R.S. Kalmbacher

Botanical composition of diets of cattle grazing south Florida rangeland.

Tbe botanical composition of the diets of 5 esophageal-fistulated steers in summer (June to August) and winter (January to March) on a south Florida range was studied in order to point out those plants or groups of plants that warrant management. Diets of steers grazing 3 ecosystems were compared: pine palmetto (Typic and Arenic Haplaquod soils), fresh-water marsh (Terric Medisaprist soil), and transition area around the marsh (Spodic Psammaquent soil). In addition we wanted to know if diets of steers regrazing a summer-grazed pasture in the winter were the same as diets from a pasture grazed only in the winter. A total of 320 diet samples were analyzed microbistologlcally, and out of 109 species, steers were found to eat 42 species. Steer diets were significantly different between summer and winter, while diets were similar on tbe regrazed-winter and winter-only pasture. Differences between summer and winter diets were mainly a decrease inPanicum hemitomon on the marsh and a decrease in Lachnanthes caroliniana in the winter diets on the pine-palmetto area, an increase in the proportion of shrubs in the winter diet on the pine-palmetto area, and an increase in Xyris spp. and Solidago jistuIosa in the latewinter on the marsh and the transition area around the pond. These diet changes were the result of changes in plant availability or palatability, which was the case with P. hemitomon. These data indicated that Andropogon spp. and Schizachyrium stoloniferum were major components of the pine-palmetto area diet of cattle and should receive management to increase their yields. Forbs, though seasonally available, should be encouraged by shrub control, careful use of selective herbicides, and promotion of natural reseeding. Shrubs, especially Serenoa repens and Ilex &bra should be available as winter foods. Florida’s southern range is primarily a flatwoods site, which is a broad flat area interspersed with 1 to IO-ha saucer-shaped depressions which form fresh-water marshes or maidencane (see Table 2 for Latin binomials) ponds. Hilmon (1964) described southern Florida rangeland and its vegetation, and indicated that the pinepalmetto ecological type comprised 75% of the range, and the fresh-marsh type made-up 15% of the range. The remaining 10% was in wet-prairie, which is a transition between pine-palmetto and fresh water marsh. As an important part of the total pasture system, range is frequently interfaced with improved pastures, and most ranching operations use range in the winter as a source of roughage for dry-pregnant cows (Kalmbacher 1978). Unlike most cultivated pastures where 1 or 2 forages are grazed, range pastures often have over 100 indigenous plants from which livestock can select. Many range plants are available seasonally and others, while available throughout the year, are only eaten seasonally. Ranchers need to know which species cattle select in order to determine supplementation needs, make best use of different pastures, and manage important plants. A review of literature pertaining to botanical .composition of range cattle diets indicated certain generalities. First, out of a large number of available species, only a few made up the major portion Authors are associate agronomist, Ona Research Center, Ona Fla. 33865; former graduate assistant, Department of Agronomy, University of Florida, Gamesville 3261 I; associate professor, School of Forestry and Wildlife Management, Louisiana State Universit)r, Baton Rouge 70893; and associate statlstlclan, Depanment of Statistics, Umversity of Florida, GaineswIle 3261 I. This article is Florida Agricultural Experiment Paper NO. 4220. Manuscript received November 29, 1982. 334 of the diet (Beck 1975, Bishop et al. 1975, Rosiere et al. 1975, Uresk and Rickard 1976, Havstad et al. 1979). Second, on a year-round basis the perennial grasses were the mainstay of the diet (Thetford et al. 1971, Beck 1975, Bishop et al. 1975, Rosiere et al. 1975, Durham and Kothmann 1977, Havstad et al. 1979, Johnson and Pearson 1981). A third common finding was that the diet changed during the year. Forbs played an important role in spring or summer (Wallace et al. 1972, Beck 1975, Vavra et al. 1977, Havstad et al. 1979), and shrubs were consumed in the greatest amount during the winter (Galt et al. 1969, Durham and Kothmann 1977). This study was designed to determine which plants should be favored by management by identifying forages serving as staples for cattle grazing south Florida range during summer and winter grazing seasons. Secondly, since range is frequently rotationally grazed, we wanted to determine if winter diets were the same on pasture grazed in the winter only vs. one grazed in the summer then regrazed in the winter.

