Elaine E. Grings

Mineral dynamics in forages of the Northern Great Plains.

Mineral concentrations of range grasses are often below that required by grazing livestock. Limited information is available on forage mineral concentrations for the Northern Great Plains and there is little data on factors influencing concentrations of forage minerals throughout the year. Therefore, a study was conducted to evaluate special and temporal variations in mineral concentrations of major forage species in the Northern Great Plains. Herbage was sampled from 4 replicates on each of 2 soils in July, August, and September 1991, April, June, July, August, and September 1992, and April 1993. Herbage was sorted by species grouping and by live and dead tissue classes. Analyses on herbage included Ca, P, Mg, K, Na, Zn, Cu, Mn, and Mo. For western wheatgrass [Pascopyrum smithii (Rydb.) Love] and annual bromes [Bromus spp.], Zn and all macrominerals except Na were greater in live than in dead tissue. Live tissues of all other species groupings contained greater amounts of P and K than did dead tissue. Live tissue Mg concentrations were greater than dead tissue concentrations for other cool-season and warm season grasses. Manganese concentrations were greater in live than dead annual brome tissues, while Cu was greater in dear than live tissue. Dead sedge tissue contained greater concentrations of Ca than live tissue. Soil type affected several nutrient but this was partially related to soil effects upon composition of species groupings and live:dead ratios. Minerals most likely to be found in quantities less than required for animal production were P, Na, K, Zn, and Cu.

Herbage dynamics on 2 Northern Great Plains range sites.

Quantity and quality of forage produced are primary determinants of level of livestock production derived from grazing lands. Moreover, species composition of herbage is often considered a primary determinant of the ecological condition of rangelands. The broad objective of this study was to quantify the productivity, growth dynamics, and quality of herbage growing on 2 Northern Great Plains range sites and to concurrently relate magnitude and composition of production to the ecological condition of the sites. Using frequent harvest techniques, the 2-year study showed herbage production on the highly productive silty range site averaged 219 g m-2 as compared to 218 g m-2 on the supposedly less productive clay pan range site. The primary reason the clay pan site proved to be as productive as the silty site was attributed to the greater amounts of introduced annual grasses on the clay pan (148 g m-2) than the silty site (104 g m-2). The annual grass component on the clay pan was a near equal mix (71 vs 51 g m-2) of Japanese brome (Bromus japonicus Thunb.) and cheatgrass (B. tectorum L.) whereas the overwhelming dominant on the silty site was cheatgrass (73 g m-2). Western wheatgrass [Pascopyrum smithii Rydh. (Love)] was the dominant perennial grass on both sites averaging 49 g m-2 on the clay pan site and 57 g m-2 on the silty site. There were minimal differences between sites in terms of nutrient quality values (i.e., crude protein, acid detergent fiber, neutral detergent fiber) with results showing clearly that age of tissue was the major factor altering seasonal forage quality values. Range condition analyses revealed the clay pan site was in fair ecological condition and the silty site was in good condition. Study results demonstrate the need for land management agencies to continue to refine productivity estimates as well as adopt new techniques for assessing the ecological condition of rangelands.

Diet quality of suckling calves and mature steers on Northern Great Plains rangelands

A study was conducted over 2 years to evaluate the quality of forage selected by suckling calves compared to mature steers. Diets were collected from esophageally cannulated suckling calves or from steers that were two-years-old or older. Sampling was conducted in June, July, September, October, and November in each of 2 years. The forage portion of diets of esophageally fistulated suckling calves (beginning 115 to 136 days of age) were 21% greater (P < 0.01) in crude protein and 5% less (P < 0.06) in neutral detergent fiber relative to those consumed by mature steers in June and July. Diets of calves also contained 14% less (P < 0.01) acid detergent fiber than diets of mature steers in June. There were no differences in diet quality due to age during September, October, and November of either year. We conclude that suckling calves selected diets of higher quality than did mature steers early in the growing season. Forage quality may have allowed selective behavior at this time, low forage intakes of calves may have allowed more time for selection, or exploratory grazing by calves may have resulted in diets with increased nutrient quality in early summer.

Suppression of annual bromes impacts rangeland: vegetation responses.

Presence of invading annual bromes (Bromus spp.) can alter seasonal patterns of forage production and quality and require management changes for efficient use of infested rangelands in the Northern Great Plains. We studied biological impacts of the presence of brome by comparing brome infested rangeland to similar sites in which brome had been suppressed with autumn applications of atrazine [6-chloro-N-ethyl-N’-(1-methylethyl)1,3,5-triazine-2,4-diamine] at 0.56 kg ha in 1992 and 1993. Each treatment was randomly assigned to three, 12-ha pastures. Vegetation was measured for 5 months (May to September) each year from 1993 to 1995. Each pasture was stocked with 8 crossbred steers (Bos taurus) from mid-May to mid-September 1993 and 1995 and to mid-August 1994. The forage base varied temporally by date and year, but generally was not less than 800 kg ha. Brome suppression increased (P ≤ 0.05) crude protein concentration for western wheatgrass (Pascopyrum smithii Rydb. [Love]) in July (7.1 vs. 9.1%) and August (6.0 vs. 7.1%). With the variation in annual brome stands among years, as influenced by growing conditions, this experiment demonstrated that improvement in forage nutritional quality can be expected from suppression of annual bromes on semiarid rangelands.

