Effect Of Sward Surface Height Research Articles

Tall fescue sward structure affects the grazing process of sheep

The study of factors influencing animal intake can provide a better understanding of the dynamics of the pasture ecosystem and serve as a basis for managing livestock in a more efficient way. We measured different sward surface heights of tall fescue in the process of short-term intake rate of sheep. There was a significant effect of sward surface height on herbage mass (P < 0.001), leaf lamina mass (P < 0.001), other species mass (P = 0.02), bite mass (P = 0.01) and short-term intake rate (P = 0.03) of sheep. There was a quadratic fit between time per bite and bite mass (P = 0.006). Multivariate analysis showed that the short-term intake rate and bite mass were positively correlated (r = 0.97), bite rate and total jaw movement rate were positively correlated but both were negatively correlated with time per bite. The sward surface height of tall fescue corresponding to the maximum short-term herbage intake rate was 22.3 cm. The underlying processes were driven by the bite mass, which was influenced by the leaf lamina bulk density and its consequences upon time per bite. This sward surface height can be adopted as a pre-grazing target for rotational stocking systems to optimize sheep nutrition on pastures.

Effect of sward surface height and level of herbage depletion on bite features of cattle grazing Sorghum bicolor swards1

To maximize herbage DMI, pregrazing sward surface height (SSH) and level of herbage depletion (HD) must be such that variables determining short-term herbage intake such as bite mass (BM) and bite rate (BR) are optimized. The objective of this study was to determine a SSH target and the level of HD as a proportion of the SSH that optimizes BM and BR of beef heifers grazing Sorghum bicolor swards. Two experiments were conducted using 2 S. bicolor swards and 4 beef heifers (25 mo old; 322 kg BW). Experiment 1 compared the effect of 6 pregrazing SSH, 30, 40, 50, 60, 70, and 80 cm, on BM, BR, and jaw movements. Experiment 2 assessed the effect of HD level as a proportion of SSH (0.17, 0.34, 0.50, 0.67 and 0.84) on BM, BR, and jaw movements using the optimal pregrazing SSH defined in Exp. 1. Short-term herbage DMI was estimated using a double-weighing technique and corrected for insensible BW loss. Herbage DMI was subsequently used to calculate the BM. Net eating time and jaw movements for apprehension and manipulation + mastication during grazing as well as total jaw movements were determined using the IGER (Institute of Grassland and Environmental Research) behavior recorders. Bite rate and the number of total jaw movements per gram herbage DMI were derived from jaw movement count and measurements of herbage DMI. The results of Exp. 1 showed low and high SSH constraint the ease of herbage harvesting. Greater BM are maintained until a SSH of 50 cm is reached (P < 0.05) and then decline at greater SSH due to herbage dispersion. The nonbiting jaw movement rate increased at greater SSH whereas BR decreased (P < 0.05). For both variables, the turning point was close to a SSH of 50 cm. Experiment 2 showed that such an optimization of BM and BR was maintained until an HD level of 0.34 was reached (P < 0.05). There was a linear increase in both the total jaw movements per unit herbage DMI and the nonbiting jaw movements rate (manipulation + mastication) subsequent to levels of HD greater than 0.34 (P < 0.05). These studies provide, for the first time, sward feature targets to manage grazing and optimize BM and BR, aiming to maximize the short-term herbage DMI of cattle grazing S. bicolor swards.

Influence of sward condition on leaf tissue turnover in tall fescue and tall wheatgrass swards under continuous grazing

SummaryTwo experiments were carried out on a tall fescue sward in two periods of spring 1994 and on a tall wheatgrass sward in autumn 2001 and spring 2003 to analyse the effect of sward surface height on herbage mass, leaf area index and leaf tissue flows under continuous grazing. The experiment on tall fescue was conducted without the application of fertilizer and the experiment with tall wheatgrass received 20 kg P ha−1 and a total of 100 kg N ha−1 in two equal dressings applied in March (autumn) and end of July (mid‐winter).Growth and senescence rates per unit area increased with increasing sward surface height of swards of both species. Maximum estimated lamina growth rates were 28 and 23 kg DM ha−1 d−1 for the tall fescue in early and late spring, respectively, and 25 and 36 kg DM ha−1 d−1 for tall wheatgrass in autumn and spring respectively. In the tall fescue sward, predicted average proportions of the current growth that were lost to senescence in early and late spring were around 0·40 for the sward surface heights of 30–80 mm, and increased to around 0·60 for sward surface heights over 130 mm. In the tall wheatgrass sward the corresponding values during spring increased from around 0·40 to 0·70 for sward surface heights between 80 and 130 mm. During autumn, senescence losses exceeded growth at sward surface heights above 90 mm. These results show the low efficiency of extensively managed grazing systems when compared with the high‐input systems based on perennial ryegrass.

