Polyethylene Glycol Supplementation Research Articles

Effects of intrinsic tannins on proteolysis dynamics, protease activity, and metabolome during sainfoin ensiling.

Condensed tannins (CT) from sainfoin have a high capacity to inhibit proteolysis. A previous study reported that CT from sainfoin can inhibit lactic acid bacteria activity and decrease ammonium-nitrogen (N) content during sainfoin ensiling; however, no study has focused on the metabolome of ensiled sainfoin. The objective of the present study was to investigate the effects of CT [following supplementation of deactivated CT with polyethylene glycol (PEG)] on protease activity, keystone bacteria, and metabolome during sainfoin ensiling. According to the results, PEG amendment increased non-protein N, amino acid, and soluble protein contents significantly (in the 49.08–59.41, 116.01–64.22, and 23.5–41.94% ranges, respectively, p < 0.05) during ensiling, whereas neutral detergent-insoluble protein and acid detergent-insoluble protein were decreased significantly (in the 55.98–64.71 and 36.58–57.55% ranges, respectively, p < 0.05). PEG supplementation increased aminopeptidase and acid protease activity after 3 days of ensiling (p < 0.05) and increased carboxypeptidase activity during the entire ensiling process (p < 0.05). The keystone bacteria changed following PEG addition (Stenotrophomonas, Pantoea, and Cellulosimicrobium in the control vs. Microbacterium, Enterococcus, and Brevundimonas in the PEG-treated group). In total, 510 metabolites were identified after 60 days of sainfoin ensiling, with 33 metabolites annotated in the Kyoto Encyclopedia of Genes and Genomes database. Among the metabolites, phospholipids were the most abundant (72.7% of 33 metabolites). In addition, 10 upregulated and 23 downregulated metabolites were identified in the PEG-treated group when compared with the control group, after 60 days of ensiling (p < 0.05). Pediococcus (correlated with 20 metabolites, R2 > 0.88, p < 0.05) and Lactobacillus (correlated with 16 metabolites, R2 > 0.88, p < 0.05) were the bacteria most correlated with metabolites. The results suggested antagonistic effects between Lactobacillus and Pediococcus during ensiling. The decreased proteolysis during sainfoin ensiling was mainly attributed to the inhibition of protease activity by CT, particularly carboxypeptidase activity. In addition, proteolysis decreased partly due to CT inhibiting Pediococcus activity during ensiling, with Pediococcus being significantly and positively correlated with dopamine after 60 days of ensiling (R2 = 0.8857, p < 0.05).

Lipidomic changes in mouse oocytes vitrified in PEG 8000-supplemented vitrification solutions

Cryopreserved oocytes are inevitably exposed to cold stress, which negatively affects the cellular aspects of the oocytes. Lipidomic analysis of the oocytes reveals quantitative changes in lipid classes under conditions of cold stress, leading to potential freezing-vulnerability. We had previously shown that specific phospholipids are significantly downregulated in vitrified-warmed mouse oocytes compared to those in fresh oocytes. In this study, we examined whether supplementation of polyethylene glycol 8000 (PEG 8000) during vitrification influences the lipidome of the oocytes. We used liquid chromatography with tandem mass spectrometry (LC-MS/MS) to study the alteration in the lipidome in three groups of mouse oocytes: fresh, vitrified-warmed, and vitrified with PEG 8000-warmed during vitrification. In these groups, we targeted to analyze 21 lipid classes. We profiled 132 lipid species in the oocytes and statistical analyses revealed lipid classes that were up- or downregulated in these groups. Overall, our data revealed that several classes of lipids were affected during vitrification, and that oocytes vitrified with PEG 8000 to some extent alleviated the levels of changes in phospholipid and sphingolipid contents during vitrification. These results suggest that phospholipids and sphingolipids are influenced by PEG 8000 during vitrification and that PEG 8000 can be considered as a potential candidate for preserving membrane integrity during oocyte cryopreservation.