Shifts in botanical composition of flatwoods range following fertilization

Three annual applications of a factorial combination of N (0, 40, 80, 120 kg ha-1), P (0, 25 kg ha-1) and K (0, 100 kg ha-1) were applied to Florida flatwoods range where 45 plant species were initially present. Addition of P and K had no effect (P > 0.05) on indices of plant diversity, density, or above-ground biomass. Both Shannons (Y = 1.6 - 0.005N, where N is kg ha-1) and Simpsons index (Y = 0.28 + 0.002N) indicated diversity decreased with increasing N because the community was being dominated by goldenrods (Solidago fistulosa and Euthamia minor) and dogfennel (Eupatorium spp.). Density of all fortes increased with increasing N (1990 plants m-2 = 17.4 + 0.4N and 1991 plants m-2 = 35.1 + 1.4N). Density of beaked panicum (Panicum rhizomatum) increased quadratically with increasing N, while density of decumbent carpetgrasses (Axonopus spp.) and low panicums (Dichanthelium spp.) declined linearly. Broomsedge (Andropogon virginicus), wiregrass (Aristida stricta), and bottlebrush 3-awn (A. spiciformis) were eliminated from the site. Above-ground biomass of fortes increased with N (1988 kg ha-1 = 934 + 16.1N and 1990 kg ha-1 = 227 + 60.6N). Grass and grasslike biomass increased linearly as N increased, but N effects were independent of year, which were different (1988 = 1,530 kg ha-1 and 1990 = 2,140 kg ha-1). The plant community at this location became less diverse when the naturally low soil N was increased by 40 kg ha-1 or more. Early successional species replaced later successional species, especially creeping bluestem (Schizachyrium scoparium).

Distribution of dry matter and chemical constituents in plant parts of four Florida native grasses

Because of the selective nature of grazing livestock, the use of whole plant samples to estimate the nutritional potential of forages may be misleading. During this 2-year study, the distribution of dry matter (DM), crude protein (CP) in vitro organic matter digestibility (IVOMD), and concentrations of P, K, Ca, Mg, Mn, Fe, Cu, and Zn were determined in the individual leaf blades, leaf sheaths, nodes plus internodes, and infloresences of creeping bluestern (Schisachyrium stolonifenrm), lopsided indiangrass (Sorghastrum secundum), maidencane (Panicurn hemitomon), and wiregrass (Aristida stricta) when they were in the anthesis stage of + maturity. Most of the DM was in the nodes plus internodes (avg. 45%), while the leaf blades (avg. 18%) generally made up the smallest amount of the total plant DM. In a progression from the bottom to top of the plant the CP, IVOMD, and most of the mineral concentration of the different leaf blades, sheaths, and nodes plus internodes increased. Crude protein, IVOMD, and most of the minerals of the grasses were higher in leaf blades, followed by sheaths, and nodes plus internodes. When compared with other grasses, maidencane had a higher proportion of CP and minerals in the leaves and nodes plus internodes and a higher percentage of plant weight in these parts. Wiregrass was found to be similar to creeping bluestem and indiangrass in CP and most minerals, but IVOMD of wiregrass parts were lower. Dietary requirements for dry, pregnant cows for P, N, Mg, and Cu might not be met by any part of the 4 grasses, while apparently adequate levels of Fe, Mn, and Zn could be provided by each part. Leaf blades and infloresences had sufficient Ca concentrations for dry pregnant cows. When evaluating pasture quality, the nutritional potential of forage may be underestimated by analyzing whole plant samples. Cattle seldom consume whole plants, but rather selectively graze individual parts. The parts of a plant [infloresence, leaf blade, leaf sheath, and culm (nodes plus internodes)] differ in their chemical and physical properties depending on their role in the plant. Florida’s sub-tropical native forage grasses are low in protein, digestibility and mineral concentration (Kalmbacher 1981a, I98 I b). This is associated with low soil fertility and high temperature during the growing season and the advanced plant maturity in winter when most Florida range is grazed. Because evaluation of whole plant samples can be misleading, this study was initiated to examine the distribution of dry matter (DM), the variation in crude protein (CP), in vitro organic matter digestibility (IVOMD), and the concentration of certain minerals in parts of 4 important grasses. The major increaser on flatwoods range, wiregrass (Aristida stricta); 2 major decreasers on flatwoods, creeping bluestem (Schizachyrium stoloniferum) and lopsided indiangrass (Sorghastrum secundum); and the major decreaser on slough sites, maidenAuthor is associate agronomist, Ona Agricultural Research Center, Box 62, Ona,

Effect of fertilizer and nematicide treatments on crops grown for biomass.

