Choice Feeding Research Articles

Chemical composition and antifeedant activity of some aromatic plants against pine weevil (Hylobius abietis)

AbstractThe pine weevil Hylobius abietis is an important pest causing severe damage to conifer seedlings in reforestation areas in Europe and Asia. Plants that have no evolutionary history with the pine weevil are of special interest in the search for compounds with a strong antifeedant activity. Thus, the essential oils of nine aromatic plants, viz Amomum subulatum, Cinnamomum tamala, Curcuma longa, Laurus nobilis, Ocimum basilicum, Origanum majorana, Origanum vulgare, Syzygium aromaticum and Trachyspermum ammi were extracted by hydrodistillation. The essential oil constituents were identified by gas chromatography–mass spectrometry, and antifeedant properties towards the pine weevil were assessed using choice feeding bioassay. The essential oils of C. longa, O. majorana, S. aromaticum and T. ammi showed an excellent antifeedant activity towards the pine weevil for 24 hr, whereas the essential oil of other plants showed the activity for 6 hr. There was a positive correlation between the amount of benzenoid compounds and the antifeedant activity of the essential oils. This study suggests that pine weevil non‐host plant compounds have potential to be used for the protection of seedlings against pine weevil feeding. However, further study will be needed to explore the antifeedant activity of individual components and oils in the laboratory as well as in the field.

Free-choice Feeding of Three Different Dietary Calcium Sources and their Influence on Egg Quality Parameters of Commercial Layers

Purpose: The study reported herein was conducted to determine the effects of choice feeding three different calcium (Ca) sources on external and internal egg quality parameters of commercial layers. Research Method: Three dietary Ca sources (oyster shells, limestone and bone meal) were choice fed ad libitumly along with a commercial layer feed. The birds fed only the commercial layer diet was used as the control. The experiment was conducted as a complete randomized design. A total of 128, 55 weeks old Hy-line white layer hens (1500 ±21g) were assigned into 16 cages of 8 birds each. Four replicate cages were randomly assigned to each of the four dietary treatments. Bird’s performances were tested weekly. Twenty eggs from each treatment were collected weekly over five weeks period and were assessed for shell and internal quality parameters. Findings: Daily Ca intakes of birds affected significantly (P<0.05) by the Ca source. The birds fed oyster shells and limestone showed the highest (P<0.05) daily Ca intakes. Feeding bone meal significantly (P<0.05) reduced damaged shell percentage. Weekly body weight gain, weekly egg production and feed conversion ratio among treatments were similar (P>0.05). Dietary supplementation of Ca significantly (P<0.05) improved the egg weight. Shape index and shell ratios among treatments were similar (P>0.05). Feeding bone meal significantly (P<0.05) improved unit surface shell weight (USSW) and the shell thickness. Calcium supplementation had no effect (P>0.05) on albumen and yolk quality parameters of eggs. Originality/value: The present study concluded that feeding bone meal to commercial layers improves USSW, shell thickness thereby reducing egg damages. Calcium source has no influence in improving internal quality parameters of chicken eggs.

Wood color changes and termiticidal properties of teak heartwood extract used as a wood preservative

Abstract The aim of this study was to evaluate the change in colorimetric patterns and the termite resistance of light-colored and low durability wood when impregnated with teak (Tectona grandis) heartwood extractives. Hot water and ethanol extracts were obtained from 20-year-old teak heartwood and used to evaluate the influence on color change and the natural resistance of 10-year-old teak sapwood and Pinus sp. For wood impregnation, a full-cell (Bethell) treatment was conducted. To verify the influence of the teak extracts, the colorimetric patterns of wood were determined using the Munsell and CIE-L*a*b* systems. Choice and no-choice feeding tests were performed under laboratory conditions to test the efficacy of the teak extract solutions against two termite species Nasutitermes corniger and Cryptotermes brevis. All of the extract solutions promoted a significant darkening of the wood, bringing the color of the impregnated wood closer to older teak heartwood than the untreated samples of the respective species. Ethanol extracts increased the resistance and mortality against N. corniger in both choice and no-choice tests. Resistance to C. brevis was not clearly affected.

