Effect of herbage in <i>Astrebla</i> spp. pastures in northwest Queensland on lamb survival

Cobon, D. H.; Carter, J. O.

doi:10.1017/s0021859600087487

Cited by 5 publications

(10 citation statements)

References 17 publications

(20 reference statements)

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“…[1][2][3][4][5] This is because the stable isotope composition of carbon, nitrogen and other elements in tissue depends on the composition of the diet, [6][7][8][9] and, thus, examination of tissue isotopic composition provides information about dietary components if these exhibit distinct isotopic signatures. The measurement of whole body isotopic composition is possible only for small animals, e.g.…”

mentioning

confidence: 99%

“…The analysis of the natural stable isotope composition of animal tissue, products or faeces has become an important tool in studies of the behavioral and nutritional ecology of animals or man. [1][2][3][4][5] This is because the stable isotope composition of carbon, nitrogen and other elements in tissue depends on the composition of the diet, [6][7][8][9] and, thus, examination of tissue isotopic composition provides information about dietary components if these exhibit distinct isotopic signatures.…”

mentioning

confidence: 99%

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Reconstruction of the isotopic history of animal diets by hair segmental analysis

Schwertl

Auerswald

Schnyder

2003

Rapid Comm Mass Spectrometry

151

156

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Carbon and nitrogen isotope signatures (delta(13)C and delta(15)N) of animal tissues provide information about the diet and, hence, the environment in which the animals are living. Hair is particularly useful as it provides a stable archive of temporal (e.g. seasonal) fluctuations in diet isotope composition. It can be sampled easily and with minimal disturbance from living subjects. However, derivation of the temporal record along the hair length may be subject to errors and uncertainties. This study investigates (and suggests means to minimize) several sources of error, including (a) incomplete sampling, (b) sampling during the quiescent (telogen) phase, (c) non-representative sub-sampling, (d) ignorance of hair growth rate, i.e. time-position relationship of isotope signatures, and (e) non-optimal compromise between analytical/procedural precision and effort/cost. Cattle tail switch hair was collected from animals of different breed, sex and age. Hair was washed, sectioned, and 5- or 10-mm-long sections were analyzed for C and N isotope composition. Signatures along paired hairs were similar (r(2) approximately 0.8) and distances between isotopic minima and maxima nearly identical, indicating that a single hair constituted a representative sample and (except for telogen hair) hair growth rate was the same for paired hairs. However, cutting hair, instead of plucking, caused a variable loss of recently grown hair and information. Telogen hair was identified and data loss due to cutting error reduced when more than one hair from the same animal and sampling region was compared to spot and delimit common and missing regions. Similarly, comparison of isotopic profiles from hair collected at different times identified the segment produced during the respective interval and allowed calculation of average hair growth rate, which varied between animals (0.69-1.06 mm d(-1)). Analysis of alternate 10-mm-long sections for two hairs per animal provided a good compromise between precision/resolution and effort. The method should be applicable to other mammalian species including man.

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mentioning

confidence: 99%

mentioning

confidence: 99%

Reconstruction of the isotopic history of animal diets by hair segmental analysis

Schwertl

Auerswald

Schnyder

2003

Rapid Comm Mass Spectrometry

151

156

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“…Pasture yield and species composition were estimated in May in the TS and October in the LDS of each annual cycle using Botanal, with 400-500 quadrat (0.5 × 0.5 m) estimates in a grid pattern per paddock on each occasion (Tothill et al 1992). Herbaceous forbs were classified as likely palatable or unpalatable to cattle according to Cunningham et al (1981) andMilson (2000), and as C3 or C4 plants according to Cobon and Carter (1994) and Sage (2016). Each 4-5 weeks, steers were mustered to yards in the late afternoon, fasted overnight with access to water, and weighed the following day.…”

Section: Pasture and Animal Measurementsmentioning

confidence: 99%

“…Mitchell grass pastures contain other perennial and annual grasses and numerous dicotyledonous herbaceous forbs, with considerable variation in their frequency and biomass among years. Where there is winter rainfall or low grass biomass owing to low summer rainfall and/or heavy grazing, forbs may comprise a substantial proportion, or even dominate, the sward (Lorimer 1978;Orr et al 1988;Cobon and Carter 1994;Orr and Phelps 2013b). Many forb species are palatable to sheep and cattle, and are generally higher in nutritive value than are grasses, especially during winter (Hall and Lee 1980;McMeniman et al 1986aMcMeniman et al , 1986b.…”

Section: Introductionmentioning

confidence: 99%

Diet quality, liveweight change and responses to N supplements by cattle grazing

Dixon

Sullivan²,

O’Connor³

et al. 2022

Rangeland J.

