Abstract

The objective of the present study was to determine the dietary effect of different growth stages of rapeseed (Brassica rapa L.) on nutrient intake and digestibility, nitrogen balance, and rumen fermentation kinetics in sheep. Four dietary treatments were utilised. A basal control diet based on alfalfa hay, oat hay, soybean meal and corn grain. Then alfalfa hay was replaced with 300 g/kg DM of rapeseed forage harvested at three different growth stages: Vegetative, Flowering and Pod. In vitro gas production was determined using three rumen cannulated Suffolk sheep in a completely randomised design, and nutrients intake and digestibility of each diet were determined using four Suffolk sheep in a 4 × 4 Latin square design with 21 d periods consisting of 14 d for diet adaptation and 7 d for sample collection. Feed intake and excretion of faeces and urine were recorded. Dry matter intake was higher for control and Pod compared to Vegetative and Flowering. The digestibility of dry matter, organic matter, neutral detergent fibre and acid detergent fibre were similar among treatments. Nitrogen intake was higher for control and Pod and lower for Vegetative and Flowering. In vitro gas production was similar among treatments (P > .05). In vitro gas yield at 24 h was higher (P < .05) for control than the rest of the treatments. Overall, inclusion of 300 g/kg DM of rapeseed forage harvested at pod stage as a substitute for alfalfa hay is an alternative source of protein without affecting nutrient intake and digestibility.

• Highlights

• Effect of different growth stages of rapeseed on nutrient intake and digestibility was determined

• Nutrient digestibility was similar between growth stages of rapeseed

• In vitro gas production was similar between growth stages of rapeseed

摘要

本研究的目的是确定菜籽（甘蓝型油菜）不同生长阶段对绵羊营养摄入和消化率，氮平衡和瘤胃发酵动力学的影响。使用了四种饮食疗法。以苜蓿干草，燕麦干草，豆粕和玉米粒为基础的基础控制饮食。然后用300 g / kg DM的菜籽草代替干草苜蓿，该菜以三个不同的生长阶段收获：营养，开花和荚果。体外使用三只瘤胃插管的萨福克羊以完全随机的设计确定产气量，并使用四只萨福克羊以4×4拉丁方形设计确定21天的周期（包括14天用于饮食适应）确定每种日粮的养分摄入和消化率。 7 d用于样品收集。记录采食量以及粪便和尿的排泄。与营养和开花相比，对照和豆荚的干物质摄入量更高。处理之间干物质，有机物质，中性洗涤剂纤维和酸性洗涤剂纤维的消化率相似。对照和荚果的氮摄入量较高，而营养和开花的氮摄入量较低。处理之间的体外产气相似（P  > .05）。体外对照的24小时气体产量高于 其余处理（P <.05）。总体而言，在豆荚阶段收获的300 g / kg DM的菜籽草料作为苜蓿干草的替代品是蛋白质的替代来源，而不会影响营养素的摄入和消化率。

• 强调

• 确定了油菜不同生长阶段对养分摄入和消化率的影响

• 油菜生长阶段之间的养分消化率相似

• 油菜生长阶段之间的体外产气相似