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Full-Text Articles in Plant Sciences
Development Of Intensive Grassland Systems: From Science To Practice, D G. Mccall, G W. Sheath
Development Of Intensive Grassland Systems: From Science To Practice, D G. Mccall, G W. Sheath
IGC Proceedings (1993-2023)
Level of nnimal production from grassland is determined by the amount of pasture grown, pasture utilisation and animal conversion efficiency. The key components affecting production are pasture growth and animal conversion efficiency. These arc mainly influenced by environment, genetics and through inputs to maintain soil fertility or animal health. Systems development aims to link pasture growth and animal conversion through efficient strategies for pasture utilisation. The means of influencing pasture utilisation is through adjustments to animal feed demand, feed supply or grazing management. Stock policies that adjust the pattern and level of feed demand are of greatest significance in developing …
Use Of Brassica Forage Crops To Extend The Grazing Season In The North-East Usa, G A. Jung, H W. Harpster, M G. Lambert, K T. Leath, R A. Byers
Use Of Brassica Forage Crops To Extend The Grazing Season In The North-East Usa, G A. Jung, H W. Harpster, M G. Lambert, K T. Leath, R A. Byers
IGC Proceedings (1993-2023)
Forage turnip (Brassica rapa L,) can be made available for animal utilisation in late summer or In late autumn-early winter, when coolseason grass pastures have a low animal carrying capacity. field trials were conducted to identify and quantify factors that influence turnip yield in December or January and to determine whether these factors affect turnip cultivars similarly. Different levels of production in late autumn-winter were attributed to summer drought, foliar diseases, freezing temperatures and rate of leaf senescence. In all instances, the effects of these factors varied with turnip cultivar. However, cultivar ranking generally was the same whether mean …
Effects Of Increasing Stocking Rate And Feeding Maize Silage On Live-Weight Gain And Pasture Utilization By Beef Cattle In Southern Australia, W J. Wales, J B. Moran
Effects Of Increasing Stocking Rate And Feeding Maize Silage On Live-Weight Gain And Pasture Utilization By Beef Cattle In Southern Australia, W J. Wales, J B. Moran
IGC Proceedings (1993-2023)
Two systems of grazing management were compared in 3 trials conducted on annual or irrigated perennial pastures over different seasons in northern Victoria, Steers grazed either at low stocking rates or at high stocking rates together with maize silage feeding, The more intensely grazed steers grew faster on autumn perennial pastures but at similar rates to steers at low stocking rates on winterspring annual and on spring perennial pastures, Higher stocking rates increased live-weight gain per ha by 90% on winter-spring annual pastures, 101% on autumn perennial pastures and 53% on spring perennial pastures. This was associated with improvements in …
Grazing Management Effects On Diverse White Clover Cultivars, G E. Brink, G A. Pederson
Grazing Management Effects On Diverse White Clover Cultivars, G E. Brink, G A. Pederson
IGC Proceedings (1993-2023)
Tall fescue (Festuca arundinacea Schreb.) was oversewn with Grasslands Huia, Louisiana S-1, and Regal white clover (Trifolimn repens L.) and stocked the following year continuously or rotationally with cattle to detennine cultivar response to grazing method. When precipitation was 59% above normal, mean leaf area, forage and stolon dry weight, and stolon growing point density in June and August were unaffected by grazing method. These parameters were reduced under continuous stocking when precipitation was 32% below normal. Cultivar ranking for mean leaf area and petiole length was the same as that for leaf size: Grasslands Huin
Acquisition And Allocation Of Phosphorus In A Population Of White Clover Plants In A Rotationally Grazed Pasture, M.J M. Hay, D F. Chapman
Acquisition And Allocation Of Phosphorus In A Population Of White Clover Plants In A Rotationally Grazed Pasture, M.J M. Hay, D F. Chapman
IGC Proceedings (1993-2023)
This paper quantifies the processes of acquisition, allocation and retranslocation of phosphorus (P) within a white clover (Trifolium repens L.) population in a mixed grass-clover pasture during a regrowth period in early winter (13 May-8 July 1991). The work described is part of a broader study examining seasonal variation in these processes. The data allows an analysis of the changing P economy of plants and of whole populations. White clover plants were grouped by !heir hierarchy of branching. Within plants, stolons were grouped by order of branching, dissected into leaf, stolon and root, oven-dried, weighed and analysed for P …