Abstract Successful production of biomass for energy requires selection of species with high annual yields and development of proper management conditions. Pennisetum purpureum, Erianthus arundinaceum, Sorghum bicolar, and Tripsacum dactyloides were grown as single biomass crops and Brassica campestris, Sorghum bicolor were grown in sequence under one nematicide and two fertilization treatments. The experiment was conducted over a three year period. P. purpureum (52·2 Mg ha−1) and Erianthus (46·4 Mg ha−1) produced highest dry biomass yield when recommended fertilizer rate for forage production was applied and the plants were cut once each year. Harvesting P. purpureum twice each year reduced yields 65% compared with the single cut. Decreasing fertilizer by one-half lowered yield 14–26% for P. purpureum and sorghums; 49% for T. dactyloides (zero fertilizer applied), whereas Erianthus increased from 46·4 to 54·0 Mg ha−1 with the lower fertility. The application of 6·7 kg ha−1 active nematicide on the soil surface in late March of each year did not control nematodes nor affect yields. Biomass yields from P. purpureum and Erianthus when grown on flatwood soils in peninsular Florida at the normal fertilizer rate and harvested once per year were higher than yields at reduced fertilizer treatments. Additional research is needed to determine optimum fertilizer levels for each grass grown under specific soil conditions.

Effect of N-P-K fertilization on yield and tiller density of creeping bluestem

Forage quality and quantity from palatable grasses, like creeping bluestem [Schizachyrium scoparium (Michx.) Nash var. polycladus (Schriber & Ball) Bruner (Syn S. stoloniferum Nash.)], are limited, especially in winter when cows graze Florida range. We anticipated that N fertilizer (0, 40, 60, 120 kg ha(-1)), P (0, 25 kg ha(-1)) and K (0, 100 kg ha(-1)) would increase bluestem yield, tiller density, and forage quality. Within sample dates yield and tiller density increased linearly with N rate. For example 31 days after fertilization, intercepts for equations predicting yield were 319 kg ha(-1) and 124 m(-2) with coefficients of 1.2 and 0.29, respectively, where the independent variable is N rate. Over sample dates yield responses to N rate were quadratic and tiller densities were cubic. Reproductive tiller density was increased by N fertilization (1989 tiller density, no. m(-2), = 30 + 0.29N). Neither yield nor tiller density was affected by P fertilizer, but K fertilizer increased reproductive tiller density, hence fall yield. After 3 years of fertilization, N had negative quadratic and negative linear effects on yield and tiller density, respectively. Tissue N concentration in the fall was reduced with N fertilization because of increases in reproductive growth (1988 calendar 145 days postfertilization, g kg(-1) = 5.7 - 0.041 N + 0.00031 N(2)). Fertilization of creeping bluestem is not a recommended practice when bluestem is to be grazed in fall and winter.

Burning and 2, 4, 5-T Application on Mortality and Carbohydrate Reserves in Saw-Palmetto