Growth, lipid peroxidation, organic solutes, and anti-oxidative enzyme content in drought-stressed date palm embryogenic callus suspension induced by polyethylene glycol

Polyethylene glycol (PEG) can be used in somatic embryogenesis to enhance embryogenic development and improve the success of in vitro culture but PEG also causes osmotic stress in developing embryos. The effects of PEG on embryo growth and development in date palm cell suspension culture and associated antioxidant enzyme activities were evaluated. Callus maintained on MS basal media was transferred to regeneration liquid media supplemented with increasing levels (0–20%) of polyethylene glycol 6000 (PEG) to induce osmotic stress. The degree of embryogenic callus formation, its fresh weight, and the percentage of normal embryo callus shapes were increased with an increase in the level of PEG up to 10%. Total soluble protein (TSP), proline, glycine betaine (GB), total soluble phenol (TSPh), total sugars (TS), and total soluble organic acids (TOA) also increased whereas superoxide dismutase (SOD) activity decreased in response to PEG supplementation. Raising the PEG level increased malondialdehyde (MDA) concentration up to 10% PEG and thereafter decreased. Glutathione reductase (GR) and catalase (CAT) activities decreased at the highest levels of PEG. The proportion of normal embryo developmental shapes were about 50% compared with 20% abnormal shapes at optimum levels of PEG. Proliferation of somatic embryos was influenced by their developmental shapes. Cv. Samani accumulated more organic solutes compared with cv. Sewi in both control and stress inducing media. In contrast, lipid peroxidation, GR, SOD, and CAT activities were significantly higher in cv. Sewi than in cv. Samani indicating that the cv. Samani had the ability to tolerate a higher level of osmotic stress compared to cv. Sewi due to the enhanced osmotic re-balancing within its tissues.

Relationship between intake of tannin-containing tropical tree forage, PEG supplementation, and salivary haze development in hair sheep and goats

The objective of this study was to estimate the relationship between tannin binding salivary protein (TBSP) and condensed tannins (CT) intake in hair sheep and creole goats. Foliage was obtained from trees with different levels of CT content; animals were offered foliage ad libitum, with or without polyethylene glycol (PEG). Saliva haze development (SHD) was evaluated as evidence for TBSP. PEG consumption did not affect dry matter intake (DMI) (P > 0.05). Lignin (R = −0.714, P < 0.001) and Crude Protein (CP) (R = 0.622, P < 0.001) contents had a stronger association with DMI than CT (R = 0.622, P < 0.011) in sheep; no significant association was found in goats. The positive relationship between tannin intake and SHD (P < 0.05) was not confirmed after PEG supplementation in sheep (P > 0.09), but remained significant for goats (P < 0.01), except for those fed Lysiloma latisiliquum (P = 0.07). Foliage lignin or CP contents are better predictors of foliage intake than CT. Sheep and goats fed with tropical tree forages containing different levels of tannins exhibited differences in intake behavior; moreover, individual variations in TBSP expression helps explaining foliage DMI.

Diet mixing and condensed tannins help explain foraging preferences by Creole goats facing the physical and chemical diversity of native woody plants in the central Monte desert (Argentina)