Nitrous Oxide Emissions From Grassland In Manawatu, New Zealand, R A. Carran, J P. Evans
Nitrous Oxide Emissions From Grassland In Manawatu, New Zealand, R A. Carran, J P. Evans
IGC Proceedings (1993-2023)
Nitrous oxide (Np) is a minor component of the atmosphere which acts as a potent greenhouse gas and also causes ozone depletion. Soil bacteria are the most important agents of N2O production, but both the New Zealand and the international data on N2O emission rates from soils are very poor at present. In order to help define the possible range of emission ranges from pasture soils· we selected sites with characteristics that would make then "high" or "low" emitters of N2O. The "high" emission site was a fine-textured, fertile but poorly drained flood plain soil. The "low" emission site was …
Climate, Land Use And Plant Life Form Distribution In A Semi-Arid Savanna, Christina Skarpe
Climate, Land Use And Plant Life Form Distribution In A Semi-Arid Savanna, Christina Skarpe
IGC Proceedings (1993-2023)
Number of plant species, total vegetation cover and the abundance of different life forms are compared over a rainfall gradient between savanna woodland and semi-desert. The effects of different land use intensities are superimposed on the differences in rainfall regimes. The outcome is discussed in the light of present global change scenarios,
Climate Change And Grasslands: A Life-Zone And Biota Perspective, Steven Archer
Climate Change And Grasslands: A Life-Zone And Biota Perspective, Steven Archer
IGC Proceedings (1993-2023)
Grasslands experiencing climatic and atmospheric change may be altered with respect to: (1) geographic extent and location of local/ regional boundaries; (2) productivity, organic matter dynamics and nutrient cycling; and (3) the relative abundance of constituent life forms (woody v. herbaceous), growth forms (tall vs. shorl-statured grasses), and/or photosynthetic physiologies (C3 v. C4). Classification models based on vegetation-climate correlations predict an increase in the global acreage of grassland and savanna at the expense of boceal forest and dry tropical forest. However, extrapolation of these relationships to climates with atmospheric CO2 concentrations without present-day analogues is suspect. Dynamic models of plant …
An Ecological Approach To Forage Management, J L. Brock, R.J M. Hay
An Ecological Approach To Forage Management, J L. Brock, R.J M. Hay
IGC Proceedings (1993-2023)
The principles of defoliation management for maximum production of quality herbage are well researched, namely the manipulation of frequency and severity of defoliation, but their impact on the various levels of ecological organisation in pastures is nol fully understood or their interpretation appreciated. Using grazed ryegrass-white clover pasture as; example, detailed sward studies have suggested the following model. Defoliation frequency and severity interact lo produce varying levels of physiological stress and morphological adaptation which affecl the survival rate and size of individual growth units, the lowest level of organisation. Increasing frequency of defoliation reduces organ size but increases survival rate …
Use Of Pasture As A Receivers For Swine Lagoon Effluent, J P. Mueller, J C. Barker, J P. Zublena, M H. Poore, R W. Harvey, J T. Green
Use Of Pasture As A Receivers For Swine Lagoon Effluent, J P. Mueller, J C. Barker, J P. Zublena, M H. Poore, R W. Harvey, J T. Green
IGC Proceedings (1993-2023)
Swine waste management-cattle grazing systems were monitored on 2 North Carolina farms from 1990-1992, Farmers co-operated directly in the project by furnishing land, labour, equipment and cattle and by maintaining records of grazing and waste applications. Local county agricultural extension agents helped with management decisions, recordkeeping and co-ordinating activities among project participants. On a fann where waste was applied to pastures for 5 years, soil N in the upper l m averaged from 230-500 kg/ha, NO3 -N in the forage remained above 10 g/kg for the grazing season and 2 of 4 test wells recorded NO3 levels above 10 mg/I. …
Foraging Strategies Of Ruminant Livestock On Intensively Managed Grasslands: Potential And Constraints, I J. Gordon, C Lascano
Foraging Strategies Of Ruminant Livestock On Intensively Managed Grasslands: Potential And Constraints, I J. Gordon, C Lascano
IGC Proceedings (1993-2023)