On the flatwoods of the southeastern United States control of saw-palmetto (Serenoa repetrs (Bartr.) Small) is an important step in the improvement of native pastures. This study, conducted at the Ona Agricultural Research Center in south Florida, measured fluctuations in total available carbohydrates (TAC) in rhizomes of burned and unburned saw-palmetto which received a June or October application of 8.9 kg/ha (acid equiv.) of 2,4,5-T. Palmetto kill, change in palmetto cover, and grass canopy cover were evaluated. Burning reduced TAC concentration in rhizomes from 48.8% in March to 14.3% in July as compared to a drop from 47.2% to 37.4% for unburned plants. Applying 2,4,5-T caused a further significant decline in TAC concentration. Both burning and 2,4,5T resulted in lower rhizome percent dry matter indicating that treatment stress caused metabolism of carbohydrate which was replaced by water. After 1 year there was higher mortality on palmetto receiving 2,4,5-T in June, but after 2 years there was no difference in mortality between June (48%) and October sprayed (39%) plants. Burning was not found to have a significant effect on mortality of sprayed plants. Burning and 2,4,5-T decreased palmetto cover, and burned plants treated with 2,4,5-T in June had less cover than burned plants treated in October with 2,4,5-T. Burning followed by 2,4,5-T application in June increased grass cover from 29.4% at the beginning of the study to 67.5% at the end. Saw-palmetto (Serenou repens (Bartr. Small)) is one of the most abundant shrubs on the sandy flatwoods from southern South Carolina to southern Mississippi and throughout all of Florida. The primary method of reproduction is by sprouting from partially buried stems or rhizomes which are capable of elongation. However, palmettos flower in late April and produce some fruit in September or October. In Florida palmettos are relatively dormant in the winter and produce 80% of their annual growth during the rainy May to October period (Hilmon 1968). Carbohydrate reserves of saw palmetto are principally starch which is stored in the rhizomes (Hough 1968). These reserves follow seasonal cycles which are influenced by periods of dormancy, frond growth, and flowering. In rhizomes of unburned plants grown in Georgia, starch was highest in winter (37%) and lowest in summer (27%). Florida cattlemen burn range every 3 to 4 years after winter grazing in order to remove old forage and litter, but palmettos regain 80% of their crown coverage the first year after burning (Hilmon 1968). Burning significantly lowered plant reserves, and three repeated summer burnings after a winter burn lowered starch to 12% (Hough 1968). Interest in reducing palmetto cover has increased with demands for forage production. McCaleb et al. (1960) tested 25 chemicals Authors are associate agronomist, Ona Agricultural Research Center. Ona, Florida 33865; and associate plant physiologist and associate statistician, University of Florida, Gainesville 326 I I. This paper is Florida Agriculture Experiment Station Paper No. 3042. Manuscript received April 30, 1981, JOURNAL OF RANGE MANAGEMENT 36(l), January 1983 and reported 2,4,5-T to be among the best for killing saw palmetto. Recent preliminary experimentation (unpublished) conducted at the Ona Agricultural Research Center (ARC) supports 2,4,5-T (2,4,5-trichloro-phenoxyacetic acid) as being the best of 10 compounds. McCaleb et al. (1961) applied herbicides to unburned palmettos in September and October and reported better mortality (75%) with 4.48 kg acid equivalent/ha (AE/ha). Burton and Hughes (1961) evaluated mortality at 20 months after the application of 3 rates of 2,4,5-T and 2 carriers applied at 3 dates to burned and unburned palmettos. They reported that main effects due to burning and rates were not significant, and date of application was significant only on burned palmettos where the best treatment (burn on March 7 and spray August 26 with 2,4,5-T and water) resulted in 76% mortality. Altobellis and Hough (1968) experimented with 7 combinations of burning and spraying of 2 rates of 2,4,5-T. Best control (61%) was obtained with 6.16 kg/ha AE applied in July 1963, burning 7 months later, respraying in July 1964 followed by reburning in July 1965. The success of this treatment was evaluated with reference to the carbohydrate reserve work of Hough (1968), although there was no report of starch analyses in this study. Because burned palmettos have a weaker energy status than unburned plants (Hough 1968) burning may predispose plants to greater mortality (Burton and Hughes 1961, Altobellis and Hough 1968) when sprayed with 2,4,5-T, which is effective in killing palmettos (McCaleb et al. 1960, McCaleb 1961, Grelen 1960, Burton and Hughes 1961, Altobellis and Hough 1968). However, time of application after burn still remains on a trial and error basis. Hough (1968) suggested that based on this carbohydrate reserve work, October application of herbicide would probably result in the best kill of winter burned palmettos. However, since carbohydrates in unburned palmettos are at their lowest level in late June and July (Hough 1968) this would be an appropriate time for herbicide application which would likely result in maximum control of unburned palmettos. The objective of this study was to measure the total available carbohydrate and relate this to mortality of winter burned and unburned palmettos which were sprayed with 2,4,5-T in June and October. Materials and Methods Work was conducted at the University of Florida’s Ona ARC (27’26’N, 8 1’55’W) in south-central Florida. Averageannual rainfall is about 140 cm, 75% of which falls from May to October. Average temperatures from May to October are maximum/minimum 31.6/ 17.8”C while the remaining months average 25.311 I .6” C. Soil on the experimental site was a Eau Gallie fine sand (Arenic haplaquod), which supported a uniform stand of saw-palmettos that had not been burned in the past 10 years... The treatments were: ( 1) burn (March 1, 1977) and no burn; and (2) time of 2,4,5-T (propylene glycol, butyl ether esters) application at 8.9 kg AE/ha applied on June 30,1977, or October 20,1977, in

