Hill Pastures Research Articles

Combined effects of fertiliser input and pasture utilisation on the growth of aerial stems of browntop (Agrostis tenuis) in hill country

Abstract The occurrence and growth of elongated aerial stems of browntop (Agrostis tenuis) were measured in hill pastures under low fertiliser input and pasture utilisation (LFLU), and under high fertiliser input and pasture utilisation (HFHU). Aerial stems grew rapidly from December until April, more so in the LFLU swards than in the HFHU swards. Under LFLU, up to 30% of tillers sampled after the end of December originated from a node on an aerial stem. Under HFHU, the maximum value was 12%. The formation of tillers at nodes on aerial stems occurred throughout the study (from July until the following May), but at a low rate in late spring and most rapidly in early summer. Where grazing pressure and fertility levels are inadequate to suppress aerial stem development, short-term grazing managements are likely to provide only limited control of rank browntop growth.

Leaf and tiller growth ofLolium perenneandAgrostisspp. and leaf appearance rates ofTrifolium repensin set-stocked and rotationally grazed hill pastures

Abstract Growth components of Lotium perenne and Agrostis spp. tillers and Trifolium repens stolon apices were compared for one year under set stocking and rotational grazing with sheep on hill pastures which had had low and high levels of fertiliser input. Leaf appearance rates of L. perenne and Agrostis spp. were unaffected by grazing management or fertiliser level. Leaf appearance in T. repens was also largely unaffected by treatments except in summer when rotational grazing allowed some relief from defoliation stresses and leaf appearance rates were greater than under set stocking during 3 grazing rotations. T. repens leaf appearance rates were slower in winter and increased later in spring than the grasses. For most of the year, tiller bud development in L. perenne was well below the maximum possible because of mutual shading in dense swards (mean total tiller density 29700 tillers/m2 under set stocking and 20 l00/m2 under rotational grazing). L. perenne lamina lengths, tiller lengths, and leaf extension rates were approximately twice those of Agrostis spp. Leaf extension rates were faster under rotational grazing for L. perenne and Agrostis spp. but tiller densities of both species were greater under set stocking. Total leaf growth per unit area is, therefore, likely to be similar under both managements. Slightly greater L. perenne growth and less Agrostis spp. growth per unit area under rotational grazing than under set stocking is indicated by a comparison of individual tiller growth and tiller density data. The results are discussed in relation to published findings from the same systems.

Nutrition and lactational control of fertility in red deer.

In many mammals, including man, lactation is associated with a delay in return of fertility. The pattern of suckling activity, particularly suckling frequency, is known to be important in determining the length of this anovulatory phase1,2. In a seasonally breeding ungulate such as red deer, lactation coincides with a photoperiodically controlled period of seasonal anoestrus3. Nevertheless, lactation may still exert an important effect on the duration of infertility as lactating red deer hinds on poor quality hill pasture resume oestrus at a later date than non-lactating hinds and frequently fail to ovulate in the year following the birth of a calf4,5. It has been proposed that this reproductive failure is due to the effect of both lactation and poor planes of nutrition on maternal body condition6–8. As a result of our recent studies on the influence of plane of nutrition on milk yield and suckling behaviour in red deer we now propose an alternative hypothesis. We suggest that the principal influence of low planes of nutrition is to increase the suckling frequency of the calf in response to a decrease in availability of milk. It is this increase in suckling frequency, and perhaps the associated increase in plasma levels of prolactin, which is the major determinant of the reproductive failure and is due to the influence of plane of nutrition on the production of milk by the mother rather than on maternal body condition. This hypothesis may have important implications for our understanding of the role of nutrition in determining the length of lactational infertility in many species including man.

Estimation of repeatability, heritability and breed differences for lamb production.

