The effect of plant structure on the intake of tropical pastures. I. Variation in the bite size of grazing cattle

1973 ◽  
Vol 24 (6) ◽  
pp. 809 ◽  
Author(s):  
TH Stobbs
Keyword(s):  
Growth Regulators ◽  
Daily Intake ◽  
Canopy Structure ◽  
In Vitro Digestibility ◽  
Trimethylammonium Chloride ◽  
Tropical Pasture ◽  
Rhodes Grass ◽  
Bite Size ◽  
Digitaria Decumbens ◽  
Grazing Cattle

To determine the effect of sward canopy structure on bite size a technique was developed for measuring the size of bite prehended by grazing cattle. Almost complete recovery (a mean of 95%) of ingested material was achieved by inserting a foam rubber plug in the lower oesophagus of oesophageal-fistulated animals, whilst the number of bites taken during grazing was automatically recorded. Theoretical calculations showed that a mean bite size of less than 0.30 g OM/bite can seriously limit daily intake of herbage by grazing cattle. Four experiments were conducted to measure the variation in bite size prehended by Jersey cows when grazing tropical pasture swards of varying canopy structure. Bite size on a nitrogen fertilized Setaria anceps cv. Kazungula sward averaged 0.39 g OM/ bite, whereas an adjacent sparse unfertilized sward averaged 0.13 g OM/bite. Mean size of bite of cows grazing 5-week-old regrowths of the trailing legume (Macroptilium atropurpureum cv. Siratro) was 0.24 g OM/bite, compared with 0.34 and 0.38 g OM/bite for nitrogen fertilized Digitaria decumbens and Setaria anceps pasture respectively. Growth regulators, gibberellic acid (GA) and 2-chloroethyl-trimethylammonium chloride (CCC), were successfully used to alter the sward canopy structure of Digitaria decumbens (pangola) and Chloris gayana (rhodes) grass pastures. GA increased herbage yield, and sward height, and produced erect stemmy plants with long internodes, whereas CCC reduced plant height and internode length, and resulted in a denser sward which was higher in nitrogen and in vitro digestibility due to a higher leaf content. Measurement of bite size prior to any changes in sward structure being manifest showed that bite size was unaffected by the growth regulators per se. However, bite size on the CCC treated pastures sampled after 6 weeks was larger (0.52 g OM/bite) than from the same cows grazing pastures treated with GA (0.40 g OM/bite). It was concluded that the size of bite prehended by cattle grazing some tropical pasture swards can limit intake of herbage, and that sward bulk density, a low stem content, and a high leaf/height ratio have a major influence upon the size of bite taken by cows grazing these pastures.

Effect of sward structure of two tropical grasses with contrasting canopies on light distribution, net photosynthesis and size of bite harvested by grazing cattle

1982 ◽  
Vol 33 (2) ◽  
pp. 187 ◽  
Author(s):  
MM Ludlow ◽  
TH Stobbs ◽  
R Davos ◽  
DA Charles-Edwards
Keyword(s):  
Leaf Area ◽  
Growth Regulators ◽  
Light Distribution ◽  
Trimethylammonium Chloride ◽  
Tropical Pastures ◽  
Area Density ◽  
Tropical Grasses ◽  
Bite Size ◽  
Leaf Area Density ◽  
Grazing Cattle

Our aim was to determine whether increasing the sward density of tropical pastures, for the purpose of enhancing the size of bite harvested by grazing cattle, would reduce yield by affecting light distribution andcanopy photosynthesis. The growth regulators (2-chloroethy1)trimethylammonium chloride (CCC) and gibberillic acid (GA) were used to alter the leaf area density of the tussock-forming grass Setavia sphacelata and of the sward-forming grass Digitaria decumbens. GA increased plant height, the length of stem internodes, and the size of bite harvested by cattle. On the other hand, CCC decreased canopy height, and increased leaf area density and bite size. The variation of leaf area density, investigated experimentally by using growth regulators (5-25 m-1) and theoretically by simulation modelling (5-40 m-1), had no significant effect on either leaf or canopy photosynthetic characteristics. Hence we believe that there would be a negligible reduction in yield of these tropical grasses if their leaf area densities were increased up to a value of 40 m-1, which exceeds those of temperate pastures. Such increases in leaf area density may increase animal production from tropical pastures where bite size limits daily intake of forage. The agricultural implications of the findings are discussed.