The effect of sward surface height on the response to mixed grazing by cattle and sheep

AbstractAn experiment was conducted to examine the effects of mixed grazing of sheep plus cattle under continuous stocking of permanent pasture at different sward heights. The experiment had a 2×3 factorial design, with two sward surface heights (4–5 and 8–10 cm) and three combinations of animal species viz., sheep only, cattle only and sheep plus cattle. There were two replicate plots of each treatment combination and the experiment was conducted over 2 years consecutively. The sheep were Beulah Speckled Face ewes and their single Suffolk-cross lambs while the cattle were yearling Charolais-cross steers. Six ‘core’ steers and six ‘core’ ewes and their lambs grazed plots, as appropriately, while additional, non-experimental steers and ewes and their lambs were used to maintain sward heights. Each year the steers and the ewes grazed the pastures from May to October, while lambs were weaned and removed each year from the experiment in July. There was no significant effect of mixed grazing on live-weight gain of steers, but ewes had significantly higher live-weight gains on the sheep plus cattle treatment than on the sheep-only treatment (82 v. 61 g/day;P&lt;0·001). The live-weight gain of the lambs was higher on the mixed grazing treatment than on the sheep only treatment on the 8–10 cm sward height treatment (243 v. 212 g/day;P&lt;0·05) but there was no significant difference on the 4–5 cm sward height treatment (260 v. 250 g/day;P&gt;0·05). The total output of live-weight gain per ha from steers, ewes and lambs was not significantly affected by animal species combination. It is concluded that while output per ha is not enhanced by mixed grazing by sheep and cattle when sward height is controlled, the live-weight gain of ewes is increased and the live-weight gain of lambs can be increased on taller swards.

Effect of sward surface height on herbage intake and performance of finishing beef cattle

This study examined the effects of contrasting sward surface height (SSH) on the herbage intake, ingestive behaviour, and performance of steers grazing perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) pastures in New Zealand during summer, and the influence of this initial treatment contrast on subsequent cattle performance under common grazing conditions during early autumn. Twenty‐four Angus‐cross steers, 26 months old and with an initial liveweight of 522 ± 7.6 kg, were continuously stocked on swards maintained at SSH of 5 and 10 cm (L versus H) from 18 November 1996. Six steers from each treatment were slaughtered on 4 March and the remaining animals were grazed for another 5 weeks on common pastures until the final slaughter on 8 April 1997. Herbage intake (estimated by the n‐alkane technique) and liveweight gain over the SSH contrast period, and carcass weight at first slaughter, were higher for steers grazed at 10 cm than for those grazed at 5 cm (7.5 ± 0.21 versus 5.0 ± 0.18 and 7.8 ± 0.38 versus 5.0 ± 0.33 kg DM d−1 from two intake estimates, P < 0.05 for each comparison; 1.10 ± 0.23 versus 0.32 ± 0.21 kg d−1, P < 0.01; and 332 ± 10.6 versus 287 ± 7.5 kg, P < 0.05, respectively). SSH did not affect carcass or meat quality characteristics. Liveweight and carcass weight gain per hectare were 71 % and 43% greater (318 versus 186 kg and 166 versus 116 kg over 105 days) for steers grazing at 10 cm despite the lower stocking rate (2.86 versus 5.80 steers ha−1) maintained by the tall swards. Significant differences in carcass weight were still evident at the end of the compensatory period between the steer groups originally on treatments H and L (335 ± 9.4 versus 297 ± 9.4 kg, P < 0.05). These results suggest that maintaining a sward height of 10 cm offers advantages in terms of individual animal output and output per hectare compared with grazing at 5 cm, and that compensatory growth does not seem to be an important phenomenon in heavy (over 500 kg liveweight) finishing steers.

Effect of sward surface height on intake and grazing behaviour by lactating Holstein Friesian cows

