Sheep In Experiment Research Articles

Individual-level correlations of rumen volatile fatty acids with enteric methane emissions for ranking methane yield in sheep fed fresh pasture

Context Total ruminal volatile fatty acids (VFA) or acetate concentrations were previously found to be moderate correlated proxies to select sheep that are genetically low methane (CH4) emitters. However, this was based on trials, with sheep fed lucerne pellets at a fixed feeding level, which is different from pastoral farming conditions in New Zealand, where the correlated proxy would be applied. Aim To determine repeatability and individual-level correlation of rumen VFAs with CH4 emissions in sheep fed ad libitum cut pasture in three and four repeated periods in Experiments 1 and 2 respectively. Sheep in Experiment 1 were also fed lucerne pellets at 2.0 × maintenance-energy requirements in two periods. Methods Methane emissions were measured from 96 and 72 animals, in Experiments 1 and 2 respectively, in respiration chambers and rumen samples were collected via oral stomach tubing before morning feeding. Repeatability estimates between periods within feed and experiment serve as an upper threshold for the estimate of heritability and ri estimates are a proxy for genetic correlation. Key results Methane (g/day) production and yield (g/kg dry-matter intake) were low to moderately repeatable traits on pasture across periods (0.58 and 0.39 for CH4 production and 0.43 and 0.32 for yield in Experiments 1 and 2 respectively). On pasture, repeatability was generally greater for VFA proportions (0.13–0.32) than for VFA concentrations (0.02–0.24), while the opposite was the case on lucerne pellets. Rumen propionate as a proportion of total VFA had strong negative ri (−0.82 and −0.87) and acetate:propionate ratio (A:P; 0.82 and 0.78) and (acetate + butyrate):(propionate + valerate) ratio (AB:PV; 0.84 and 0.82) had a strong positive ri with CH4 yield in sheep fed cut pasture, while the ri of total ruminal VFA (−0.13 and 0.35) and acetate (−0.08 and 0.38) concentrations with CH4 yield were only moderate and non-significant. Conclusion The VFA traits propionate proportion and A:P and AB:PV ratios had strong individual-level correlations with CH4 yield in sheep fed pasture ad libitum, suggesting that they would be useful correlated proxies to rank sheep CH4 yields.

Experimental poisoning by Enterolobium contortisiliquum in sheep

ABSTRACT: Ingestion of Enterolobium contortisiliquum pods causes digestive disturbances, secondary hepatogenous photosensitization and abortions in ruminants. Pods were administered to sheep via a ruminal cannula to characterize acute poisoning. In Experiment 1, a single dose of 12g/kg of body weight (BW) was administered to three sheep in one experiment. One sheep died, and the other two recovered after presenting clinical signs. In Experiment 2, 10g/kg BW were administered daily to 15 sheep until the onset of clinical signs or for three consecutive days. Fourteen sheep showed mild to severe signs after the ingestion of 1-3 doses. Two sheep died, and the others recovered. Clinical signs in both experiments were diarrhea, anorexia, rumen atony, apathy, dehydration and tachypnea. The main macroscopic findings were an orange, frothy ruminal content witch contained pods fragments. The intestinal content was liquid. Detachment of the mucosa from the submucosa and ballooning degeneration of mucosal cells were observed histologically in the forestomachs. Evaluation of ruminal contents revealed acute lactic ruminal acidosis (ALRA). Bromatological analysis of E. contortisiliquum pods revealed 537.8g/kg DM (dry matter) of non-fibrous carbohydrates, which is sufficient to cause ALRA. Only one sheep in Experiment 2 had liver failure, characterized by jaundice, elevated serum activity of liver enzymes and histological lesions in liver biopsies. It is concluded that the administration of E. contortisiliquum pods in forage-fed sheep at doses of 10g/kg BW or higher may cause ALRA. The induction of liver failure in one sheep suggests that liver damage may occur in those sheep that do not develop acidosis.