All grazed swards exhibit heterogeneity in the spatial (horizontal and vertical) dispersion of species/biomass. A herbivore foraging at random within such a heterogeneous environment would ingest less nutrients than wou Id one which exploited the heterogeneity on offer through selective grazing. The suite of decision-making processes involved in the selective grazing we observe is termed the animal's foraging strategy. On first observation, intensively managed sown swards appear to offer little opportunity for a herbivore to exhibit a foraging strategy; however, opporlunities do exist and there is empirical evidence that herbivores foraging on sown swards tend to have a diet higher …
Field Test Of Optimal Foraging With Cattle: The Marginal Value Theorem Predicts Patch Selection And Utilization, Emilio A. Laca, R A. Distel, T C. Griggs, G Deo, M W. Demment
Field Test Of Optimal Foraging With Cattle: The Marginal Value Theorem Predicts Patch Selection And Utilization, Emilio A. Laca, R A. Distel, T C. Griggs, G Deo, M W. Demment
IGC Proceedings (1993-2023)
Grazers selectively forage within heterogeneous vegetation. Prediction of intake rate necessitates theoretical developments to understand site selection. We tested III optimal foraging model to predict patch selection by cattle in the field, Nine "grazing environments" (GB) consisting of 16 0.36 m2 patches each were created by mowing. Treatments were a factorial of 3 distances between patches and 3 sets of patch heights. Patch residence time (T,) was accurately predicted (r2=0.89), and increased linearly whh patch distance (P
A Conceptual Model To Explain Variation In Ingestive Behavior Within A Feeding Patch, Emilio M. Laca, M W. Demment, R A. Distel, T C. Griggs
A Conceptual Model To Explain Variation In Ingestive Behavior Within A Feeding Patch, Emilio M. Laca, M W. Demment, R A. Distel, T C. Griggs
IGC Proceedings (1993-2023)
A conceptual model is presented that links the mechanics of bite formation to the characteristics of the sward to explain variation in bite weight, bite area, bite depth and biting rate measured in a series of experiments with hand-constructed swards. Bite area is determined by the behaviour used by the animal to collect and grasp the tillers, and the length and stiffness of the sward, Bite depth is affected by height and the degree of vertical heterogeneity in stiffness. Time per bite is controlled by bite weight. These mechanisms of bite formation and time per bite ex.plain many observed effects, …
Selective Behaviour Of Cattle Grazing Ryegrass Swards With Horizontal Heterogeneity In Patch Height And Bulk Density, Montague W. Demment, R A. Distel, T C. Griggs, E A. Laca, G P. Deo
Selective Behaviour Of Cattle Grazing Ryegrass Swards With Horizontal Heterogeneity In Patch Height And Bulk Density, Montague W. Demment, R A. Distel, T C. Griggs, E A. Laca, G P. Deo
IGC Proceedings (1993-2023)
Patches of different height and/or bulk density were created in ryegrass pasture to study selective responses of steers to horizontal variability in patch structure. The experiment involved 3 heterogeneity treatments with 2 patch types each. Steers encountered and entered both patch types available in each treatment with the same frequency. In contrast, they grazed for a longer time (T,) at; and removed more bites (B) from the patch type that yielded greater intake rates. While T, and B varied for a patch type depending on the alternative patch, bite rate and likely bite size were constant for a given patch …
Computer Recording Of The Variation In Intake Of Supplements Provided To Grazing Cattler, R M. Tait, L J. Fisher
Computer Recording Of The Variation In Intake Of Supplements Provided To Grazing Cattler, R M. Tait, L J. Fisher
IGC Proceedings (1993-2023)
A computer system has been developed to record the consumption of' supplements provided free choice to grazing cattle. The system is based on electronic animal identification and one or more weatherproof electronic scales located in simple feed stations connected by telephone cable to a computer at a distance of up to 1 km. The software program identifies and records individual animals, • time and duration of visits, and the quantity of supplement consumed. The system has been tested in the field using 40 kg molasses-based feed blocks with up to 20 steers per feed station in paddocks of approximately 4 …
Diet Selection By Lambs In Ryegrass-White Clover Swards Differing In The Horizontal Distribution Of Clover, R H. Armstrong, E Robertson, C S. Lamb, I J. Gordon, D A. Elston
Diet Selection By Lambs In Ryegrass-White Clover Swards Differing In The Horizontal Distribution Of Clover, R H. Armstrong, E Robertson, C S. Lamb, I J. Gordon, D A. Elston