The effect of sward surface height (SSH) on grazing behaviour and intake by lactating Holstein Friesian cows on continuously stocked grass pastures maintained at mean heights of 5, 7 and 9 cm was studied during the growing season. Intake rate was estimated over periods of 1 h by weighing animals before and after grazing, with a correction made for insensible weight loss. Grazing behaviour during that hour and over 24 h was recorded automatically using sensors to measure jaw movements.Although maintained at the overall mean SSH, swards had a patchy appearance with short, frequently grazed areas interspersed with taller, infrequently grazed areas, which is typical of pastures continuously stocked with cattle. Daily organic matter (OM) intake, calculated as the product of daily grazing time and intake rate, was greater at a SSH of 7 cm than at 5 or 9 cm (14·1 vs. 10·5 and 12·1 kg respectively). On the 5‐cm sward, OM intake per grazing jaw movement (GJM) was reduced compared with that on the 7‐cm sward (0·182 vs. 0·264 g respectively), and because cows were unable either to increase significantly GJM rate (95·8 vs. 90·1 GJM min−1) or the proportion of GJM that were bites (0·80 vs. 0·81) OM intake rate was reduced (16·9 vs. 23·5 g min−1). Cows were unable to increase their grazing time significantly (628 vs. 604 min d−1) to compensate for the reduction in intake rate, and as a result daily intakes were lower. Cows grazing the 9‐cm sward also incurred a reduction in OM intake GJM−1 compared with those on the 7‐cm sward (0·237 vs. 0·264 g respectively) and therefore there was a reduction in OM intake rate (21·6 vs. 23·5 g min−1). These animals did not compensate by increasing the time spent grazing (581 min d−1), probably owing to an increased ruminating requirement per kg of herbage ingested compared with those on 7 cm SSH (2264 vs. 1780 ruminating jaw movements respectively). The results show that SSH can significantly influence intake rate, but, while the cow's only effective strategy to compensate for any reduction in intake rate is to increase grazing time, this may be limited by the requirement for ruminating and non‐grazing, non‐ruminating activities, which is influenced by qualitative and quantitative aspects of the herbage ingested, whereas the cows' only effective strategy to compensate for any reduction in intake rate is to increase grazing time.

Effect of sward surface height on intake and grazing behaviour by lactating Holstein Friesian cows

Effect of sward surface height on intake and grazing behaviour by lactating Holstein Friesian cows

The effect of sward surface height on grazing behaviour by lactating holstein-friesian cows

Sward surface height (SSH) has been shown to have an effect on the performance of dairy cows. However, to understand precisely how cows adapt to such differing sward conditions, it is necessary to study the interactions between bite mass, biting rate, and thus intake rate, and time spent grazing. An experiment was therefore designed to examine grazing behaviour and intake by lactating cows at three sward heights.

The effect of sward surface height on grazing behaviour by lactating holstein-friesian cows

Sward surface height (SSH) has been shown to have an effect on the performance of dairy cows. However, to understand precisely how cows adapt to such differing sward conditions, it is necessary to study the interactions between bite mass, biting rate, and thus intake rate, and time spent grazing. An experiment was therefore designed to examine grazing behaviour and intake by lactating cows at three sward heights.

Effect of sward surface height on herbage intake and performance of lactating ewes lambed in winter and continuously stocked on pasture

SUMMARYThirty-six 4-year-old Border Leicester × Romney (BR), Poll Dorset × BR (PBR) and Suffolk × BR (SBR) ewes balanced for litter size were assigned, 6 days after the mid-point of lambing (29 June 1989), to one of three sward surface height (SSH) treatments replicated twice (six ewes/1 ha paddock). The mean SSH during the 54 days of the trial were 2·6, 4·4 and 7·8 cm. Herbage organic matter intake (OMI) was measured using intraruminal chromium controlled release capsules during weeks 3, 4, 7 and 8 of lactation. Ewe OMI was not influenced by SSH during week 3 of lactation. During weeks 4 and 7 of lactation, ewe OMI increased with SSH up to a SSH of 7·8 cm. In week 8 of lactation there was no significant difference in OMI between ewes grazing the 4·4 or 7·8 cm SSH treatments, suggesting maximum intake at this stage of lactation is reached at 4·4 cm SSH. A maximum OMI of 2·6±0·1 and 3·0±0·1 kg OM/ewe per day (P&lt; 0·05) was reached in week 4 of lactation on the 4·4and 7·8 cm SSH treatments, respectively. Ewes grazing the 2·6 cm swards had a relatively constant OMI throughout the experiment (range 1·8±0·1 to 2·0±0·1 kg OM/ewe per day). However, these ewes lost 10·5 kg of liveweight while those on the 4·4 and 7·8 cm SSH treatments maintained a constant liveweight. Sward surface height had no effect on ewe midside wool growth rate or mean fibre diameter (measured at day 60 of lactation) or on lamb liveweight gain. Ewe breed cross had no effect on ewe OMI or midside wool growth. Lambs reared by SBR ewes were heavier (20·4±0·5 kg) at day 60 of lactation than lambs reared by PBR (18·7±0·6 kg) or BR (18·4±0·6 kg) ewes (P&lt; 0·05). These results suggest that for Winter(June)-lambing ewes in good condition a SSH of 4·0 cm under continuous stocking should ensure near to maximum ewe and lamb performance. However, ewes in good body condition at lambing stocked on a SSH down to 3 cm will rear lambs to acceptable weaning weights but at the expense of ewe liveweight loss and possible long-term carry-over effects on future productionif compensatory weight gains are not achieved during the spring pasture growth period.

