Effects of dietary vitamin A level on meat quality of steers

Chinese. 为了研究日粮维生素A（VA）水平与肉牛牛肉品质的关系，选用16头12月龄利木赞×鲁西黄牛阉牛，以添加0，1 100，2 200，4 400 IU/kg VA的日粮育肥6个月后屠宰，分析不同日粮VA添加水平对牛肉品质的影响。结果表明：（1）在肉牛屠宰特性方面，VA水平对肉牛屠宰率、肋部皮下脂肪厚度、肠系膜脂肪质量/活体质量、眼肌面积和肉品大理石花纹评分均无显著（P0.05）影响，但大理石花纹随VA水平的降低而改善；VA水平显著（P0.05）影响肉牛日增质量、背部皮下脂肪厚度和肉品剪切力，其中日增质量以2 200 IU/kg VA添加水平时最高，低于此水平则有随VA水平升高而增加的趋势，而背部皮下脂肪厚度和剪切力均以1 100 IU/kg VA水平时最低；（2）在肉品常规成分（以鲜样为基础）方面，VA水平显著（P0.05）影响臀中肌干物质含量和背最长肌粗蛋白含量，而对臀中肌粗脂肪、粗蛋白和粗灰分含量及背最长肌干物质、粗脂肪和粗灰分含量无显著（P0.05）影响；（3）在肉品氧化稳定性方面，VA水平对吊挂成熟的臀中肌和背最长肌的总色素含量、硫代巴比妥酸反应物值（TBARS）和滴水损失有显著（P0.05）影响。其中，总色素含量在臀中肌和背最长肌均以1 100 IU/kg VA水平时最高，TBARS值在臀中肌以1 100 IU/kg VA水平时最低，而在背最长肌以2 200 IU/kg VA水平时最低。综合考虑，在该试验条件下，以1 100 IU/kg VA水平日粮饲喂肉牛的效果最好。

English. A slaughter trial was conducted to evaluate the effects of dietary vitamin A (VA) supplementing level on meat quality by using 16 limosin×luxi crosses steers at 12-month age in a complete randomized design after 6 months of finishing period with diets contained 0, 1 100, 2 200, and 4 400 IU/kg. The results showed that: ①VA level did not affect (P0.05) dressing percentage, subcutaneous fat thickness, mesenteric fat weight/living weight, longissimus area, and marbling score which was better with the decrease of VA level. But VA level significantly affected back fat thickness and shear force (P0.05), both of which were lowest at 1 100 IU/kg, and average daily gain which had a tendency was numerically greater with VA level increment when dietary VA level was less than 2 200 IU/ kg. ②VA level had no significant effect on the chemical composition of GM and LD (P0.05) except for dry matter of GM and crude protein of LD. ③VA level had significant effect on drip loss, total pigment concentration and TBARS (P0.05) during aging, and different beef cuts responses to VA level were not identical. Considering these results, the effect was the best when the steers were fed with the diet contained 1 100 IU /kg._