e-Cow: an animal model that predicts herbage intake, milk yield and live weight change in dairy cows grazing temperate pastures, with and without supplementary feeding.

This animal simulation model, named e-Cow, represents a single dairy cow at grazing. The model integrates algorithms from three previously published models: a model that predicts herbage dry matter (DM) intake by grazing dairy cows, a mammary gland model that predicts potential milk yield and a body lipid model that predicts genetically driven live weight (LW) and body condition score (BCS). Both nutritional and genetic drives are accounted for in the prediction of energy intake and its partitioning. The main inputs are herbage allowance (HA; kg DM offered/cow per day), metabolisable energy and NDF concentrations in herbage and supplements, supplements offered (kg DM/cow per day), type of pasture (ryegrass or lucerne), days in milk, days pregnant, lactation number, BCS and LW at calving, breed or strain of cow and genetic merit, that is, potential yields of milk, fat and protein. Separate equations are used to predict herbage intake, depending on the cutting heights at which HA is expressed. The e-Cow model is written in Visual Basic programming language within Microsoft Excel®. The model predicts whole-lactation performance of dairy cows on a daily basis, and the main outputs are the daily and annual DM intake, milk yield and changes in BCS and LW. In the e-Cow model, neither herbage DM intake nor milk yield or LW change are needed as inputs; instead, they are predicted by the e-Cow model. The e-Cow model was validated against experimental data for Holstein-Friesian cows with both North American (NA) and New Zealand (NZ) genetics grazing ryegrass-based pastures, with or without supplementary feeding and for three complete lactations, divided into weekly periods. The model was able to predict animal performance with satisfactory accuracy, with concordance correlation coefficients of 0.81, 0.76 and 0.62 for herbage DM intake, milk yield and LW change, respectively. Simulations performed with the model showed that it is sensitive to genotype by feeding environment interactions. The e-Cow model tended to overestimate the milk yield of NA genotype cows at low milk yields, while it underestimated the milk yield of NZ genotype cows at high milk yields. The approach used to define the potential milk yield of the cow and equations used to predict herbage DM intake make the model applicable for predictions in countries with temperate pastures.

Lotus corniculatus condensed tannins decrease in vivo populations of proteolytic bacteria and affect nitrogen metabolism in the rumen of sheep.

Condensed tannins in forage legumes improve the nutrition of sheep by reducing ruminal degradation of plant protein and increasing crude protein flow to the intestine. However, the effects of condensed tannins in forage legumes on rumen bacterial populations in vivo are poorly understood. The aim of this study was to investigate the specific effects of condensed tannins from Lotus corniculatus on four proteolytic rumen bacteria in sheep during and after transition from a ryegrass (Lolium perenne)-white clover (Trifolium repens) diet (i.e., low condensed tannins) to a Lotus corniculatus diet (i.e., higher condensed tannins). The bacterial populations were quantified using a competitive polymerase chain reaction. Lotus corniculatus was fed with or without ruminal infusions of polyethylene glycol (PEG), which binds to and inactivates condensed tannins, enabling the effect of condensed tannins on bacterial populations to be examined. When sheep fed on ryegrass-white clover, populations of Clostridium proteoclasticum B316T, Butyrivibrio fibrisolvens C211a, Eubacterium sp. C12b, and Streptococcus bovis B315 were 1.5 x 10(8), 1.1 x 10(6), 4.6 x 10(8), and 7.1 x 10(6) mL(-1), respectively. When the diet was changed to Lotus corniculatus, the average populations (after 8-120 h) of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis decreased (P < 0.001) to 2.4 x 10(7), 1.1 x 10(5), 1.1 x 10(8), and 2.5 x 10(5) mL(-1), respectively. When PEG was infused into the rumen of sheep fed Lotus corniculatus, the populations of C. proteoclasticum, B. fibrisolvens, Eubacterium sp., and S. bovis were higher (P < 0.01-0.001) than in sheep fed Lotus corniculatus without the PEG infusion, with average populations (after 8-120 h) of 4.9 x 10(7), 3.8 x 10(5), 1.9 x 10(8), and 1.0 x 10(6), respectively. Sheep fed the Lotus corniculatus diet had lower rumen proteinase activity, ammonia, and soluble nitrogen (P < 0.05-0.001) than sheep that were fed Lotus corniculatus plus PEG. The Lotus corniculatus diet reduced rumen nitrogen digestibility (P < 0.05) and ammonia pool size and increased the flow of undegraded feed nitrogen to the abomasum. The nitrogen intake, rumen non-ammonia nitrogen pool size, rumen microbial non-ammonia nitrogen pool size, and abomasal microbial non-ammonia nitrogen fluxes were similar both in sheep fed only Lotus corniculatus and in sheep fed Lotus corniculatus plus PEG, but nonmicrobial non-ammonia nitrogen flux to the abomasum was higher (P < 0.01) for the sheep fed only Lotus corniculatus. Although condensed tannins in Lotus corniculatus reduced the populations of some proteolytic bacteria, total ruminal microbial protein and microbial protein outflow to the abomasum were unchanged, suggesting a species-specific effect of condensed tannins on bacteria in the rumen.