Free Choice Feeding on the Quality of Quail Eggs (Coturnix coturnix-japonica)

Quail is one of the potential sources of animal protein from poultry as egg producers. An egg contains complete nutrients, namely protein, fat, vitamins, and minerals. As food, eggs must be maintained both physically and chemically to be safe for consumption. This study aimeds to examine the effect of selective feeding on the quality of quail eggs. This research was carried out at Percut Sei Tuan Subdistrict, Deli Serdang Regency, North Sumatra, which had been implemented from August to November in 2018. The study used a completely randomized design with 4 treatments and 5 plots. The study used egg samples from quail aged five (5) months. The treatment consists of Commercial feed (T0), 2 energy source feed (rice bran, corn) with 2 (T1), 3 (T2), 4 (T3) protein source feeds (fish meal, soybean meal, coconut meal, Poultry Meat Meal). The results showed that the treatment gave a significant effect (P<0.05) on egg weight, albumen, and eggshell weight, commercial feed showed eggs weight higher than free choice feeding treatments, while among free choice feeding treatment did not show significant effect. The free choice feeding treatment has a significant effect on the yolk weight, where T2 has the lowest yield. Percentage of yolk, albumen, quail eggshell and egg index, egg yolk index, albumen index, haugh unit and quail yolk color did not show significantly different (P>0.05) among treatment. It can be concluded that the commercial feed showed higher egg weight but had no significant effect (P>0.05) on the proportion of eggs and the interior quality of quail eggs, while among free choicee feeding treatment has no effect.

Choice preference of diets with different protein levels depending on water temperature in Nile tilapia

AbstractThis study tested a choice feeding model for Nile tilapia that allowed the selection of a higher or lower protein content in the diet depending on water temperature. Nile tilapia were reared in twelve 200‐L tanks for 63 days with 12 fish (body weight 38 g/fish at start) per tank. Two temperatures (22 or 30°C) and two color combinations (yellow and red each) for a two‐component diet containing 30% (low) and a 38% (high) crude protein content based on dry matter were used. High water temperature (30 vs. 22°C) resulted in a significantly higher feed rate (1.93 ± 0.123 and 1.26 ± 0.100%, respectively), body weight gain (39.3 ± 4.29 and 4.75 ± 0.66 g, respectively), final body weight (70.3 ± 9.31 and 43.0 ± 7.49 g, respectively), and feed efficiency (55.4 ± 6.09 and 14.6 ± 2.86%, respectively), as well as protein efficiency ratio (1.687 ± 0.186 and 0.450 ± 0.087, respectively), regardless of color codes. No significant differences of color codes on growth parameters, body composition, and fatty acid profile were seen. Higher water temperature (30 vs. 22°C) only had an effect on percentage‐specific fatty acids of total fatty acids of the whole body (biggest difference: C16:0, 20.5 ± 1.00 and 17.4 ± 1.11%, respectively). Therefore, water temperature clearly influences growth and fatty acid composition of the body.

Production losses in laying hens during infestation with the poultry red mite Dermanyssus gallinae

ABSTRACTA research centre with 30,568 laying hens, kept in enriched cages and in aviaries, had become naturally infested with poultry red mites (PRM) in 32 of its 48 bird units. Therefore, at the age of 52 weeks all hens were treated with fluralaner through the drinking water. After this treatment, PRM were no longer observed. As all birds were of the same age, and since production figures were measured daily in all 48 units, this offered a unique opportunity to examine how PRM had affected performance. Statistical analyses were done to compare the evolution of production data from the pre-treatment to the post-treatment period in units that were visually free of PRM or infested with PRM to different levels. Production standards provided by the breeding organizations were used as a reference. The results demonstrated significant posttreatment increases of laying percentage, egg weight, egg mass, percentage first choice eggs, feed intake and body weight in heavily infested hens of one or both housing systems, as compared to the non-infested controls. These data confirm that PRM infestations can impact the main performance traits related to profitability of laying hen farms as well as the hens' general condition.

Microbial metabolites elicit distinct olfactory and gustatory preferences in bumblebees.

Animals such as bumblebees use chemosensory cues to both locate and evaluate essential resources. Increasingly, it is recognized that microbes can alter the quality of foraged resources and produce metabolites that may act as foraging cues. The distinct nature of these chemosensory cues however and their use in animal foraging remain poorly understood. Here, we test the hypothesis that species of nectar-inhabiting microbes differentially influence pollinator attraction and feeding via microbial metabolites produced in nectar. We first examined the electrophysiological potential for bumblebee (Bombus impatiens) antennal olfactory neurons to respond to microbial volatile organic compounds (mVOCs), followed by an olfactory preference test. We also assessed gustatory preferences for microbial-altered nectar through both no-choice and choice feeding assays. Antennal olfactory neurons responded to some mVOCs, and bees preferred nectar solutions inoculated with the bacterium Asaia astilbes over the yeast Metschnikowia reukaufii based on volatiles alone. However, B. impatiens foragers consumed significantly more Metschnikowia-inoculated nectar, suggesting distinct roles for mVOCs and non-volatile metabolites in mediating both attraction and feeding decisions. Collectively, our results suggest that microbial metabolites have significant potential to shape interspecific, plant-pollinator signalling, with consequences for forager learning, economics and floral host reproduction.