Патофизиологические реакции пульпы и пародонта аутотрансплантированных зубов в эксперименте

Патофизиологические реакции пульпы и пародонта аутотрансплантированных зубов в эксперименте

Патофизиологические реакции пульпы и пародонта аутотрансплантированных зубов в эксперименте

Патофизиологические реакции пульпы и пародонта аутотрансплантированных зубов в эксперименте

Early Word Recognition in Sentence Context: French and English 24‐Month‐Olds' Sensitivity to Sentence‐Medial Mispronunciations and Assimilations

Recent work has shown that young children can use fine phonetic detail during the recognition of isolated and sentence‐final words from early in lexical development. The present study investigates 24‐month‐olds' word recognition in sentence‐medial position in two experiments using an Intermodal Preferential Looking paradigm. In Experiment 1, French toddlers detect word‐final voicing mispronunciations (e.g., buz [byz] for bus [bys] “bus”), and they compensate for native voicing assimilations (e.g., buz devant toi [buzdəvɑ̃twa] “bus in front of you”) in the middle of sentences. Similarly, English toddlers detect word‐final voicing mispronunciations (e.g., sheeb for sheep) in Experiment 2, but they do not compensate for illicit voicing assimilations (e.g., sheeb there). Thus, French and English 24‐month‐olds can take into account fine phonetic detail even if words are presented in the middle of sentences, and French toddlers show language‐specific compensation abilities for pronunciation variation caused by native voicing assimilation.

Effects of feed intake on enteric methane emissions from sheep fed fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne) forages

Published analyses of enteric methane (CH4) emissions from sheep and cattle show an inverse relationship between feed intake and CH4 yield (gCH4/kg dry matter (DM) intake), which suggests opportunities for reducing CH4 emissions from feed eaten and per unit of animal production. Most relationships between feed intake and CH4 yield have been based on animals fed conserved feeds, especially silages and grains. Our research is a series of experiments with fresh white clover (Trifolium repens) and perennial ryegrass (Lolium perenne; ryegrass) forages fed to sheep at a range of feed intake levels. This study was comprised of four experiments where good quality freshly harvested white clover or ryegrass were fed to sheep over a three-fold range in DM intake, and CH4 emissions were measured in respiration chambers for two consecutive days in each experiment. Measurements were made from 16 sheep in Experiment 1 (fed at 1.6×metabolizable energy requirements for maintenance; MEm), 28 sheep in Experiment 2 (at 0.8 and 2.0×MEm), eight sheep and two measurement periods in Experiment 3 (at 1.6×MEm), and 30 sheep in Experiment 4 (fed at 0.8, 1.2, 1.6, 2.0 and 2.5×MEm). Prior to each experiment, sheep had a 10d acclimatization period to diets. Apparent digestibility was measured over 7d from sheep in Experiments 1, 3 and 4, along with collection of rumen digesta for volatile fatty acid (VFA) determination. Although CH4 yields differed when sheep were fed white clover or ryegrass at similar intakes, the differences were inconsistent and mean values similar across all experiments. This, and a similar structure of all experiments, enabled combined analysis of data from all four experiments using the restricted maximum likelihood (REML) procedure to estimate effects of feed intake level on digestibility, digestible nutrient intake, gas emissions, and VFA concentrations in the rumen. The REML analysis showed that when DM intake increased from 0.40 to 1.60kg/d, the predicted responses were an increase in CH4 production (g/d) of 187% (12.4–35.6g/d; P<0.001), and a decline in CH4 yield of 21% (25.6–20.2g/kg DM intake; P<0.001). High feed intake levels were associated with increased molar proportions (mM of total VFA) of propionate from 0.17 to 0.21 (P=0.038). Single and multiple regressions were completed on the data from all experiments, with organic matter (OM) intake predicting 0.87 of the variation in CH4 production, and molar proportion of propionate predicting 0.60 of the variation in CH4 yield. Increasing feed intakes by 1kg/d of DM reduced CH4 yield by 4.5g/kg DM intake. Plant chemical composition was weakly related to CH4 yield. High intakes of fresh forages will lower CH4 yield from fermentation, but effects of feed composition on CH4 emissions were minor. The interaction between effects of feed intake and rumen function requires further investigation to understand relationships with CH4 emissions.