Effect of condensed tannins extracted from four forages on the viability of the larvae of deer lungworms and gastrointestinal nematodes.

The inhibitory activity of condensed tannins extracted from four forage legume plants were evaluated by using a larval migration inhibition assay. The first (L1) and third (L3) stages of deer lungworm (Dictyocaulus viviparus), and the third stage (L3) of deer gastrointestinal nematodes were incubated with tannins extracted from Lotus pedunculatus, Lotus corniculatus, sulla (Hedysarum coronarium) and sainfoin (Onobrychus viciifolia). The tannins extracted from all the forages had inhibitory activity as measured by their ability to paralyse the larvae and inhibit them from passing through sieves. At the highest concentration used (1200 microg/ml) the tannins extracted from sainfoin had the highest activity against ensheathed L1 lungworm larvae (58 per cent), followed by L. pedunculatus (45 per cent), sulla (42 per cent) and L. comiculatus (35 per cent) when the larvae were incubated at 37 degrees C. The same trend, but with lower activities, was observed when the larvae were incubated at 22 degrees C. Anthelmintic activity against L3 lungworm larvae was evaluated by measuring the death rate of ensheathed L3 larvae after incubation with condensed tannins for two, 24 and 48 hours at room temperature (22 degrees C). The death rate was significantly higher (P<0.001) after 48 hours incubation than after two hours or 24 hours, and significantly higher (P<0.001) after 24 hours than after two hours incubation. Condensed tannins from sainfoin had the highest inhibitory activity followed by L. pedunculatus, sulla and L. comiculatus. The tannins from sainfoin also had the highest activity against L3 larvae of gastrointestinal nematodes, followed by L. pedunculatus, sulla and L. comiculatus. Exsheathed larvae of gastrointestinal nematodes were significantly more susceptible to the action of the tannins than ensheathed larvae.

Effect of forage legumes containing condensed tannins on lungworm (Dictyocaulus sp.) and gastrointestinal parasitism in young red deer (Cervus elaphus).

To investigate the effect of feeding forage legumes containing condensed tannins (CT) on internal parasitism, red deer calves were fed either lucerne (Medicago sativa; 0.1 per cent CT), birdsfoot trefoil (Lotus corniculatus; 1.9 per cent CT) or sulla (Hedysarum coronarium; 3.5 per cent CT) and trickle-infected with deer-origin gastrointestinal nematode and lungworm (Dictyocaulus sp.) larvae for 5 weeks, then slaughtered at 7 weeks. There was a significant negative linear relationship between dietary CT concentration and abomasal nematode burdens. No significant differences in faecal egg counts, lungworm burdens or voluntary feed intake were found. Deer fed sulla had higher liveweight gain, carcass weight and carcass dressing-out percentage, higher serum total protein and albumin concentration and lower serum gastrin concentration and faecal lungworm larval count, compared with lucerne-fed deer. Inclusion of sulla in diets for young red deer may reduce the impact of internal parasites and/or reduce the dependence on anthelmintic treatment.

The effect of condensed tannins in Lotus pedunculatus on the solubilization and degradation of ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39; Rubisco) protein in the rumen and the sites of Rubisco digestion.