Limpograss and hymenachne grown on flatwoods range pond margins.

Limpograss (Hemarthria altissima [Poir] Stapf and C.E. Hubb) and hymenachne (Hymenachne amplexicaulis [Rudge] Nees) may reduce weight loss of cows grazing Florida range from September to March. These grasses were grown on maidencane (Panicum hemitomon Schult) pond margins and were evaluated as stockpiled forage (ungrazed 6-10 months) at 2 locations over 4 years. Floralta limpograss received 0 or 3,000 kg dolomite ha (2 whole plots) and N-P-K fertilizer (5 subplots): 50-25-50, 50-25-0, 50-0-50, 50-0-0, 0-0-0 kg/ha. Hymenachne was grown without dolomite, N, P, or K. Hymenachne failed to establish at Ona in central Florida, but persisted for 1 year at Immokalee near the Everglades where dry matter production in October to January was 1,540, 2,160, and 2,910 kg/ha at 35, 70, and 105 days after N fertilization, respectively. Crude protein (56 g/kg) was highest at 70 days and IVOMD (47.4%) was highest at 105 days. Limpograss established without dolomite, N, P, or K fertilization, and forage available for winter grazing often exceeded 7,000 kg/ha. Application of 50 kg N/ha to stockpiled limpograss increased yield (compared to no N) in 1 of 4 years at Ona and in both years at Immokalee. Applying N to stockpiled limpograss always increased crude protein and IVOMD above that of grass receiving no N, but increases were slight (10 g crude protein/kg). Crude protein seldom exceeded 50 g/kg with 50 kg N/ha applied in late August at Ona or in October at Immokalee. In vitro organic matter digestion often exceeded 45%, which could help limit weight loss of cows grazing range in winter. Neither grass was observed to be invasive, as growth was confined to plots after 5 and 8 years at Immokalee and Ona, respectively.

Effects of clipping on burned and unburned creeping bluestem.

