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 本研究旨在评估以向日葵青贮（sunflower silage）或玉米青贮（corn silage）、以及以柑橘渣（citrus pulp）或碎玉米（ground corn）为基础配制精补料的日粮，对泌乳奶牛（dairy cows）的采食量、表观消化率、采食行为、微生物蛋白合成，以及产奶量、乳成分与乳脂肪酸谱（fatty acid profile）的影响。选取8头经产泌乳荷斯坦奶牛（Holstein cows），其平均活体重为586±61 kg，处于泌乳80~120天阶段，日产奶量为25.0±4.0 kg；试验采用含2×2析因排列的双4×4拉丁方设计（double 4 × 4 Latin square design），将受试奶牛随机分组。试验日粮共设置4组：向日葵青贮+柑橘渣型精补料组、向日葵青贮+碎玉米型精补料组、玉米青贮+柑橘渣型精补料组，以及玉米青贮+碎玉米型精补料组。结果显示，饲喂向日葵青贮组的干物质采食量最高，而饲喂以柑橘渣为基础配制精补料的组干物质采食量最低。向日葵青贮组的粗蛋白（crude protein）、中性洗涤纤维（neutral detergent fiber）与乙醚浸出物（ether extract，即粗脂肪）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，但饲喂向日葵青贮组的奶牛反刍时间（rumination time）与咀嚼活动（chewing activity）均有所降低。日粮组成对微生物蛋白合成无显著影响。除乳尿素氮（milk urea nitrogen）与乳糖浓度（lactose concentration）外，各组产奶量与乳成分均无显著差异。饲草类型对乳脂肪酸谱存在显著影响：玉米青贮组的碳链长度≤17的脂肪酸含量更高。与玉米青贮+碎玉米日粮相比，添加向日葵青贮与柑橘渣的日粮可改变干物质采食量与采食行为，且可维持产奶量与乳成分水平，乳脂肪酸谱特性优异，可为泌乳奶牛提供一种新型饲料原料。