The aim of this study was to understand the benefit of diet mixing for Creole goats grazing native forage species in the central Monte desert of Argentina and the drivers of preference in the mixed diet. To achieve this goal, cafeteria-style experiments were conducted with thirty female Creole goats (2 years old; 44±1.4kg) and forage species that are typically ingested by goats in this region: Two tanniniferous (Tricomaria usillo, Mimosa ephedroides) and three non-tanniniferous shrubs (Prosopis flexuosa, Capparis atamisquea, Atriplex lampa). In Experiment 1, goats were assigned to three groups (n=10); two groups were offered single tannin-containing shrubs as their basal diet (T. usillo; SDTU or M. ephedroides, SDME), whereas the third group received a combination of all five forages (Mixed diet of forages, MD). After a fifteen-day adaptation period, half the animals in each group (n=5) were dosed with polyethylene glycol (PEG), a polymer that neutralizes the negative effects of tannins, whereas the other half (Control) were not dosed (CG). Daily dry matter intake (DMI), in vivo apparent digestibility of the diet (ADD) and nitrogen (ADN) were determined. For goats fed MD, preference was estimated based on the DMI of each of the forages offered. Jugular blood samples were collected on the first and last days of the experiment to determine concentrations of blood urea nitrogen (BUN) and serum metabolites indicative of liver damage. In experiment 2, intake rates (IR) of the five forage species were estimated. No significant differences in DMI were detected among treatments. However, goats offered a choice of forages (MD) in the CG treatment had greater diet digestibility and lower BUN than animals fed the single shrubs, showing evidence of a nutritional benefit with dietary diversity. Goats changed their foraging preferences in response to PEG supplementation. Animals in the CG treatment preferred M. ephedroides whereas animals in the PEGG treatment preferred A. lampa. There was a positive correlation between forage preference and IR of crude protein (r=0.65; P<0.001) in PEGG goats, and between forage preference and IR of total tannins (r=0.77, P<0.001) in CG goats. When PEG attenuated biological effects of condensed tannins, goats switched their preference from forages that offered the greatest IR of total tannins (i.e., M. ephedroides) to those that led to the greatest IR of crude protein (i.e., A. lampa). In summary, a mixed diet led to greater nutritional benefits than single diets, which contribute to explain the diverse array of food items goats typically show when browsing in the central Monte desert of Argentina. Our results also show that CP, tannins and plant structure (which offer variable intake rates) play significant roles in goats’ foraging preferences in this environment.

Continuous polyethylene glycol precipitation of recombinant antibodies: Sequential precipitation and resolubilization

A continuous precipitation-based capture step for recombinant monoclonal antibodies (mAbs) has been developed using polyethylene glycol (PEG) in a sequential precipitation approach. In the first step, impurities are removed by precipitation at low pH and low PEG concentrations. After removing the precipitate, mAbs are precipitated by pH adjustment and PEG supplementation. Yields of 86–94% and a reduction in host cell proteins (HCPs) to 7200–15,000ppm were reached depending on the mAb. Host cell DNA was removed to 18–29ng/ml, which was independent of the starting DNA concentration. The secondary structure and isoform distribution of mAbs are unaltered compared with the chromatographically purified reference material. The method was then shifted to a continuous operating mode in a single-use tubular reactor by converting the time to reach equilibrium into residence time. Tangential flow filtration (TFF) has been used as an alternative precipitate capture step to centrifugation. The yield was not compromised with the use of TFF (>92%), and impurity removal was even enhanced compared with centrifugation. Concentration of the mAb precipitate by TFF and washing by diafiltration preserves the floc structure of the precipitate, thereby accelerating the subsequent resolubilization.

Polyethylene glycol protects primary hepatocytes during supercooling preservation

Cold storage (at 4°C) offers a compromise between the benefits and disadvantages of cooling. It allows storage of organs or cells for later use that would otherwise quickly succumb to warm ischemia, but comprises cold ischemia that, when not controlled properly, can result in severe damage as well by both similar and unique mechanisms. We hypothesized that polyethylene glycol (PEG) 35kDa would ameliorate these injury pathways and improve cold primary hepatocyte preservation. We show that reduction of the storage temperature to below zero by means of supercooling, or subzero non-freezing, together with PEG supplementation increases the viable storage time of primary rat hepatocytes in University of Wisconsin (UW) solution from 1day to 4days. We find that the addition of 5% PEG 35kDa to the storage medium prevents cold-induced lipid peroxidation and maintains hepatocyte viability and functionality during storage. These results suggest that PEG supplementation in combination with supercooling may enable a more optimized cell and organ preservation.