Three experiments were undertaken to determine the effect of condensed tannin (CT) in Lotus pedunculatus (45-55 g extractable CT/kg DM) on the digestion of the principal leaf protein, ribulose-1,5-bisphosphate carboxylase (EC 4.1.1.39; Rubisco; fraction 1 leaf protein). In two of the experiments Lotus pedunculatus was fed to sheep, with one group receiving a continuous intraruminal infusion (per fistulum) of PEG (molecular weight 3500) to bind and inactivate the CT (PEG group). The other group, which did not receive PEG, was termed the control sheep (CT acting). Expt 3 involved in vitro incubations of Lotus pedunculatus in buffered rumen fluid, with and without PEG added. In all experiments the results have been interpreted in terms of the effects of CT on Rubisco solubilization and degradation. Disappearance of N and Rubisco from Lotus pedunculatus suspended in polyester bags in the rumen was used as a measure of solubilization. Degradation was defined as the disappearance of Rubisco from in vitro incubations of Lotus pedunculatus in rumen fluid. In Expt 1, CT reduced the digestion of Rubisco in the rumen from 0.96 to 0.72 of intake (P < 0.01). Rubisco digestion in the small intestine was 0.27 of intake in control sheep and 0.04 of intake in PEG sheep. In Expt 2, PEG had no effect on the loss of Rubisco from Lotus pedunculatus contained in polyester bags which were incubated in the rumen, hence CT did not affect the solubilization of Rubisco. Observations in Expt 1 were confirmed by in vitro incubations in Expt 3, where PEG addition substantially increased the rate of degradation of plant protein to NH3. Addition of PEG decreased the period of time taken to degrade 50% of the Rubisco from about 13.8 h to about 3.0 h. It was concluded that the action of CT reduced the digestion of Rubisco in the rumen of sheep fed on fresh Lotus pedunculatus, and that this was primarily due to the ability of CT to slow its degradation by rumen micro-organisms, without affecting its solubilization. Both fresh-minced, and freeze-dried and ground lotus were used for in sacco and in vitro incubations; however, fresh-minced lotus was more suitable for the evaluation of protein solubilization and degradation in fresh forages.

The effect of condensed tannins from heated and unheated cottonseed on the ileal digestibility of amino acids for the growing rat and pig.

The effect of condensed tannins (CT) from heated and unheated cottonseed on the apparent ileal digestibility of amino acids for the growing rat and pig was determined. In Expt 1, twenty-four rats were allocated to four semi-purified diets which contained cottonseed kernel and hulls as the only protein source. Two of the diets contained unheated solvent-extracted cottonseed kernel and hulls, while the remaining two diets contained similar material but which had been heat-treated by autoclaving at 110 degrees for 120 min. In Expt 2, twelve rats and twelve pigs were fed on four semi-purified diets containing commercial cottonseed meal (CSM) as the only protein source. Cr2O3 was added to all diets as an indigestible marker. For each pair of diets in both experiments, PEG was either included or excluded. The effect of CT was assessed by comparing control animals (-PEG; CT acting) with PEG-supplemented animals (+PEG; CT inactivated). Ileal contents from the terminal 150 and 450 mm of ileum were collected at slaughter, 7 h from the start of feeding, for the rats and pigs respectively. Apparent ileal amino acid digestibility for rats fed on the diet containing cottonseed kernel and hulls was significantly depressed by the heat treatment, particularly for lysine and threonine. On average, apparent ileal amino acid digestibility in the diets without PEG was decreased from 0.80 to 0.70 by heat treatment. Dietary cottonseed CT depressed apparent ileal protein digestibility in the pig and in the rat. The addition of PEG to the diets significantly increased the apparent ileal digestibility of N and some amino acids for the pigs and the rats. The mean increase in apparent ileal digestibility due to PEG addition for the fourteen amino acids was 2 percentage units in both species fed on the commercial CSM diets, and 2 or 4 percentage units in rats fed on the unheated or the heated cottonseed kernel and hull diets respectively. The effect of PEG was similar in the heated and unheated cottonseed kernel and hulls for most amino acids, but apparent ileal digestibilities of threonine, tyrosine and lysine were increased more by PEG in heated than in unheated CSM. Apparent ileal N digestibility was lower in the pig than in the rat. For several of the amino acids there were significant animal species differences in apparent ileal digestibility. Studies into the effects of cottonseed CT should be carried out in the target animal species. The commercial CSM had a low apparent ileal amino acid digestibility overall, particularly for the essential amino acids lysine and threonine. It was concluded that effects of heating did not eliminate the reversible reactivity of cottonseed CT on amino acid digestion in rats and pigs but rather appeared to increase it for threonine, tyrosine and lysine in Expt 1, causing large reductions in apparent ileal digestibility of these amino acids.

