G. C. Waghorn

Effects of condensed tannins in Lotus pedunculatus on its nutritive value for sheep. 1. Non-nitrogenous aspects

Lotus pedunculatus was grown under high fertility conditions and its nutritive value was determined in a feeding trial with sheep at Palmerston North, New Zealand in 1989. The condensed tannins (CT) accounted for 5.5% of lotus dry matter (DM) and its effect on digestion was evaluated by giving an intraruminal infusion of polyethylene glycol (PEG) to six of the sheep (PEG group). PEG preferentially binds with CT so that the lotus becomes essentially CT-free. The experiment was carried out with 14 sheep (six PEG and eight «Tannin») held in metabolism crates indoors and given freshly cut lotus hourly, for 32 days. This paper presents data relating to carbohydrate and mineral digestion, together with aspects of rumen function [...]

Effect of condensed tannins upon the performance of lambs grazing Lotus corniculatus and lucerne ( Medicago sativa )

A grazing experiment, conducted for 22 weeks in 1992/93 at Aorangi Research Station, AgResearch Grasslands, Manawatu, New Zealand, compared the productivity of weaned lambs grazing Lotus corniculatus (birdsfoot trefoil) and lucerne (Medicago sativa). Effects of condensed tannins (CT) in lotus were evaluated by studying the responses of lambs to twice daily oral supplementation with polyethylene glycol (PEG). A rotational grazing system with restricted feed allowance was used. Measurements were made of pre- and post-grazing herbage mass, the composition of the feed on offer and diet selected, voluntary feed intake (VFI), liveweight gain (LWG), carcass growth, wool growth and the concentration of metabolites in rumen fluid. For both lotus and lucerne swards, the diet selected was mainly leaf. Lotus contained 34 g total CT/kg dry matter in the diet selected, whilst there were essentially no CT in lucerne. Compared to lambs grazing lucerne, lambs grazing lotus had slightly lower VFI, and higher LWG, carcass weight gain, carcass dressing-out percentage and wool growth. PEG supplementation had no effect on these measurements or upon the composition of rumen fluid in lambs grazing lucerne. However, in lambs grazing lotus, PEG supplementation reduced wool growth (10.9 v. 12.1 g/day), slightly reduced LWG (188 v. 203 g/day), increased rumen ammonia concentration, and increased the molar proportions of iso-butyric, isovaleric and n-valeric acids and protozoa numbers in rumen fluid. PEG supplementation did not affect carcass gain, carcass fatness or the molar proportion of rumen acetic, propionic or n-butyric acids in lambs grazing lotus. It was concluded that the principal effect of CT in growing lambs grazing lotus was to increase wool growth without affecting VFI, thereby increasing the efficiency of wool production, that the greater rate of carcass gain of lambs grazing lotus than those grazing lucerne was mainly caused by factors other than CT and that CT did not affect the rumen fermentation of carbohydrate to major volatile fatty acids.

Effect of condensed tannins in Lotus corniculatus upon lactation performance in ewes