Biochemical and physiological responses to polyethylene glycol (PEG) treatment in protocorm-like bodies (PLBs) of Aranda Broga Blue Bell

Effects of different concentrations of polyethylene glycol 400 (PEG 400) on viability, relative water content, total chlorophyll content, total soluble protein and antioxidant enzymes activities of protocorm-like bodies (PLBs) of Aranda Broga Blue Bell orchid hybrid were determined. Different concentrations of in vitro drought-inducing chemical, PEG 400 at 0, 5, 10, and 15% (v/v) were used in this study. From the results obtained, lower concentration of PEG 400 at 5% produce minimum impact on the relative water content and morphological changes of treated PLBs. Percentage of viable PLBs at 5% PEG 400 treatment showed no significant difference with the control PLBs. However, significant reduction in total chlorophyll content and total soluble protein content of PLBs verified that supplementation of PEG 400 into Vacin and Went medium caused severe interruptions on various biochemical processes. Excessive production of free radical molecules increased the total activity of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX). Specific localization, affinity and role of these enzymes resulted in different patterns of their overall activity. These findings suggested that the PLBs of Aranda Broga Blue Bell were drought tolerant orchid explants at low intensity of in vitro drought stress condition.

Effect of oak acorn (Quercus persica) on ruminal fermentation of sheep

The objectives of this study were to evaluate the effect of oak fruit (Quercus persica) in the diet of sheep with and without polyethylene glycol (PEG) on nutrients digestibility, rumen fermentation parameters, protozoal count and microbial protein supply. In Exp. 1, five fistulated mature male sheep were used in a 5×5 Latin square design, with 5 dietary treatments arranged in a 2×2+1 factorial: (1) control as a basal diet; (2) control plus 10% oak acorn (OA); (3) control plus 30% OA; (4) control plus 10% OA with 100g PEG; and (5) control plus 30% OA with 100g PEG. Incorporation of OA decreased digestible organic matter (DOM), digestible crude protein (DCP) and digestible neutral detergent fiber (DNDF) and the lowest values were observed at the level of 30% OA. However, administration of PEG to the diets overcame deleterious effect of acorn on these parameters, significantly (P<0.01). With the addition of OA a noticeable decrease in ammonia and TVFA concentration was observed and adding PEG to the diets increased these values even higher than those of control (P<0.01). Incorporation of acorn to the diets lowered urinary purine derivatives (PD) and urinary, retained and absorbed nitrogen and increased fecal and endogenous nitrogen (P<0.01). Meanwhile, addition of PEG increased PD and urinary, retained and absorbed nitrogen and decreased fecal and endogenous nitrogen. Total protozoa content was affected in somewhat by OA and PEG supplementation. Isotricha, dasytricha and, diplodinium contents did not differ due to inclusion of OA, however, the trend for entodinium and ophryoscolex was to be decreased (P<0.05). There was a significant effect on individual genera of protozoa following addition of PEG to the diets. Cellulolytic and proteolytic bacteria were not influenced by incorporation of OA but the trend was in decreasing manor. In Exp. 2, in vitro gas production was conducted to evaluate kinetics of gas produced by diets. The parameter “A” did not differ among experimental treatments. Half-time of gas production in control group was higher than that of other treatments. Methane production from diets containing OA and PEG were lower than that of control group. In conclusion, supplementation of OA with PEG may be a practical approach to overcome detrimental effects of tannins in this feedstuff.

Effect of feeding pistachio by-products silage supplemented with polyethylene glycol and urea on Holstein dairy cows performance in early lactation

This study was conducted to evaluate the effect of feeding pistachio by-products silage with or without supplementation of polyethylene glycol (PEG) and urea on intake, apparent total digestibility, ruminal fermentation and performance of dairy cows. Eight multiparous Holstein dairy cows averaging 61±23 DIM and 38±3.6kg of milk production were used in a 4×4 replicated Latin square design. Fresh pistachio by-products (PB) averaging 32% dry matter (DM) were supplemented with PEG and urea at 1.0% and 0.5% of DM, respectively, and then ensiled for 60 day. Experimental treatments were as follows: (1) corn silage (15% of diet DM) as a control, substitution of corn silage with: (2) pistachio-by products silage (PBS), (3) PBS supplemented with urea, and (4) PBS supplemented with PEG. Intake of DM and apparent digestibility were not affected by treatments (P>0.05). There was no difference in milk yield and composition (P>0.05). However, a trend (P<0.07) for more milk protein production (kg/d) and more (P<0.09) milk fat concentration (%) was observed in cows fed PBS compared to those fed corn silage. The ruminal pH was similar among treatments (P>0.05). There was significant difference in ruminal NH3–N and serum urea N among treatments (P<0.05). Results of this study show that under our experimental conditions, PBS can be substituted with corn silage up to 15% of diet DM in dairy cows ration without negative effects on animal performance.

