Assessing a Simple Technique to Predict Forage Selection by Cattle Grazing Northern Queensland Rangelands

Diet selection of sheep shifted from quality to quantity characteristics of forages as sward availability decreased

The role of diet selection by farmed deer in their nutrient intake and species selection, and the consequences for the management of forages, is considered. In common with sheep and cattle, sward surface height (SSH) is the most influential sward physical factor on the ability of deer to meet their daily nutrient demand from grazed pasture, and a SSH of 10cm is required for maximum intake and performance. Deer discriminate among pasture species, generally preferring legumes and herbs to grasses. The grass dominance and low proportion of clover in typical permanent pasture grazed by deer reflects their selection for clover and avoidance of grass. This dominance of grass and the difficulty deer face in selecting for alternative species that are present only in a low proportion may constrain intake even when sward height is not limiting. Summer-growing forage species such as red clover (Trif olium pratense), white clover (Tri folium repens), birdsfoot trefoil (Lotus corniculatus), sulla (Hedysarum coronarium) and chicory (Cichorium intybus) have high nutritive value, and result in high liveweight gains by deer when provided as specialist swards at critical feeding times. Recent studies indicate that ruminants prefer to eat mixed diets, and management systems that enable mixed grass-clover pastures with a high proportion of legume to be sustained under selective grazing by deer would provide high nutritive value and maintain a balance between winter and summer in the seasonal distribution of pasture dry matter production. Keywords: Cervidae, deer, diet selection, forage, grazing behaviour, nutrient intake, preference

Livestock production is an agricultural system that serves as humanity’s protein and calorie source. Its production is the main economic stay for some people and a complementary source for others. However, land misappropriation and draught constrain the sustainable production of pasture for feeding livestock. Further aggravated by farmer/herder clashes and wetlands extinction. The need for an experiment for the selection of the best pasture species in the Sudan Savannah region that can thrive well under diverse soil textures and moisture status becomes imperative. This trial was conducted in the screen house of Babcock University, objectively to test the performances of Sorghum almum, Andropogon gayanus, Brachiaria mulato and Centrosema pascuorum under Sand, Sandy Clay Loam, and Sandy Loam textures and four water regimes: 100%, 75%, 50%, and 25%. Standard agronomic recommendations were practised throughout the experiment. Data collected included plant height, fresh and dry shoot and root weights, number of leaves, and leaf length. Data generated were analyzed using ANOVA. According to the results, Sandy Loam soil (Soil type from Gamawa) was the best for supporting all the pasture species, followed by Sandy Clay Loam (Soil type from Zaki). S. almum outperformed other pasture species significantly irrespective of soil textural type and water stress level treatments, followed by B. mulato. For water levels; 100% and 75% had the most promising biomass outcome. Based on the results, a 75% water regime which represents 25% deficit of the actual crop water requirement is recommended for the production of the tested pastures in the area.

Thirteen current and potential pasture species in southern Australia were examined for differences in their nutritive values and in vitro rumen fermentation profiles, including methane production by rumen microbes, to assist in selection of pasture species for mitigation of methane emission from ruminant livestock. Plants were grown in a glasshouse and harvested at 7 and 11 weeks after sowing for in vitro batch fermentation, with nutritive values assessed at 11 weeks of growth. The pasture species tested differed significantly (P < 0.001) in methane production during in vitro rumen fermentation, with the lowest methane-producing species, Biserrula pelecinus L., producing 90% less methane (4 mL CH4 g–1 dry matter incubated) than the highest methane-producing species, Trifolium spumosum L. (51 mL CH4 g–1 dry matter incubated). Proxy nutritive values of species were found not to be useful predictors of plant fermentation characteristics or methane production. In conclusion, there were significant differences in fermentative traits, including methane production, among selected pasture species in Australia, indicating that the choice of fodder species may offer a way to reduce the impact on the environment from enteric fermentation.

Navua sedge (Cyperus aromaticus), a perennial monocot plant native to tropical Africa, is a major weed in pasture and cropping areas in the wet tropical regions of Australia and South Pacific countries. In grazing pasture lands, rapid growth and reproduction of unpalatable Navua sedge leads to displacement of co‐occurring pasture species and depletion of livestock carrying capacity and production. Understanding the interspecific competitive ability of Navua sedge with co‐occurring desirable grasses and in response to varying ecological scenarios (e.g., grazing and plant density) is critical for the management of the weed in pasture situations. In a glasshouse setting, two co‐occurring pasture species—humidicola (Urochloa humidicola) and Rhodes grass (Chloris gayana) were grown with Navua sedge, in pots using a replacement series model. For each Navua sedge weed–pasture species pair, the experimental setup comprised of four ratios in two densities under simulated grazing and nongrazing conditions of the pasture grasses. Navua sedge growth and reproduction was highest when it grew as a monoculture or when co‐occurring pastures were exposed to simulated grazing as this action, reduced the competitiveness of the pasture grasses. Overall and using biomass gained, tiller production and relative yield as indices of growth dynamics, Rhodes grass was more competitive against Navua sedge than humidicola in both grazed and nongrazed conditions especially under high plant density. These results suggest the potential to include competitive pastures in integrated management strategies for Navua sedge, but species selection and grazing practices may influence the effectiveness of this approach.