The effect of cottonseed condensed tannins on the ileal digestibility of amino acids in casein and cottonseed kernel.

The effect of adding cottonseed hulls to casein- and cottonseed-kernel-based diets on the apparent and true ileal digestibility of N and amino acids, and the proportion of this effect accounted for by condensed tannin (CT), were determined using the growing rat. Sixty rats were allocated randomly to ten semipurified diets, containing either casein (four diets) or purified unheated solvent-extracted cottonseed kernel (six diets) as the sole protein source, with Cr2O3 added as an indigestible marker. Two of the casein diets contained no hulls whilst the remaining two diets contained 70 g cottonseed hulls/kg. Two of the cottonseed-kernel-based diets contained no hulls, with two containing 23 g hulls/kg and the remaining two containing 46 g hulls/kg. For each pair of diets, PEG was either included or excluded. The effect of CT was quantified by comparing control rats (-PEG; CT acting) with PEG-supplemented rats (+PEG; CT inactivated) at each level of dietary hulls. The rats were given their respective experimental diets for 14 d. Each rat was given the food ad libitum for 10 min hourly from 08.00 to 18.00 hours. On day 14, samples of digesta were collected at death from the terminal 150 mm of ileum at 7 h from the first meal. Apparent and true ileal digestibilities were calculated for DM, N and the individual amino acids. The principal finding was that the inclusion of hulls depressed the apparent and true ileal digestibilities of N and amino acids, but with the response differing between diets. With the casein-based diet the mean apparent and true ileal amino acid digestibilities were significantly depressed from 0.89 and 0.96 to 0.85 and 0.92 respectively, by the inclusion of 70 g hulls/kg in the diet, and addition of PEG then restored these to 0.89 and 0.95. All of the depression could be explained by the CT content of the hulls. However, with the cottonseed-kernel-based diet the responses fell into three categories. The apparent and true ileal digestibilities of the essential amino acids cystine and methionine were not affected by hull addition, ileal digestibilities of leucine, isoleucine, lysine, threonine and valine were markedly depressed by hull addition with approximately 50% of the depression being explained by CT, whilst the ileal digestibilities of histidine, arginine and phenylalanine were depressed by hull addition but little or none of this effect could be explained by CT. Thus the effect of hulls on protein digestion clearly differed with source of protein. With the cottonseed-kernel-based diet it seems that components of the hulls other than CT also depressed the apparent and true ileal digestibilities of N and amino acids. The identity of these components is unknown.

The effect of condensed tannins in Lotus corniculatus on plasma metabolism of methionine, cystine and inorganic sulphate by sheep.