Performance of Sheep and Goats Fed Arctostaphylos canescens With and Without Polyethylene Glycol Supplementation

Abstract Arctostaphylos canescens Eastw. is considered an important element in the chaparral fire matrix and an invasive plant in coniferous forest plantations in California. Previous studies reported that dry matter intake of Arctostaphylos was low, presumably because of its low nutritional quality and high condensed tannin (CT) content. We hypothesized that intake and digestibility of Arctostaphylos could be increased by the provision of a tannin-complexing agent polyethylene glycol (PEG). This study determined the effects of PEG (MW 4000) supplementation on intake (I) and digestibility (D) of Arctostaphylos in goats and sheep. Polyethylene glycol was added to drinking water at four levels (0.3%, 0.15%, 0.05%, and 0%) of body weight (BW). Alfalfa pellets were used as diet supplement at 1.5% of BW. Nutritional quality of Arctostaphylos was low as compared with alfalfa pellets. Arctostaphylos crude protein (CP) levels were low (4.5% vs. 17.9%) and CT concentration was high (23.1% vs. 0%), whereas estimates of in vitro organic matter digestibility (OMD, 36.6%) and metabolizable energy (5.1 MJ · kg −1 dry matter [DM]) in Arctostaphylos were almost half of those found for alfalfa pellets (70.3% and 9.5 MJ · kg −1 DM). A curvilinear increase ( P −1 and per kg BW 0.75 ) was observed in goats and sheep as PEG levels increased, although a linear increase ( P −1 ) of Arctostaphylos by goats. Addition of PEG curvilinearly increased ( P P Arctostaphylos. However, the success in adopting this practice as a useful tool in vegetation management programs will depend on the cost–benefit ratio.

The effect of polyethylene glycol on browsing behaviour of beef cattle in a tanniferous shrubby Mediterranean range

The aim of the present study was to determine the effect of polyethylene glycol (PEG) supplementation on grazing behaviour of beef cattle and on utilization of the woody components of a Mediterranean shrubland. Two experiments were conducted on two different sites in Northern Israel, Ramat Hanadiv (RH) and Hatal. On each site, the study area was divided into two paddocks, in one cattle were supplemented with 50 g PEG day − 1 per cow, while the other served as a control, with no PEG supplementation. In RH site the cows had free access to Prolix and in Hatal to poultry litter, both serving as a nitrogen supplement during the experiment. In the RH site, the consumption of Pistacia lentiscus, a shrub whose leaves contain high concentration of tannins, was found higher ( P = 0.001) in the PEG group diet than in the control group. In Hatal site PEG increased foraging time by 18%, daily foraging distance by 15% and reduced the use of supplementary feed (poultry litter) by 20%. However, PEG did not affect the average cow body weight or water consumption on either site. It is concluded that PEG influences grazing behaviour of beef cattle on shrubby rangeland and increases the use of woody species with high tannin concentrations.

Effect of selected amino acids and polyethylene glycol on maturation and germination of somatic embryos of guava ( Psidium guajava L.)

Two selected amino acids ( l-glutamine and l-proline) and polyethylene glycol (PEG) were evaluated for their effects on maturation and germination of somatic embryos in guava ( Psidium guajava L.) cv. Banarasi local. Among the treatments of two amino acids ( l-glutamine and l-proline) and PEG tested, 0.87 mM l-proline was most effective for maturation of somatic embryos. As compared to control, supplementation of PEG (1.0% or 2.0%) in maturation media showed significantly better maturation (increased maturation frequency). Lower stage somatic embryos showed prematuration germination with development of abnormal plantlets and only mature somatic embryos produced morphologically normal plantlets.

