**4. Forage grazing sequence and steers**

#### **4.1 Forage grazing sequence**

Spring seeded annual forages require adequate growing time before grazing suitability is reached; therefore, yearling steers grazed native range pasture until annual forages were ready for grazing. On average, the steers grazed native range for approximately 108 days between the first week of May and mid-August. Western North Dakota native range pasture grass specie composition consists of both cool- and warm-season grasses: cool-season: western wheatgrass (*Pascopynum smithi*), slender wheatgrass (*Elymus trachycaulus*), prairie junegrass (*Koeleria macrantha*), bluebunch wheatgrass (*Pseudorognerta spiacata*), green needlegrass (*Nassella viridula*), slender wheatgrass (*Elymus trachycaulus*), warm-season: prairie sandreed (*Calamovilfa longifolia*), indiangrass (*sorghastrum nutans*), blue grama (*Bouteloua gracilis*), sideoats grama (*Bouteloua curtipendula*), and little bluestem (*Schizachyrium scoparium*). For the research, control groups grazed native range for the full grazing season; however, grazing groups that were assigned to graze annual forages began grazing field pea-barley (*Pisum sativum*, var. Arvika; *Hordeum vulgare*, var. Stockford) as the first annual forage in the grazing sequence followed by corn and cover crop grazing. Crop grazing readiness for pea-barley was determined when the barley grain was in the early milk stage and peas were small and soft (2–3 mm).

#### **4.2 Steers, stocking density, and grazing management**

Over the course of multiple experiments steers of differing frame score have been used as grazing animals and described as small frame (SF: Frame Score Range: 3.77–3.82) and large frame (LF; Frame Score Range: 5.53–5.63). Frame score determination is computed according to the formula: −11.548+(0.4878 \* Ht) – (0.0289 \* Age) + (0.00001947 \* Age2 ) +(0.0000334 \*Ht \* Age), where age = days, and height = inches [16]. For one research evaluation [17] only one steer frame score type was used (LF), and in other studies [18, 19] steers of both SF and LF types were used. Grazing equivalents for steers used in these research investigations were computed from a reference cow (454 kg) nursing a six-month old calf [20]. Grazing equivalents for each steer type were calculated by conversion of reference animal cow weight and SF and LF steer weights to metabolic weight, which resulted in grazing steer equivalents of 0.840 and 0.934 for steers

categorized as being of SF and LF. Each of the pastures in the grazing sequence were 1.74 ha in size, replicated three times and each pen replicate stocking rate was 0.2138 ha per steer. The field pea-forage barley intercrop mix was grazed for 27–32 days and varied by year. The mixed intercrop maturity progresses rapidly from seeding to full maturity and it was determined that extending the grazing period beyond 27–28 days resulted in a decline in steer gain performance. For some of the studies, the intercrop mix was windrowed to capture forage quality before the onset of grazing and in other studies the crop was grazed as standing crop. Windrowing was not always successful. Above average precipitation one year resulted in moldy feed in the windrows, which was undesirable. Therefore, windrowing was suspended for subsequent research projects. Corn grown for sequence grazing was unharvested (not combined residue) vegetative actively growing plant of a forage-type categorized as being later maturing and used for silage due to the plant's stalk to leaf ratio and soluble sugar content. Days of forage corn grazing ranged from 52 to as much as 71 days and was largely dependent on the amount of rain received. Cover crop mix was the last crop grazed in the sequence and the amount of above ground biomass available for grazing was more variable than the preceding pea-barley and corn crops. The observed variability is directly related to available soil moisture and precipitation following harvest of the winter triticale-hairy vetch cover crop mix. Insufficient soil moisture delayed germination for as much as four to five weeks before precipitation was received, which negatively impacted total above ground biomass for grazing.

Upon completion of sequence crop grazing, bale grazing was initiated. For bale grazing, cover crop hay is produced using a full-season cover crop consisting of oats, peas, sorghum-sudan, and clover (crimson var. and berseem var.). Nutrient analysis of the cover crop bales and the starting and ending forage analysis for the other sequence crops that were grazed are shown in **Table 3**. Native range, field pea-barley, corn, cover crop mix, and cover crop baled hay were analyzed for crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), invitro organic matter


#### **Table 3.**

*Forage nutrient analysis for grazing sequence crops and cover crop bales.*

*Perspective Chapter: Alternative Intensive Animal Farming Tactics That Minimize Negative… DOI: http://dx.doi.org/10.5772/intechopen.108339*

disappearance (IVOMD), invitro dry matter disappearance (IVDMD), calcium and phosphorus (Ca/Phos), and total digestible nutrients (TDN).