Effects of Cross-Inoculation From Elk and Feeding Pine Needles On the Protozoan Fauna of Pregnant Cows: Occurrence of Parentodinium Africanum In Domestic U.S. Cattle (Bos Taurus)

ABSTRACT Consumption of pine needles tends to cause abortion in domestic cattle but not in elk. the present study was undertaken to determine whether this difference was associated with the rumen microbial population. After emptying the rumen, pregnant cattle were inoculated with either elk or cattle rumen contents. For those cows fed the pine needle diet, there was no difference in abortion rate between those inoculated with rumen contents from either elk or cattle. Protozoal concentrations and number of genera were observed to decrease markedly in all cows fed the diet containing pine needles. the cycloposthiid ciliate Parentodinium africanum was observed in rumen contents from several of the domestic cattle (Bos taurus). Concentrations ranged from 1.4 to 130.6 × 104 per ml of rumen contents, which comprised 4.6 to 80.3% of the total ciliate population. Mean dimensions of this species were: length, 33.4 μm: width, 19.7 μm: length/width ratio, 1.70. which were similar to those previously reported for this species from Bos indicus in Brazil. This is the first observation of P. africanum. originally observed and described in stomach contents of the hippopotamus, either in Bos taurus or in and host in the northern hemisphere.

Effect of reduced heifer nutrition during in utero and post-weaning development on glucose and acetate kinetics.

Energetic efficiency was evaluated in composite bred heifers born from dams receiving 1·8 or 1·2 kg/d winter supplementation for approximately 80 d before parturition. Heifers were then developed post-weaning and randomly assigned to heifer development treatments of either control (100 %; ad libitum; n 8/year) or restricted (80 %; fed 80 % of supplementation fed to controls adjusted to a common body weight: n 8/year) in a 2-year study. A glucose tolerance test (GTT) and acetate irreversible loss test (AILT) were administered to heifers at the termination of a 140 d development period when the heifers were approximately 403 d of age and consumed a silage-based diet, and again at 940 d of age when pregnant with their second calf and grazing dormant forage. No differences were measured (P>0·08) for dam winter nutrition or heifer development treatment for baseline serum metabolites or measures in either the GTT or the AILT. However, changes in baseline serum concentrations (P>0·05) were different between metabolic challenges, which occurred at different stages of development. No difference in acetate disappearance (P = 0·18) and half-life (P = 0·66) was measured between the two metabolic challenges. A trend for glucose half-life to be shorter in heifers born from dams receiving in utero winter treatments that supplied 1·2 kg/d of winter supplementation was observed (P = 0·083). Heifers developed with lower total DM intake during a 140 d development period had similar glucose and acetate incorporation rates as ad libitum-fed heifers when evaluated at two different production stages.

Late summer protein supplementation for yearling cattle

Abstract Three studies were conducted to evaluate late summer protein supplementation for growing steers on Northern Great Plains rangeland. In Experiment 1, crossbred yearling steers (N = 80 per year, mean initial live-weight = 275 kg) were allotted to 1 of 2 treatments replicated in 3 pastures in each of 3 years. Treatments were summer-long grazing with or without protein supplementation in late summer. Protein supplement (26% crude protein) was fed at a rate of 1.68 kg (dry matter basis) every third day. In 1995, a third treatment was added to additional pastures consisting of 1.62 kg (dry matter basis) of a 40% crude protein supplement fed every third day. There was no weight gain response to protein supplementation. In Experiment 2, yearling steers grazing rangeland from May to September were fed either no supplement, 1.5 kg of a 22% crude protein safflower meal-based supplement, 1.2 kg of 26% soybean meal-based supplement or 1.2 kg of a 26% safflower and soybean meal-based supplement every third day in late summer. Live-weight gain, forage intake, and digestibility were not affected by supplementation. A third experiment using ruminally cannulated steers fed grass hay and the 3 protein supplements based on safflower and soybean meals showed an increase in ruminal ammonia concentrations but no other appreciable change in ruminal fermentation with protein supplementation. Supplementation with as much as 648 grams of protein every third day was not a viable means to increase gains of steers grazing Northern Great Plains rangelands during late summer under the conditions of this experiment.

Yield and quality of RS-2, a quackgrass X bluebunch wheatgrass hybrid.

Understanding the effect of defoliation frequency and N fertilization on plant growth, forage yield, and quality of RS-2, a quackgrass [Elytrigia repens (L.) Nevski.] x bluebunch wheat grass [Pseudoroegneria spicata (Pursh.) Love] hybrid, will help promote efficient use of this hybrid in livestock production systems. Plants were fertilized with 0, 112, or 224 kg N ha-1 in spring 1988 and 1989, or with a 112 + 112 kg N ha-1 split in spring and summer. One set of plants was unmowed or mowed to a 5cm stubble height once in July or August in 1988 and another set was mowed initially in May, June, July, August, September, or October 1989 and monthly thereafter through October. Peak standing crop of unmowed plants was 3,470 kg ha-1 in 1988 and 5,850 kg ha-1 in 1989. In 1989 yields of fertilized plants exceeded those of unfertilized plants by 1,000 kg ha-1. In 1988, crude protein exceeded 12% in unmowed forage and in 1989 varied from 20% in May to 8% in August. After fertilization, crude protein was increased by 2 to 4 percentage units in 1988 and by 2 percentage units in 1989, but fertilization had no effect on in vitro digestible organic matter. Regrowth contained more crude protein (15-22%) and digestible organic matter (29-40%) than unmowed forage. Sequential harvesting enhanced quality of regrowth, but standing crops did not exceed 350 kg ha-1; except in June 1989. Sixty percent of the accumulated yield was harvested with the first mowing during May through August. Plots harvested initially in September and October were only harvested once. Our findings indicate an increase in forage yield potential and forage quality of RS-2 after harvesting and fertilizing the RS-2 hybrid.