Supplemental polyethylene glycol affects intake of and preference for sericea lespedeza by cattle12

We tested the hypothesis that supplemental polyethylene glycol (PEG), a polymer that neutralizes the effects of tannins, would increase intake and preference of cattle for fresh-cut sericea lespedeza (SL; Lespedeza cuneata), a legume with high concentrations of condensed tannins. Sixteen crossbred steers (initial BW of 249 +/- 6.6 kg) were randomly assigned to 2 treatments: 1) grain supplement with PEG (PEG-S) and 2) grain supplement without PEG (control). To assess intake, we conducted a trial with 6 sample periods, each 6 d in duration, with steers fed SL and prairie hay (PH) in separate meals. Steers were fasted overnight and fed their respective supplements (with and without PEG) at 0800 h. Animals were then offered fresh-cut SL from 1050 to 1550 h, PH was fed from 1600 to 2000 h, and they were without food from 2000 to 0800 h the next day. To assess preference, we conducted 1-d tests in which steers had simultaneous access to SL and PH on the day following periods 2 to 6. As with the intake experiment, steers were fasted overnight and fed their respective supplements at 0800 h, but from 1050 to 1250 h all steers had access to SL and PH simultaneously. We weighed steers before and at the completion of the study and calculated ADG. Steers treated with PEG consumed more SL per unit of BW than control steers in periods 2 to 6 (period x treatment interaction, P < 0.001). In contrast, controls consumed more PH than steers given PEG (period x treatment x day interaction, P = 0.009). The PEG-S steers consumed more total DM (SL + PH) than controls in periods 3, 5, and 6 but not in periods 1, 2, and 4 (period x treatment interaction, P = 0.004). Sericea lespedeza intake as a percentage of total DMI was greater for the PEG-S steers every day except d 1 and 2 of period 1 (period x treatment x day interaction, P = 0.03). Averaged across the 5 preference tests, PEG-S steers selected a greater proportion of SL than did control steers (39 vs. 9%), and the magnitude of the difference was greater in the later tests (test x treatment interaction, P = 0.004). The PEG-S steers had greater ADG than controls (0.44 vs. 0.24 kg/d; P = 0.005). Our results indicate PEG increases intake of and preference for SL and suggest that PEG supplementation of cattle may increase intake of SL and improve ADG in pastures that contain SL.

In vitro ruminal fermentation of tanniniferous tropical plants: Plant-specific tannin effects and counteracting efficiency of PEG

Two experiments with the gas pressure transducer technique were conducted to investigate the effects of different types and levels of tannins. Forage samples were incubated in batch cultures together with rumen fluid and digestion medium in order to model rumen fermentation dynamics in vitro. In Experiment 1, graded levels (0, 25, 50, 75 and 100 mg/g of forage dry matter (DM)) of purified condensed tannins (CT) obtained from four tanniniferous tropical shrub legumes, Flemingia macrophylla, Leucaena leucocephala and two provenances of Calliandra calothyrsus (San Ramón and Patulul), were added to a CT-free mixture of the grass Brachiaria humidicola and the herbaceous legume Vigna unguiculata. The statistical models used for data evaluation included the two main effects (origin and level of CT) and their interaction. Apart from dose-dependent effects (P<0.001) there were clear plant-specific effects (mostly P<0.001) in fermentation dynamics, in vitro DM degradation and apparent degradation of N-containing compounds. Tannins from C. calothyrsus had the most pronounced effects on fermentation dynamics and nutrient degradation, followed by F. macrophylla and L. leucocephala. Within C. calothyrsus, CT from the provenance San Ramón suppressed asymptotic gas production and DM degradation to a larger extent (P<0.05) than CT from the provenance Patulul. Low addition (25 mg/g DM) of CT from C. calothyrsus was only slightly detrimental while high CT levels (75 and 100 mg/g DM) had clearly negative effects on asymptotic gas production and DM degradation. In a first incubation in Experiment 2, the grass in mixtures with foliage of the different tanniniferous shrub legumes was incubated with graded levels of polyethylene glycol (PEG) corresponding to 0/3, 1/3, 2/3 and 3/3 of the contents of CT in these mixtures. In a second incubation, all mixtures based on tanniniferous shrub legumes and mixtures containing non-tanniniferous shrub legumes ( Cratylia argentea, Desmodium velutinum) or a herbaceous legume ( V. unguiculata) were tested without PEG and with 80 g/kg supplementary PEG. In general, addition of PEG had no effect (P>0.05) on fermentation parameters in non-tanniniferous legumes. With tanniniferous species, response curves in fermentation parameters were mostly non-linear reaching a plateau at a PEG:CT-ratio between 1:3 and 2:3. One exception was that undegraded dietary N decreased (P<0.05) with increasing PEG addition until the highest level. In conclusion, the study demonstrated that to a large extent the effects of CT-rich plants on in vitro ruminal fermentation can be explained by the specific CT properties. Furthermore, apart from binding CT, PEG seems to have no major side-effects on ruminal fermentation, and for most fermentation variables and species, PEG supplementation equivalent to the CT content in the forage mixtures seems sufficient to prevent negative effects of CT on fermentation parameters.