Suitability of Host Plants and Insect Preys to the Zoophytophagous Tomato Bug Nesidiocoris tenuis (Reuter) (Heteroptera :Miridae)

The tomato bug Nesidiocoris tenuis (Reuter) (Miridae, Heteroptera)is one of the mirid bugs that can feed on plants and preys on different insect pests. It’s generally appears with large numbers in greenhouses and open fields of tomato crop in Egypt. It can complete the development of immature stages and survive on solanaceous plants with no choice feed. Tomato plants found to be the suitable host plant with survival rate 42.5%, followed by eggplant and pepper and represented by 21.7 and 10.0 %, respectively. Meanwhile, the duration of the total immature stage found to be the shortest duration when it reared on pepper plants and represented by 7.3 ±0.33days, followed by eggplant and pepper and represented by 8.3±0.3 and 7.7 ±0.3 days, respectively. In addition tomato bug can develop and survive when the immature stage feed on different insects as prey with no choice feed. The survival rate increased by feeding the immature stages insects as prey, the highest survival rate recorded when the tomato bug reared with the tomato borer, Tuta absoluta Meyrick. ranged between 80.8%, meanwhile the lowest survival rate record when reared immature stages on the cotton leafworm Spodoptera littoralis Bosid.,and ranged 63.3%, respectively .On other hand the duration found to be short with 6.33±0.33 days on the cotton whitefly Bemisia tabaci Genn., and T.absoluta followed by the cotton worm and plant hoppers Empoasca spp., and represented by 6.33±0.33 days, respectively. When tomato plants and insects as prey introduced to the immature stages with choice feed, the highest survivals rate were record and ranged 95.8 % on tomato with B. tabaci followed by tomato plants with T.absoluta ,S.littoralis and Empoasca spp.and represented by 92.9 , 90.8 and 89.2 ,respectively.

Cover crop seed preference of four common weed seed predators

AbstractInvertebrate seed predators (ISPs) are an important component of agroecosystems that help regulate weed populations. Previous research has shown that ISPs' seed preference depends on the plant and ISP species. Although numerous studies have quantified weed seed losses from ISPs, limited research has been conducted on the potential for ISPs to consume cover crop seeds. Cover crops are sometimes broadcast seeded, and because seeds are left on the soil surface, they are susceptible to ISPs. We hypothesized that (1) ISPs will consume cover crop seeds to the same extent as weed seeds, (2) seed preference will vary by plant and ISP species, and (3) seed consumption will be influenced by seed morphology and nutritional characteristics. We conducted seed preference trials with four common ISPs [Pennsylvania dingy ground beetle (Harpalus pensylvanicus), common black ground beetle (Pterostichus melanarius), Allard's ground cricket (Allonemobius allardi) and fall field cricket (Gryllus pennsylvanicus)] in laboratory no choice and choice feeding assays. We compared seed predation of ten commonly used cover crop species [barley (Hordeum vulgare), annual ryegrass (Lolium multiflorum), pearl millet (Pennisetum glaucum), forage radish (Raphanus sativus), cereal rye (Secale cereale), white mustard (Sinapis alba), crimson clover (Trifolium incarnatum), red clover (Trifolium pratense), triticale (×Triticosecale) and hairy vetch (Vicia villosa)] and three weed species [velvetleaf (Abutilon theophrasti), common ragweed (Ambrosia artemisiifolia) and giant foxtail (Setaria faberi)]. All four ISPs readily consumed cover crop seeds (P < 0.05), but cover crops with hard seed coats and seed hulls such as hairy vetch and barley were less preferred. Our results suggest that farmers should select cover crop species that are avoided by ISPs if they plan on broadcasting the seed, such as with aerial interseeding.

