Harinder P. S. Makkar

Antinutritional factors present in plant-derived alternate fish feed ingredients and their effects in fish.

The use of plant-derived materials such as legume seeds, different types of oilseed cake, leaf meals, leaf protein concentrates, and root tuber meals as fish feed ingredients is limited by the presence of a wide variety of antinutritional substances. Important among these are protease inhibitors, phytates, glucosinolates, saponins tannins, lectins, oligosaccharides and non-starch polysaccharides, phytoestrogens, alkaloids, antigenic compounds, gossypols, cyanogens, mimosine, cyclopropenoid fatty acids, canavanine, antivitamins, and phorbol esters. The effects of these substances on finfish are reviewed. Evidently, little unanimity exists between the results of different studies as to the specific effects of antinutrients, since most studies have been conducted using an ingredient rich in one particular factor and the observed effects have been attributed to this factor without considering other antinutrients present in the ingredient, or interactions between them. Tentatively, protease inhibitors, phytates, antigenic compounds, and alkaloids, at levels usually present in fish diets containing commercially available plant-derived protein sources, are unlikely to affect fish growth performance. In contrast, glucosinolates, saponins, tannins, soluble non-starch polysaccharides, gossypol, and phorbol esters, are more important from a practical point of view. The effectiveness of common processing techniques such as dry and wet heating, solvent extraction and enzyme treatment in removing the deleterious effects of antinutrients from feed materials is discussed. More insights into the nutritional, physiological and ecological effects of antinutrients on fish need to be accumulated through studies using purified individual antinutrients and their mixtures in proportions similar to those in alternative nutritional sources in fish feeds. Such studies would provide data useful for designing optimum inclusion levels of plant-derived materials and treatment methods that would neutralise the negative effects of the antinutritional factors.

The biological action of saponins in animal systems: a review

Saponins are steroid or triterpenoid glycosides, common in a large number of plants and plant products that are important in human and animal nutrition. Several biological effects have been ascribed to saponins. Extensive research has been carried out into the membrane-permeabilising, immunostimulant, hypocholesterolaemic and anticarcinogenic properties of saponins and they have also been found to significantly affect growth, feed intake and reproduction in animals. These structurally diverse compounds have also been observed to kill protozoans and molluscs, to be antioxidants, to impair the digestion of protein and the uptake of vitamins and minerals in the gut, to cause hypoglycaemia, and to act as antifungal and antiviral agents. These compounds can thus affect animals in a host of different ways both positive and negative.

Formation of complexes between polyvinyl pyrrolidones or polyethylene glycols and tannins, and their implication in gas production and true digestibility in in vitro techniques

Various tannin-complexing agents have been used to study the potential adverse effects of tannins on rumen metabolism. Using a method based on turbidity formation, the binding of various tannin-complexing agents (polyvinyl polypyrrolidone (PVPP), polyethylene glycol (PEG) of molecular weights 2000 to 35,000, and polyvinyl pyrrolidone (PVP) of molecular weight 10,000, 40,000 and 360,000) to tannins (tannic acid, purified tannins from quebracho (Aspidosperma quebracho) and leaves of trees and shrubs (Acioa barteri, Dichostachys cinerea, Guiera senegalensis, Piliostigma reticulatum)) was investigated at different pH values. The binding of all the tannins with PVPP was highest at pH 3-4 and lowest at pH 7. For all the pH range (3-7) studied, the binding of PEG was higher than that of PVP. For all the tannins except tannic acid, the binding to PVP was the same from pH 4.7 to 7. Similar results were observed for the PEG of molecular weight 6000 or higher for all the tannins except quebracho tannins for which the binding increased as the pH increased from 3 to 7. The binding with PEG 2000 decreased to a greater extent as the pH reached near neutral and for PEG 4000 this decrease was slightly lower. Addition of these tannin-complexing agents to the in vitro gas system resulted in higher gas production from tannin-rich feeds (increase varied from 0 to 135%). The PEG were the most effective followed by PVP and PVPP. The PEG 35,000 was least effective. The efficiency of other PEG was similar. The PEG 6000 was preferred to PEG 2000 or 4000 as its binding to tannins was higher at near neutral pH values. The gas production increased with an increase in the amount of PEG 6000 up to 0.6 g/40 ml rumen-fluid-containing medium containing 0.5 g tannin-rich feed, beyond which no increase was observed. The percentage increase in gas value at 24 h fermentation correlated significantly with tannin values, the highest correlation (r 0.95) being with protein precipitation capacity of tannins. The increase in gas production was associated with higher production of short-chain fatty acids with little change in their molar proportions, suggesting an increase in organic matter digestibility by inclusion of the PEG in tannin-rich feeds. However, apparent and true digestibilities were lower on addition of the PEG, due to the presence of PEG-tannin complexes in the residues. The use of this bioassay (percentage increase in gas production in the presence of PEG 6000) along with other tannin assays would provide a better insight into the nutritional significance of tannins.