Polyethylene glycol influences feeding behaviour of dairy goats browsing on bushland with different herbage cover

The effects of supplemental polyethylene glycol (PEG) on feeding behaviour, diet composition, intake and milk production were studied in late lactating Sarda goats browsing on a lentisk-based bushland with different herbage cover. The goats were allotted to two groups that browsed 7 h daily on 2 plots characterised by different cover proportions of woody and herbaceous species. These proportions were 90% woody vs. 10% herbaceous species in one plot (W — woody, close bushland with low herbage cover) and 70% woody vs. 30% herbaceous species in the other plot (H — herbaceous, open bushland with high herbage cover). Each group was divided into two sub-groups: one fed with 50 g day − 1 of PEG 4000 MW (PEG +) and the other receiving no PEG supplementation (PEG −). The feeding behaviour was different between groups; goats in herbaceous plot (H-goats), had a longer grazing time, expressed as percentage of total observation time than the counterparts (64% vs. 58%, P < 0.05). The intake was not affected by the treatments. The percentage of the species eaten by the goats was different in the two groups: H-goats ate more herbaceous and less woody species than goats in woody plot (W-goats). In each group the PEG tended to affect the botanical composition of the diet. PEG dosed goats ate more tanniferous species than control counterparts ( P = 0.12). The average daily milk production was 473, 591, 541 and 589 ml, respectively in W-PEG −, W-PEG +, H-PEG − and H-PEG + sub-groups with significant effect of herbage cover × PEG dose interaction ( P < 0.05). The milk urea was affected by herbage cover ( P < 0.001) and PEG supplementation ( P < 0.001). In conclusion, the effect of PEG is strictly dependent on pasture composition. In open bushland, featured by moderate woody cover, the effect of PEG is more intense on diet selection, due to its marked post-ingestive effects. In close bushland, characterised by high proportion of tanniferous species prevails the efficacy of PEG as a performance booster.

Intramuscular fatty acid composition of lambs given a tanniniferous diet with or without polyethylene glycol supplementation

The aim of this trial was to investigate the effects that dietary tannins have on lamb intramuscular fatty acids. Twenty-seven lambs were divided into three homogeneous groups: control group, receiving commercial concentrate based on maize; tannin group, fed a diet based on carob pulp (45% as fed basis); PEG group, receiving the same diet as the latter with addition of 42 g/kg of polyethylene glycol (PEG, a binding agent that eliminates the effects of condensed tannins). The duration of the trial was 45 d. Intramuscular fatty acids were measured in the longissimus dorsi muscle. The isomer cis-9 trans-11 of linoleic acid (conjugated linoleic acid or CLA) and linolenic acid were higher in the longissimus muscle fat from animals fed the control diet compared to the other groups ( P < 0.0005); these fatty acids were higher in the fat from animals fed the carob diet supplemented with PEG compared to those fed the same diet without PEG ( P < 0.05). trans-Vaccenic acid (C18:1 trans-11) was found at higher concentration in fat from control and PEG lambs compared to tannin lambs ( P < 0.01); the CLA/C18:1 trans-11 ratio was lower in lambs fed control and PEG diets than in tannin-fed animals ( P < 0.05).

