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COMPARATIVE NUTRITIONAL QUALITY AND ANIMAL PERFORMANCE OF IRRIGATED FORAGES CONSISTING OF ALFALFA, CICER MILKVETCH AND A COOL SEASON GRASS MIXTURE
Abstract
Five irrigated forages in western Nebraska were evaluated under rotation grazing with yearling steers. Average daily gains, live weight gain/ha and grazing potentials were determined from 1977 through 1979. Three of the forages were evaluated during 1978 and 1979 for forage yield, forage disappearance per kg of live weight gain and forage quality. Cumulative forage yield available prior to grazing during spring through late summer was determined for alfalfa, cicer milkvetch, and a grass mixture composed of smooth brome (Bromus inermis), meadow brome (Bromus biebersteinii), orchardgrass (Dactylis glomerata), and creeping foxtail (Alopecurus arundinaceus). Cumulative forage yields (14,315, 15,040, and 13,634 kg/ha, respectively) were not different (P > .05). Forage disappearance per steer averaged 8.78, 10.73, and 6.71 kg/day for alfalfa, cicer milkvetch, and the grass mixture, respectively. Forage disappearance per kg of steer gain averaged 10.8, 15.15, and 7.68 kg, respectively. Average daily forage disappearance was higher (P < .05) for both alfalfa and cicer milkvetch than for the grass mixture. In vitro dry matter digestibility was not different (P > .01) for alfalfa (68.72%), cicer milkvetch (69.26%), and the grass mixture (66.96%). For each forage, the average IVDMD of forage available prior to grazing was greater (P < .01) that the IVDMD of the residue after grazing. Percentage crude protein averaged higher (P < .05) in alfalfa (22.49%) and cicer milkvetch (22.37%) than in the grass mixture (19.44%). Crude protein averaged higher (P < .01) in all forages prior to grazing than in residue after grazing. Average NO(,3)-N values were different (P < .05) for alfalfa (.210%), cicer milvetch (.269%), and the grass mixture (.315%). Nitrate-N values of alfalfa averaged lower (P < .01) in forage available prior to grazing than in residue after grazing. Each forage was analyzed for Ca, P, K, Mg, Zn, Cu, Fe, Mn, and Na before and after grazing throughout the growing season. Periodic mineral deficiencies occurred in forage available prior to grazing in some forages. In each instance, an even lower concentration of a deficient mineral in forage residue after grazing implied that selective grazing may have been compensating for these deficiencies. When steers received .45 kg corn/head/day, ADG from 1977 through 1979 was .87, .88, .90, .93 and .73 kg for alfalfa, the grass mixture, the grass-alfalfa mixture, the grass-cicer milkvetch mixture and the cicer milkvetch, respectively. Average daily gains were not different (P > .05) except on cicer milkvetch which was lower (P < .05). Average grazing potentials were 825, 1100, 1102, 983, and 672 steer days/ha for alfalfa, the grass mixture, the grass-alfalfa mixture, the grass-cicer milkvetch mixture and the cicer milkvetch, respectively. Grazing capacities among forages having a grass component were not different (P > .05) and all had higher (P < .05) grazing capacities than either of the pure legume forages. The grazing capacity of alfalfa was higher (P < .05) than that of cicer milkvetch. Average live weight gains were higher (P < .05) on grass-alfalfa (987 kg/ha), grass-cicer milkvetch (908 kg/ha) and the grass mixture (965 kg/ha), than on either of the pure legume forages. Alfalfa produced higher (P < .05) live weight gains (710 kg/ha) than did cicer milkvetch (563 kg/ha). When corn supplementation was increased to 1.8 kg/head/day, ADG on alfalfa (.98 kg) and the grass mixture (.97 kg) increased 10 to 12% on both forages. Grazing capacity increased 9 and 10% on alfalfa (896 steer days/ha) and the grass mixture (1208) steer days/ha), respectively. Live weight gains per hectare increased by 36% for both alfalfa (860 kg/ha) and the grass mixture (1166 kg/ha).
Subject Area
Agronomy
Recommended Citation
GRAY, ALAN MICHAEL, "COMPARATIVE NUTRITIONAL QUALITY AND ANIMAL PERFORMANCE OF IRRIGATED FORAGES CONSISTING OF ALFALFA, CICER MILKVETCH AND A COOL SEASON GRASS MIXTURE" (1980). ETD collection for University of Nebraska-Lincoln. AAI8109983.
https://digitalcommons.unl.edu/dissertations/AAI8109983