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Experiments during 4 years examined the diets selected, growth, and responses to N supplements by Bos indicus-cross steers grazing summer-rainfall semi-arid C4 Astrebla spp. (Mitchell grass) rangelands at a site in north-western Queensland, Australia. Paddock groups of steers were not supplemented (T-NIL), or were fed a non-protein N (T-NPN) or a cottonseed meal (T-CSM) supplement. In Experiment 1, young and older steers were measured during the late dry season (LDS) and the rainy season (RS), while steers in Experiments 2–4 were measured through the annual cycle. Because of severe drought the measurements during Experiment 3 annual cycle were limited to T-NIL steers. Pasture availability and species composition were measured twice annually. Diet was measured at 1–2 week intervals using near infrared spectroscopy of faeces (F.NIRS). Annual rainfalls (1 July–30 June) were 42–68% of the long-term average (471 mm), and the seasonal break ranged from 17 December to 3 March. There was wide variation in pasture, diet (crude protein (CP), DM digestibility (DMD), the CP to metabolisable energy (CP/ME) ratio) and steer liveweight change (LWC) within and between annual cycles. High diet quality and steer liveweight (LW) gain during the RS declined progressively through the transition season (TS) and early dry season (EDS), and often the first part of the LDS. Steers commenced losing LW as the LDS progressed. In Experiments 1 and 2 where forbs comprised ≤15 g/kg of the pasture sward, steers selected strongly for forbs so that they comprised 117–236 g/kg of the diet. However, in Experiments 3 and 4 where forbs comprised substantial proportions of the pasture (173–397 g/kg), there were comparable proportions in the diet (300–396 g/kg). With appropriate stocking rates the annual steer LW gains were acceptable (121–220 kg) despite the low rainfall. The N supplements had no effect on steer LW during the TS and the EDS, but usually reduced steer LW loss by 20–30 kg during the LDS. Thus during low rainfall years in Mitchell grass pastures there were substantial LW responses by steers to N supplements towards the end of the dry season when the diet contained c. <58 g CP/kg or c. <7.0 g CP/MJ ME.

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“…this finding also explains why the calibrations described in this paper often over-estimate d 13 c (negative sign omitted) in the faeces of cattle grazing Mitchell grass pastures where c 4 forbs are common. 32 this became quite obvious in a batch of samples collected at rosebank research Station near longreach at a time when there was an appreciable amount of edible non-grass herbage on offer and where laboratory d 13 c analysis revealed 5 of 15 forbs sampled to be c 4 species. nIr predictions of faecal d 13 c averaged 3.5‰ higher (range of -0.93 to +6.73, n = 33) than d 13 c values determined by mass spectrometry.…”

Section: Dietmentioning

confidence: 99%

Development of near Infrared Analysis of Faeces to Estimate Non-Grass Proportions in Diets Selected by Cattle Grazing Tropical Pastures

Coates

Dixon²

2008

Journal of Near Infrared Spectroscopy

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Grass (monocots) and non-grass (dicots) proportions in ruminant diets are important nutritionally because the non-grasses are usually higher in nutritive value, particularly protein, than the grasses, especially in tropical pastures. For ruminants grazing tropical pastures where the grasses are C4 species and most non-grasses are C3 species, the ratio of 13C/12C in diet and faeces, measured as δ13C‰, is proportional to dietary non-grass%. This paper describes the development of a faecal near infrared (NIR) spectroscopy calibration equation for predicting faecal δ13C from which dietary grass and non-grass proportions can be calculated. Calibration development used cattle faeces derived from diets containing only C3 non-grass and C4 grass components, and a series of expansion and validation steps was employed to develop robustness and predictive reliability. The final calibration equation contained 1637 samples and faecal δ13C range (‰) of [12.27]–[27.65]. Calibration statistics were: standard error of calibration (SEC) of 0.78, standard error of cross-validation (SECV) of 0.80, standard deviation ( SD) of reference values of 3.11 and R2 of 0.94. Validation statistics for the final calibration equation applied to 60 samples were: standard error of prediction ( SEP) of 0.87, bias of −0.15, R2 of 0.92 and RPD of 3.16. The calibration equation was also tested on faeces from diets containing C4 non-grass species or temperate C3 grass species. Faecal δ13C predictions indicated that the spectral basis of the calibration was not related to 13C/12C ratios per se but to consistent differences between grasses and non-grasses in chemical composition and that the differences were modified by photosynthetic pathway. Thus, although the calibration equation could not be used to make valid faecal δ13C predictions when the diet contained either C3 grass or C4 non-grass, it could be used to make useful estimates of dietary non-grass proportions. It could also be used to make useful estimates of non-grass in mixed C3 grass/non-grass diets by applying a modified formula to calculate non-grass from predicted faecal δ13C. The development of a robust faecal-NIR calibration equation for estimating non-grass proportions in the diets of grazing cattle demonstrated a novel and useful application of NIR spectroscopy in agriculture.

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Effect of herbage in Astrebla spp. pastures in northwest Queensland on lamb survival

Cited by 5 publications

References 17 publications

Reconstruction of the isotopic history of animal diets by hair segmental analysis

Reconstruction of the isotopic history of animal diets by hair segmental analysis

Diet quality, liveweight change and responses to N supplements by cattle grazing

Development of near Infrared Analysis of Faeces to Estimate Non-Grass Proportions in Diets Selected by Cattle Grazing Tropical Pastures

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