Production records of crossbred ewes, including weight at mating (WTM), fertility (FRT), number of lambs born per ewe lambing (BRN), number of lambs weaned (WEN), litter weight in April (WTA) and litter weight at weaning (WTW), were analyzed for the estimation of breed differences, genotype x environment interactions and repeatability and heritability of ewe production. All ewes were from Suffolk- or Columbia-type dams. Breed of sire of ewe was Finnsheep, Dorset, North Country Cheviot or Romney, Suffolk-cross (SX) ewes were heavier at mating than Columbia-cross (CX) ewes. Cheviot-cross (NX) and Finnsheep-cross (FX) ewes were the most fertile on hill pastures, while Dorset-cross (DX) ewes were the most fertile on irrigated pastures. The FX ewes had larger litters at birth and at weaning. Columbia-cross ewes had larger litters than SX ewes on hill pastures, but the SX ewes had larger litters than CX ewes on irrigated pastures. Finnsheep-cross ewes on both types of pastures and DX ewes on irrigated pastures had heavier litter weights than NX or Romney-cross ewes at weaning. Repeatability estimates for WTM, FRT, BRN, WEN, WTA and WTW were .61, .15, .19, .08, .07 and .09, respectively. Heritabilities, from the sire-of-ewe component, were .40, .02, .12, .0, -.02 and -.05 for WTM, FRT, BRN, WEN, WTA and WTW, respectively.

Effects of Lime, P, and Mo Application on Mo Concentration in Subclover1

AbstractSubterranean clover (Trifolium subterranium L.) is a winter annual legume grown in the hill pastures and hay fields of western Oregon. Soils are acid (pH 4.5 to 5.5) and yield responses to lime, P, and Mo are common. Lime, P, and Mo application can result in increased Mo concentrations in plants. Forage containing more than 10 µg Mo/g is potentially toxic to ruminants. An experiment involving subterranean clover and perennial ryegrass (Lolium perenne L.) was established in the fall of 1976 on a Typic Haploxeralf, fine, mixed, mesic soil to evaluate the effects of lime, P, and Mo applications on: (1) the Mo concentration in subterranean clover leaflets and petioles and in the clover‐grass mixture and (2) the longevity of the treatment effects on Mo concentration in the clover‐grass mixture. Lime was applied at 0, 4.5, or 9.0 metric tons/ha, P was applied as concentrated superphosphate at 0, 19, or 57 kg/ha, and Mo was applied as Na2Mo04 2H20 at 0 or 0.5 kg/ha. All treatments received adequate K, S, and B. Clover leaflet and petiole samples were analyzed to determine the Mo critical level for the clover and establish the maximum Mo concentration that would be consumed by a grazing animal. Clover grass mixture samples were analyzed to determine the average Mo and Cu concentration that would be consumed. The Mo concentration in clover leaflet and petiole samples collected 18 Mar. and 12 Apr. 1977 was increased from 1.5 to over 25 µg Mo/g by application of lime, P, and Mo. The Mo concentration decreased to less than 15 µg/g by 12 May 1977. Application of lime, P, and Mo increased the Mo concentration in the clover‐grass mixture from 1 to over 5 µg Mo/g and decreased the Cu:Mo ratio to below 2, which is potentially toxic to livestock.The highest Mo concentration was less than 10 µg Mo/g in clover leaflet and petiole samples collected the second growing season and the Mo concentration in the clover‐grass mixture was less than 5 µg Mo/g for all treatments except one. The Mo concentration was below 2 µg Mo/g in all samples collected the third growing season. Although the Mo concentration was as low as 0.1 µg/g, yield responses from Mo application were not evident.

THE INOCULATION OF WHITE CLOVER WITH MYCORRHIZAL FUNGI IN UNSTERILE HILL SOILS

SUMMARYThe response of two cultivars of white clover (Aberystwyth S184 and New Zealand Grasslands Huia), grown under laboratory and field conditions, to inoculation with two endophytes (Glomus mosseae L1 and Glomus etunicatus) was investigated in two hill soils with various amounts of added phosphate.In the experiment with the deep peat soil in the laboratory, inoculation with either endophyte increased infection from 2% to up to 70%, the increase being less the higher the amount of added P. Shoot growth of white clover was significantly increased (P≤ 0.05) by inoculation at the 0 and 20 kg P ha−1 level and decreased at the highest level of added P (200 kg P ha−1). Both endophytes produced similar effects. With the brown earth soil, total infection of roots with indigenous endophytes ranged from 30 to 50 % and this was significantly (P≤ 0.05) increased by inoculation only at 40 kg P ha−1. However, the introduced coarse endophytes had replaced between a quarter and a half of the predominantly fine indigenous endophyte at each level of added P. This change of endophyte was without significant effect on dry wt of shoots and roots although there was a general trend for inoculation, and with Glomus etunicatus more than with Glomus mosseae LI, to increase shoot and root dry wt. Inoculation also tended to increase the P content of shoots and roots but this was statistically significant only at 40 kg P ha−1.In the field experiment with the deep peat soil, inoculation with Giomus mosseae L1 doubled the amount of infected root from 18 to 42% but there was no effect on shoot growth or the concentration of P. With the brown earth soil, although the amount of infection was not increased, the introduced coarse endophytes had become established in the roots but no effect on shoot growth was observed in the year of sowing. However, in the first harvest year, in the presence of 40 kg P ha−1, clover inoculated with Glomus etunicatus produced double the amount of dry shoot per hectare produced by uninoculated plants and 75% greater than that produced with Glomus mosseae L1.These observations encourage the view that inoculation with mycorrhizal fungi of white clover for improved hill pastures might have a practical role if the responses could be made more predictable. It is concluded that further work is justified to understand the ecology of mycorrhizal fungi in hill pastures and how the symbiosis functions, to select suitable endophytes and to develop methods of inoculation appropriate for use in routine field practice.