A grazing experiment was conducted for 8 weeks in the spring/summer of 1993 at Palmerston North, New Zealand, to study the effects of condensed tannins (CT) in Lotus corniculatus (birdsfoot trefoil cv. Grasslands Goldie) upon the lactation performance of ewes rearing twin lambs. Effects of CT were evaluated by studying the responses of ewes to twice daily oral supplementation with polyethylene glycol (PEG; MW 3500), which binds and inactivates CT. A rotational grazing system with restricted feed allowance was used. Measurements were made of pre- and post-grazing herbage mass, the composition of the feed on offer and diet selected, voluntary feed intake (VF1), milk yield and composition, liveweight gain and wool production. The concentration of metabolites in rumen fluid and in blood plasma was also measured. Lotus contained 35–5 g total nitrogen and 44–5 g total CT/kg dry matter in the diet selected, with an in vitro digestibility of 73%. At peak lactation (weeks 3 and 4) milk yield and composition were similar for control (CT-acting) and PEG-supplemented (CTinactivated) ewes but, as lactation progressed, the decline in milk production and in the secretion rates of protein and lactose were less for control than for PEG-supplemented ewes. In mid and late lactation (weeks 6–11), control ewes secreted more milk (21 %), more milk protein (14%) and more lactose (12%) than PEG-supplemented ewes. Milk fat percentage was lower for control than for PEG-supplemented ewes, but secretion rates of fat were similar for the two groups. VFI, liveweight gain and wool growth were similar for both groups. Plasma urea and glucose concentrations were lower for control than for PEG-supplemented ewes, but concentrations of non-esterified fatty acids (NEFA), growth hormone and insulin were similar for the two groups. The concentrations of ammonia and molar proportions of iso -butyric, iso -and n -valeric acids in rumen fluid were lower for control than for PEG-supplemented ewes; molar proportions of acetic, propionic and H-butyric acids were similar for the two groups. It was concluded that for ewes rearing twin lambs grazing L. corniculatus , the action of CT increased milk yield and the secretion rates of protein and lactose without affecting VFI, thereby increasing the efficiency of milk production. The increased milk production did not appear to be mediated by effects on plasma concentrations of growth hormone or insulin.

Effect of condensed tannins in Lotus corniculatus on the nutritive value of pasture for sheep

The extent to which condensed tannins (CT) in Lotus corniculatus were able to affect protein degradation and the nutritive value of pasture were evaluated at Palmerston North, New Zealand in 1992 in an indoor feeding trial with sheep and using in vitro incubations. The feeding trial involved three groups of seven young wether sheep held indoors in metabolism crates for the 32-day experimental period with one group fed freshly cut ryegrass/clover pasture (Pasture group) whilst the other two groups received a mixture of c . 37% freshly cut Lotus corniculatus and 63% pasture (dry matter (DM) basis). One of the latter groups was given twice daily oral drenches of polyethylene glycol (PEG) to bind with and remove the effects of the CT (PEG group) whilst the remaining sheep (Tannin group) were not drenched. Intakes of sheep given the mixed diets were constrained to that of the pasture group. The CT concentration in the lotus was 26·1 g/kg DM so that the mixed diets contained c . 10g CT/kg DM. Effects of CT on digestion and sheep performance were minimal. Apparent digestibility of N was lower in the Tannin group (76·4%) than PEG (79·8%) or Pasture (79·4%) sheep ( P <0·001), but there were no differences in DM digestibility (75%) or wool growth from mid-side patches. Rumen ammonia and soluble protein concentrations appeared to be similar in PEG and Tannin sheep and volatile fatty acid (VFA) concentrations were similar in all groups (100 mmol/l). For incubations in vitro , several ratios of Lotus corniculatus : pasture were used to determine the effects of CT on precipitation of soluble proteins and the net yield of ammonia and gas with and without PEG. Homogenates of Lotus corniculatus leaves and pasture showed that 50% of soluble protein was precipitated by 1·3% CT in homogenate DM and there was a substantial decrease in in vitro degradation to ammonia when lotus leaf accounted for 33% or more of DM with pasture. This work emphasises the need for caution when extrapolating from in vitro to the in vivo situation and suggests that 1% CT from Lotus corniculatus may be insufficient to affect the nutritive value of fresh forages for sheep.

Liveweight gain and wool production of sheep grazing Lotus corniculatus and lucerne (Medicago sativa)

Abstract Two grazing experiments were conducted to compare the productivity of lactating ewes (Experiment 1) and weaned lambs (Experiment 2) grazing swards of Lotus corniculatus (birdsfoot trefoil; cv. Grasslands Goldie), lucerne (Medicago sativa; cv. Grasslands Oranga), and a mixture of lucerne and lotus. Measurements were made of pre‐ and post‐grazing herbage mass, the composition of the feed on offer and diet selected, and of voluntary feed intake (VFI; Experiment 2 only), body growth, and wool growth. From the agronomic measurements, it was concluded that the diet selected was mainly leaf in both experiments. Total condensed tannin (CT) content was 32–57 g/kg DM for lotus, 8–10 g/kg DM for the mixture, and negligible for lucerne (less than 2 g/kg DM). In Experiment 1, ewe wool production and lamb liveweight gain (LWG) did not differ between forages, but ewe LWG was greater on lotus than on lucerne (251 versus 65 g/day; P < 0.001), with the mixture being intermediate (115 g/day). In Experiment 2, VFI (...

