Impact of animal density on cattle nutrition in dry Mediterranean rangelands: a faecal near-IR spectroscopy-aided study.

In the context of determining the sustainable carrying capacity of dry-Mediterranean herbaceous rangelands, we examined the effect of animal density on cattle nutrition, which is fundamental to animal performance and welfare. The effects on dietary components of low (0.56 cows/ha; L) and high (1.11 cows/ha; H) animal densities were monitored for three consecutive years in grazing beef cows. In the dry season (summer and early autumn), cows had free access to N-rich poultry litter (PL) given as a dietary supplement. In each season, near-IR spectroscopy (NIRS) was used to predict the chemical composition of herbage samples (ash, NDF, CP, in vitro dry matter digestibility (IVDMD) and metabolizable energy (ME) content from IVDMD). Near-IR spectroscopy was applied also to faecal samples to determine the chemical composition of the diet selected by the animal, as well as the contents of ash, NDF and CP in the faeces themselves. A faecal-NIRS equation was applied to estimate the dietary proportion of PL. Seasonal categories were green, dry without PL supplementation and dry with it. We found no effects of animal density on nutrition during the green season but effects were apparent when cows consumed dry pasture. Ash content predicted by faecal NIRS was higher in the diet than in plant samples clipped from pasture, which infers that cows ingested soil. Dietary and faecal ash contents were higher (P<0.05) at the H, implying greater soil intake in these animals. During the dry period, dietary contents of ME were higher in L than in H (P<0.05). Poultry litter supplementation was associated with a marked increase (P<0.01) in dietary and faecal CP contents. Poultry litter represented 0.45 and 0.59 of the diet in treatments L and H, respectively (P<0.05). Consequently, treatment H had higher faecal protein (P<0.05). A tendency of higher dietary protein (P=0.08) and lower dietary NDF (P=0.10) in treatment H was probably related to greater PL ingestion. Given that high and sustained rates of poultry litter consumption are detrimental to animal health, the above results cast doubts on the long-term sustainability of the higher of the animal densities tested. Although it may be sustainable vis-à-vis the vegetation, treatment H may have exceeded the boundaries of what is acceptable for cow health. Chemical information revealed with NIRS can be used to evaluate whether animal densities are compatible with animal health and welfare standards and can play a role in determining the carrying capacity of Mediterranean rangelands.

Faecal near-IR spectroscopy to determine the nutritional value of diets consumed by beef cattle in east Mediterranean rangelands.

Rapid assessment of the nutritional quality of diets ingested by grazing animals is pivotal for successful cow-calf management in east Mediterranean rangelands, which receive unpredictable rainfall and are subject to hot-spells. Clipped vegetation samples are seldom representative of diets consumed, as cows locate and graze selectively. In contrast, faeces are easily sampled and their near-IR spectra contain information about nutrients and their utilization. However, a pre-requisite for successful faecal near-infrared reflectance spectroscopy (FNIRS) is that the calibration database encompass the spectral variability of samples to be analyzed. Using confined beef cows in Northern and Southern Israel, we calibrated prediction equations based on individual pairs of known dietary attributes and the NIR spectra of associated faeces (n=125). Diets were composed of fresh-cut green fodder of monocots (wheat and barley), dicots (safflower and garden pea) and natural pasture collected at various phenological states over 2 consecutive years, and, optionally, supplements of barley grain and dried poultry litter. A total of 48 additional pairs of faeces and diets sourced from cows fed six complete mixed rations covering a wide range of energy and CP concentrations. Precision (linearity of calibration, R2cal, and of cross-validation, R2cv) and accuracy (standard error of cross-validation, SEcv) were criteria for calibration quality. The calibrations for dietary ash, CP, NDF and in vitro dry matter digestibility yielded R2cal values >0.87, R2cv of 0.81 to 0.89 and SEcv values of 16, 13, 39 and 31 g/kg dry matter, respectively. Equations for nutrient intake were of low quality, with the exception of CP. Evaluation of FNIRS predictions was carried out with grazing animals supplemented or not with poultry litter, and implementation of the method in one herd over 2 years is presented. The potential usefulness of equations was also established by calculating the Mahalanobis (H) distance to the spectral centroid of a calibration population of 796 faecal samples collected throughout 2 years in four herds. Seasonal trends in pasture quality and responses to management practices were identified adequately and H<3.0 for 98% of faecal samples collected. We conclude that the development of FNIRS equations with confined animals is not only unexpensive and ethically acceptable, but their predictions are also sufficiently accurate to monitor dietary composition (but not intake) of beef cattle in east Mediterranean rangelands.

Consumption of Pistacia lentiscus foliage alleviates coccidiosis in young goats.