IGC Proceedings (1993-2023)
Weaned 5-month-old lambs grazed 2 series of perennial ryegrass (Lolium perenne L.) plots containing patches of mixed perennial ryegrass and white clover (Trifolium repens L.) varying in either a) the size of patches or b) the distance between patches. Both series embraced the same range of percentages (1-25) of ryegrass-clover patches in each plot. Diet composition was estimated from the pattern of naturAI alkanes in faeces collected between days 6 to 15 after allocation of the lambs to the treatments. The percentage of clover in the diet declined markedly from days 6 to 11 and thereafter increased slightly. Dietary …
Comparison Of Bite Weight And Bite Dimensions Of Sheep And Goats Grazing A Range Of Grasses And Clovers, Y Gong, J Hodgson, M G. Lambert, A.C P. Chu, I L. Gordon
Comparison Of Bite Weight And Bite Dimensions Of Sheep And Goats Grazing A Range Of Grasses And Clovers, Y Gong, J Hodgson, M G. Lambert, A.C P. Chu, I L. Gordon
IGC Proceedings (1993-2023)
Response patterns in bite weight and bite dimensions of sheep and goats were evaluated using 3 grasses and 3 clovers sampled at 2 stages of maturity offered as prepared turves to animals confined in metabolism crates. Average bite weight across 12 sward types (6 forages x 2- stages) was similar for sheep and goats, but goats had greater bile weight per unit LW0•75 tlian sheep, Despite being shorter, the much denser clover swards resulted in larger bite weight than did grass swards. The taller reproductive swards enabled animals to harvest greater bite weights than did vegetative swards. Sheep obtained heavier …
Bite And Bolus Size Of Japanese Black Cattle Grazing Trays Of Perennial Ryegrass Of Different Heights, Shigeru Shioya, Kazuhiko Ochiai, Yasuko Togamura, K Betteridge
Bite And Bolus Size Of Japanese Black Cattle Grazing Trays Of Perennial Ryegrass Of Different Heights, Shigeru Shioya, Kazuhiko Ochiai, Yasuko Togamura, K Betteridge
IGC Proceedings (1993-2023)
To determine the influence of grass .height on ingestive behaviour of Japanese Black cattle, bite size and bolus size of a Japanese Black heifer (230 kg body weight) and a Japanese Black cow (450 kg body weight) were estimated on perennial ryegrass (Lolium pere,me L.) turfs. Turfs in trays (460x600xl00 mm) were fed to the cattle for up to 3 min and reductions in turf weight were measured. One high (25 cm), 2 medium (13 cm) and 2 low (6 cm) turfs were offered to each animal. Bite size (dry matter intake/bite) both for the heifer and cow was greatest …
Grazing Behavior Of Beef Cattle During First-Time Exposure To A Pearl Millet Pasture Treated With A Chemical Plant-Growth Regulator, J E. Arias, C T. Dougherty, M Collins
Grazing Behavior Of Beef Cattle During First-Time Exposure To A Pearl Millet Pasture Treated With A Chemical Plant-Growth Regulator, J E. Arias, C T. Dougherty, M Collins
IGC Proceedings (1993-2023)
Twelve tethered Angus cows were used to estimate 1he effect of structure and chemical composition of a pearl millet (Pennisetum americanum L. Leeke cv, Tifleaf-.2. hybrid) pasture.on grazing. behaviour. Cerone (ethephon (2-chloroethyl) phosphonic acid) plant growth retardant (fOR) was broadcast, establishing canopy heights of 0.855, 0.716 and 0,829 m;• neutral detergent fibr (NDP) of 65,3, 63 .. 4 ·and 64.91/'; acid detergent • fibre (ADF) of 37.6, 36.2 and,37.5%: and in vitro organic .matter digestibility (lVOMD) of 66.4, 67 .9 and 66.9% (Treatment 1. (Tl), T2 and ·T3, respectively). ·Effective biting rate (BBR) averaged 24, 28 an!l 25 bites/min …
Early And Late Grazing Of Cocksfoot And Tall Fescue Hay Fields Overseeded With Red Clover, E C. Prigge, W B. Bryan, E S. Goldman, G E. D'Souza
Early And Late Grazing Of Cocksfoot And Tall Fescue Hay Fields Overseeded With Red Clover, E C. Prigge, W B. Bryan, E S. Goldman, G E. D'Souza
IGC Proceedings (1993-2023)
Grazing hay fields with beef cattle during portions of the year when hay is traditionally fed, was examined to yield, quality of forage and composition of the sward. Pour managements were compared: early spring, one hay cutting, and late autumn grazing (GHG), 2 hay cuttings (HH), early spring grazing and 2 hay cuttings (GHH), and 1 hay culling and late au1umn· grazing (HG). The managements were applied lo tall foscue (Festuca arundinacea Schreb.) (TP) and cocksfool (Dactylis glomerata L.) (Cfl) hay fields, overseeded with red clover (Trifolium pratense L.). Annual herbage dry mailer production from the plots …
Use Of A Simple Model Of Continuous And Rotational Grazing To Compare Herbage Consumption, Simon J.R Woodward, G `C Wake, D G. Mccall, A B. Pleasants