Effects of feeding fresh white clover (Trifolium repens) or perennial ryegrass (Lolium perenne) on enteric methane emissions from sheep

Enteric CH4 contributes about one third of New Zealand's greenhouse gas emissions. Measurements from our laboratory using the sulfur hexafluoride (SF6) technique suggested much lower CH4 yields (as gCH4/kg dry matter (DM) intake) from sheep fed fresh white clover (Trifolium repens) compared with fresh perennial ryegrass (Lolium perenne). Thus, white clover offers an opportunity to reduce CH4 emissions from pastoral based ruminant livestock systems if its lower CH4 yield can be confirmed using respiration chambers. This study was comprised of 2 experiments where good nutritional quality freshly harvested white clover and perennial ryegrass were fed to 16 sheep in Experiment 1 (8/diet) and 32 sheep in Experiment 2 (16/diet). Intakes were about 1.6 times metabolizable energy requirements for maintenance (×MEm) in Experiment 1 and 0.8×MEm and 2.0×MEm in Experiment 2 (8/diet/feeding level). In both experiments sheep had a 10 d acclimatization to their diets and CH4 emissions were measured in respiration chambers for 2 consecutive days. Methane yield (gCH4/kg DM intake) was 12% lower (P=0.04) for white clover (19.8) compared with ryegrass fed sheep (22.5) in Experiment 1. In Experiment 2, there were no effects of forage on CH4 yield (as gCH4/kg DM intake) at 0.8×MEm (27.1 and 25.5, respectively) but, at 2.0×MEm, CH4 yield (as gCH4/kg DM intake) was 7% higher (P=0.05) for white clover (23.4) compared with ryegrass (21.7). Analyses of combined data from both experiments show that there were no overall dietary effects on CH4 yield, but increased intakes reduced CH4 yield (P<0.01). Use of white clover as an alternative fresh forage to ryegrass is not an opportunity to reduce enteric CH4 emissions from sheep.This paper is part of the special issue entitled: Greenhouse Gases in Animal Agriculture – Finding a Balance Between Food and Emissions, Guest Edited by T.A. McAllister, Section Guest Editors: K.A. Beauchemin, X. Hao, S. McGinn and Editor for Animal Feed Science and Technology, P.H. Robinson.

Effects of intercropping and fertilizer application on the yield and nutritive value of maize and amaranth forages in Nigeria

AbstractMaize and amaranth forages, produced during the wet season, have the potential to bridge the gap in forage supply to ruminants during the dry season in Nigeria. In two growing seasons (2006 and 2007), effects of intercropping and fertilizer application on dry matter (DM) yield and chemical composition of forages, and land use efficiency, were studied in two experiments. The digestibility of sun‐dried or ensiled maize, amaranth or maize–amaranth mixtures was measured using West African dwarf sheep in a third experiment. Maize showed a higher response to fertilizer application than amaranth or maize–amaranth mixtures. With fertilizer application, DM yield varied significantly (P &lt; 0·05) between species and intercropped mixtures. Dry matter yield ranged from 7·1 (amaranth) to 12·6 t ha−1 (maize) in 2006 and 6·9 (amaranth) to 11·3 t ha−1 (70:30 maize–amaranth population mixture) in 2007. Crude protein (CP) concentration of whole plants ranged from 99·0 (maize) to 227·0 g kg−1 DM (amaranth). Dry matter digestibility values of sun‐dried maize, sun‐dried maize:amaranth 50:50 mixture, sun‐dried amaranth, ensiled maize, ensiled maize:amaranth 50:50 mixture and ensiled amaranth were 0·718, 0·607, 0·573, 0·737, 0·553 and 0·526 respectively. Intercropping increased forage yield and land use efficiency compared to amaranth but had no yield advantage over maize. Although DM digestibility of maize was higher than that of amaranth or the maize:amaranth mixture, digestible CP yield ha−1 was higher with amaranth in the cropping mixture, showing that amaranth could complement maize in systems where CP is the limiting factor to livestock production.

A note on modification of pancreatic juice and bile collection method in sheep

The aim of the study was to modify and evaluate the method of management of pancreatic juice and bile secretions in sheep in chronic experiment. Experiment was performed on 12 adult male Corriedale sheep of 54 ± 2.4 kg body weight, fi tted with two biomedical silicone catheters in the common bile duct according to the method described by Kato and Young (Kato et al., 1999) and our modifi cation duodenal cannula. Duodenal cannula was equipped with silicone valve in the basement part to prevent secretions backfl ow. Except the collection time, animals were freely moving in the individual pens and all secretions were returned to duodenum by means of constructed device. During all experimental treatments secretion volume of pancreatic juice was from 11.7 to 34.8 ml·h -1 . Modifi cation of Kato and Young method allows extending the period of animals use even up to more than 6 months. Moreover, it positively impacts animals welfare by reducing time spending in the metabolic cages, and saves labour expenses.