Testing the importance of predation refuge vs. food quality in determining the use of macroalgal hosts by a generalist marine mesograzer

Bottom-up (e.g. resource quality) and top-down (e.g. predation) factors have strong effects on the fitness and distribution of small herbivores. Herein, we investigated how food quality and refuge offered by macroalgal hosts influence the distribution of a mesograzer. We used the herbivorous amphipod Cymadusa filosa and seasonally evaluated its association with the macroalgal hosts Sargassum filipendula, Padina gymnospora, and Dichotomaria marginata on a subtropical rocky shore from the Brazilian southeastern coast. Feeding experiments were conducted to test the food value of hosts, while predation experiments in the field and laboratory were performed to investigate the refuge value of the macroalgae. Cymadusa occurred on Padina in a density greater than that observed on Dichotomaria and Sargassum, while Dichotomaria harbored more amphipods than Sargassum. Adults of Cymadusa showed a higher consumption of Padina and Sargassum in both choice and no-choice feeding experiments and juveniles had greater growth and reproductive potential when feeding on such macroalgae. In the predation experiment in the field, Padina was a better refuge for Cymadusa than Sargassum. However, no difference in refuge value among hosts was observed in the laboratory assays. The distribution of Cymadusa was explained by a balance between food and refuge values of hosts, with higher abundances being observed in the high-quality food alga that provides refuge against predators (e.g. Padina), while fewer individuals occurred in other high-quality food that was less suitable as refuge (e.g. Sargassum). Therefore, predation may be more of a determinant for distribution of that mesograzer than resource quality.

School Choice in China: Past, Present, and Future

Purpose: Focusing on the hot-debating issue of school choice in China, this article aims to present a narrative of the policy interventions, especially promulgated by the Chinese central government during the past 20 years, and to discuss those challenges facing the governments and the society as a whole in the new era. Design/Approach/Methods: This article conceptually approaches the topic based on policy texts analysis and literature review. Findings: This article pictures the historical dynamics of school choice phenomenon and its interaction with the corresponding policy initiatives promoted by the central government. It argues that school choice governing in China basically experienced three stages since the middle of 1990s, namely controlling “choice fees,” promoting equalization and equity as well as comprehensive governance toward greater quality and equity. The effective implementation of these policy measures is gradually cooling down the “choice fever” in urban areas and restoring order for student enrollment in compulsory education, but great challenges are still lying ahead since the problem of school choice turns to be “wicked” in nature and cannot be simply solved within the education sector. Originality/Value: This article contributes to the global discourse of school choice research with much updated information of policy initiatives and the newly emerged situations since 2014, calling for close attention and deeper research from researchers both from China and from abroad.

Whole and ground grain sorghum and the free choice feeding system in broiler diets

This experiment evaluates the zootechnical performance, yield of cuts, carcass composition, and intake of metabolizable energy, lysine, and methionine + cystine in male broilers from 21 to 42 days of age fed diets based on whole and ground grain sorghum and corn. A total of 112 birds of the Cobb 500 lineage were divided into 28 cages (four animals per cage) in a completely randomized design with four treatments and seven replications. Treatments consisted of diets based on ground corn and soybean meal (control, T1), ground sorghum and soybean meal (treatment 2, T2), whole grain sorghum and soybean meal (treatment 3, T3), and the diet T3 separated in feeders in the fractions (a) whole grain sorghum and (b) concentrate containing the other ingredients of the mixed feed (free choice feeding) (treatment 4, T4). The variables feed intake, body weight, feed conversion, viability, breast, drumstick and thigh yield , bromatological composition of breast and drumstick + thigh, and daily intakes of metabolizable energy, lysine and methionine + cystine were studied. The whole grain sorghum in diets is viable, contributes to reducing factory and logistics costs in the poultry industry, and promotes the same results of zootechnical performance, yields, and bromatological composition of cuts when compared to diets with ground corn and sorghum. Diets with whole grain sorghum in the free choice feeding system may be a viable alternative because birds sought to meet their daily needs for metabolizable energy and digestible amino acids even in short periods of adaptation to the diets, as demonstrated in the experiment.

Antifeedant and ovicidal activities of ginsenosides against Asian corn borer, Ostrinia furnacalis (Guenee).

