ( p < .01)，并且血清 IGF-1 水平显着升高 ( p  < .001)。用于育肥羔羊的REO剂量率对育肥性能、胴体和肉质的影响有限。结果表明，虽然它不影响最终活重，但 REO 在 500 mg/kg 时对采食量的负面影响被认为是一个限制因素，250 mg/kg 剂量的 REO 可能对瘤胃发酵产生积极影响。因此，在进一步研究中尝试低于 500 mg 的剂量可能是有益的。

• 强调

• 迷迭香油可以改善瘤胃 pH 值和丙酸 (PA) 浓度，250 mg REO/kg DM 日粮。

• 血清 IGF-1 水平随着 REO 的 250 mg/kg 剂量显着增加。

• 饲料摄入量和饲料转化率受到 500 mg/kg DM 的 REO 的负面影响。

• 在饮食中补充 500 毫克 REO/kg DM 的羔羊具有最低的 CLA。

• 迷迭香油对屠宰胴体特性和肉质的影响有限。