Methane emission by alpaca and sheep fed on lucerne hay or grazed on pastures of perennial ryegrass/white clover or birdsfoot trefoil

Based on the knowledge that alpaca (Lama paces) have a lower fractional outflow rate of feed particles (particulate FOR) from their forestomach than sheep (San Martin 1987), the current study measured methane (CH 4 ) production and other digestion parameters in these species in three successive experiments (1, 2 and 3): Experiment 1, lucerne hay fed indoors; Experiment 2, grazed on perennial ryegrass/white clover pasture (PRG/WC); and Experiment 3, grazed on birdsfoot trefoil (Lotus corniculatus) pasture (Lotus). Six male alpaca and six castrated Romney sheep were simultaneously and successively fed on the forages either ad libitum or at generous herbage allowances (grazing). CH 4 production (g/day) (using the sulphur hexafluoride tracer technique), voluntary feed intake (VFI), diet quality, and protozoa counts and volatile fatty acid concentrations in samples of forestomach contents were determined. In addition, feed digestibility, energy and nitrogen (N) balances and microbial N supply from the forestomach (using purine derivatives excretion) were measured in Experiment 1. Diets selected by alpaca were of lower quality than those selected by sheep, and the voluntary gross energy intakes (GEI, MJ) per kg of liveweight 0.75 were consistently lower (P 0-05) in their CH 4 yields (% GEI) when fed on lucerne hay (5.1 v. 4.7), but alpaca had a higher CH 4 yield when fed on PRG/WC (9.4 v. 7.5, P 0.05) in diet N partition or microbial N yield, but alpaca had higher (P<0.05) neutral detergent fibre digestibility (0.478 v. 0.461) and lower (P<0.01) urinary energy losses (5.2 v. 5.8 % GEI) than sheep. It is suggested that differences between these species in forestomach particulate FOR might have been the underlying physiological mechanism responsible for the differences in CH 4 yield, although the between-species differences in VFI and diet quality also had a major effect on it.

Effect of condensed tannins in Lotus corniculatus upon the digestion of methionine and cysteine in the small intestine of sheep

An experiment was conducted at Palmerston North, New Zealand, to determine the effect of condensed tannins (CT) on the true and apparent digestion of methionine and cysteine in the small intestine (SI) of sheep fed fresh Lotus corniculatus. The lotus contained c. 30 g total CT/kg dry matter (DM) and was fed hourly to sheep in metabolism crates. Four sheep were prepared with rumen and abomasal cannulae which enabled the indigestible liquid phase marker, chromium ethylene diamine tetra-acetic acid (Cr-EDTA), to be infused into the rumen to estimate digesta flow. True digestibility of plant methionine and cysteine in the SI and their site of absorption in the SI were determined from 35 S-labelled L. corniculatus homogenate continuously infused into the abomasum. After 9 h infusion of the 35 S-labelled lotus homogenate, the sheep were slaughtered and digesta samples were taken at intervals along the small and large intestines. The effect of CT was determined by comparing two control sheep (CT-acting) with two sheep given a continuous intraruminal infusion of polyethylene glycol (PEG, MW 3500) to bind and inactivate the CT. The CT reduced the true digestibility of plant methionine (0.72 v. 0.88) and cysteine (0.65 v. 0.81) in the SI relative to sheep receiving PEG. Condensed tannins also appeared to alter the site of digestion of both [ 35 S]methionine and [ 35 S]cysteine in the SI, and increased the flux of both amino acids in the mid and latter thirds of the SI. CT did not affect the apparent digestibility of total methionine (0.82 v. 0.84) in the SI but reduced the apparent digestibility of total cysteine from 0.77 to 0.66. In control sheep CT increased the abomasal flux (as a proportion of eaten) of total digesta methionine (0.88 v. 0.76) and total digesta cysteine (0.74 v. 0.62). The apparent absorption of total methionine (plant + microbial + endogenous) was increased by the action of CT (0.72 v. 0.63 g/g eaten) but was similar for total cysteine (0.49 v. 0.48 g/g eaten) in both groups. It was concluded that CT reduced the true digestibility of plant methionine and cysteine in the SI. However, it was calculated that the action of CT actually increased the total amounts (g/g eaten) of plant methionine and cysteine absorbed from the SI, due to its effect in increasing abomasal flux.

