Performance of lactating dairy cows fed sunflower or corn silages and concentrate based on citrus pulp or ground corn

ABSTRACT This study aimed to evaluate the effect of diets containing sunflower or corn silages and concentrate based on citrus pulp or ground corn on intake, apparent digestibility, feeding behavior, microbial protein production, and production, composition, and fatty acid profile of milk from dairy cows. Eight multiparous lactating Holstein cows (586±61 kg live weight; 25.0±4.0 kg daily milk yield at 80 to 120 days in milk) were randomly assigned to a double 4 × 4 Latin square design with a 2 × 2 factorial array. The experimental diets were: sunflower silage + citrus pulp-based concentrate; sunflower silage + ground corn-based concentrate; corn silage + citrus pulp-based concentrate; and corn silage + ground corn-based concentrate. The dry matter intake was highest for diets containing sunflower silage and lowest for diets with citrus pulp. Sunflower silage provided the highest intakes of crude protein, neutral detergent fiber, and ether extract. Except for the ether extract, the type of forage and carbohydrate did not influence the apparent nutrient digestibility. The forage and carbohydrate sources did not influence the feed eating time, but animals fed sunflower silage showed decreased rumination time and chewing activity. The microbial protein production was not altered with the diets. No differences were observed for milk production or composition, except for the milk urea nitrogen and lactose concentration. The type of forage influenced the milk fatty acid profile, to which corn silage presented higher values for fatty acids up to a 17-carbon chain length. The inclusion of sunflower silage and citrus pulp, compared with corn silage and ground corn, alters dry matter intake and ingestive behavior, but maintains milk production and composition with satisfactory characteristics of the milk fatty acid profile, providing an alternative feed for dairy cows.

摘要
本研究旨在评估以葵花青贮饲料（sunflower silages）或玉米青贮饲料（corn silages），以及以柑橘渣（citrus pulp）或碎玉米（ground corn）为原料的精料补充料（concentrate）组成的日粮，对泌乳奶牛的采食量、表观消化率（apparent digestibility）、采食行为（feeding behavior）、微生物蛋白产量（microbial protein production），以及牛奶产量、乳成分和脂肪酸谱（fatty acid profile）的影响。选取8头经产泌乳荷斯坦奶牛，其活体重为586±61 kg，泌乳80~120天时的日产奶量为25.0±4.0 kg；采用带有2×2因子排列的双4×4拉丁方试验设计进行随机分组。试验日粮设置如下：葵花青贮饲料+以柑橘渣为原料的精料补充料组；葵花青贮饲料+以碎玉米为原料的精料补充料组；玉米青贮饲料+以柑橘渣为原料的精料补充料组；以及玉米青贮饲料+以碎玉米为原料的精料补充料组。干物质采食量（dry matter intake）在饲喂含葵花青贮饲料的日粮时最高，饲喂以柑橘渣为原料的精料日粮时最低。葵花青贮饲料组的粗蛋白（crude protein）、中性洗涤纤维（neutral detergent fiber）与乙醚浸出物（ether extract）采食量均为最高。除乙醚浸出物外，饲草类型与碳水化合物来源对养分表观消化率无显著影响。饲草类型与碳水化合物来源对采食时长无显著影响，但饲喂葵花青贮饲料的奶牛反刍时间（rumination time）与咀嚼活动（chewing activity）均有所降低。日粮组成对微生物蛋白产量无显著影响。除乳尿素氮（milk urea nitrogen）与乳糖浓度（lactose concentration）外，各组牛奶产量与乳成分均无显著差异。饲草类型对牛奶脂肪酸谱存在显著影响：玉米青贮饲料组中碳链长度（carbon chain length）≤17的脂肪酸含量更高。与玉米青贮饲料+碎玉米日粮相比，添加葵花青贮饲料与柑橘渣的日粮可改变泌乳奶牛的干物质采食量与采食行为，但可维持牛奶产量与乳成分稳定，且牛奶脂肪酸谱表现出优良特性，可为泌乳奶牛提供一种新型饲料原料。