H. P. S. Makkar

In vitro gas measuring techniques for assessment of nutritional quality of feeds: a review

The close association between rumen fermentation and gas production has been recognised for over a century, but it is only since the 1940s that quantification techniques for measuring gas production have been evolved. The gas measuring technique has been widely used for evaluation of nutritive value of feeds. More recently, the upsurge of interest in the efficient utilisation of roughage diets has led to an increase in the use of this technique due to the advantage in studying fermentation kinetics. Gas measurement provides a useful data on digestion kinetics of both soluble and insoluble fractions of feedstuffs. This review describes the available in vitro gas measuring techniques used for feed evaluation with emphasis on assessing their relative advantages and disadvantages. Origin of gas, stoichiometry of gas production, and various areas for application of gas measurement in feed evaluation are discussed. Some important results obtained using gas measuring techniques have been highlighted, and the potential of gas techniques for tackling some interesting areas of research are presented. The need to consider substrate incorporation into microbial cells in gas measuring technique is pointed out.

Effect of polyethylene glycol on in vitro degradability of nitrogen and microbial protein synthesis from tannin-rich browse and herbaceous legumes.

Determination of microbial degradability of N is important in formulating a sound supplementation strategy for efficient utilisation of basal as well as supplementary diet components. In vitro degradability of N (IVDN) from tannin-containing browses (Acacia cyanophylla, Acacia albida, Acioa barteri and Quercus ilex) and two herbaceous legumes (Desmodium intortum and Desmodium uncinatum) was determined using the in vitro gas-production method coupled with NH3-N measurement in the presence and absence of a tannin-binding agent (polyethylene glycol (PEG), molecular mass 6000). Addition of PEG to tannin-containing feeds significantly (P < 0.05) increased in vitro gas and short-chain fatty acid (SCFA) production, and IVDN. The use of PEG as a tannin-binding agent increased IVDN from 28 to 59, 32 to 72, 19 to 40, 32 to 73, 40 to 80, and 26 to 77% in A. cyanophylla, A. albida, A. barteri, D. intortum, D. uncinatum and Q. ilex respectively. There was significant correlation between total phenolic compounds (total phenol, TP; total tannin, TT) in leguminous forages and percentage increase in IVDN on addition of PEG (P < 0.05; R2 0.70 and 0.82 for TP and TT respectively). The difference in IVDN observed in the absence and presence of PEG indicates the amount of protein protected from degradation in the rumen by tannins. When measured after 24 h incubation, tannin-containing feeds incubated in absence of PEG resulted in higher microbial protein synthesis than in the presence of PEG. Addition of PEG significantly (P < 0.05) reduced the efficiency of microbial protein synthesis expressed as mumol purine/mmol SCFA.

Effects of dietary tannic acid and quebracho tannin on growth performance and metabolic rates of common carp (Cyprinus carpio L.)

Abstract The effects of tannic acid (a hydrolysable tannin) and quebracho tannin (a condensed tannin) on common carp at a level of 2% in a soybean and fish meal-based diet containing about 40% crude protein have been studied. Quebracho tannin did not affect feed intake, body weight gain, average metabolic growth rate and oxygen consumption during the experimental period (84 days). The carp grew from an initial body weight of about 30 g to a final body weight of 150 g, and the carcass composition was also not affected by quebracho tannin. On the other hand, tannic acid produced adverse effects after day 28. The rejection of diet started on day 28 and a complete rejection of the diet was observed on day 40. The feeding of this diet was discontinued after day 42. The average metabolic growth rate for days 35–42 was significantly lower ( P

METHOD OF POLYETHYLENE GLYCOL APPLICATION TO TANNIN-CONTAINING BROWSES TO IMPROVE MICROBIAL FERMENTATION AND EFFICIENCY OF MICROBIAL PROTEIN SYNTHESIS FROM TANNIN-CONTAINING BROWSES

Abstract The effects of application of different amounts of a tannin-complexing agent, polyethylene glycol (PEG, MW 6000) together with different methods of application (addition of PEG at one time as a single dose; or at different times of incubation as split doses) on in vitro rumen fermentation of tannin-containing browses ( Acacia albida , Acacia cyanophylla and Calliandra calothyrsus ) were investigated. Addition of PEG increased the in vitro gas production, ammonia–nitrogen (NH 3 –N) concentration and net production of short chain fatty acid (SCFA). The split application of PEG resulted in significantly ( P A. albida and tended to increase in A. cyanophylla and C. calothyrsus . The method of application of PEG did not affect the SCFA production in A. cyanophylla and A. albida but significantly increased in C. calothyrsus . NH 3 –N concentration was significantly lower in A. cyanophylla and C. calothyrsus when PEG was applied in the split manner compared to single dose. The split application of PEG resulted in a higher production of microbial protein and a higher efficiency of microbial protein synthesis (EMPS; μmol purines/mmol SCFA) than the single application. This study demonstrated the possibility to improve the efficiency of utilisation of tannin-containing browses using the split application of PEG which improved rumen fermentation resulting from better synchronisation of energy availability and N degradability.