Simple SummaryDiverse pastures based on combinations of the forage herb species plantain and chicory with red clover and white clover, provide superior annual feeding value to finish lambs in temperate regions, compared to the traditionally used perennial ryegrass and white clover pastures. The success of herb-clover diverse pastures is dependent on maintaining the relative abundance of each species in the mix over time. The selective grazing by lambs on herb-clover mixes was compared with their selection on perennial ryegrass and white clover pasture, by using randomly tagged individual plants, to determine if selective grazing changed the relative abundance of any of the herb or clover species. Variations in the selection of the forage species over the seasons of the year were observed, but best practice grazing management was shown to maintain the relative abundance of species in herb-clover pastures required for superior lamb live weight gains.Plantain (Plantago lanceolata) and chicory (Cichorium intybus) are now widely used in combination with clover species to provide greater annual lamb live weight gains than perennial ryegrass and white clover pasture. Reported selective grazing of the species in herb-clover mixes could potentially detrimentally change the relative abundance of species and decrease lamb production. Lambs were offered three herbage treatments: Pasture (perennial ryegrass and white clover) mix, plantain (plantain, red clover and white clover) mix and a chicory (chicory, plantain, red clover and white clover) mix in each of four seasons for two years. The experiment was a randomized complete block design with three replicates with 18–30 lambs per treatment replicate depending on the season. Lambs were rotationally grazed and fed ad libitum. Selection by the lambs of individually tagged plants within the pasture treatments was observed for three days on two occasions per season. Red clover was the most selected species on day 1, but by day 3 there was no difference in the selection of the species (p < 0.05). Plantain and chicory in the plantain and chicory mixes were selected less on day 1 in autumn relative to the other seasons (p < 0.05). It was concluded that three days of grazing before moving lambs maintained the relative abundance of species in the herb-clover mixes.

Offering livestock dietary choice through access to different pasture species enables livestock to regulate their own feed intake, select for nutrients and minerals, balance rumen health and display natural grazing and foraging behaviours, which could in turn result in increased livestock productivity. An experiment was conducted at Hamilton, Victoria, Australia, to test the hypothesis that offering lambs dietary choice through spatially separated combinations of pasture species would improve lamb performance, relative to lambs with no dietary choice. The experiment tested seven treatments, replicated four times in a randomised complete block design with plot sizes of 1 ± 0.1 ha. The treatments were: 100% perennial ryegrass (Lolium perenne L.) (PR), 100% plantain (Plantago lanceolata L.) (PL), 100% lucerne (Medicago sativa L.) (LU), 50 : 50 perennial ryegrass/plantain (PR + PL), 50 : 50 perennial ryegrass/lucerne (PR + LU), 50 : 50 plantain/lucerne (PL + LU) and 33 : 33 : 33 perennial ryegrass/plantain/lucerne (PR + PL + LU). In the multiple species swards, the pasture species were separated spatially (by area). Plots were grazed by weaned lambs between March and June 2011. Pre-grazing herbage mass during March and April were highest (P &lt; 0.05) from the lucerne and lowest (P &lt; 0.05) from the plantain, with lucerne producing 4.5–5.5 t DM/ha during this time, whereas the perennial ryegrass and plantain produced 3.5–3.9 t DM/ha and 2.3–3.0 t DM/ha, respectively. Herbage disappearance (calculated estimate of feed intake) was highest (P &lt; 0.05) from the lucerne and lowest (P &lt; 0.05) from the plantain during March and April. Leaf crude protein between the perennial ryegrass and plantain did not differ (P &gt; 0.05) and were lower (P &lt; 0.05) than the lucerne, but the perennial ryegrass and plantain had higher (P &lt; 0.05) leaf on offer (kg DM/ha). Plantain leaf had higher (P &lt; 0.05) Fe, Zn, Co, Ca and S than the perennial ryegrass leaf and higher (P &lt; 0.05) Se, Cu, Mg, Na and Cl than the perennial ryegrass and lucerne leaf and a more negative (P &lt; 0.05) dietary cation : anion difference. The agronomic data presented in this paper provides support for the hypothesis, with lambs showing dietary preferences between pasture species and morphological components, and forms to basis for why these preferences exist. The two subsequent papers show how offering lambs dietary choice affected the performance of male lambs to slaughter and female lambs to first joining.