Phorbol Esters: Structure, Biological Activity, and Toxicity in Animals:

Phorbol esters are the tetracyclic diterpenoids generally known for their tumor promoting activity. The phorbol esters mimic the action of diacyl glycerol (DAG), activator of protein kinase C, which regulates different signal transduction pathways and other cellular metabolic activities. They occur naturally in many plants of the family Euphorbiacaeae and Thymelaeaceae. The biological activities of the phorbol esters are highly structure specific. The phorbol esters, even at very low concentrations, show toxicological manifestations in animals fed diets containing them. This toxicity limits the use of many nutritive plants and agricultural by-products containing phorbol esters to be used as animal feed. Therefore, various chemical and physical treatments have been evaluated to extract or inactivate phorbol esters so that seed meals rich in proteins could be used as feed resources. However, not much progress has been reported so far. The detoxifying ability has also been reported in some molluscs and in liver homogenate of mice. Besides, possessing antinutritional and toxic effects, few derivatives of the phorbol esters are also known for their antimicrobial and antitumor activities. The molluscicidal and insecticidal properties of phorbol esters indicate its potential to be used as an effective biopesticide and insecticide.

Comparative evaluation of non-toxic and toxic varieties of Jatropha curcas for chemical composition, digestibility, protein degradability and toxic factors.

Four varieties of Jatropha curcas which originated from Nicaragua (Cape Verde and Nicaragua toxic varieties cultivated in Managua), Nigeria (a wild variety from Ife; toxicity unknown) and Mexico (a wild non-toxic variety collected from Papantla) were studied. The average seed weight was 0.69, 0.86, 0.53 and 0.65 g for Cape Verde, Nicaragua, Ife-Nigeria and non-toxic Mexico varieties, respectively. The kernel to shell ratio in seeds was relatively similar (62.7:37.3 for both Cape Verde and Nicaraguan, 60:40 for Ife-Nigerian and 63.5:36.5 for non-toxic Mexican). The shell of the seeds composed mainly of fiber (>83% neutral detergent fiber) and very little crude protein (CP < 6%). The kernels were rich in CP (22.2–27.7%) and lipid (53.9–58.5%). The meal (defatted kernels) had a CP content of 57.3, 61.9, 56.1 and 64.4% for Cape Verde, Nicaragua, Ife-Nigeria and non-toxic Mexico varieties, respectively, and about 90% of this CP was true protein. The pepsin insoluble nitrogen was from 5.5 to 7%. The amino acid composition of meals from Cape Verde, Nicaragua and non-toxic Mexico varieties was similar. The levels of essential amino acids except lysine were higher than that for the FAO reference protein. The meal from the toxic variety (Cape Verde) did not have any anti-fermentative activity on rumen microbes. The estimated digestible organic matter (DOM) and metabolizable energy (ME) for the shells were low (26.2–27.1% and 2.4–2.8 MJ kg−1), whereas these values for Jatropha meals were 77.3–78.4% and 10.7–10.9MJ kg−1. For commercially available (heat-treated) soyabean meal, DOM and ME were 87.9% and 13.3MJ kg−1, respectively. The in-vitro rumen degradable nitrogen (% of total nitrogen) for meals from Cape Verde, Nicaragua, Ife-Nigeria and non-toxic Mexico varieties was 43.3, 37.7, 38.7 and 28.9, respectively, and for the soyabean meal it was 80.9%. Tannins, cyanogens, glucosinolates and amylase inhibitors were not detected in meals of any of the four varieties. A small amount of tannins were present in shells (2.0–2.9% as tannic acid equivalent). High levels of trypsin inhibitor activity (18.4–26.5 mg trypsin inhibited g−1), lectin (51–102; inverse of the minimum amount in mg ml−1 of the assay which produced haemagglutination in presence of 10 mM Mn2+) and phytate (7.2–10.1%) were observed in the meals. The concentrations of phorbol esters in kernels of Cape Verde, Nicaragua and Ife-Nigeria varieties were 2.70, 2.17 and 2.30mg g−1, whereas kernels of non-toxic Mexican had a very low level (O.11 mg g−1) of phorbol esters.