Adaptation of cattle to tannins: rôle of proline-rich proteins in oak-fed cattle

Saliva and faecal samples were collected from hill cattle (no. = 10) given tannin-rich oak (Quercus incana) leaves in the north-west Himalayan region of India. Amino acid composition of the saliva samples after thawing to remove precipitated proteins by centrifugation, and dialysis (molecular weight cut off: 3500) to remove small moieties revealed 6·4 (s.d. 0·6) % proline, 15·6 (s.d. 0·6) % glutamine plus glutamate and 9·2 (s.d. 1·0) % glycine on molar basis. For Holstein Friesian cattle (no. = 4) which had no history of consumption of tannin-containing foods, these values were 6·5 (s.d. 0·4) %, 15·2 (s.d. 0·5) % and 9·8 (s.d. 0·7) % respectively. Proline concentration in the proteins present either as free or as tannin-protein complexes in the lyophilized faecal samples from hill cattle was 4·7 (s.d. 0·2) % (on molar basis) of the total amino acids and 5·3 (s.d. 0·2) % in Holstein Friesian cattle. In the faeces of oak-fed cattle, the tannin and condensed tannin levels on dry-weight basis were 0·81 (s.d. 0·20) % as tannin acid equivalent and 0·06 (s.d. 0·04) % as leucocyanidin equivalent respectively. For tannic acid, the relative affinity of salivary proteins, using the competitive binding assay, was about six-times higher than that of bovine serum albumin (BSA) and was of the same order as that of gelatin. Turbidity of complexes formed between salivary proteins or BSA and tannic acid showed proportionately about 0·50 lower turbidity for salivary proteins in 0-2 mol/I acetate buffer (pH 4·9 containing 0·17 mol/l NaCl) and proportionately about 0·84 lower turbidity in distilled water. The results suggest that unlike rats or mice, the proline-rich proteins do not appear to be of any physiological significance in the adaptation of cattle to tannins. However, the salivary proteins of cattle though not rich in proline, have a high affinity for tannins and these proteins have a high tendency to form soluble tannin-protein complexes.

Biodegradation of Jatropha curcas phorbol esters in soil

BACKGROUND Jatropha curcas seed cake is generated as a by-product during biodiesel production. Seed cake containing toxic phorbol esters (PEs) is currently used as a fertiliser and thus it is of eco-toxicological concern. In the present study the fate of PEs in soil was studied. RESULTS Two approaches for the incorporation of PEs in soil were used. In the first, silica was bound to PEs, and in the second, seedcake was used. At day 0, the concentration of PEs in soil was 2.6 and 0.37 mg g(-1) for approach 1 and 2 respectively. PEs from silica bound PEs were completely degraded after 19, 12, 12 days (at 130 g kg(-1) moisture) and after 17, 9, 9 days (at 230 g kg(-1) moisture) at room temperature, 32 degrees C and 42 degrees C respectively. Similarly at these temperatures PEs from seed cake were degraded after 21, 17 and 17 days (at 130 g kg(-1) moisture) and after 23, 17, and 15 days (at 230 g kg(-1) moisture). Increase in temperature and moisture increased rate of PEs degradation. Using the snail (Physa fontinalis) bioassay, mortality by PE-amended soil extracts decreased with the decrease in PE concentration in soil. CONCLUSION Jatropha PEs are biodegradable. The degraded products are innocuous.

Acacia saligna as a supplementary feed for grazing desert sheep and goats

Acacia saligna, a leguminous tree, has a high crude protein content, remains green all year and can be grown in deserts using only runoff water. However, dry matter intake (DMI) by sheep and goats of A. saligna is low, presumably due to its high tannin content. It has been suggested that DMI could be increased by such methods as wilting of the forage and by neutralizing the negative effects of tannins by tannin-complexing agents. The purpose of this study was to determine DMI of supplementary A. saligna (phyllodes and small stems) by grazing sheep (∼ 50 kg) and goats (∼ 37 kg) when the animals were (1) offered wilted or fresh material (Expt 1); and (2) administered with polyethylene glycol (PEG), a tannin-binding agent (Expt 2). In this second experiment, there were three 14-day periods in which one group each of sheep and goats was on a regime of: No PEG-PEG-No PEG, whereas another group was on a regime of: No PEG-No PEG-PEG. In Expt 1, the DMI of A. saligna was statistically higher in goats than in sheep, but there was no difference in intake between fresh and wilted material. Average DMI of A. saligna, both fresh and wilted, was 124.1 g/day or 8.41 g/kg 0.75 per day for goats and 94.1 g/day or 5.05 g/kg 0.75 per day for sheep. Goats and sheep consuming fresh A. saligna gained more body mass than their respective controls; the difference was significantly greater in goats but not in sheep. In Expt 2, DMI of fresh A. saligna in the first period (before PEG) was 104.1 g/day or 7.16 g/kg 0.75 per day for goats and 84.8 g/day or 4.51 g/kg 0.75 per day for sheep. Administration of PEG during the second period resulted in an increase in DMI of 62% in goats and 83% in sheep. These animals maintained a high A. saligna intake in the third period when PEG was withdrawn. Goats and sheep that did not receive PEG in the second period had similar A. saligna intake as in the first period, but increased intake by 62 % and 47%, respectively, with PEG in the third period. Overall, the two goat groups and two sheep groups consuming A. saligna lost less body mass than their respective controls; the difference was significantly less in sheep but not in goats. It was concluded that wilting A, saligna did not increase DMI. Administration of PEG increased A. saligna intake and the intake remained high after PEG was withdrawn. Offering A. saligna as a supplement had a positive effect on body mass change.