Flushing Ewes on Chemically Cured Hill Pastures

Flushing Ewes on Chemically Cured Hill Pastures

The dependence of the productivity of a semi-arid mediterranean hill pasture ecosystem on climatic fluctuations

The results of a 6-year grazing trial in open Tabor oak woodland, dominated by annual plants, were used for the determination of the dependence of productivity on climatic fluctuations. Stepwise multiple regressions between October–November, December–January and February–March rainfall and minimum December–January temperatures resulted in high correlation coefficients, explaining 76% of the variance in the unfertilized, and even 99% of the variance in the more intensively improved and fertilized, pastures. Legumes were more dependent on total rainfall but also highly responsive to N or P dressings, whereas grasses were more responsive to early rains, especially after N dressings. This is the first study in any mediterranean annual grassland where such close correlations between climate and productivity could be determined. In the drier years this productivity is typical of semi-desertic biomes but in more favorable rainfall years it is well within the range of the subhumid woodland-grassland biome. This great responsiveness to climatic fluctuations was apparently of large adaptive importance in the evolution of these grasslands and has contributed much to their striking resilience and persistence as dissipative structures, “creating order through fluctuation”. It was concluded that this great climatic dependence, as a major bottleneck for rational livestock production, can be overcome only by improving the efficiency of moisture utilisation by introducing deeper-rooted, drought resistant and summer-green folder shrubs and trees.

Brush Control with Herbicides on Hill Pasture Sites in Southern Oregon

Brush Control with Herbicides on Hill Pasture Sites in Southern Oregon

Field trials in south-west Scotland

SynopsisSouth-west and west Scotland contains a large proportion of the bracken-infested hill pasture in that country and considerable effort has been expended over the past five decades on a scientific approach to bracken control. The trials of various, more or less successful, herbicides culminated in the current work based on the use of asulam or glyphosate which will control, but only in rare cases eradicate, bracken. Current work is aimed at improving the control effect by investigating and refining timing, rate and method of application, additives and mixtures. Particular emphasis is placed on techniques of improving the underlying sward, where present, and of investigating the factors influencing its growth. Experimental work has not shown any degree of allelopathy towards sown-in grass and clover seed growth, but depth of bracken litter is shown to be important. Doubt is expressed regarding the requirement for a total programme of bracken control and follow-up fertiliser treatment in all cases before grant aid is approved

Effect of body condition and pasture type on herbage intake, performance during lactation and subsequent ovulation rate in Scottish Blackface ewes

ABSTRACTScottish Blackface ewes in uniform, good, body condition at mating were differentially fed during pregnancy, such that two groups lost 0·15 to 0·20 (groups A and B) and one group gained 0·05 (group C) of maternal live weight by lambing time. The treatments had little effect on the number of lambs born per ewe lambing (1·39, 1·46 and 148 respectively).Prior to parturition, group A was transferred to a poor hill pasture, and groups B and C to an improved upland reseeded pasture. Herbage intake by six single- and six twin-suckling ewes from each group was estimated in the 3rd, 6th and 8th week after parturition, and mean daily milk production was estimated on 1 day following each intake measurement period. Herbage intake by six dry ewes in each of groups A and B was also estimated.There were significant differences amongst groups A, B and C, respectively, in mean organic matter digestibility of the herbage consumed (0·701, 0·771 and 0·773), mean daily digestible organic-matter intake (1·06, 1·46 and 1·46kg), mean live-weight change over the period ( –2·9, +5·4 and +l·3kg) and mean daily milk yield (0·64, 1·93 and 1·95 kg).By the following mating time, after grazing the same pasture from weaning, there was still a difference in body condition score according to pasture type during lactation (2·08, 2·36 and 2·29, respectively). Ovulation rate measured after mating was consistent with the direct effect of body condition (1·34, 1·56 and 1·52, respectively).