Nutrional value and antinutritional components of whole and ethanol extracted Moringa oleifera leaves

Chemical constituents, organic matter digestibility, gross and metabolizable energy, rumen degradable and undegradable nitrogen, amino acid composition, digestion kinetics (leaves, their neutral-detergent fiber and cell solubles), and antinutritional factors were determined in extracted (80% aqueous ethanol; the extract is used as a source of growth promoting factors) and unextracted Moringa oleifera leaves. The metabolizable energy and organic matter digestibility predicted from the extent of fermentation in in vitro incubation were 9.2 MJ kg−1 and 75.7% for the extracted leaves and 9.5 MJ kg−1 and 74.1% for the unextracted leaves. The crude protein contents of the extracted and unextracted leaves were 43.5 and 25.1% respectively. The true protein contents of these leaves were 93.8% and 81.3% of the total crude protein (non protein nitrogen contents of 2.7 and 4.7% were observed in the extracted and unextracted leaves). In vitro rumen crude protein degradability at 24 h of incubation was 44.8 and 48.6% for the extracted and unextracted leaves. One of the factors responsible for the low rumen protein degradability could be the low solubility of the proteins (about 7 and 24% of the crude protein was soluble in phosphate buffer (pH 7, 0.05 M) for the extracted and unextracted leaves). The protein insoluble in acid-detergent fiber (ADIP; protein unavailable to animals) was 13.2 and 9.8% in ADF of the extracted and unextracted leaves respectively (absolute values of 22 g and 11 g ADIP kg−1 leaves). The protein potentially digestible in the intestine (PDI) was 50 and 47% of the total crude protein for the extracted and unextracted leaves respectively. The rate (h−1) and potential extent (ml g−1) of gas production calculated using the exponential model for the extracted and unextracted leaves were 0.0424 and 274.3, and 0.0824 and 248.5 respectively. These values for their NDF were 0.0542 and 265.8, and 0.0645 and 271.7 and for their cell solubles were 0.0338 and 286.3, and 0.089 and 242.2 respectively. M. oleifera leaves had negligible tannins; saponins content (5.0% as diosgenin equivalent) was similar to that present in soyabean meal, and trypsin inhibitors and lectins were not detected. The phytate content was 3.1%. The ethanol extracted leaves were virtually free of tannins, lectins, trypsin inhibitors and saponins, and phytate content was 2.5%. All essential amino acids including sulfur-containing amino acids were higher than adequate concentration when compared with recommended amino acid pattern of FAO/WHO/UNO reference protein for a 2 to 5-year-old child.

Nutrients and antiquality factors in different morphological parts of the Moringa oleifera tree

Moringa oleifera grows throughout most of the tropics and has several industrial and medicinal uses. The objective of this study was to evaluate the potential of different morphological parts of this tree as animal feed. The crude protein (CP) content of leaves, soft twigs and stems was 260, 70 and 60 g kg −1 respectively. About 64, 79 and 67% of the total CP present in the leaves, twigs and stems respectively was found to be degradable after 24 h in the rumen. The protein insoluble in acid detergent fibre (ADIP), considered unavailable to animals, in these samples was 30, 150 and 170 g kg −1 respectively. About 87% of the total CP was in the form of true protein in the leaves (60 and 53% in twigs and stems respectively). The leaves had negligible amounts of tannins (12 g kg −1 ), and trypsin and amylase inhibitors, lectins, cyanogenic glucosides and glucosinolates were not detected. The saponin content of the leaves was 80 g kg −1 as diosgenin equivalent, which did not show any haemolytic activity. The phytate content of the leaves was 21 g kg −1 . Tannins, saponins, cyanogenic glucosides and glucosinolates were detected in twigs and stems but the concentrations were negligible. Trypsin and amylase inhibitors were not detected in twigs and stems. Phytate contents of both twigs and stems were c . 30 g k −1 . In leaves, amounts of all the essential amino acids were higher than the amino acid pattern of the FAO reference protein and comparable to those in soyabeans. The CP and lipid contents of the kernel were 370 and 420 g kg −1 respectively, and the CP of the meal (fat-free) was 610 g kg −1 . The kernels and meal are extracted with water and the extract is used for the purification of water in some developing countries. The residues left after water extraction of kernels and meal (designated as extracted-kernel and extracted-meal) had a CP content of 350 and 700 g kg −1 respectively and all of this CP was in the form of true protein. After taking into account the ADIP contents in these samples, c . 38 and 69% of the total protein was calculated to be available in the post-rumen in extracted-kernel and extracted-meal respectively. The pepsin digestibility of these samples was 91 and 84% respectively. The sulphur-containing amino acids in kernel proteins were present at higher concentrations than those specified in the amino acid pattern of the FAO reference protein but other essential amino acids were deficient. Amongst the antinutritional factors mentioned above, glucosinolates and phytate were present in appreciable amounts (65·5 μmol/g and 41 g kg −1 respectively) in meal. Haemagglutination activity was also detected in the meal. The extracted-meal was virtually free of all the antinutritional factors examined except for phytate (67 g kg −1 ). The leaves of Moringa oleifera and the residue obtained after the recovery of oil and coagulants can be good sources of proteins for animal feeds.