Digestibility and effects of condensed tannins on digestion of sulla (Hedysarum coronarium) when fed to sheep

Abstract Sulla (Hedysarum coronarium) is a short‐lived perennial legume with an erect growth habit which is grown as a fodder crop in Mediterranean regions but is not common in New Zealand agriculture. Recent experimental work has shown potential benefits of sulla for reducing the impact and numbers of intestinal nematodes in sheep and possible benefits for wool production, so that a feeding trial was undertaken to determine its digestibility. Twelve sheep aged about 6 months were held in metabolism crates and fed sulla as a sole diet for the 20‐day experimental period. Sulla contains condensed tannins (CT) so that one group of 6 sheep were given twice‐daily oral drenches of polyethylene glycol (PEG) to bind with and deactivate the CT (PEG group) enabling a comparison with the undrenched Tannin group. The dry matter (DM) content of the sulla was 15.5%, comprising (DM basis) 33% leaf, 41% stem, and 26% flower, and all portions of the plant were eaten. The DM contained about 7.2% CT and 3.0% nitrogen (N). D...

Effect of condensed tannins in birdsfoot trefoil (Lotus corniculatus) and sulla (Hedysarum coronarium) on body weight, carcass fat depth, and wool growth of lambs in New Zealand

Abstract The effects of dietary condensed tannins (CT) on growth and performance of young male weaned lambs were measured during a 4‐month grazing trial when either birdsfoot trefoil (Lotus corniculatus) cv. Grasslands Goldie or sulla (Hedysarum coronarium) cv. Grasslands Aokau were fed. Each legume was offered at restricted and ad libitum allowances and the effects of CT were determined by giving half the lambs in each treatment a twice‐daily drench of polyethylene glycol (PEG; mol wt 3350) to deactivate the CT. Both agronomic and animal performance characteristics were recorded. Sulla had higher (P < 0.01) pre‐grazing herbage masses than birdsfoot trefoil (11.6 cf. 7.1 t DM ha−1) and sulla stem (<6 mm diam.) was eaten, in contrast to birdsfoot trefoil where stem was rejected by the lambs. The sulla and birdsfoot trefoil diets had similar protein concentrations in the DM, but sulla had a higher concentration of total CT (88 cf. 50 g CT kg1 DM) and less structural carbohydrate (189 cf. 328 g kg−1 DM) rela...

Gas production and nitrogen digestion by rumen microbes from deer and sheep

Abstract The rates at which gas was produced by rumen microbes from red deer (Cervus elaphus) and sheep were measured in vitro. The objective was to test the hypothesis that the lower frequency of rumen eructation contractions in deer, compared to sheep and other ruminants, may have been associated with a lower rate of gas production. Two sheep and two deer were held indoors, given the same feed (chaffed lucerne hay) under an identical regimen, and rumen samples obtained on 5 consecutive days from each animal. Duplicate incubations were carried out on each day with a rumen liquor inoculum from each animal in a buffered medium and a ground lucerne hay substrate. The rates of gas production were monitored for 9 h and net ammonia production determined. There were no differences between species in rate of gas production but incubation with deer liquor resulted in a 27% greater (P < 0.01) net conversion of substrate nitrogen (N) to ammonia compared to sheep. Gas production averaged 0.23 ml/min per g substrate ...