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The study investigated the effect of in-feed administration of dried thyme leaf and celery seed mixture (at 1 : 1 DM basis) compared with salinomycin ionophore on milk production and milk nutritive value of Barki ewes. Thirty ewes (37.5 ± 1.8 kg), divided into 3 treatment groups, were fed: (1) a complete control diet comprising concentrates and fodder maize (Zea mays L.) at 60 : 40 dry matter basis, (2) the control diet plus 20 g of thyme and celery mixture supplementation and (3) the control diet supplemented with 1 g of salinomycin per ewe daily for 90 days. Inclusion of thyme–celery treatment increased (P < 0.05) weight gain, average daily gain, milk yield, milk component yields, and feed efficiency, without affecting milk composition. In addition, the thyme–celery treatment enhanced (P < 0.05) nutrient intake and digestibility, total ruminal volatile fatty acids, branched chain fatty acids, and acetate proportions and decreased ammonia-N concentration. Thyme–celery treatment increased (P < 0.05) serum glucose, thyroxine, and glutamate-pyruvate transaminase concentrations. It is concluded that the thyme and celery mixture (1 : 1 DM basis) at 20 g per lactating ewe daily can replace the salinomycin ionophore. Enhanced feed utilization and lactational performance as well as milk nutritive value for human consumption were observed with the natural additive mixture supplementation.

This is the first integrated study of the effects on gastric secretion, inflammation and fundic mucins after infection with L3 T. circumcincta and in the very early period following transplantation of adult worms. At 3 months-of-age, 20 Coopworth lambs were infected intraruminally with 35,000 L3; infected animals were killed on Days 5, 10, 15, 20 and 30 post-infection and 6 controls on either Day 0 or 30 post-infection. Another 15 Romney cross lambs received 10,000 adult worms at 4-5 months-of-age though surgically-implanted abomasal cannulae and were killed after 6, 12, 24 and 72 hours; uninfected controls were also killed at 72 hours. Blood was collected at regular intervals from all animals for measurement of serum gastrin and pepsinogen and abomasal fluid for pH measurement from cannulated sheep. Tissues collected at necropsy were fixed in Bouin's fluid for light microscopy, immunocytochemistry and mucin staining and in Karnovsky's fluid for electron microscopy. Nodules around glands containing developing larvae were seen on Day 5 p.i., but generalised effects on secretion occurred only after parasite emergence and within hours after transplantation of adult worms. After L3 infection, there were maximum worm burdens on Days 10-15 post-infection, together with peak tissue eosinophilia, inhibition of gastric acid secretion, hypergastrinaemia, hyperpepsinogenaemia, loss of parietal cells, enlarged gastric pits containing less mucin and increased numbers of mucous neck cells. After adult transplantation, serum pepsinogen was significantly increased after 9 hours and serum gastrin after 18 hours. Parallel changes in host tissues and the numbers of parasites in the abomasal lumen suggest that luminal parasites, but not those in the tissues, are key drivers of the pathophysiology and inflammatory response in animals exposed to parasites for the first time. These results are consistent with initiation of the host response by parasite chemicals diffusing across the surface epithelium, possibly aided by components of ES products which increased permeability. Parietal cells appear to be a key target, resulting in secondary increases in serum gastrin, pit elongation, loss of surface mucins and inhibition of chief cell maturation. Inflammation occurs in parallel, and could either cause the pathology or exacerbate the direct effects of ES products.

This study aimed to evaluate the behavior of sheep fed babassu cake as a substitution for elephant grass silage. The experiment was conducted at the Federal Rural University of Amazonia (Universidade Federal Rural da Amazônia - UFRA), Brazil, using 45 sheep housed in individual stalls, with unlimited access to feed and distributed in a completely randomized design with five treatments (0, 12.5, 25, 37.5 and 50% inclusion of babassu cake) and nine replications. All of the treatments contained a roughage-to-concentrate ratio of 40:60. No differences were observed in the time spent feeding (P 0.05), regardless of the source of roughage used. However, there was a reduction in the time spent in rumination (P 0.05) and an increase in time spent idling (P 0.05) when babassu cake was included in the diet. Although there was a reduction in the time spent chewing the ruminal bolus (P 0.05), the total daily chewing time was the same for all animals (P 0.05). However, the sheep fed babassu cake showed higher feeding and rumination efficiency (P 0.05). Therefore, the substitution of elephant grass silage with babassu cake can be performed at up to 50% without compromising the total time spent eating and chewing, which allows increased feeding and rumination efficiency.