Influence of sward characteristics on grazing behaviour and growth of Hereford steers grazing tropical grass pastures

1978 ◽  
Vol 29 (1) ◽  
pp. 89 ◽  
Author(s):  
EA Chacon ◽  
TH Stobbs ◽  
MB Dale
Keyword(s):  
Nitrogen Content ◽  
Nutritive Value ◽  
In Vitro Digestibility ◽  
Relative Importance ◽  
Stocking Rate ◽  
Bite Size ◽  
Plant Parts ◽  
Digitaria Decumbens ◽  
Grazing Behaviour

Relationships between sward characteristics, grazing behaviour and growth of Hereford steers were studied on nitrogen-fertilized (378 kg ha-1 yr-1) Setaria anceps cv. Nandi and Digitaria decumbens swards continuously stocked at 4.3, 6.2 and 8.0 beasts ha-1 during five periods over 2 years. Availability of herbage, as measured by bite size, and nitrogen content and in vitro digestibility of herbage in the top of the swards were the two most important factors influencing the performance of steers. The relative importance of these factors varied between seasons, between stocking rate treatments and to a lesser extent between pasture species. The highest growth rates were measured on the leniently stocked pastures because steers were able to harvest feed easily (a large bite size) and could more readily select the more nutritious plant parts from the top of the sward. The swards were highly heterogeneous, and numerical analysis of data showed that at the same herbage yield, spatial distribution of herbage (leaf bulk density and leaf to stem ratio) and the nutritive value (in vitro digestibility and nitrogen content) of herbage greatly influenced the growth of steers. Cattle were unable to satisfy their feed requirements on some high quality but low-yielding swards, despite increasing grazing time to compensate for the small bites prehended (up to 707 min in 24 hr in spring). Consequently nitrogen and digestibility contents of extrusa samples were at times poor indicators of performance.

The effect of plant structure on the intake of tropical pastures. II.* Differences in sward structure, nutritive value, and bite size of animals grazing Setaria anceps and Chloris gayana at various stages of growth

1973 ◽  
Vol 24 (6) ◽  
pp. 821 ◽  
Author(s):  
TH Stobbs
Keyword(s):  
Nutritive Value ◽  
Organic Matter Content ◽  
In Vitro Digestibility ◽  
Plant Structure ◽  
Tropical Pastures ◽  
Rhodes Grass ◽  
Bite Size ◽  
Leaf Density ◽  
Chloris Gayana

Bite size (organic matter content per bite) of cows grazing swards of Chloris gayana (rhodes) and Setaria anceps (setaria) regrown for 2, 4, 6, and 8 weeks was measured using oesophageal fistulated animals. Sward canopy structure was measured by stratification into five vertical layers, each 15 cm high; for each layer weights of leaf and stem components were estimated. Chemical composition and in vitro digestibility of plant fractions and oesophageal fistulae samples were determined. Cows grazing the 4 week regrowths of rhodes grass had a larger bite size (0.32 g OM/bite) than when grazing 2 week regrowths (0.27 g OM/bite) when the availability of herbage and leaf material was lowest. Despite a marked increase in herbage yield as the pastures matured (up to 8427 kg/ha) the mean bite size decreased to a mean of 0.15 g OM/bite at 6 and 8 weeks. The bite size of cows grazing setaria pastures was lower than on the rhodes grass pastures but followed a similar pattern. A high density of leaf within the sward (sward leaf density) as well as a low stem content were considered to be the main factors affecting bite size. Setaria and rhodes grass pastures had both low sward bulk densities (a range of 14–96 kg/ha cm) and low sward leaf bulk densities (a range of 12–43 kg/ha cm) compared with temperate pastures. Basal layers of the sward contained more dense herbage (up to 148 kg/ha cm), but sward leaf density was usually less than 80 kg/ha cm and apparently inaccessible. ___________________ *Part I, Aust. J. Agric. Res., 24: 809 (1973).

The effect of plant structure on the intake of tropical pasture. III.* Influence of fertilizer nitrogen on the size of bite harvested by Jersey cows grazing Setaria anceps cv. Kazungula swards

1975 ◽  
Vol 26 (6) ◽  
pp. 997 ◽  
Author(s):  
TH Stobbs
Keyword(s):  
Organic Matter ◽  
Dry Matter ◽  
Canopy Structure ◽  
Tropical Pasture ◽  
Plant Structure ◽  
Fertilizer Nitrogen ◽  
Bite Size ◽  
Nitrogen Levels ◽  
The Mean ◽  
Jersey Cows