Determination of Nutritive Value of Citrus Tree Leaves for Sheep Using In vitro Gas Production Technique

The nutritive values of leaves of Citrus grandis, Citrus aurantium, Citrus oranges, Citrus limon, and Citrus deliciosa were evaluated by chemical composition and in vitro gas production techniques. There were significant (p<0.001) differences among citrus species in terms of chemical composition. Crude protein (CP) contents ranged from 123.0 to 148.3 g/kg DM. Neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents were varied with species in the range 219.4-355.4 and 215.0-278.8 g/kg DM respectively. Condensed tannin (CT) contents were ranged from 5.9 to 10.2 g/kg DM. The PEG addition significantly (p<0.001) increased the gas production and some estimated parameters of citrus tree leaves. However, species showed variable responses to polyethylene glycol (PEG) treatment. There were also significant (p<0.001) differences among species in terms of gas production and estimated parameters. The OMD and ME contents of citrus leaves without PEG supplementation were ranged from 66.5 to 73.3% and 9.8 to 10.9 MJ/kg DM respectively. The improvement in gas production, organic matter digestibility (OMD) and metabolizable energy (ME) with PEG emphasized the negative effect of tannins on digestibility. The increase (%) in the estimated OMD and ME contents ranged from 5.5 to 9.8% and 5.7 to 10.2% respectively. All citrus tree leaves studied in this experiment have potential nutritive values indicated by high crude protein content, OMD, ME and low fiber values.

Effects of tannin-containing diets on small ruminant meat quality

Tannins are phenolic compounds present in several forages, tree leaves and by-products used for small ruminant feeding in the Mediterranean area. Although the effects of dietary tannins on small ruminant growth performances have been largely studied, only in the last ten years researchers have started to study the effects of tannins on meat quality. Meat from small ruminants given tanniniferous diets is lighter in colour compared to meat from animals given the same diets but in which the effects of tannins have been eliminated by the supplementation of polyethylene glycol. This result has been obtained with tannins from different feeds (carob pulp, acacia leaves or sulla fresh herbage). Recent in vitro studies seem to indicate that a possible effect of tannins on meat colour could be due to a reduced microbial biosynthesis of vitamin B12 which is a precursor for the synthesis of haeme pigments. Meat from lambs given carob contains less conjugated linoleic acid compared to meat from animals fed the same diet but supplemented with polyethylene glycol. A possible explanation of this result has been proposed recently after an in vitro experiment on linoleic acid isomerase; it has been shown that when cattle ruminal fluid is incubated with tannins exctracted from acacia, carob or quebracho, the conjugated linoleic acid formed from linoleic acid was lower compared to the mount of conjugated linoleic acid produced in tannin-free rumen fluid. Also, the ruminal biosynthesis of odour-active compounds seems to be affected by tanniniferous diets. This is the case of skatole (3-methylindole) and indole which confer unpleasant flavour connotations to lamb meat.

Reproductive and productivity traits of goats grazing Acacia cyanophylla Lindl. with and without daily PEG supplementation

Abstract A grazing experiment, conducted for 90 days compared the effect of polyethylene glycol (PEG) supplementation on postpartum reproductive traits and productivity of suckling goats grazing Acacia cyanophylla Lindl. A total of 54 native adult goats (34.4 ± 5.49 kg) were randomly allocated, 24 h after kidding, to 2 treatment groups balanced for age and the number of reared kids. Goats in both treatment groups designed C and PEG grazed in acacia for approximately 5 h every day and received each on daily basis 0.3 and 0.4 kg of hay and concentrate respectively. In addition, goats in treatment PEG were initially supplemented with 10 g/day of PEG and this supplement was then increased to 20 g /goat/day over the last 60 days of the trial. Goats receiving PEG tended ( P > 0.05) to spend more time browsing acacia than those in treatment C. There were no treatment effects on live weight change of the goats, growth of their kids until 90 days of age or composition of their milk in terms of fat, protein and urea contents. Similar proportions of 74.1 and 77.8% of goats resumed postpartum ovulation with a mean ovulation rate of 1.50 ± 0.61 and 1.67 ± 0.47 ( P > 0.05) in respectively the PEG and C treatments. PEG supplementation was associated with an increase ( P P