The in vitro gas coupled with ammonia measurement for evaluation of nitrogen degradability in low quality roughages using incubation medium of different buffering capacity

Owing to low N content in low quality roughages, the estimation of in vitro rumen degradable nitrogen (IVRDN) by the method of Raab et al (Br J Nutr 1983 50 569–582) is expected to have a high standard deviation. Incubation of larger amounts of sample will increase the amount of N in the system and decrease analytical errors in the determination of IVRDN. The increase in the amount of sample necessitated an increase in the amount of buffer in the medium. In this study the effect of 30 ml (as is in original method) and 40 ml buffered rumen fluid (containing double the amount of hydrogen carbonate buffer as in the original method) on rumen degradation of N from low quality roughages was evaluated. N degradability of seven cereal straws (barley, millet, oat, rice, sorghum, triticale and wheat) and one grass hay was calculated from the linear regressions of NH3-N concentration vs in vitro gas production. The strength of association (r2) for gas production and NH3-N concentration between 30 and 40 ml system was significantly (P<0·05) different for grass hay and rice straw but not significant for other feeds. Using both systems, the IVRDN for triticale straw was virtually nil, and for others the values obtained using 40 ml system were either similar (oat straw, rice straw, sorghum stover and wheat straw) or higher (barley straw, grass hay and millet stover) than those obtained using 30 ml system. Although no significant difference was found in the standard deviation by increasing the amount of sample, the larger sample has an advantage in that it allows concomitant determination of in vitro apparent and true digestibility.

Effect of dietary saponins from Quillaja saponaria L. on fatty acid composition and cholesterol content in muscle Longissimus dorsi of lambs

The purpose of this study was to evaluate the effects of increasing levels of saponins from Quillaja saponaria on fatty acid (FA) composition and cholesterol content in muscle Longissimus dorsi of lambs. A total of 24 Barbarine lambs were assigned to four dietary treatments: control diet (C) consisting of oat hay ad libitum and 400 g of concentrate (80% barley, 17.5% soybean meal and 2.5% vitamin and mineral supplement); C diet plus 30 ppm of Q. saponaria L. (QS30); C diet plus 60 ppm of Quillaja (QS60); C diet plus 90 ppm of Quillaja (QS90). Saponin supplementation reduced the concentration of C14:1 cis-9 (P = 0.001) and of its desaturation index (P = 0.002). None of the FA intermediates of ruminal biohydrogenation (BH) was affected by Quillaja saponin supplementation (P > 0.05). The concentration of C20:4n-6 was higher in the meat of animals receiving 60 ppm of Quillaja than C and QS30 groups. Supplementing 60 ppm of Quillaja reduced the ratio between α-linolenic and linoleic acids compared with the C group (P = 0.023). We did not find any significant effect of Quillaja saponins on muscle cholesterol level. Further investigations are necessary to assess the metabolic fate of saponins in the rumen and to understand whether there is an effect of saponin on Δ9-desaturase enzyme activity, ruminal BH and cholesterol metabolism in ruminants. Supplementing up to 90 ppm of Quillaja saponins did not produce detrimental effects on the overall meat FA profile.

Are Jatropha curcas phorbol esters degraded by rumen microbes

BACKGROUND Jatropha curcas, a non-edible oil plant, is being promoted as a biofuel plant in a number of countries in tropical and subtropical regions. The kernel meal left after extraction of the oil is a potentially protein-rich feed ingredient. However, the presence of highly toxic phorbol esters limits its use. Degradation of J. curcas phorbol esters by rumen microbes, using an in vitro rumen fermentation system, has been investigated in this study. RESULTS The difference between phorbol ester contents in the residues obtained with and without substrates at 0, 24, 48 or 72 h of the incubations was statistically similar. Phorbol esters did not affect either the gas or short chain production in the in vitro rumen fermentation system. CONCLUSIONS Rumen microbes can not degrade phorbol esters. In addition, the phorbol esters do not adversely affect rumen fermentation. Ruminants are expected to be as prone as monogastric animals to the toxicity of Jatropha seeds.