Effect of sward surface height on the performance of ewes and Iambs continuously grazed on grass/clover and nitrogen‐fertilized grass swards

AbstractIn three successive years, sward height was maintained at 3, 5, 7 or 9 cm on grass swards receiving a total of 300 kg N ha−1 in six equal monthly dressings from April, and on grass/clover swards receiving 50 kg N ha−1 as a single dressing in early spring. From turnout in April until weaning in July, 64 ewes and their lambs (mean litter size 1·5) were continuously grazed at the four sward surface heights on the two sward types. White clover content of grass/clover swards remained low throughout the experiment ranging from 0·2 to 7·4% of the herbage mass. During the first two years, lamb gains averaged over sward types were 204, 260, 285 and 308 g d−1 up to weaning, while in the third year gains were 238, 296, 296 and 260 g d−1 on 3, 5, 7 and 9 cm swards respectively. Ewes lost live weight on 3 cm swards but apart from this sward height had little effect on performance. During the autumn, weaned lambs gained — 27, 87, 147 and 167 g d−1 on 3, 5, 7 and 9 cm swards respectively. Sward type had only a small effect on the performance of lambs up to weaning but in the autumn, mean gains of weaned lambs were lower on grass/N swards (73 g d−1) than on grass/clover swards (115 g d−1). Relative to 3 cm swards, carrying capacities of 5, 7 and 9 cm swards were 0·76, 0·57 and 0·52 respectively from turnout to weaning and 0·66, 0·52 and 0·44 respectively during autumn. Grass/clover swards carried 0·67 of the ewes carried by grass/N swards from turnout to weaning and 0·51 of the live weight carried by grass/N swards during autumn.The reaction of the two sward types to sward height did not appear to differ but in the third year there was evidence of a reduction in white clover content when swards were grazed at 9 cm. The data suggest that lamb growth rates will increase as sward height increases up to 9 cm and the evidence for this was stronger with weaned lambs in autumn than with suckling lambs in spring.

The Effect of Sward Surface Height on Ewe and Lamb Performance

Sward Surface Height (SSH) can be used as a guide for grazing control and recommendations are available for target SSH at various times of the year and at different levels of performance (Hodgson et al 1986).188 mule ewes with Suffolk cross lambs were allocated to 2 target SSH, 1-6 cm and 6-8 cm. Each treatment was replicated twice and balanced for ewe age, liveweight and condition score and the age, sex and rearing status of the lambs. The areas grazed were under permanent grass (mainly perennial ryegrass) and received 255 kg N/ha applied in 4 dressings with balancing P. and K. The initial stocking rate was 14.7 ewes/ha with 23.2 lambs/ha. SSH was measured weekly using an HFRO swardstlck with 40 readings taken per area. SSH was maintained using a temporary electric fence to adjust the size of the grazing area. Adjustments were made on a pre-set pattern which took into account any difference between current and target SSH and any change in SSH over the previous week. The area adjustments are shown in Table 1.Lambs were weighed at fortnightly intervals initially and at weekly intervals from the beginning of July. Lambs were drawn for slaughter at constant condition (3L). Ewes were condition scored and weighed at turnout (12th May), 6 weeks after turnout and at weaning (11th August).

Effect of sward surface height of mixed swards of ryegrass/white clover on the intake and performance by ewes and their twin lambs

Mixed swards of perennial ryegrass (Lolium perenne cv. S23) and white clover (Trifolium repens cv. Huia) were maintained at sward surface heights (SSH) of 3 (GC3), 6 (GC6) and 9 cm (GC9) by continuous variable stocking to examine effects on sward and animal performance. In addition, a pure grass sward of S23 was kept at 6 cm (G6) and fertilized with 14 applications of 30 kg N per ha at fortnightly intervals, beginning on 25 March. The swards were sown in August 1983, cut twice in 1984, in May and June, and then grazed thereafter. Fertilizer was applied to the seedbed at 40 kg N per ha, 20 kg P205 per ha and 20 kg K20 per ha. In March 1984 and 1985, 20 kg per ha each of P205 and K2O were applied to all plots.Dry sheep grazed the paddocks (0.69 ha) to the required SSH's with grazing starting on 4 April, 9 April, 12 April and 24 April for treatments GC3, G6, GC6 and GC9, respectively. On 24 April, two days after lambing, core groups of 8 Scottish Halfbred ewes with twin lambs were put on the plots. Additional ewes, kept on swards similar to the treatment areas, were used to adjust the stocking rate to maintain the SSH's. These were measured three times each week with 200 readings per plot.