Endozoochorous dispersal, seedling emergence and fruiting success in disturbed and undisturbed successional stages of sheep-grazed inland sand ecosystems

This study examines the seedling emergence and fruiting success of plant species endozoochorously dispersed by sheep in a field experiment in a Koelerion glaucae area. We designed a factorial experiment (faeces/soil disturbance/successional stage/year) that mimics sheep-mediated microsites and analysed all occurring vascular plant species from September 2002–December 2004. The faeces samples were collected in the same ecosystem and additionally analysed in a common-garden experiment (seedling emergence potential). According to the latter, 28 vascular plant taxa were identified (on average 124 seedlings per 100 g air-dry sheep faeces). In the field, 15 species emerged directly out of faeces, only five of which were able to set seeds (the threatened species Medicago minima, Phleum arenarium, Silene conica, Vicia lathyroides and the non-threatened Vulpia myuros). Graminoid competitors were not able to set seedlings in the field but did so in the common-garden experiment (mainly Carex hirta). The total numbers of seedlings emerging out of faeces (5% of the potential) and reaching fruit ripeness (0.4%) were very low. In the stage of seedling emergence, ten of 42 species were significantly influenced by faeces, 11 species by disturbance and two species by an interaction of the two treatment factors ( Bromus tectorum, Saxifraga tridactylites). In the fruiting stage, two species profited by faeces ( Bromus tectorum, Vulpia myuros) and two species by disturbance ( Erophila verna, Corynephorus canescens). Overall, the density and diversity of fruiting individuals were significantly influenced by both treatment factors. The faeces factor showed a strong dependence on year (increasing effect on both dependent variables in the first year, decreasing effect in the second year). The disturbance factor is dependent particularly on successional stage (increasing effect especially in the later successional stage). Our study revealed the paradox that threatened species with low nutrient demands are the most successful direct colonisers of sheep-faeces deposits. For them to reach the fruiting stage is rare but is of importance if new habitats are to be made accessible.

Long-term suppression of reproductive function by a single dose of gonadotropin-releasing hormone antagonists in a sheep model

To determine the effect of single long-acting doses of GnRH antagonists on reproductive function in a sheep model. Observational, model study. University-affiliated research unit. Nine intact mature Merino sheep in experiment 1 and 12 mature Merino-crossed ewes with the ovary autotransplanted to the neck in experiment 2. Synchronization of estrous cycle either with intravaginal progestins or prostaglandin F2alpha analogues and treatment with a single dose of GnRH antagonist; evaluation of reproductive activity, plasma sampling, and ovarian ultrasonography. Determination of estrus behavior; plasma concentrations of P, FSH, LH, and inhibin A; and number and size of ovarian follicles. In both experiments, the concentrations of FSH and LH were suppressed when compared with those in control ewes. In experiment 1, the ovulatory cycles were suppressed for > or = 55 days in treated sheep. In experiment 2, there were no follicles sized > or = 5 mm in treated ewes for 50 days. The suppression of the development of large follicles for > or = 30 days after a single injection of a long-acting GnRH antagonist provides a novel convenient method of pretreatment before COS.

Effects of cadmium in herbage on the apparent absorption of elements by sheep in comparison with inorganic cadmium added to their diet

A meta-analysis of existing scientific literature recently suggested that Cd is absorbed more efficiently by sheep if it is in the organic form in grass, than if it is added as an inorganic supplement to the diet. We tested this experimentally by feeding sheep grass from contaminated soil, compared with uncontaminated grass and with Cd added to the diet. To produce contaminated herbage, Cd nitrate was added to soil in 11 lysimeters sown with perennial ryegrass, with a further 11 lysimeters receiving no Cd to produce uncontaminated herbage. In the Cd-treated lysimeters, soil had increased exchangeable K, Mg, and Ca, leachate had increased K, Mg, Ca, Na, and P, grass had increased Cd and reduced Mg, Na, P, Mn, Fe, Cr, Al, and Ni, and there was some reduction in grass yield compared with untreated lysimeters. Grass from Cd-treated or untreated lysimeters was fed to groups of 12 ewes for 2 days, with Cd intake equated by adding Cd nitrate to the concentrate feed of ewes receiving the uncontaminated grass. The apparent absorption of Cd, Zn, Mo, Cr, and Al was increased for ewes receiving Cd-enriched grass, and apparent absorption of Cu was reduced, compared to those receiving supplementary inorganic Cd. Most of the unabsorbed Cd was excreted in feces within 4 days of feeding. The ewes consuming Cd in grass had increased B concentrations in their urine, possibly due to adverse effects of Cd on kidney function. Finally, the ewes were offered a choice of the two herbages and they ate significantly more of the uncontaminated grass. It is concluded that the apparent absorption of Cd and other heavy metals by sheep in a short-term experiment was greater when Cd was in the grass than when the Cd was added in in an inorganic form and that sheep partially avoided herbage with a high Cd concentration.