Creeping bluestem (Schizachyriwn stolon&mm), a major decreaser on Florida range, is adversely affected by grazing during tbe growing season after a winter bum. To compare tbe effect of defoliation of burned and unburned bluestem range, creeping bluestem was burned (or not burned) on 2 similar sites in February 1978 and 1979 and cut at 2,4,6,8, and 10 months after burning. Once forage was initially cut, it was recut every 2 months. Dry matter (DM) yield, tiller density, total nonstructural carbohydrate (TNC), crude protein (CP), and in vitro organic matter digestibility (IVOMD) were determined. When forage was cut in April and recut every 2 months, average yield of creeping bluestem from unburned areas was 3,000 kg/ha while that of burned was 2,390 kg/ha. Creeping bluestem yield from unburned areas declined linearly within both yearsas initial harvest was delayed, but delaying initial barvest date bad no effect on forage yield from burned areas. Final tiller density was usually a cubic response in burned and unburned plants. Tiller density generally increased in plants cut 1 month after treatment, decreased in plants cut 2,4,6 months after treatment, and increased in plants cut 10 and 12 months after treatment. Rhizomes of plants burned in February 1979, cut initially in April, and rebarvested 4 times bad 9.0% TNC in March 1980, while unburned plants contained 10.2% TNC. Tbe response of CP and IVOMD in initial growth was quadratic or cubic with time of initial harvest because percentages were raised initially due to burning, then they dropped steadily to a low in August, after which they began to rise sligbtly. Protein content in unburned forage bad either a negative linear response or bad no significant regression with time of initial harvest. IVOMD in unburned forage exhibited a quadratic (1978) or a polynomial (1979) response with time of initial harvest where IVOMD increased or fluctuated in the growing season, usually decreasing in fall and winter. Analysis of regrowth data indicated that the response of crude protein and IVOMD was similar regardless of bum treatment. Quality of regrowth declined from June to August and steadily increased from August to December. Creeping bluestem would be weakened by grazing on 6O-day intervals after a February bum. When prescribed burning of creeping bluestem range is carried out every 3 to 4 years, deferment of grazing until June after a February burn will allow grazing of relatively high quality forage and still maintain creeping bluestem stand vigor. Proper timing of burning and grazing should assure the longevity and improve forage quality of creeping bluestem (Schizuchyrium stoloniferum) (Yarlett 1963), one of the most important grasses on the flatwoods range. Many ranges have been depleted of creeping bluestem as a result of repeated burning and uncontrolled grazing and now are dominated with wiregrass (Aristida stricta) (Yarlett 1963). Burning is important on wiregrass range because both forage (Lewis and Hart 1972) and calf production (Kirk et al. 1974) are reduced with long-term protection from fire. However, management that is beneficial for wiregrass is detrimental for creeping bluestem. White and Terry (1979) indicated that burning Authors are agronomist, Ona Agricultural Research Center, Ona, Fla. 33865; statistician and biologist, University of Florida, Gainesville 3261 I; environmental manager, Utah International, Inc., Fruitland, N. Mex. 87416; and extension range specialist, Texas Agricultural Extension Service, Uvalde 78801. This article is Florida Agr. Exp. Sta. Pap. No. 4710. Manuscript accepted 13 March 1985. JOURNAL OF RANGE MANAGEMENT 36(6), November 1965 and grazing creeping bluestem resulted in reduced dry matter yield and leaf area, and there were fewer total tillers at the end of the growing season as compared with unburned areas. Creeping bluestem is relatively high in dry matter yield (Kalmbather et al. 198 1) and it is palatable and dominant in cattle diets (Kalmbacher et al. 1984). Crude protein and in vitro organic matter digestiblity (IVOMD) of creeping bluestem, like that of most flatwoods forages, is low (Kalmbacher et al. 1981, Kalmbacher 1983b). If pastures are winter burned and deferred during the following summer, as suggested by White and Terry (1979), forage quality will be poor as compared to that of forage grazed in the spring or summer. The purpose of this study was to determine when clipping (after burning) might reduce creeping bluestem stands and to measure the effects of burning on crude protein and digestibility in regrowth forage. Materials and Methods The experiment was conducted in 1978 and 1979 at the University of Florida’s Ona Agricultural Research Center (27O25’ N, 81°55’ W). Different areas were used each year to eliminate the cumulative effect of burning on creeping bluestem. The soil on both areas was an unlimed, unfertilized Pomona fine sand (sandy, siliceous, hyperthermic Typic Haplaquod). Vegetation on the 2 areas was similar and almost entirely a natural stand of creeping bluestem with scattered Aristida spp., Dichanthelium spp, Andropogon spp., various forbs, and no palmetto (Serenoa repens) or other shrubs. The creeping bluestem was rank, well established, and had not been burned, grazed, or disturbed for 8 years. The study plots were permanent l-m* quadrats (20 in 1978,28 in 1979), and they were selected to assure uniformity of creeping bluestem. Live bluestem tillers in each quadrat were counted in February prior to treatment. An additional 20 quadrats 0.25 m* were harvested (1 to 2cm stubble) and separated into dead and living components for dry matter yield determination so that yield of green herbage that was burned could be subtracted from initial harvests of unburned forage. Initial harvest values would then represent dry matter accumulated between the burn and initial harvest. One half of the experiment was back-fired (25 Feb. 1978,9 Feb. 1979), and the other half was not burned. After 2,4,6, 8, and 10 (and 1 and 12 months in 1979) months following the burn, tillers were recounted, and all forage in the appropriate l-m* area was harvested 7 cm above the soil surface. Once quadrats were harvested initially, they were reharvested on succeeding 2-month intervals. Quadrats harvested initially 2 months after the February burn were reharvested 4 times, plots harvested initially 4 months after burning were reharvested 3 times, etc. Harvested forage from each quadrat was analyzed for dry matter content, crude protein (CP = N X 6.25) (Gallaher et al. 1977, Issac and Johnson 1976), and in vitro organic matter digestibility (IVOMD) (Moore et al. 1972). Total nonstructural carbohydrate (TNC) in rhizomes of creeping bluestem were analyzed in 1979 (Smith 198 1) with the following modifications: (1) amylo-glucosidase and invertase were used instead of takadiastase enzyme, and (2) the filtrate was not treated after enzyme hydrolysis with lead acetate and potassium oxalate. The extract was analyzed for reducing sugars using the calorimetric test of Nelson (1944) and Somogyi