Copper deficiency: a study of prophylaxis and the interaction with cobalt therapy in lambs on improved hill pastures

ABSTRACTAn experiment was conducted with 84 suckling Scottish Blackface twin lambs on an improved hill pasture with a history of cobalt deficiency and molybdenum/sulphur-induced copper deficiency. The dams of 13 pairs of twins were treated with 90 mg copper at parturition (Cue) and one member of each pair was given a cobalt bullet (Co + ). One member of each of a further 29 pairs was treated periodically with 5 to 15mg copper to maintain plasma copper concentrations >0·6mg/l (Cu+) while their siblings received no supplementary copper (Cu). Fourteen of these pairs also received a cobalt bullet (Co + ). Lambs not treated with cobalt are designated Co−.The Cue treatment increased milk copper concentrations, but only for a short time, and resulted in transitory increases in lamb plasma copper concentrations and rate of live-weight gain. At the end of the grazing phase, at approximately 20 weeks of age, Cu+ lambs had gained 0-28 kg more weight than Cue lambs and 158 kg more than Cue lambs, and had higher liver copper concentrations. Cu+ and Cue lambs had heavier and fatter empty bodies and carcasses than Cu− lambs. The cobalt treatment produced no effects at this stage.Fifty-four of the lambs were housed and given dried grass pellets ad libitum. After 83 days liver copper concentrations were higher in Co− than Co+ lambs, and in Cu+ than in Cu− and Cue lambs. The copper treatments had no effect on rate or efficiency of live-weight gain, but Co− lambs gained weight more quickly and more efficiently than Co+ lambs.

Visual estimates of available herbage on hill country sheep pastures

Abstract Available standing herbage over a range of sheep-grazed hill pastures was visually estimated by the same observer at regular intervals throughout the year. The results were compared with dry matter (DM) yield cuts from nine quadrats sited within each paddock. Linear regressions of yield on visual estimates were significant at all times (r2= 0.6-0.9). The analyses showed that the same observer can consistently assess paddock differences throughout the year and between years without using yield cut calibrations. However, the conversion of visual estimates to DM yield values was only possible on occasions in spring and early summer when pastures were green and residual coefficients of variability (RCV) were low. At other times of the year, when RCV values; were high, the observer tended to under-estimate total DM over whole paddocks by over-estimating the green fraction and under-estimating the dead material and had difficulty in maintaining consistency with between-paddock assessments of paddocks o...

Carcass characteristics of young red deer farmed on hill pasture

SUMMARYCarcass characteristics were studied in young red deer raised on a Scottish hill farm with heather·dominant pasture. Stags slaughtered in September when 15 or 27 months old were very lean, and entire and castrate animals were similar in weight. At 15 months they were barely a half of their expected mature weight. With no pre-slaughter fasting, dressed carcass weight was 49–51% of live weight. A more detailed analysis of carcass conformation was made in a study of entire stags, castrate stags and hinds slaughtered when 15 months old after being held overnight without food or water. The three groups were similar in that their dressed carcasses weighed about 52% of live weight and the content of first class lean meat amounted to 32% of live weight. There was only 4·5% of chemical fat in the empty carcass.The pH of the meat 36 h post mortem often remained high in the stag groups, relative to a mean value of pH 5·7 found in shot wild stags. This high-pH character was little affected by the severity of stress immediately before slaughter, nor by the availability of food. It seemed to be caused by holding the animals in unfamiliar surroundings for some 16 h before slaughter.