Methane suppression by coconut oil and associated effects on nutrient and energy balance in sheep

Three different diets with increasing proportions of coconut oil (0, 3.5 and 7%) were fed to six sheep in an incomplete Latin square experiment with four replicates per diet. The diets were composed of hay and concentrates either without or with coconut oil. Concentrate comprised 28.8 and 54.6% of the diet DM in the treatments containing 3.5 and 7% coconut oil, respectively. Wethers on all treatments were fed at 1.2 × maintenance. Gaseous exchange was measured in respiratory chambers. Protozoa counts were reduced (P &lt; 0.05) by 88 and 97% when diets contained 3.5 and 7% coconut oil, respectively, whereas bacteria counts increased (P &lt; 0.05). Supplementation of coconut oil at proportions of 3.5 and 7% suppressed (P &lt; 0.001) methane production by 28 and 73%, respectively, as related to the unsupplemented diet. This proportionately reduced (P &lt; 0.001) the amount of gross energy lost through methane from 7.5 to 5.7 and 2.5%, in diets containing 0, 3.5 and 7% coconut oil, respectively. Assuming a linear suppressive effect of coconut oil, about half of the additional methane reduction with the 7% coconut oil diet as compared with the 3.5% diet was attributed to the substitution of concentrate for hay. Digestibility of cell wall constituents was numerically decreased by coconut oil. Apart from this and its effect on methane emissions coconut oil had no major influence on digestion or on energy and nitrogen balance. Key words: Coconut oil, methane, energy balance, sheep, ruminants

In Vitro Digestibility and Preference by Sheep for Silages Made from Whole-Plant Soybeans

Maturity group IV (‘Stafford’) vs group V (‘Bay’) soybean forages were harvested and ensiled at either full bloom (R2), full pod (R4), or full seed (R6) growth stages, with or without a silage inoculant and offered to sheep in a consumption experiment having a balanced incomplete block design. Silage samples were collected at the time of feeding for in vitro total DM digestibility determination. Three sheep were adapted to ensiled R6 Bay silage, then individually offered a selection of four different silages (soybean silage combinations or com silage) daily for 13 d. Quantity of each silage was limited to 50% of the total daily silage consumption. In 1988, the indigestible fraction was higher and digestibility at 18, 24, and 72h was lower from R4 Stafford than from the other cultivar and growth stage combinations (P<.05). In 1989, the indigestible fraction was lower and digestibility higher at 24, 48, and 72h from R2 than R4 and R6 silages (P<.05). Com silage was preferred (P<.05) to any of the soybean silages. Consumption of R6 silage was greater (Ρ<·05) than that 0fR2 and R4 in 1988 and 0fR4 in 1989·Silage consumption was conelated positively (P<.05) with forage DM content; DM yield; molar percentage of isovaleric and valeric acids; and lactic acid, ethanol, and acid-detergent lignin contents and negatively with acetic, propionic, isobutyric, butyric, and total volatile fatty acid concentrations; molar percentage of propionic and isobutyric acids; pH; and N, Ca, and P contents. Delaying ensiling of whole-plant soybeans until the R6 growth stage some-what compromises digestibility of the forage but provides a silage of higher acceptance by sheep.