IntroductionGinsenosides, including protopanaxdiol (PPD) and protopanaxtriol (PPT) type ginsenosides, have been identified as natural insecticidess. This study aimed to investigate the antifeedant and ovicidal activities of total ginsenosides, protopanaxdiol saponins (PDS) and protopanaxtriol saponins (PTS) against Asian corn borer, O. furnacalis (Guenee).Methods and resultsO. furnacalis egg masses (> 40 eggs) at 0-, 1- and 2-day-old were dipped into ginsenosides and egg hatchability was significantly inhibited by total ginsenosides, PDS, and PTS in dose and egg-age dependent manners. 100 mg/ml PDS had the strongest ovicidal activity against 0- (80.58 ± 0.95%), 1- (71.48 ± 5.70%), and 2-day-old eggs (64.31 ± 3.20%). In no-choice and choice feeding tests, we observed that the 3rd instar larvae consumed decreased area of leaves treated with ginsenosides, and the antifeedant activities of total ginsenosides, PDS, and PTS against the 3rd instar larvae were time and dose-dependent, with higher activities at 48 h. 100 mg/ml PDS had relative higher antifeedant activity (88.39 ± 3.43% in no-choice and 80.9±4.36% in choice) than total ginsenosides and PTS at all time intervals, except at 48 h in no-choice test. In further experiments, we found PPD ginsenosides (Rb1, Rb2, Rc, and Rd) had relative higher time and dose dependent antifeedant activities than PPT ginsenosides (Re and Rg1).ConclusionsOur results suggested the insecticidal action of total ginsenosides, PDS, and PTS on O. furnacalis. All ginsenosides, especially PDS, showed antifeedant and ovicidal activities against O. furnacalis.

Effects of choice feeding and lower ambient temperature on feed intake, growth, foot health, and panting of fast- and slow-growing broiler strains.

Effects of lowering ambient temperature in the second half of the growth period were studied in 2 broiler strains with different genetic potential for growth (Ross from 1972 and 2004) when given ad libitum access or pre-mixed increasing proportion of whole wheat in their diet. A total of 48 groups of day-old broilers (n = 64) from the 2 strains were housed as hatched in 48 pens in 4 houses and slaughtered at 6 wk of age. Half of the groups had access to pelleted feed pre-mixed with increasing proportion of whole wheat, the other half had access to pelleted feed and whole wheat in separate troughs. Ambient temperature from 28 d of age was either 21 or 15°C. The fast-growing strain had greater (P < 0.001) live weight throughout (mean slaughter weights 2.6 (±0.014) kg and 1.0 (±0.006) kg). When given a choice, the fast-growing strain consumed a lower (P ≤ 0.004) proportion of whole wheat in their diet in weeks 5 and 6 (20 and 26 (±0.9) % whole wheat), and the slow-growing strain chose a higher (P < 0.001) wheat proportion (45 and 56 (±1.7) %) than the pre-mixed inclusion of 25 and 30%, respectively. The slow-growing strain grew slightly faster in the colder ambient temperature, and slower when given a free choice of whole wheat. Both strains drank more water per feed consumed in the warmer ambient temperature treatment. Foot pad dermatitis, only seen in the fast-growing birds, had a higher occurrence in the colder and in the choice feeding treatments. Gait scoring on day 34 showed perfect gait in more than 85% of the slow-growing and less than 1% of the fast-growing birds. Activity was higher and panting levels were lower in the slow-growing strain (P < 0.001) toward the end of the growth period, with no effect of the temperature treatment on panting. Slow-growing strains increase their energy intake, and fast-growing strains increase their protein intake when given a choice.

Moringa leaf meal improves haemato-biochemical and production indices in broiler chickens: a review

The high cost of feed materials and feed additives in developing nations has elicited interest in the search for sustainable alternatives having in mind the human food security. Moringa (Moringa oleifera), one of such sustainable alternatives, is a tropical plant with excellent nutritive and phytochemical content. It is one of the species in the family of Moringaceae and thrives well in the tropics. The excellent nutritional quality of M. oleifera has positioned it as a choice feed ingredient/additive for broiler production. Furthermore, the high carotenoid content of moringa leaves offers great potential for its use in pigmentation of egg yolk and broiler meat. Moringa has antibacterial, antifungal, anti-inflammatory, antihypercholesterolemic and antioxidant properties. Besides the nutritional and phytochemical value of this plant, their use as a feed supplement or feedstuff and their beneficial attributes on production indices and heamato-biochemical values of broiler chickens are also discussed. Alongside their excellent chemical composition, this paper also tends to showcase the plant as a promising novel feedstuff/additive source in broiler nutrition. The use of moringa in broiler nutrition as a novel feed additive and nutrient source will not only reduce feed cost but will also improve production performance, ensure healthy animal products and a better environment.