Use Of A Simple Model Of Continuous And Rotational Grazing To Compare Herbage Consumption, Simon J.R Woodward, G `C Wake, D G. Mccall, A B. Pleasants
IGC Proceedings (1993-2023)
A simple mathematical model (a linear dynamical system) was constructed to predict herbage consumption by grazing animals. This model was used to compare 3 grazing methods over a range of stocking rates at low pasture mass. The grazing methods compared were: continuous grazing (CTS), rotational grazing with equal time intervals (BQ), and rotational grazing where the time of shift was optimal for maximising intake (OPT). The rotational methods were the simplest possible, the land being subdivided into 2 fields, each of which was grazed once. The order of grazing the fields was also considered. The model predicts (I) that at …
Relative Productivity And Persistense Of White Clover Cultivars Under Cutting Or Continuous Stocking By Sheep, D A. Davies, M Fothergill
Relative Productivity And Persistense Of White Clover Cultivars Under Cutting Or Continuous Stocking By Sheep, D A. Davies, M Fothergill
IGC Proceedings (1993-2023)
Perennial ryegrass-white clover (Lolium perenne-Trlfollium repens) swards of 3 clover cultivars were studied at a lowland (30 m) and upland (340 m) site in mid Wales over 3 years (1989-91). Lamb production from small-leaved Aberystwyth S 184 at 1021 kg/ha was 25% and 1191, more than from small-leaved Ac3351 and medium-leaved Grasslands Huia respectively. The relative lamb output from Huia was poorer at the upland location. Clover production, survival and morphology under a number of cutting heights and frequencies were different from those in the continuously stocked pastures. Cutting every 10 days at 2-3 cm resulted in poor clover and …
Morphological Changes In Three Clover (Trifolium Repens L.) Cultivars Under Continuous Stocking, M Fothergill, D A. Davies
Morphological Changes In Three Clover (Trifolium Repens L.) Cultivars Under Continuous Stocking, M Fothergill, D A. Davies
IGC Proceedings (1993-2023)
Individual plant morphology of 3 white clover (Trifolium repens L.) cultivars was studied during 1990 and 1991. Seasonal shifts were demonstrated by all cultivars towards a higher proportion of less complex plants from winter to mid summer. Over the latter half of the year the population tended lo return towards its original distribution. Seasonal fluctuations in stolon dry weight/plant and root number/plant were also identified, with the small-leaved Ac3351 maintaining a greater stolon OW/plant than Aberystwyth S184 and Grasslands Huia during 1990. Ac3351 and S184 also maintained a larger root number/plant over this period. However, no significant differences were detected …
Contribution Of Undomesticated Germplasm To Development Of Persistent, Grazing-Tolerant Lucerne, I Kaehne, E T. Kobelt, J A. Horsenell
Contribution Of Undomesticated Germplasm To Development Of Persistent, Grazing-Tolerant Lucerne, I Kaehne, E T. Kobelt, J A. Horsenell
IGC Proceedings (1993-2023)
The development of lucerne (Medicago saliva L.) germplasms which are tolerant to continuous grazing, adapted to dryland agriculture in the mediterranean zone and resistant to aphids, is described, Undomesticated lucerne accessions from 14 countries were crossed with winter-active cultivated lucerne accessions adapted to mediterranean climates to produce 4 S populations which were selected for tolerance to continuous intense grazing by sheep, The most tolerant populations were screened to develop germplasms resistant to spotted alfalfa aphid and blue-green aphid. The 72 populations that were developed from these germplasms by further selection for grazing tolerance and aphid resistance were tested for …
An Approach For Testing The Ecological Amplitude Of Herbage Cultivars, B D. Campbell
An Approach For Testing The Ecological Amplitude Of Herbage Cultivars, B D. Campbell
IGC Proceedings (1993-2023)
A technique is described for testing the response of cultivars to environmental factors using crossed, controlled gradients of mineral nutrient supply and simulated grazing. The usefulness of the technique was tested by growing the perennial ryegrass (Lolium perenne L.) cultivar Melle and the cocksfoot (Dactylis glomerata L.) cultivar Sylvan in isolation and in a complex mixture on the matrix. Contour maps of the frequency of tillers of the cultivars after 2 years' growth indicated that Melle is better suited to high fertility, heavily stocked sites. The technique may be useful as a compact, standardised method for cultivar testing.