Comparative diet selection by cattle and sheep grazing two contrasting heathland communities

Diet selection of beef cattle on Atlantic grassland-heathland mosaic: Are heathers more preferred than expected?

We used Oedaleus asiaticus Bey-Bienko (Acrididae: Oedipodinae) as a model species to examine how plant community composition influenced grasshopper population densities and feeding habits. Our results show that in the Xinli Gol Grassland ecosystem, both plant community composition and grasshopper density vary considerably over fairly small distances, and that O. asiaticus density was directly related to the proportional abundance of specific plant species. A 60-d field-cage study showed that O. asiaticus food preference and consumption differed when the ratios of three dominant grass species (Leymus chinensis (Trin.) Tzvel, Stipa krylovii Roshev, and Cleistogenes squarrosa (Trin.) Keng) differed. The consumption of both S. krylovii and C. squarrosa increased with a corresponding increase in their respective biomass availability. Although O. asiaticus preferred S. krylovii and ate only small amounts of L. chinensis, a specific amount of L. chinensis was always consumed. Feeding of these three plant species could be divided into three levels based on diet selectivity index (SI), with O. asiaticus showing a strong preference for S. krylovii (SI > 1), over that for C. squarrosa (0.5 < SI ≤ 1), and a low acceptance for L. chinensis (0 < SI ≤ 0.5). Plant consumption and preference by O. asiaticus was in decreasing order S. krylovii>C. squarrosa>L. chinensis. This study shows that small-scale changes in plant community composition can have large affects on grasshopper diets and populations. As such, this study is useful for developing guidelines for the monitoring of O. asiaticus impacts against the background of vegetation succession and changing plant communities in response to grazing or human activities.

Grazing annual cool-season forages after oat grain harvest in South Dakota may allow an opportunity to increase efficient use of tillable land. However, data are limited regarding effects of stocking density on diet selection, nutrient digestion, performance, and N retention by cattle grazing annual cool-season forage. Heifers were blocked by initial BW (261 ± 11.7 kg) and randomly assigned to 1 of 12 paddocks (1.1 ha) to graze a mixture of grass and brassica for 48 d. Each paddock contained 3, 4, or 5 heifers to achieve 4 replicates of each stocking density treatment. Ruminally cannulated heifers were used to measure diet and nutrient intake. Effects of stocking density on diet and nutrient selection were measured after 2, 24, and 46 d of grazing, and BW was measured at the beginning, middle, and end of the experiment as the average of d 1 and 2, d 22 and 23, and d 47 and 48 BW, respectively. Measures of DMI and DM, OM, NDF, and ADF digestion were collected from d 18 to 23. Increased stocking density increased intake of brassica relative to grass on d 24 (quadratic, = 0.02), but increased stocking density decreased (linear, ≤ 0.01) intake of brassica compared with grass on d 48 (stocking density × time, < 0.01). Increased stocking density increased DM (quadratic, < 0.01), OM (quadratic, = 0.01), and NDF (quadratic, = 0.05) digestion, and stocking density tended to increase DMI (quadratic, = 0.07). Additionally, increased stocking density quadratically increased ( = 0.05) N retention but did not affect overall BW gains. Increased stocking density did, however, contribute to linearly decreased ( = 0.05) BW gains from d 1 to 22 of grazing, but BW gains during the latter half of the experiment were greater than BW gains from d 1 to 22. Ruminal concentration of acetate:propionate was least on d 24 of grazing, and ruminal nitrate concentration tended to linearly decrease ( = 0.06) with greater amounts of time on pasture. Ruminal liquid and particulate fill and amounts of VFA were less (quadratic, ≤ 0.01) with greater amounts of time on pasture. Apparently, binary mixtures of brassica and grass planted after oat grain harvest can provide an opportunity to increase efficient use of land by providing forage resources. Increased stocking density may facilitate a more rapid adaptation to and intake of brassica among cattle grazing brassica-grass-based pastures.

This paper reports on diet selection of goats offered six browse species (i.e. Acacia natalitia [Vachellia natalitia], Acacia nilotica [Vachellia nilotica], Dichrostachys cinerea, Grewia occidentalis, Gymnosporia maranguensis and Scutia myrtina) commonly found in moist Zululand thornveld. The hypotheses tested were: (1) plant species and season affect diet selection, (2) physical traits such as leaf phenology, spinescence, shoot morphology and leaf size affect selection, and (3) selection is related to tannins, fibre and protein in ways that indicate nutrient maximisation. Six 2-year-old castrated indigenous goats weighing an average of 26 kg each were individually penned and maintained on a basal diet of pellets and grass hay. Six branches were offered simultaneously to individual goats and intake per branch recorded and used as an index for diet selection. Diet selection was significantly influenced by interactions between plant species and season. Scutia myrtina and Grewia occidentalis were consistently the most preferred species, whereas Gynmosporia maranguensis and Acacia nilotica were least preferred throughout the seasons. Goats preferred broad-leaf and long-shoot species over fine-leaf and short-shoot species across all seasons. These results suggest that short-term diet selection in subhumid areas is not as strongly influenced by leaf phenology and plant chemistry as in semi-arid savannas.