Protein, acetate and propionate for roughage-fed lambs. 1. Body and blood composition

AbstractSixty castrated male lambs fca. 37 kg) were allocated to an initial slaughter group (no. = 12) or to one of six treatment groups (no. = 8). Chopped oaten hay (sprayed with 10 g urea per kg) was offered ad libitum with 57 gjday chopped lucerne hay. Additional supplements were 0 or 57 g/day formaldehyde-treated casein (protected casein) and volatile fatty acids (VFAs) at ca. 1·45 MJ gross energy per day. The VFAs given were acetate or propionate or a mixture of these (molar ratio 4: 1). Daily food intake and weekly live-weight (LW) gain were measured and rumen fluid and blood were collected. The lambs were shorn, slaughtered and body composition was determined.Food intake (g/kg LW) was not affected by treatments. Supplementation with protected casein increased LW gain and wool growth. Supplementation with propionate reduced LW gain, but not when given with protected casein. Plasma concentrations of urea-nitrogen and insulin were increased, and plasma somatotropin decreased in lambs given protected casein. Final body content of water, fat, protein and gross energy, adjusted to the mean fleece/digesta-free body weight of 36·5 kg, was not affected by the treatments. The partitioning of water, fat and energy between the carcass and the rest of the body was affected by the treatments. Excretion of VFAs in urine was measured in two sheep in experiment 2, and was negligible compared with the quantity of VFAs given. It is concluded that energy from salts of VFAs, in particular propionate, is used inefficiently for body-weight gain in lambs given low-protein roughage diets. The nutritional treatments had only marginal effects on the composition of body gain.

Effects of treating corn stover with wood ashes and sodium hydroxide on nutrient digestibility by sheep and goats

In expt I, twelve lambs (average BW 30 kg) were fed diets containing 85% corn stover (CS) treated with 0, 10, 20 and 30% solutions ( w/v) of wood ash (WA). Digestibility of DM was increased ( P < 0.01) from 56.3% to 62.0%, CP, ADF and NDF digestibilities increased ( P<0.05) from 57.3, 53.0, 60.5% to 66.2, 61.3 68.6% for 0 to 30% WA, respectively. In expt II, nine wether lambs (average BW 29.2 kg) were fed diets containing untreated CS or stover treated with a 20% solution ( w/v) of WA or a solution of NaOH (4 g/100 g CS). There were no differences ( P>0.05) in ADF and NDF digestibilities between sheep fed diets containing CS treated with WA (56.6, 65.7%) or NaOH (55.7, 63.5%), but both were greater ( P<0.05) than ADF and NDF digestion in control lambs (43.4, 50.5%). In expt III, nine male castrated goats (average BW 32.6 kg) were fed the same diets as sheep in experiment II. Goats responded to treatments in a similar manner to sheep. Results suggest that treating CS with a 20% solution of WA can increase fiber digestibility in sheep and goats to a degree comparable to that observed with NaOH treatment.

Liveweight gain and wool growth in sheep fed rations containing virginiamycin

The feed additive virginiamycin was evaluated for its potential to improve wool growth and liveweight gain in Merino sheep in 2 experiments. In the first experiment 84 wethers (about 10 months old) were housed individually and fed ad libitum a pelleted diet based on lucerne chaff, lupin, and barley grain. Control sheep (28) were fed an unmedicated diet, and 14 in each of 4 groups were given diets containing 10, 20, 40, or 60 mg virginiamycin/kg pellets. Virginiamycin was found to reduce feed intake during the first 4-5 weeks of the experiment when included at levels 220 g/t. There was a dose-related reduction in liveweight gain. There was no significant effect of virginiamycin on wool growth. In the second experiment, weaners and adults from 2 locations in Western Australia, Mount Barker (relatively high rainfall) and Wongan Hills (relatively low rainfall and shorter pasture-growing period), were housed individually in a shed and fed a pelleted diet at rates equivalent to 3.5 and 3.1%, respectively, of liveweight for weaners and adults. The pelleted ration was based on wheat and lucerne chaff, lupin grain, and fishmeal. Virginiamycin was included at 20 mg/kg pellets for 16 of 40 sheep of each age and location. The remaining sheep were fed the unmedicated diet. Feed conversion and liveweight gain improved (P&lt;0.05) in response to the inclusion of virginiamycin during the first 4 weeks of the trial, but wool growth was reduced over the same period. Virginiamycin had no effect on fibre diameter in sheep in either experiment.

Heterologous resistance to Fasciola hepatica conferred upon rats by passive transfer of serum from different breeds of sheep

Two experiments compared the protection against oral challenge with 20 metacercariae of Fasciola hepatica conferred on rats by intraperitoneal injection of serum from three breeds of sheep infected with F. hepatica (Barbados Blackbelly, St. Croix, Florida Native). Experiment 1 used serum from sheep 5–6 months of age following two infections of 250 metacercariae each, while Experiment 2 utilized serum collected from the same sheep at 10–11 months of age following either a primary (first exposure) or challenge (after two previous exposures of 250 metacercariae each) infection with 500 metacercariae. Similar numbers of flukes were recovered from rats given either immune or nonimmune (control) serum from each breed of sheep in Experiment 1. In Experiment 2, rats given serum from infected St. Croix sheep had significantly fewer flukes than rats given either control or immune serum from Barbados Blackbelly or Florida Native sheep. There was no significant correlation of fluke counts between individual serum donors (sheep) and serum recipients (rats).