Botanical Composition, Improvement Intervention And Cattle Weight Gain Of Natural Pastures Of Western Ethiopia, L Gizachew, A Tadesse, A Hassen
Botanical Composition, Improvement Intervention And Cattle Weight Gain Of Natural Pastures Of Western Ethiopia, L Gizachew, A Tadesse, A Hassen
IGC Proceedings (1993-2023)
The dominant indigenous grass and legume species in the highland (above 2000 m) and mid-altitude (1600-2000 m) parts of western Ethiopia were determined. Grasslands in the high altitude contain a higher proportion of a nutritious grass and legume species than grasslands in the mid altitude. Fertiliser, manuring and legume oversowing improved dry matter yield and live-weight gains of grazing animals. Incorporating forage legumes into natural pastures by oversowing is the best pasture improvement strategy.
Effects Of Quantity And Pattern Of Herbage Removal On Botanical Composition Of A Temperate Pasture, W Harris
Effects Of Quantity And Pattern Of Herbage Removal On Botanical Composition Of A Temperate Pasture, W Harris
IGC Proceedings (1993-2023)
Ryegrass-white clover (Lolium perenne L.- Trifolium repens L.) pasture was cut in continuous and .rotational patterns to provide herbage for 15, 20 and 25 ewes/ha. A comparison was made with grazed pasture. Dead matter content from rotational management decreased as stocking rate increased, but was high for high stocking rate continuous management when herbage requirements were high. Ryegrass decreased and clover content increased under continuous . management particularly as stocking rate increased. Unsown species • increased markedly under continuous management at high stocking. Changes of ryegrass and clover content under grazing were less than' under cutting possibly owing to …
Structure Of Plant Communities In A Pastoral System In Northern Spain, I Alonso, A Garcia
Structure Of Plant Communities In A Pastoral System In Northern Spain, I Alonso, A Garcia
IGC Proceedings (1993-2023)
Six grassland communities on different soil types in northern Spain were analysed for species life-form and growth form composition, diversity, height and above-ground biomass in relation to grazing. Hemicryptophytic life-form was the most characteristic form. The grasslands on calcareous soils showed the greatest diversity values and the lowest peak above-ground biomass. Grasses were more abundant in siliceous soils than in calcareous soils, but in all communities the group "other families" was dominant.
Fattening Performance Of Weaned Lambs Grazed On Common Vetch-Barley Mixture Sown On Fallow Land, A Elicin, M Ilaslan, M Munzur, S Cangir, A Karabulut
Fattening Performance Of Weaned Lambs Grazed On Common Vetch-Barley Mixture Sown On Fallow Land, A Elicin, M Ilaslan, M Munzur, S Cangir, A Karabulut
IGC Proceedings (1993-2023)
The aim of investigation was to estimate faltening performance of 40 weaned 2.5-month-old single male Akkaraman lambs grazed on a barley and common vetch mixture grown on summer fallow. The first group was grazed on the mixture only, the second group was grazed on the mixture + 500 g concentrate feed a day, the third group was grazed on the mixture + ad lib. concentrate feed and the last group was fed solely on concentrate feed. The investigation lasted 42 days, Average live-weight gains of the groups were 10.2, I 1.3, 11.3 and 10.3 kg and their daily live-weight gains …
Rumen Digestion Of Temperate Pasture: Effects Of Milk Yield And Composition, D H. Rearte, F J. Santini
Rumen Digestion Of Temperate Pasture: Effects Of Milk Yield And Composition, D H. Rearte, F J. Santini
IGC Proceedings (1993-2023)
Dairy production in Argentina is based on grazing of temperate pasture. Concentrate is used as a supplement at a level no higher than 30% of the diet. Milk yield is high but butterfat content of milk is lower on pasture than on indoor feeding diet based on processed forage and concentrate. Rumen fluid of cows on grazing was characterised by low pH (5.8-6.2), high volatile fatty acid concentration (90-120 mmoUI) and a low acetate:propionate ratio (<2.5). Hydrolysis of forage protein in rumen is high and the percentage of dietary amino acids reaching the duodenum is low (20- 30% ). This rumen environment occurs only with cows on grazing because when fresh forage is cut and fed to cows Indoors, pH and acetate:propionate ratio is higher and NH3 concentration is lower. Rumen fermentation was also modified when pasture forage was offered wilted instead of fresh. Concentrate supplementation at a level no higher than 30% of total diet did not affect the rumen environment, but it was modified by corn silage supplementation.