The effect of fertilizing Setaria anceps cv. Kazungula swards with nitrogen on the size of bite harvested by cattle was determined and the influence of sward canopy structure upon bite size was investigated in two experiments. The first experiment measured the effect of nitrogen at 0, 40, 60 and 100 kg/ha on 6-week regrowth, and the second measured the effect at 50 and 100 kg/ha on 4- and 6-week regrowths of both unfertilized swards and others which had received 350 kg nitrogen per hectare in each of the previous three years. The mean bite size of cows grazing immature (4-week) regrowths increased linearly with increasing applications of nitrogen, averaging 0.29, 0.33 and 0.37 g organic matter (OM) per bite on the 0, 50 and 100 kg/ha treatments respectively. Swards which allowed the largest bites to be prehended had the highest leaf yields and the highest leaf bulk densities. The mean bite size on 6-week regrowths was lower (0.28 g OM/bite) than on 4-week regrowths (0.33 g OM/bite). Cows selected leaf from the upper layers of the swards, and inaccessibility of leaf resulting from a high stem and inflorescence content prevented animals from taking larger bites. In both experiments high levels of nitrogen fertilizer advanced the maturity of 6-week regrowths, and the bite size of cows grazing these pastures did not increase beyond the level recorded at intermediate nitrogen levels. It was concluded that fertilizer nitrogen increases dry matter and leaf yields, particularly in the uppermost layers of the sward, allowing cows to harvest large bites of immature herbage. A higher stem and inflorescence content in heavily fertilized swards can result in inaccessibility of leaf when mature herbage is grazed. ________________ *Part II, Aust. J. Agric. Res., 24: 821 (1973).

scholarly journals Action of growth regulators on flowering and pod production of soybean cultivar Davis

1981 ◽  
Vol 38 (1) ◽  
pp. 99-112
Author(s):  
Paulo R.C. Castro ◽  
Roberto S. Moraes
Keyword(s):  
Glycine Max ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Lower Number ◽  
Soybean Cultivar ◽  
Soybean Plant ◽  
Trimethylammonium Chloride ◽  
Triiodobenzoic Acid ◽  
Soybean Plants

This research deals with the effects of growth regulators on flowering and pod formation in soybean plant (Glycine max cv. Davis). Under greenhouse conditions, soybean plants were sprayed with 2,3,5-triiodobenzoic acid (TIBA) 20 ppm, Agrostemmin (1g/10 ml/3 l) gibberellic acid (GA) 100 ppm, and (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm. Application of TIBA increased number of flowers. 'Davis' soybean treated with CCC and TIBA presented a tendency to produce a lower number of pods.

scholarly journals Action of growth regulators on production of soybean cultivar Davis

1981 ◽  
Vol 38 (1) ◽  
pp. 127-138 ◽  
Author(s):  
Paulo R.C. Castro ◽  
Roberto S. Moraes
Keyword(s):  
Glycine Max ◽  
Gibberellic Acid ◽  
Growth Regulators ◽  
Seed Weight ◽  
Dry Weight ◽  
Soybean Plant ◽  
Trimethylammonium Chloride ◽  
Seed Number ◽  
Exogenous Growth ◽  
Soybean Plants

This research deals with the effects of exogenous growth regulators on production of soybean plant (Glycine max cv.. Davis) under greenhouse conditions, At the flower anthesis, 2,3,5-triiodobenzoic acid (TIBA) 20 ppm was applied. Other two applications with TiBA, with intervals of four days, were realized. Before flowering, Agrostemin (1 g/10 ml/3 1), gibberellic acid (GA) 100 ppm, and (2-chloroethyl) trimethylammonium chloride (CCC) 2,000 ppm were applied. It was observed that CCC and TIBA reduced stem dry weight. Soybean plants treated with TIBA reduced weight of pods without seeds , seed number and seed weight.

Milk production, milk composition, rate of milking and grazing behaviour of dairy cows grazing two tropical grass pastures under a leader and follower system

1978 ◽  
Vol 18 (90) ◽  
pp. 5 ◽  
Author(s):  
TH Stobbs
Keyword(s):  
Milk Production ◽  
Latin Square ◽  
Milk Composition ◽  
Panicum Maximum ◽  
Tropical Pastures ◽  
Rhodes Grass ◽  
Bite Size ◽  
Leaders And Followers ◽  
Jersey Cows ◽  
Grazing Behaviour