Coccidiosis near weaning is a major cause of diarrhea, ill-thrift, and impaired performance in small ruminants. A recent survey showed that in villages of the Samaria Hills, Israel, shepherds treat young, weaned goat kids afflicted with diarrhea by cutting and feeding them the foliage of Pistacia lentiscus L. (lentisk) or by tethering them close to lentisk bushes which they browse. The aim of the present study was to assess whether lentisk leaves do indeed have anti-coccidial value, and, if positive, to ascertain the role of tannins in this effect. We monitored for 24 (Experiment 1) and 30 (Experiment 2) days the effect of lentisk feeding on the development of naturally occurring coccidiosis in weaned kids artificially infected with parasitic nematodes. In Experiment 1, kids were infected with nematodes and fed lentisk foliage (PIS) or cereal hay (HAY). Coccidiosis developed at the early stage of the nematode infection, when dietary treatments were initiated. Kids in the PIS group had a lower (P<0.02) concentration of oocysts per gram feces (opg). In Experiment 2, aimed at verifying if tannins are the active component in lentisk foliage, coccidiosis occurred at the peak of the nematode infection, before experimental diets were initiated. Dietary treatments were: cereal hay (HAY), or lentisk foliage consumed without (PIS) or with (PISPEG) a 20-g daily supplement of polyethylene glycol (PEG; MW 4000), a molecule that impairs tannin-bonding with proteins. Goats fed the PIS diet had lower fecal opg counts than counterparts of the HAY (P<0.001) and PISPEG (P<0.002) treatments. Fecal opg counts for the HAY and PISPEG treatments did not differ, suggesting that the anti-coccidial moiety in lentisk was indeed tannins. Our results strongly suggest that: (i) in agreement with the ethno-veterinary anecdotal evidence, exposure of young, weaned goat kids to lentisk foliage alleviates coccidiosis; and (ii) this positive effect is associated with tannins. As coccidiosis is a major affliction of kids, providing them with tannin-rich browse near weaning could be an environmentally friendly way of improving their welfare and health status, in particular under bio-organic farm management.

A fecal near-infrared reflectance spectroscopy-aided methodology to determine goat dietary composition in a Mediterranean shrubland.

An ecologically sound approach to the problem of brush encroachment onto Israeli rangeland might be their utilization by goats, but better knowledge of the feeding selectivity and ability of goats to thrive in encroached areas is required to devise viable production systems. Direct observation of bites could provide precise and accurate estimates of diet selection, but construction of a sufficiently large database would require too much time. The present study describes the first attempt to construct fecal near-infrared reflectance spectroscopy (NIRS) calibrations of the botanical and nutritional composition of the diet, and of the total intake of free-ranging goats, based on reference values determined with bite-count procedures. Calibration of fecal NIRS was based on 43 observations encompassing 3 goat breeds and 4 periods (spring, summer, and fall of 2004, and spring of 2005). Each observation comprised 242 min of continuous recording of the species and bite-type category selected by a single animal, on each of 2 consecutive days. The mass and chemical quality of each species and bite-type category-a total of more than 200,000 bites-were determined by using the simulated bite technique. Associated feces were scanned in the 1,100- to 2,500-nm range with a reflectance monochromator. Fecal NIRS calibrations had reasonable precision for dietary percentages of the 3 main botanical components: herbaceous vegetation (as one category; R(2) = 0.85), Phillyrea latifolia (R(2) = 0.89), and tannin-rich Pistacia lentiscus (R(2) = 0.77), with SE of cross-validation (SECV) of 7.8, 6.3, and 5.6% of DM, respectively. The R(2) values for dietary percentages of CP, NDF, IVDMD, and polyethylene glycol-binding tannins were 0.93, 0.88, 0.91, and 0.74, respectively, with SECV values of 0.9, 2.1, 4.3, and 0.9% of DM, respectively. The R(2) values for intakes of herbaceous vegetation, P. latifolia, and P. lentiscus were 0.80, 0.75, and 0.65, with SECV values of 71, 64, and 46 g of DM/d, respectively. The R(2) values for the daily nutrient intakes were below 0.60. Fecal NIRS data can be used to expand the databases of botanical and nutritional dietary composition when observed and resident animals graze simultaneously, but intakes should be calculated from fecal NIRS-predicted dietary DM composition and an independent evaluation of DMI.

Determination by near-infrared spectroscopy of perseitol used as a marker for the botanical origin of avocado (Persea americana Mill.) honey.

This paper reports the application of near-infrared (NIR) reflectance spectroscopy to determine the concentration in honey of perseitol, a sugar that is specific to avocado honey. Reference values for perseitol were obtained by high-performance liquid chromatography analysis in 109 honey samples. Although the average concentration of perseitol in honey samples was only 0.48%, accurate prediction equations were successfully developed. The regression model of modified partial least squares was superior to that of principal component regressions. Calibrations based on the first or second derivative of Log(1/R) were equally good (R(2) > 0.95). Using half of the samples for calibration and the second half for validation, the correlation between actual and predicted values of the second half was satisfactory (R(2) = 0.87), the slope did not differ from 1, bias was low (0.005%), and the standard error of prediction was relatively low (0.13%). It was concluded that NIRS analysis may be used to detect to what extent honeybees have harvested avocado nectar but not to authenticate avocado honey as unifloral.