Effects of Stocking Rate on Sheep and Hill Pasture Performance

Effects of Stocking Rate on Sheep and Hill Pasture Performance

Fertiliser nitrogen responses on two hill pastures of different phosphate fertiliser history

Abstract Fertiliser nitrogen responses with and without applied phosphate, were measured over spring on slopes and flat areas within two sheep-grazed hill pastures of different P status. One pasture had received little phosphate in recent years and contained low levels of legume (9.2%) and ryegrass (6.3%), whereas the other had received large P inputs and contained substantially more legume (14.9%) and ryegrass (13.9%). Pasture N responses on both pastures were large in spite of differences in species composition. Application of phosphate along with the N fertiliser did not affect total pasture production, or grass species yields, on either pasture. Legume production was little affected by fertiliser N, but was substantially greater with P on lower P status soils. Increases in pasture production with N were similar on flat (0–10°) and steep (10–25°) sites, despite different productivity and species composition. This suggests that N deficiency over spring is general in these soils and essentially independent of pasture types.

Phosphorus uptake and return in grazed, steep hill pastures

The uptake of phosphorus (P) in pasture and return in plant litter and animal dung were measured on campsites, 25° slopes, and 45° slopes within two separate north aspect and south aspect hill pastures, for 1 year. Annual Puptake by pasture, and more particularly P return via dung from grazing sheep, were high on campsites, but both decreased sharply as ground slope increased. By contrast P return via litter was much more uniform, but under the intensive grazing was equivalent to only approximately 13—21% of pasture Puptake. The derived net P balances showed a large annual gain of P on campsites (50.1 and 119.8 kg/ha on north and south aspects respectively). The net loss ofP from slopes was equivalent to 29—71% of annual Puptake. It was therefore concluded that the maintenance of soil P levels and of pasture growth would continue to depend highlyon fertiliser inputs, particularly on steep slopes. Because ofthe high P concentration in pasture from all strata the respective annual net P balances sh...

Phosphorus uptake and return in grazed, steep hill pastures

Abstract Pasture production and dung and litter accumulation were measured on a range of slopes on both a north-facing and a south-facing steep hill paddock for 1 year. All parameters decreased in the following order: campsites, 25° slopes, 45° slopes. Pasture production and dung accumulation declined sharply with increase in surface slope. In particular dung accumulation ranged from very high on campsites to negligible on 45° slopes. The accumulation of pasture litter was more uniform although greater on north-aspect than on south-aspect slopes. There was no significant difference between aspects in the mean annual level of other parameters measured on similar slopes. Pasture species and litter composition varied between campsites and slopes and also with season and aspect. Although legurnes and weeds together at times comprised an appreciable proportion of total pasture production on slopes, these species made a negligible contribution to pasture litter. Uprooted grass plants forrned a significant portion of pasture litter, particularly on slopes.

Fertiliser and lime effects on some southern North Island hill pastures

Abstract Pasture responses to superphosphate, lime (fine-ground), Mo, and ‘other nutrients’ (ON) mixture (Cu, B, Zn, Mg, K) were assessed in a trial at Ballantrae Hill Country Research Station. Trial sites were on a steepland soil related to YBEs (Mangamahu), a YBE hill soil (Ngamoka), and a steepland soil related to YBE-YGE integrades (Taihape). Soils are from Tertiary sandy and silty parent materials. Olsen P values were low (7–10 μg/g dry soil). Pastures were dominated by low-fertility-tolerant grasses. Large responses in legume vigour occurred to lime and superphosphate, to Mo without lime, and to ON with lime. Response to lime and Mo (over the 15 month measurement period) appeared to be due to increased availability of soil Mo. Superphosphate increased soil Olsen P, soil Truog P, and legume herbage N and P, but decreased legume Cu. Lime increased soil pH and legume Mo, but decreased soil Olsen P and legume herbage Mg, Cu, and Mn. Legume vigour and soil Truog P showed a positive response to lower lime rates, then a small negative response to lime rates above c. 3500 kg/ha.

Genetic resources in high-rainfall hill pastures of New Zealand

Abstract Sixty-six ryegrass (chiefly Lolium perenne L.) populations colleeted from high-rainfall hill country were grown as spaeed plants for 3 years at Palmerston North for deseriptive analysis. All populations were highly variable and most were similar. They were mostly early heading, free seeding, but quite persistent. An unusually vigorous population came from old experimental plots in tussock grassland near Waiouru, and a very late-heading population from a terraee at Te Awa. Southland populations were ereet, small in diameter, and not very vigorous. Eastern districts of the North Island provided several unusually vigorous, leafy, erect populations, most of which came from unimproved farms with low available soil P. In general, populations from low-P sites grew better than those from high-P sites. Oversowing and topdressing did not appear to have altered the characteristics of the ryegrass populations and aspect had only a weak effect.