Nitrogen and carbon flows between the caecum, blood and rumen in sheep given chopped lucerne (Medicago sativa) hay.

1. Experiments involving 15N and 14C tracers were made in sheep consuming 800 g air-dry chopped lucerne (Medicago sativa) hay/d and providing 20.4 g N/d to study N and C flows within the caecal digesta and between the caecum, blood and rumen. 2. Continuous infusions of 15N tracers were made into the caecal ammonia, blood urea and rumen NH3 pools. The concentration and enrichment of caecal digesta NH3-N, caecal microbial N, caecal digesta non-urea, non-ammonia-N (NU-NAN), faecal NU-NAN, blood urea-N, rumen digesta NH3-N and rumen bacterial N were estimated at intervals during the infusions. A three-pool open-compartment model was solved to estimate N flows between the caecal digesta NH3-N, blood urea-N and rumen digesta NH3-N pools. 3. The rate of irreversible loss from the caecal digesta NH3-N pool was 2.17 (SE 0.623) g N/d. On average 0.9 (SE 0.56) g N/d of caecal digesta NH3-N was derived from blood urea and 0.1 (SE 0.08) g caecal digesta NH3-N/d was apparently derived from the fermentation of undigested rumen microbes in the caecum. The amount of NH3-N produced by proteolysis and deamination of dietary and endogenous N was 1.1 (SE 0.13) g/d. 4. There was net incorporation of 0.56 (SE 0.306) g caecal digesta NH3-N/d into caecal microbes. The microbial N synthesized de novo in the caecum was not determined, but 2.9 (SE 0.52) g microbial N/d of both rumen and caecal origin flowed out of the caecum and constituted 0.48 of the NU-NAN flow. The majority (mean 0.83 (SE 0.044] of this microbial N was excreted in faeces. 5. On average 1.8 (SE 0.80) g caecal digesta NH3-N/d were absorbed. Of this NH3-N, 0.92 (SE 0.054) was converted to blood urea, contributing 0.10 (SE 0.031) of blood urea-N. Only 0.012 (SE 0.0041) of rumen digesta NH3-N and 0.005 (SE 0.0009) of rumen bacterial N were derived from caecal digesta NH3-N. 6. Infusions of 14C tracers were made into the caecal digesta bicarbonate, blood bicarbonate, rumen digesta bicarbonate and blood urea pools, and samples were obtained at intervals to determine the specific radioactivity of each pool. A four-pool open-compartment model was solved to estimate C flows between these pools. 7. The rate of irreversible loss of blood urea estimated with [14C]urea (17.1 (SE 1.18) g N/d) was greater (P less than 0.01) than that estimated with [15N]urea (14.0 (SE 0.87) g N/d).(ABSTRACT TRUNCATED AT 400 WORDS)

Differences between strains of Bacteroides nodosus in their effects on the severity of foot-rot, bodyweight and wool growth in Merino sheep.

The effects of 3 ovine and one bovine strains of Bacteroides nodosus on the severity of foot-rot, bodyweight and wool growth were compared in Merino sheep in a field experiment. Based on the severity of the induced foot lesions, one strain was classed as virulent (causing underrunning lesions in most feet), one was benign (causing lesions of the interdigital skin only), and 2, including the bovine strain, were of intermediate virulence (causing underrunning lesions in a small proportion of feet). Differences among strains in their effect on foot-rot severity and bodyweight were significant when compared over the whole experimental period, but were not significant at any single time of measurement, because of large differences between replicates. Bodyweight loss and severity of foot-rot caused by the virulent strain were significantly greater than that caused by the benign strain. The intermediate strains lay between these 2 extremes in terms of both bodyweight and foot-rot scores but were not significantly different from either in a statistical sense. Total greasy wool weight did not differ among groups over the whole experiment, but the rate of wool growth during the period when foot lesions were most prevalent and severe was reduced appreciably by the virulent strain and to a lesser extent by the intermediate strains.