Fresh Lotus corniculatus containing 27 g extractable condensed tannin (CT)/kg dry matter (DM) and 8 g bound CT/kg DM was fed at hourly intervals to sheep held in metabolism cages to study the effects of CT on nutrient digestion and on metabolism of methionine, cystine and inorganic sulphate in plasma. Polyethylene glycol (PEG) was continuously infused into the rumen of half the sheep to remove the effects of CT. Principal measurements in the two groups were plasma irreversible loss (IRL) rate and interconversions of methionine, cystine and inorganic sulphate using 35S labelling. CT in Lotus corniculatus had no effects on the apparent digestion of cellulose and minerals, slightly depressed DM, organic matter and hemicellulose digestion and markedly reduced the apparent digestion of N (P < 0.01). The concentration of NH3 and molar proportions of iso-butyric acid, iso-valeric acid and n-valeric acid in rumen fluid were markedly increased by the PEG infusion (P < 0.01), whereas total volatile fatty acid concentration and molar proportions of acetic acid, propionic acid and n-butyric acid were not affected. PEG infusion temporarily increased rumen protozoa numbers. CT greatly increased the IRL of plasma cystine (13.1 v. 7.0 mumol/min; P < 0.05) and reduced IRL of plasma inorganic sulphate (36.8 v. 48.1 mumol/min; P < 0.01) but had no effect on methionine IRL. CT increased transulphuration of methionine to cystine (4.37 v. 1.24 mumol/min; P < 0.05), increased cystine entering the plasma from whole-body protein turnover plus absorption from the small intestine (9.34 v. 5.75 mumol/min; P < 0.05) and increased cystine flux to body synthetic reactions (11.89 v. 5.41 mumol/min; P < 0.05). CT had no effect on the proportion of methionine total flux transferred to sulphate (0.05 v. 0.06; P < 0.05), reduced the proportion of methionine flux transferred to body synthetic reactions (0.68 v. 0.86) and markedly reduced the proportion of cystine flux transferred to sulphate (0.09 v. 0.27; P < 0.01). It was concluded that CT in Lotus corniculatus reduced rumen protein degradation and markedly increased utilization of plasma cystine for body synthetic reactions.

The effect of condensed tannins in Lotus pedunculatus on the digestion and metabolism of methionine, cystine and inorganic sulphur in sheep.

Two experiments were conducted with sheep fed on fresh Lotus pedunculatus containing 50-55 g condensed tannin (CT)/kg dry matter. Effects of CT were assessed by comparing control sheep (CT operating) with sheep receiving a continuous intraruminal infusion of polyethylene glycol (PEG) to bind and inactivate CT. Digestion of methionine and cystine was determined using a continuous intraruminal infusion of indigestible markers, whilst plasma irreversible loss (IRL) of methionine, cystine and inorganic sulphate was determined using 35S labelling. The proportion of microbial non-NH3-N (NAN) in whole rumen digesta NAN and the IRL of reducible S from the rumen were determined using a continuous intraruminal infusion of (NH4)2(35)SO4. The proportion of microbial NAN in whole rumen digesta NAN (0.44 v. 0.71) and the IRL of reducible S from the rumen (0.84 v. 2.49 g S/d) were lower in control than PEG sheep. PEG sheep lost 30% of ingested methionine and cystine across the rumen, whereas the control sheep lost no methionine and cystine across the rumen. Apparent absorption of methionine from the small intestine was 27% higher in control than PEG sheep, but both groups had a similar apparent absorption of cystine. The apparent digestibility of cystine in the small intestine was lower in control (0.42) than PEG (0.53) sheep, whereas the apparent digestibility of methionine was similar (0.78) for both groups. CT had no effect on plasma methionine IRL, but markedly increased the IRL of cystine (39.8 v. 22.4 mumol/min) and reduced the IRL of plasma inorganic sulphate (35.9 v. 50.2 mumol/min). A three-pool model comparing interconversions between the three plasma metabolites showed that CT increased the flow of cystine to body synthetic reactions (36.5 v. 17.3 mumol/min). This was due to trans-sulphuration of methionine to cystine being greater in control than in PEG sheep, whilst the oxidation of both methionine and cystine were reduced in control sheep. It was concluded that CT reduced the proteolysis of forage protein and the degradation of S amino acids to inorganic sulphide in the rumen, resulting in increased net absorption of methionine and increased utilization of cystine for body synthetic reactions in sheep with a high capacity for wool growth (and, hence, high cystine requirement).

Responses to oral methionine supplementation in sheep fed on kale (Brassica oleracea) diets containing S-methyl-L-cysteine sulphoxide.