The results of a three‐year study in New Zealand undertaken to compare the effect of alternating sheep and cattle grazing and of different pasture species on internal parasitism in lambs is reported. Despite the commonly held belief that the use of cattle in sheep production systems improves sheep health by reducing nematode burdens, this did not occur. Cattle substantially reduced pasture larval numbers. However, this failed to reduce parasite burdens in lambs as those managed in the absence of cattle apparently developed increased immunity to parasites in response to the greater larval availability. Varying the number of successive grazings by sheep or cattle from 1 to 4 did not change this result. Lamb carcass weights were improved by the presence of cattle, primarily because of improvements in pasture quality. Substituting 30% of the ryegrass area with lucerne or replacing ryegrass with a multi‐species mix consisting predominantly of bromes, tall fescue, phalaris, timothy, and red and white clover, had no effect on lamb faecal egg counts or worm burdens. Lamb liveweight was not affected by herbage species. Both lucerne and the multi‐species mix increased the requirement for conserved feed during winter compared with ryegrass‐based systems.

Navua sedge (Cyperus aromaticus) is threatening crops, pasture species and natural ecosystems in Pacific Island countries and northern Queensland, Australia. To aid future management efforts of this exotic invasive weed, research was conducted to understand the soil seed bank dynamics of pastures invaded by Navua sedge. Six grazing properties were chosen across two landscapes, coastal and inland/upland, with areas that had Navua sedge infestations in Queensland, Australia. At each site, soil was collected from two soil depths, 0-5 and 5-10 cm, and from plots with high and low infestation levels of Navua sedge. It was observed that the soil seed bank dynamics varied significantly between these study sites. Navua sedge was the dominant species in the soil seed bank at all the sites contributing between 62% to 95% of the total seed bank, while pasture seeds occupied only 3% to 24%. Broadleaf seeds were even lower in abundance, showing between 2% to 13% of the total seed count. The abundance of Navua sedge seed present in the soil was significantly correlated with the aboveground biomass of Navua sedge (r=0.53, p=0.006), but no correlation was found with the infestation age of Navua sedge. Based on this work, it is clear that the seed bank of Navua sedge is very large and concentrated within the top 0-5 cm of the soil, with, 83% of total Navua sedge seeds being in this layer. It was also noted that, although, high infestation plots had significantly higher number of seeds than low infestation plots, more than 18,000 Navua sedge seeds/m2 were still found in the 0-5 cm soil layer of plots regarded as low infestation. We suggest that insights achieved from our soil seed bank study may be used to devise management strategies to minimise the impact of Navua sedge weed in critical grazing and agricultural areas.

The effects of soil compaction and deep ripping on the growth and yield of crop (wheat, barley, oats, triticale, narrow leaf lupins and field peas) and pasture species (barrel medic and subterranean clover) were investigated for deep, sandy soils near Geraldton, Western Australia. In 1984 (an average rainfall season), growth and yields of all species were substantially reduced by soil compaction. Lupins were not included in the experiment. Barley, wheat and pea yields were reduced by around 45%; oat and triticale yields by 30%; and spring biomass of both pasture species was reduced by about 30%. The differences in response between the species were not significant (P&gt;0.05). In 1985 (a very dry year), amelioration of soil compaction by deep ripping increased the dry matter at flowering of all the species, including lupins, by about 30%. Severe water stress in the cereals after flowering prevented the conversion of this dry matter advantage into grain yield differences. Because of late flowering and slow maturation, the yield of the oats was significantly (P&lt;0.05) lower on the deep-ripped areas, compared with the yield on the compacted soil. Deep ripping increased the yield of peas by 60% and lupins by 20%, probably because flowering and seed filling were completed before the onset of severe water stress. For deep, sandy soils in mediterranean environments, maximum economic benefit would normally accrue from deep ripping prior to the cereal phase, given that current agronomic principles generally preclude the growing of peas on these soils. Selection of cereal species mainly depends on relative yields and prices; however, the results suggest that use of cultivars with rapid early growth, early flowering and quick maturity would maximise the response to compaction amelioration and minimise the risk of poor grain filling.