Ferreira Gonzalo, Teets Christy L, Kingori Anthony M, Ondiek James O
School of Animal Sciences, Virginia Polytechnic Institute and State University, Blacksburg 24061.
Department of Animal Science, Egerton University, Njoro, Kenya, 20115.
JDS Commun. 2023 Feb 2;4(3):196-201. doi: 10.3168/jdsc.2022-0326. eCollection 2023 May.
The objective of this study was to determine the effect of irrigation on in situ neutral detergent fiber (NDF) degradability of corn tissues from plants grown under controlled conditions in a greenhouse. Five commercial corn hybrids were planted in 6 pots that were placed in a greenhouse. Pots were randomly subjected to 2 irrigation regimens, which consisted of either abundant (A; 598 mm) or restricted (R; 273 mm) irrigation. At harvesting, leaf blades and stem internodes were collected from the upper and bottom portion of the plants. Tissue samples were incubated in the rumen of 3 rumen-cannulated cows for 0, 3, 6, 12, 24, 48, 96, and 240 h to determine in situ NDF degradation kinetics. Drought stress did not affect the concentration of undegraded NDF (uNDF) in upper or bottom internodes but slightly decreased it in upper leaf blades (17.5 and 15.7% for A and R, respectively). The concentration of uNDF differed substantially among corn hybrids in upper internodes (13.4 to 28.3% uNDF), bottom internodes (21.5 to 42.3% uNDF), and upper leaf blades (11.6 to 20.1% uNDF). No interactions existed between irrigation treatment and corn hybrid for uNDF concentration. Drought stress did not affect the fractional degradation rate () of NDF in upper internodes, bottom internodes, or upper leaf blades. The of NDF differed among corn hybrids in upper (3.8 to 6.6%/h) and bottom internodes (4.2 to 6.7%/h) but did not vary in upper leaf blades (3.8%/h). No interactions existed between irrigation treatment and corn hybrids for the of NDF. Significant interactions existed between irrigation treatment and corn hybrids for the effective ruminal degradation (ERD) of NDF in upper and bottom internodes. This interaction did not exist for upper leaf blades. The ERD of NDF differed substantially among corn hybrids in upper leaf blades (32.5 to 39.1%). In conclusion, drought-stressed corn had a marginal increase of NDF degradability of leaf blades but not in stem internodes, and drought stress had no effects on ERD of NDF. The effect of drought stress on NDF degradability of corn for silage is still inconclusive and deserves further investigation.
本研究的目的是确定灌溉对温室控制条件下生长的玉米植株原位中性洗涤纤维（NDF）降解性的影响。将五个商业玉米杂交种种植在放置于温室中的6个花盆中。花盆被随机分为2种灌溉方案，分别为充足灌溉（A；598毫米）或限制灌溉（R；273毫米）。收获时，从植株的上部和下部采集叶片和茎节。将组织样本在3头装有瘤胃瘘管的奶牛瘤胃中培养0、3、6、12、24、48、96和240小时，以确定原位NDF降解动力学。干旱胁迫未影响上部或下部茎节中未降解NDF（uNDF）的浓度，但上部叶片中的uNDF浓度略有下降（A和R分别为17.5%和15.7%）。上部茎节（uNDF为13.4%至28.3%）、下部茎节（uNDF为21.5%至42.3%）和上部叶片（uNDF为11.6%至20.1%）中，不同玉米杂交种的uNDF浓度差异很大。灌溉处理与玉米杂交种之间在uNDF浓度方面不存在交互作用。干旱胁迫未影响上部茎节、下部茎节或上部叶片中NDF的降解率（）。上部（3.8%至6.6%/小时）和下部茎节（4.2%至6.7%/小时）中，不同玉米杂交种的NDF降解率有所不同，但上部叶片中的降解率没有变化（3.8%/小时）。灌溉处理与玉米杂交种之间在NDF降解率方面不存在交互作用。上部和下部茎节中，灌溉处理与玉米杂交种之间在NDF的有效瘤胃降解（ERD）方面存在显著交互作用。上部叶片中不存在这种交互作用。上部叶片中，不同玉米杂交种的NDF的ERD差异很大（32.5%至39.1%）。总之，干旱胁迫的玉米叶片的NDF降解性略有增加，但茎节中没有，并且干旱胁迫对NDF的ERD没有影响。干旱胁迫对青贮玉米NDF降解性的影响仍无定论，值得进一步研究。