1. Responses to twice-weekly oral supplementation with 4.0 g methionine were measured with lambs (27 kg) grazing kale (Brassica oleracea) for 10 weeks (Expt 1). In a second experiment with sheep fed on kale at hourly intervals, rumen fractional outflow rates of CrEDTA and ruthenium Tris(1,10 phenanthroline) markers were measured from the rates of decline in their concentrations. Rumen turnover of S-methyl-L-cysteine sulphoxide (SMCO) and of carbohydrate (CHO) constituents were also measured. The kale fed contained 11.4 g SMCO/kg dry matter and the ratio, readily-fermentable: structural CHO was high at 2.9. 2. Severe haemolytic anaemia, associated with low live-weight gain (LWG), occurred in the lambs during the initial 5 weeks of grazing, due to rumen fermentation of SMCO. Oral methionine supplementation raised plasma concentrations of methionine and cysteine, increased wool growth rate, and increased LWG during the initial 5 weeks. Methionine supplementation also increased rumen pool and plasma SMCO concentrations, suggesting reduced rumen SMCO fermentation. 3. In Expt 2, rumen degradation rate of SMCO (1.2/h) was calculated to be twice as fast as that of the most rapidly fermented dietary CHO constituents and eight times faster than the rate of water outflow (0.16/h), thus explaining its virtually complete rumen degradation and toxicity in brassica diets. It was estimated that 1.2 g of each 4.0 g methionine administered would have escaped rumen degradation, due to the high rate of water outflow from the rumen. 4. Disappearance rates of CHO constituents from the rumen were as predicted for normal ruminant diets, showing that rumen metabolism of SMCO did not have a depressive effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocrine regulation of metabolism in sheep given kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) fresh-forage diets.

Diets of fresh kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) herbage were fed to growing sheep in three experiments. In Expts 1 and 3 the sheep were confined indoors and fed at hourly intervals, and all were given supplementary iodine to counteract kale goitrogens. Lambs grazed the two forages for 24 weeks in Expt 2, with and without intramuscular injections of iodized oil. The kale and herbage contained respectively 11 and less than 0.1 g S-methyl-L-cysteine sulphoxide (SMCO)/kg dry matter (DM) and values for readily fermentable: structural carbohydrate (CHO) were 3.1 and 0.8, respectively. Blood samples were withdrawn from indwelling catheters (Expts 1 and 3) or venipuncture (Expt 2) and the plasma analysed for a range of hormones using radioimmunoassay procedures. Glucose irreversible loss (GIL) was measured in Expt 1 using primed continuous infusions of D-[U-14C]glucose. Samples of adipose tissue were removed from the shoulder area in Expt 3, and rates of D-[U-14C]glucose and [U-14C]acetate incorporation and oxidation were measured in vitro, together with the rate of glycerol release. In the presence of supplementary I2, kale feeding was associated with an elevation in plasma concentration of free thyroxine (T4). Regardless of I2 supplementation, sheep fed on kale had much higher plasma growth hormone concentrations than sheep fed on ryegrass-clover herbage, and this was accompanied by reduced plasma somatostatin concentrations. Plasma insulin and glucagon concentrations were similar for sheep fed on the two diets; GIL tended to be slightly but not significantly greater (9.4%) for sheep fed on kale than for those fed on ryegrass-clover herbage.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 1. Voluntary intake.

Voluntary intake was determined with vegetative Lotus pedunculatus cut and fed fresh to growing sheep of 42-46 kg live weight. Effects attributable to condensed tannins were assessed by growing the plant under high and low levels of soil fertility, inducing low and high concentrations of tannin (Expt 1), or by binding the tannins through spraying the herbage with polyethylene glycol (molecular weight 3350, PEG; Expt 2). Primary-growth lotus was used in Expt 1 and secondary-growth lotus in Expt 2. Concentrations of total and free condensed tannin were determined in fresh lotus, free tanning being defined as that not bound by mascerates of the plant. In Expt 1 the herbages fed contained respectively 46 and 106 g total condensed tannin/kg dry matter (DM) and 3 and 14 g free condensed tannin/kg DM. Mean metabolizable energy (ME) intakes were 0.89 and 0.77 MJ/kg live weight0 .75 per d (P less than 0.05) respectively. The lotus used in Expt 2 contained 63 and 5 g total reactive condensed tannin and free condensed tannin/kg DM respectively. After spraying with PEG at 2.4 g/g total condensed tannin, these values were reduced to 7 and 0.5 g/kg DM respectively. PEG addition increased apparent digestibility (proportion of each nutrient ingested) of cellulose, hemicellulose and nitrogen by 0.05, 0.08 and 0.26, and increased ME intake from 0.48 to 0.69 MJ/kg live weight0 .75 per d. It was concluded that high concentrations of condensed tannins depressed ME intake, due to depressions in both the voluntary intake and digestion of organic matter.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of condensed tannins in the nutritional value of Lotus pedunculatus for sheep. 2. Quantitative digestion of carbohydrates and proteins.