Milk production, milk composition, rate of milking and grazing behaviour were measured for lactating Jersey cows having both the first opportunity to graze (leaders) and also when offered the remaining herbage (followers) from 3-week regrowths of two nitrogen-fertilized tropical pastures, Rhodes grass (Choris gayana cv. Pioneer) and Gatton panic (Panicum maximum cv. Gatton). Twenty-four cows were used in a latin-square design with experimental periods of 14 days. Both leaders and followers were allocated 40 kg DM cow-1 day-1. Leader cows produced 8.0 kg milk cow-1 day-1 compared with 5.8 kg milk cow-1 day-1 for followers, a difference of 38 per cent. Both leader and follower cows grazing Gatton panic produced more milk than cows grazing Rhodes grass. Milk from leader cows contained a higher percentage of solids-not-fat and protein and a lower butterfat percentage indicating a higher intake of digestible nutrients. Cows showed a preference for leaf, and after easily accessible leaf was removed by leader cows the follower cows had a small bite size. Follower cows partially compensated by increasing grazing time, mainly at night. Follower cows had a longer let-down time and a longer milking time per kilogram of milk produced. Milk production was linearly related to bite size and availability and accessibility of leaf were considered to be the main factors influencing production.

The competitive and yielding ability of some sub-tropical pasture species sown alone and in mixtures under intermittent grazing at Samford, south-eastern Queensland

1969 ◽  
Vol 9 (37) ◽  
pp. 181 ◽  
Author(s):  
RJ Jones ◽  
Davies J Griffiths ◽  
RB Waite
Keyword(s):  
White Clover ◽  
Competitive Ability ◽  
Grazing Management ◽  
Tropical Pasture ◽  
Weed Species ◽  
Rhodes Grass ◽  
Nitrogen Levels ◽  
Tropical Legumes ◽  
High Yields ◽  
Low Nitrogen

Eleven introduced tropical grasses were compared in single grass swards and nine of these were compared in mixtures containing two or three grasses. The pastures received 300 lb nitrogen an acre a year as urea and were grazed five times a year. A basal legume mixture of tropical legumes and white clover sown with the grasses failed to persist. There were large differences between the grasses in competitive ability and this varied with time. Samford Rhodes grass, Nandi setaria, and Pangola were the most aggressive, and the Paspalum species-P. plicatulum P. dilatum and P. commersonii the least aggressive. Hyparrhenia hirta, which had done well at low nitrogen levels, failed to compete with weed grasses at the higher nitrogen level used in this study. Rhyncheytrum repens and commercial Rhodes grass were the dominant weed grasses in the establishment year. These rapidly decreased with time, and Digitaria didacola-blue couch, became the dominant weed species. Plots containing Nandi setaria, Samford Rhodes grass, or Pangola, gave the highest yields, and plots containing P. dilatatum the lowest. There was no yield advantage in combining grasses in mixtures-the mixture giving similar or lower yields than the best grass in the mixture grown alone. Under a period of farm grazing the three Rhodes grasses used declined sharply and the proportion of blue couch increased. The high yields from plots dominated by blue couch indicate that, agronomically, this has been a neglected naturalized species. Only Nandi setaria and Pangola were able to compete effectively with blue couch under the 'farm grazing' management imposed.

Cotton radiation use efficiency response to plant growth regulators

2012 ◽  
Vol 150 (5) ◽  
pp. 595-602 ◽  
Author(s):  
E. D. GONIAS ◽  
D. M. OOSTERHUIS ◽  
A. C. BIBI
Keyword(s):  
Plant Growth ◽  
Plant Growth Regulators ◽  
Growth Regulators ◽  
Untreated Control ◽  
Canopy Structure ◽  
Field Studies ◽  
Radiation Use Efficiency ◽  
Cotton Production ◽  
Use Efficiency ◽  
Radiation Use

SUMMARYPlant growth regulators are widely used in cotton production to improve crop management. Previous research has demonstrated changes in crop growth, dry matter (DM) partitioning and lint yield of cotton after the application of plant growth regulators. However, no reports are available demonstrating the effect of plant growth regulators on light interception and radiation use efficiency (RUE). Field studies were conducted in Fayetteville, Arkansas, USA in 2006 and 2007. RUE was estimated for the period between the pinhead square stage (PHS) of growth and 3 weeks after first flower (FF+3) from plots receiving three applications of the nitrophenolate and mepiquat chloride with Bacillus cereus plant growth regulators (Chaperone™) at 7·19 g a.i./ha and Pix Plus® at 41·94 g a.i./ha compared with an untreated control. No differences between the Chaperone treatment and the untreated control were found in the present study. However, Pix Plus significantly reduced plant height (both 2006 and 2007) and leaf area (2007 only), and altered the canopy structure of the crop as recorded by increased values of canopy extinction coefficient. Although DM accumulation was found not to be affected by plant growth regulator treatments, RUE was significantly increased after Pix Plus application, by 33·2%. RUE was increased because less light was intercepted by the Pix Plus treatment for the same biomass production, and this is probably a result of changes in photosynthetic capacity of the leaves and changes in light distribution throughout the canopy.

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