Endophyte Infection and Methyl Jasmonate Treatment Increased the Resistance of Achnatherum sibiricum to Insect Herbivores Independently.

Alkaloids are usually thought to be responsible for protecting endophyte-infected (EI) grasses from their herbivores. For EI grasses that produce few alkaloids, can endophyte infection enhance their resistance to herbivores? Related studies are limited. In the Inner Mongolian steppe, Achnatherum sibiricum is highly infected by Epichloë endophytes, but produces few alkaloids. Locusts are the common insect herbivores of grasses. In this study, A. sibiricum was used as plant material. Methyl jasmonate (MJ, when applied exogenously, can induce responses similar to herbivore damage) treatment was performed. The effects of endophyte infection and MJ treatment on the resistance of A. sibiricum to Locusta migratoria were studied. We found that locusts preferred EF (endophyte-free) plants to EI plants in both choice and no-choice feeding experiments. Endophyte infection enhanced the resistance of A. sibiricum to locusts. Endophyte infection decreased soluble sugar concentrations, while it increased the total phenolic content and phenylalanine ammonia lyase (PAL) activity, which may contribute to the resistance of A. sibiricum to locusts. There was an interaction effect between MJ treatment and endophyte infection on the growth of the host. MJ treatment was a negative regulator of the plant growth-promoting effects of endophyte infection. There was no interaction effect between MJ treatment and endophyte infection on the defense characteristics of the host. In groups not exposed to locusts, MJ treatment and endophyte infection had a similar effect in decreasing the soluble sugar content, while increasing the total phenolic content and the PAL activity. In groups exposed to locusts, the effect of MJ treatment on the above characteristics disappeared, while the effect of endophyte infection became more obvious. All of these results suggest that even for endophytes producing few alkaloids, they could still increase the resistance of native grasses to insect herbivores. Furthermore, endophyte infection might mediate the defense responses of the host, independent of jasmonic acid (JA) pathways.

The Buckwheat Effect: A Biopesticide for Wireworm?

Growing buckwheat (Fagopyrum esculentum Moench. Caryophyllales: Polygonaceae) in rotation with potato and other vegetable crops has been reported to decrease the density of an invasive wireworm species (Agriotes sputator Linnaeus. Coleoptera: Elateridae) in Nova Scotia, Canada. It was predicted that the negative effects on wireworm populations result from phytochemicals by buckwheat that act as deterrents, anti-feedants, or toxins in the roots or when released into the soil. Choice assays were conducted to test the attractiveness of germinating, branching, and flowering buckwheat, red spring wheat (Triticum aestivum Linnaeus. Poales: Poaceae) and island barley (Hordeum vulgare Linnaeus. Poales: Poaceae) to the larvae. Twenty-one day, no choice feeding assays were conducted to determine change in mass and mortality of A. sputator larvae when fed buckwheat or barley. There was no evidence that the wireworms were deterred by buckwheat and the germinating stage of all three crops was the most attractive based on the 24-h choice assays. After the 21-d no choice feeding assays, no differences between hosts were observed; however, wireworm herbivory significantly reduced the growth of barley but not buckwheat. The findings from the no choice feeding assays suggest that buckwheat may produce anti-feedants, but longer term feeding assays and field trials are required to confirm this possibility.

Zinc Phosphide and Argel (Gomphocarpus sinaicus Boiss) leaves as a rodenticide on the Norway rat, Rattus norvegicus Comparative Studies under Laboratory and Field Conditions

The rodenticidal effect of crude argel (Gomphocarpus sinaicus Boiss) leaves was carried out on Norway rat under laboratory and field circumstances with zinc phosphide in Menofyia Governorate. The laboratory results proved that non-choice also, free - choice feeding tests gave the same trend; a bait 1% either zinc phosphide and argel ethanolic extract excepted 100% mortality for Norway rat as well as shorter time to death for zinc phosphide treatment. Argel ethanolic extract bait was more accepted than zinc phosphide with 57.1 and 34.5%, respectively. Also cleared that zinc phosphide more toxic than argel ethanolic leaves extract whereas the acute oral LD50 values were 0.255 and 85.78mg/kg b.w respectively, for rattus norvegicus. Oral administration of sub-leathal dose (¼ LD50) of each compound induced a noticeable disfunction in (AST), (ALT) enzymes and TP levels as they increased in plasma at 24 and 48 hours after treatment indicating a hepatic damage. Aprolongation of the prothrombin time (PT) had occurred following administration of Argel leaves ethanolic extract indicating disorders in blood coagulation mechanism but no effect on (PT) was observed with zinc phosphide treatment. Under the field conditions, zinc phosphide caused 70.6% population reduction, While Argel leaves ethanol extract reduced 68.0% of Norway rat, Rattus norvegicus population, while the water extract gave the lowest value (11.3%).