Primary growth vegetative Lotus pedunculatus containing 46 and 106 g/kg dry matter (DM) of total condensed tannin and 3 and 14 g/kg DM of free condensed tannin, was cut and fed fresh at hourly intervals (750 g DM/d) to sheep fitted with permanent cannulas into the rumen and duodenum. Low- and high-tannin lotus contained respectively 41.3 and 31.6 g total nitrogen/kg DM and 132 and 152 g lignin/kg DM. The two forms of lotus were similar in carbohydrate composition. Nutrient intake was recorded and faecal output measured by direct collection. Digesta flow to the duodenum was estimated by measuring dilution at the duodenum of inert ruthenium phenanthroline (Ru-P) and chromium-EDTA markers continuously infused into the rumen. Effects attributable to condensed tannins were assessed by comparing the digestion of the two diets, and by comparing the digestion of each with predicted values for non-tannin-containing fresh forages fed at similar intakes. Apparent digestibility of all nutrients measured was less for high- than for low-tannin lotus (P less than 0.01). The levels of cellulose digested ruminally and post- ruminally in both forms of lotus were similar to predicted values. However, less hemicellulose and readily fermentable carbohydrate (RFC; soluble carbohydrate + pectin) was digested in the rumen in sheep given both forms of lotus than would be predicted for non-tannin-containing fresh forage diets, but this was compensated for by greater post-ruminal absorption of both nutrients. Total N gains across the rumen (duodenal N flow--total N intake) were 1.8 and 10.5 g/d for low- and high-tannin lotus v. predicted losses of 3.7 and 2.1 g/d for non-tannin-containing fresh forages given at the same total N intakes. Post-ruminal digestion of non- amonia -N (NAN; proportion NAN flowing at duodenum) was 0.71 and 0.67 for low- and high-tannin lotus respectively v. 0.76 for comparable non-tannin-containing fresh forages. Energy absorbed as amino acids from the small intestine was calculated to be 0.29 of metabolizable energy for both forms of lotus, compared with 0.17 and 0.21 for perennial ryegrass and white clover. It was concluded that the presence of condensed tannins in lotus markedly increased post-ruminal NAN absorption compared with non-tannin-containing fresh forage diets, but depressed ruminal digestion of RFC and hemicellulose.

Copper metabolism in growing sheep given kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) fresh forage diets.

Kale (Brassica oleracea) and ryegrass (Lolium perenne)-clover (Trifolium repens) pasture grown under similar soil conditions were grazed in the vegetative state by growing lambs of 23.6 kg initial live weight for 24 weeks. Forty-eight lambs grazed each forage. The kale and pasture contained respectively 4 and 14 mg copper/kg dry matter (DM), 7.2 and 3.1 g total sulphur/kg DM and 0.4 and 1.1 mg molybdenum/kg DM. Subcutaneous injections of Cu (12 mg) were given to half the animals grazing each forage during weeks 1, 6, 12 and 18. All ninety-six animals were slaughtered at the end of the experiment and an additional group of twelve animals was slaughtered when the experiment commenced. Liver Cu was determined on all slaughtered animals and heart muscle cytochrome oxidase (EC 1.9.3.1) activity on those slaughtered at week 24. Blood samples removed at 6-week intervals were assayed for activity of superoxide dismutase (EC 1.15.1.1; SOD) and serum Cu concentration determined. Wool growth, live-weight gain and cytochrome oxidase activity of biopsied hind-limb muscle were also measured at 6-week intervals. Control animals grazing pasture showed an accumulation of total liver Cu during the experiment. Animals grazing this diet and given Cu injections showed an additional accumulation of liver Cu equivalent to the supplementary Cu administered, but Cu supplementation did not affect the activity of any of the Cu-containing enzymes measured and did not affect live-weight gain or wool growth. Control animals grazing kale showed a depletion of total liver Cu and reductions in serum Cu concentrations during weeks 18 and 24.(ABSTRACT TRUNCATED AT 250 WORDS)