Pitcher Lance R, MacAdam Jennifer W, Ward Robert E, Han Kun-Jun, Griggs Thomas C, Dai Xin
Amalgamated Sugar Company, Boise, ID 83709, USA.
Department of Plants, Soils and Climate, Utah State University, Logan, UT 84322, USA.
Animals (Basel). 2022 Apr 14;12(8):1017. doi: 10.3390/ani12081017.
Fall- or spring-born steers grazed monoculture irrigated birdsfoot trefoil (BFT; Lotus corniculatus L.) or cicer milkvetch (CMV; Astragalus cicer L.) pastures for approximately 12 weeks for 3 years and were compared with steers on concentrate diets. In the 3rd year, an irrigated meadow bromegrass (MBG; Bromus biebersteinii Roem. and Schult.) pasture treatment was added for further comparison. Steer average daily gain (ADG) was 1.31, 0.94, 0.83 and 0.69 kg d−1 on concentrate, ‘Norcen’ BFT, ‘Oberhaunstadter’ BFT, and ‘Monarch’ CMV diets, respectively; ADG on grass pastures was 0.43 kg d−1. The ADG on the concentrate diet was greater than ADG on legume or grass pastures, ADG was greater on BFT than CMV in every year (p < 0.03), and ADG on BFT was greater than ADG on grass (p < 0.03). The rate constant of gas production of an in vitro rumen fermentation demonstrated a slower rate of microbial digestion for CMV than for BFT. The elevated ADG on BFT pastures may be due to greater non-fiber carbohydrate (NFC) concentration and reduced neutral detergent fiber (NDF) concentration combined with condensed tannins that protect proteins in the rumen but do not impede protein digestion in the abomasum and intestines.
秋季或春季出生的阉牛在单作灌溉的百脉根（BFT；百脉根属）或鹰嘴紫云英（CMV；紫云英属）牧场上放牧约12周，持续3年，并与采食精饲料的阉牛进行比较。在第3年，增加了一个灌溉草地早熟禾（MBG；草地早熟禾）牧场处理以作进一步比较。采食精饲料、‘Norcen’百脉根、‘Oberhaunstadter’百脉根和‘Monarch’鹰嘴紫云英日粮的阉牛平均日增重（ADG）分别为1.31、0.94、0.83和0.69千克/天；在青草牧场上的ADG为0.43千克/天。精饲料日粮的ADG高于豆科或青草牧场的ADG，每年百脉根的ADG均高于鹰嘴紫云英（p < 0.03），且百脉根的ADG高于青草的ADG（p < 0.03）。体外瘤胃发酵产气的速率常数表明，鹰嘴紫云英的微生物消化速率比百脉根慢。百脉根牧场ADG升高可能是由于非纤维碳水化合物（NFC）浓度较高、中性洗涤纤维（NDF）浓度降低，以及缩合单宁的存在，缩合单宁可保护瘤胃中的蛋白质，但不妨碍皱胃和肠道中的蛋白质消化。