Decision-making of goats when exposed to choice feeding: Triggered by taste or smell?

Animals recognise known forages. However, it is unclear whether recognition is mainly based on sensory characteristics linked to postingestive feedback or whether the latter is activated each time before a choice is made. Moreover, knowledge is scarce regarding the duration of the memory process and if the memory is primarily activated by smell or a combination of smell and taste. The hypothesis of this study was that in choice situations (1) the preference for one of two offered forages develops in the initial moments of feeding, and (2) this is led by recognition via smell linked to postingestive feedback. In order to study the potential relationships between initial feed intake (FI) (3 min) and short-term FI (3 h), a preference trial as a special form of feed choice experiments with Saanen-type wethers was undertaken. Forages comprised lucerne (Medicago sativa L., first cut), red clover (Trifolium pratense L., first cut) and Italian ryegrass (Lolium multiflorum Lam., second cut). Six different treatments of each forage type were ensiled such that silages of varying quality were produced. Each possible two-way combination of silages and standard hay (n = 21 combinations) was offered and complemented with video recordings of the first 3 min of feed consumption in the morning. Data were analysed via correlation and regression analysis using PROC CORR (Pearson correlation coefficients) and PROC REG of SAS for examination of the relationships between dry matter intake (DMI; g/30 min and g/3 h) and the duration (s) of FI in the first 3 min. The head was moved 0.8–3.0 times between both boxes until the decision was made, and no differences were observed in the frequency of head movements between the silage treatments. The decision did not seem to occur by chance: the initially selected lucerne silages were consumed in greater amounts than the initially non-selected silages within the first 3 min of feeding in 88.3% of the pairwise comparisons. With the red clover silages the proportion was 90.1%, and with the grass silages, 87.3%; 81.7%, 77.5% and 58.9% of the initially non-selected lucerne, red clover and Italian ryegrass silages respectively were not eaten at all (i.e. 0 s). A strong relationship was observed between DMI (g/30 min and g/3 h) and the duration of FI in the first 3 min, indicating a high predictive power of initial FI for the preference that develops within 3 h. Around 90% of the variation in DMI, both expressed as g/3 h and g/30 min, was explained by the duration of FI in the first 3 min of feeding. The results suggest that already in the very first minutes of feeding, recognition of the silages and decision-making processes take place based on the smell emitted by the silages.

High phenolic content fails to deter mesograzer consumption of Myriophyllum spicatum (Eurasian watermilfoil) in New England

Eurasian watermilfoil (Myriophyllum spicatum) is often considered one of the most aggressive macrophyte invaders in freshwater habitats throughout the USA. However, conditions leading to successful milfoil invasions are not well understood. This study sought to illuminate the role of herbivores in determining milfoil invasion success via the potential mechanisms of enemy release and biotic resistance. We determined feeding preferences of three herbivores native to the northeastern United States and measured macrophyte phenolic content, which may act as an herbivore feeding deterrent. We found that phenolic content in milfoil was more than two times higher than in the most abundant native macrophytes at our study sites, consistent with enemy release. However, laboratory feeding experiments demonstrated that milfoil phenolics did not deter amphipod (Hyalella azteca), snail (Physella sp.), or weevil (Euhrychiopsis lecontei) herbivory. Furthermore, amphipod consumption rates in our study were an order of magnitude higher than amphipod consumption rates reported in milfoil’s native range, contrary to the predictions of enemy release. Amphipods and snails from habitats invaded by milfoil consumed similar quantities of both milfoil and the low-phenolic native plant Elodea canadensis. In contrast, weevils consumed milfoil but not E. canadensis in choice experiments. Amphipods collected from milfoil-free habitats also readily consumed milfoil, and they consumed 2.5 times more milfoil than E. canadensis in a choice feeding trial. These results suggest that high phenolic levels do not prevent native herbivores from consuming invasive milfoil. Instead, native generalist grazers like amphipods and snails may limit milfoil proliferation and provide a measure of biotic resistance.