Plant secondary metabolites.

Plant secondary metabolites , Plant secondary metabolites , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Bioactivity of phytochemicals in some lesser-known plants and their effects and potential applications in livestock and aquaculture production systems

Livestock and aquaculture production is under political and social pressure, especially in the European Union (EU), to decrease pollution and environmental damage arising due to animal agriculture. The EU has banned the use of antibiotics and other chemicals, which have been shown to be effective in promoting growth and reducing environment pollutants because of the risk caused to humans by chemical residues in food and by antibiotic resistance being passed on to human pathogens. As a result of this, scientists have intensified efforts in exploiting plants, plant extracts or natural plant compounds as potential natural alternatives for enhancing the livestock productivity. This paper discusses work on the effects of various phytochemicals and plant secondary metabolites in ruminant and fish species. The focus is on (i) plants such as Ananas comosus (pine apple), Momordica charantia (bitter gourd) and Azadirachta indica (neem) containing anthelmintic compounds and for their use for controlling internal parasites; (ii) plants containing polyphenols and their applications for protecting proteins from degradation in the rumen, increasing efficiency of microbial protein synthesis in rumen and decreasing methane emission; for using as antioxidants, antibacterial and antihelmintic agents; and for changing meat colour and for increasing n-3 fatty acids and conjugated linoleic acid in meat; (iii) saponin-rich plants such as quillaja, yucca and Sapindus saponaria for increasing the efficiency of rumen fermentation, decreasing methane emission and enhancing growth; for producing desired nutritional attributes such as lowering of cholesterol in monogastric animals; for increasing growth of fish (common carp and Nile tilapia) and for changing male to female ratio in tilapia; and for use as molluscicidal agents; (iv) Moringa oleifera leaves as a source of plant growth factor(s), antioxidants, beta-carotene, vitamin C, and various glucosinolates and their degraded products for possible use as antibacterial, antioxidant, anticarcinogenic and antipest agents; (v) Jatropha curcas toxic variety with high levels of various phytochemicals such as trypsin inhibitor, lectin, phytate and phorbol esters in seeds limiting the use of seed meal in fish and livestock diets; and the use of phorbol esters as bio-pesticidal agent; and (vi) lesser-known legumes such as Entada phaseoloides seeds containing high levels of trypsin inhibitor and saponins, Sesbania aculeate seeds rich in non-starch polysaccharides and Mucuna pruriens var. utilis seeds rich in l-3,4-dihydroxyphenylalanine and their potential as fish feed; Cassia fistula seeds as a source of antioxidants; and the use of Canavalia ensiformis, C. gladiata and C. virosa seeds containing high levels of trypsin inhinitor, lectins and canavanine. The paper also presents some challenges and future areas of work in this field.

Purine quantification in digesta from ruminants by spectrophotometric and HPLC methods

The method of Zinn & Owens (1986; Canadian Journal of Animal Science 66, 157-166), based on release of purine bases by HClO4 followed by their precipitation with AgNO3, was used to study recovery of purines from lyophilized rumen microbial or Escherichia coli preparations added to matrices such as cellulose, starch and neutral-detergent fibre. The recovery of purines was poor (approximately 50%). Under the hydrolysis conditions (12 M-HClO4, 90-95 degrees for 1 h) used in the method of Zinn & Owens (1986), the recovery of purines from the rumen microbial preparations added to matrices measured using an HPLC method was 95-102%, suggesting that the lower recovery of purines in the method of Zinn & Owens (1986) was not due to incomplete hydrolysis of nucleic acids. Using the HPLC method, adenine and allopurinol (an internal standard) were found to be heat-labile as substantial destruction was observed on heating at 121 degrees. On the other hand, another commonly used internal standard, caffeine, was stable at 121 degrees. A complete hydrolysis of nucleic acids from the rumen microbial preparation was observed with 2.5 ml 0.6 M-HClO4 in a total volume of 3 ml (0.5 M-HClO4 during hydrolysis) at 90-95 degrees for 1 h, and under these conditions adenine, guanine, allopurinol and caffeine were stable. Moreover, under these milder hydrolysis conditions, the recovery of purine bases from the rumen microbial or E. coli preparations added to matrices ranged from 92 to 108% using the method of Zinn & Owens (1986). Based on the results, changes in hydrolysis conditions have been proposed for accurate determination of purine bases using spectrophotometric or HPLC methods.