Waghorn G C, Collier K, Bryant M, Dalley D E
a DairyNZ , Cnr Ruakura and Morrinsville Roads, Hamilton 3240 , New Zealand.
c Current address: 6 Berkley Avenue , Hamilton, 3216 , New Zealand.
N Z Vet J. 2018 Jul;66(4):178-185. doi: 10.1080/00480169.2018.1465484. Epub 2018 May 3.
To determine the suitability of diets containing either approximately 85% fodder beet (Beta vulgaris L.) with barley straw or 65% fodder beet with pasture silage when fed to non-lactating dairy cows, by measuring intakes, digestibility, rumen function including microbial growth, and N excretion.
Holstein-Friesian cows fitted with permanent rumen fistulae were fed either 65% fodder beet with pasture silage (Silage; n=8) or 85% fodder beet with barley (Hordeum vulgare L.) straw (Straw; n=8) in an indoor facility over a 9-day period, for measurement of intakes, digestibility, rumen function and urine production. The cows were adapted to the diets over 2 weeks before the indoor measurements. Feed was available for about 6 hours/day, as practiced commercially for wintering non-lactating cows.
Five cows fed the Straw diet had to be removed from the trial because of acute acidosis; four on Day 1 of the measurement period and one on Day 7. One cow allocated to the Silage diet refused to eat fodder beet bulbs and was also removed from the trial. Two cows fed the Silage diet were also treated for acidosis. DM intakes were lower with the Straw than Silage diets (6.4 (SE 0.4) vs. 8.3 (SE 0.5) kg/day) and organic matter (OM) digestibility was lower with the Straw than Silage diets (77 (SE 1) vs. 83 (SE 1) g/100g). The N content of the two diets was 1.14 and 1.75 g/100 g DM and there was a net loss of N by cows fed the Straw diet (-22.7 (SE 7) g/day). Rumen microbial N production was much lower in cows fed the Straw than the Silage diet (6.6 (SE 1.3) vs. 15.8 (SE 0.7) g microbial N/kg digestible OM intake). Concentrations of ammonia in rumen liquid collected on Days 5-6 were below detection limits (<0.1 mmol/L) in 36/48 (75%) samples collected from cows fed the Straw diet and in 27/48 (56%) cows fed the Silage diet. Mean urinary N excretion was lower in cows fed the Straw than the Silage diet (52.0 (SE 5.8) vs. 87.7 (SE 5.9) g/day).
An over-wintering diet for dry cows comprising about 65% fodder beet with 35% pasture silage provided adequate nutrition, although there was some risk of acidosis. In contrast, the diet containing about 85% fodder beet with barley straw resulted in lower DM intakes, poor rumen function, negative N balance so that both nutrition and welfare were compromised.
通过测量采食量、消化率、瘤胃功能（包括微生物生长）和氮排泄，来确定当给非泌乳奶牛饲喂含约85%饲用甜菜（Beta vulgaris L.）与大麦秸秆或65%饲用甜菜与青贮牧草的日粮时的适宜性。
在室内设施中，给安装了永久性瘤胃瘘管的荷斯坦-弗里生奶牛饲喂65%饲用甜菜与青贮牧草（青贮组；n = 8）或85%饲用甜菜与大麦（Hordeum vulgare L.）秸秆（秸秆组；n = 8），为期9天，以测量采食量、消化率、瘤胃功能和尿液生成。在室内测量前，奶牛用2周时间适应日粮。饲料每天供应约6小时，这是商业上非泌乳奶牛越冬的常规做法。
饲喂秸秆日粮的5头奶牛因急性酸中毒不得不退出试验；4头在测量期第1天，1头在第7天。分配到青贮日粮组的1头奶牛拒绝吃饲用甜菜球茎，也被退出试验。饲喂青贮日粮的2头奶牛也因酸中毒接受了治疗。秸秆组的干物质采食量低于青贮组（6.4（标准误0.4）对8.3（标准误0.5）千克/天），秸秆组的有机物（OM）消化率低于青贮组（77（标准误1）对83（标准误1）克/100克）。两种日粮的氮含量分别为1.14和1.75克/100克干物质，饲喂秸秆日粮的奶牛出现氮净损失（-22.7（标准误7）克/天）。饲喂秸秆日粮的奶牛瘤胃微生物氮产量远低于青贮日粮组（6.6（标准误1.3）对15.8（标准误0.7）克微生物氮/千克可消化有机物摄入量）。在第5 - 6天采集的瘤胃液样本中，从饲喂秸秆日粮的奶牛采集的48份样本中有36份（75%）、从饲喂青贮日粮的奶牛采集的48份样本中有27份（56%）的氨浓度低于检测限（<0.1毫摩尔/升）。饲喂秸秆日粮的奶牛平均尿氮排泄量低于青贮日粮组（52.0（标准误5.8）对87.7（标准误5.9）克/天）。
由约65%饲用甜菜与35%青贮牧草组成的干奶牛越冬日粮提供了充足的营养，尽管存在一定的酸中毒风险。相比之下，含约85%饲用甜菜与大麦秸秆的日粮导致干物质采食量降低、瘤胃功能差、氮负平衡，从而使营养和福利都受到损害。