Evaluating breeding seasons for cows grazing winter range and bahiagrass

Florida native range is grazed in winter and cows are moved to bahiagrass (Paspalum notatum Flugge) pasture in March for breeding and calf rearing. Winter weight loss of cows is a major problem, and one possibility to reduce it is to alter the breeding season. This 4-year study evaluated October-February range grazing with movement of cows to bahiagrass in late February for breeding and calf rearing beginning in March (spring-bred cows) vs. December-April range grazing with movement of cows to bahiagrass in May (summer-bred cows). Spring-bred cows weighed less coming off range (439 kg) than summer-bred cows (459 kg), but spring-bred cows gained more weight on bahiagrass (38 kg) by the time calves were weaned than summer-bred cows (1 kg). At weaning, there were no differences in weights of cows. Weight loss of cows on range was related to weight going onto range in the fall (r = -0.62 and -0.49 for spring- and summer-bred cows). Declining nutritive value of bahiagrass and heavy rains in the late summer and early fall appeared to lead to the inability of summer-bred cows to regain weight on bahiagrass. In 2 years, rain interfered with range burning in October which was needed to improve the palatability and nutritive value of forages for spring-bred cows, but this appeared to have no effect on cow performance. Weaning weight of calves from the spring-bred cows (205 kg) tended to be higher than that of calves from summer-bred cows (181 kg). There were no differences in pregnancy rates (74.5%). A March-May breeding season is recommended over a May-July breeding season for cows using a combination of range and bahiagrass. DOI:10.2458/azu_jrm_v53i4_pate

Effect of grazing stubble height and season on establishment, persistence, and quality of creeping bluestem.

Creeping bluestem (Schizachyrium stoloniferum) was grazed every 6O-days to 15 or 30-cm stubble heights during the following 4 periods (seasons): (1) June, Aug., Oct. (JAO); (2) Oct., Dec., Feb. (ODF); (3) Feb., Apr., June (FAJ); (4) year-long (YL). Average diameter (37 cm) of piants grnzed in JAO and YL to lS-cm stubble was less (PC 0.05) than piants (43 cm) grazed to 30 cm. There was no difference in diameter of piants grazed to 15 and 3O-cm stubble in ODF and FAJ (45 cm). Tiller density was influenced by stubble height only in 1982 and 1983 when density for the 15 cm stubble averaged lll/m2 vs. 142/m2for the 3O-cm stubble. Tiller density in 1980,1982, and 1983 was less (X0.05) in JAO and YL treatments (109/m’) than in ODF and FAJ (167/mz). Forage dry matter yield in 1979-80 and 1982-83 depended on stubble height and seasons. Avenge yield at H-cm height was greater for the FAJ treatment (1,700 kg/ha), similar for JAO (910 kg/ha) and ODF (910 kg/ha) and lowest for YL (660 kg/ha), but yield was simiIar at aii seasons (510 kg/ha) at 3O-cm stubble. Crude protein and IVOMD were influenced more by grazing time within a season than by seasons or stubble height. Poorest quality forage was at the beginning of the seasons (especially ODF and FAJ treatments). Best quality came from regrowth. Winter or spring grazing resulted in better stands of creeping bluestem than summer or year-long grazing.