Ghrelin and growth hormone (GH) play a key role in regulating energy balance, metabolic hormone secretion and food intake. Ghrelin and GH responses to dietary compositions have not yet been fully clarified, although there may be significant relationships between dietary compositions and ghrelin and GH responses. In the present study, therefore, we assessed whether dietary compositions influence postprandial plasma ghrelin and GH levels in wethers. Four wethers were respectively fed concentrate (C) or timothy hay (R) for 14 days. The levels of total digestive nutrients (TDN) and crude protein (CP) were adjusted to be at the same level. The basal ghrelin in both groups was rapidly and significantly decreased after feeding. Although the decline of ghrelin levels in C was greater and shorter than that in R, no significant difference was observed in the area under the curve (AUC) or in the incremental area. The plasma GH levels were also rapidly and significantly decreased after feeding in both groups and a significant difference was observed between the two groups for AUC of GH. Interestingly, the circadian changes in the plasma ghrelin levels were close to those in the GH levels in C, but this was not the case in R. These data suggest that dietary compositions influence postprandial plasma ghrelin and GH levels, and that these differences may be caused by several factors, including nutrients and ruminal fermentation.

An isocratic ion-pair high-performance liquid chromatography (IP-RP-HPLC) method with UV detection was developed to identify and quantify ellagic acid (EA). This phenolic compound is widely distributed in the plants and is often present in the diet of ruminants. The method was validated and validation parameters were: linearity range 5-100 mg/L; correlation coefficient, 0.9995; mean recoveries (99.94 and 101.07%) and detection limit 1.4 mg/L. Method was applied for the determination of ellagic acid in oak leaves and in ruminal fluid from to a vitro ruminal system. The proposed method proved to be rapid and accurate and can be successfully used in ruminant nutrition studies.

This research was conducted in order to investigate rumen degradability of some factors includes; Dray Matter (DM), Organic Matter (OM), Crude Protein (CP), Acid Detergent Fiber (ADF) in three different plant protein supplements includes; soybean, canola and cottonseed meal. The experiment was carried out using in three castrated and fistulated male Zel sheep. Each feedstuff was weighed into duplicate nylon bags and incubated in each of the three rumen fistulated sheep for 0, 2, 4, 8, 16, 24 and 48 h. Results revealed that effective degradability of DM of soybean, canola and cottonseed meal were 55.8, 73.8 and 48.5%, respectively. Effective degradabilities of the CP in feedstuffs were 55.8, 62 and 48.3% for the respective feedstuffs. Effective degradabilities of the OM were 55.7, 56.4 and 47.4%, respectively. Results also showed that effective degradabilities of the ADF were 55, 56.4 and 37.6, respectively. According to the results the researchers concluded that canola and soybean were more degradable in the rumen of the sheep while cottonseed meal were less degradable and, hence resulted in higher rumen undegradable protein.

The comparative in vitro sulphoreduction of the (+) and (-) enantiomers of albendazole sulphoxide (ABZSO) and oxfendazole (OFZ) by ruminal fluid obtained from sheep and cattle, was investigated, under anaerobic conditions, in this study. Ruminal fluid samples were obtained from Holstein steers fitted with a permanent rumen fistula and from Corriedale lambs via an oesophageal tube. Albendazole sulphoxide, incubated as either the racemic (rac) mixture or as each individual enantiomeric form, was extensively sulphoreduced to form albendazole (ABZ) by ruminal fluid from both species. The concentrations of ABZ formed at different incubation times were between 55 and 158% greater after the incubation of cattle ruminal fluid with (+) ABZSO, compared with that produced when (-) ABZSO was the incubated substrate. Similarly, the concentrations of ABZ were 1.3--3.0-fold higher when (+) ABZSO was incubated with sheep ruminal fluid. Significantly higher rates of depletion were observed for the (+) enantiomeric form when ABZSO was incubated with ruminal fluid from both species. The rates of ABZ formation from both ABZSO enantiomeric forms were significantly higher in sheep compared with cattle ruminal fluid. Fenbendazole (FBZ) was the metabolite formed after the incubation of the racemic form of OFZ with ruminal fluid obtained from both species. The metabolic profile of both OFZ enantiomers followed a similar pattern to that observed for ABZSO enantiomers. A bi-directional chiral inversion of one enantiomer into its antipode was observed. The (+) enantiomer appeared in the incubation medium when (-) ABZSO was the incubated substrate, and also the (-) antipode was detected after (+) ABZSO incubation with ruminal fluid obtained from both species. The results reported here demonstrate an enantioselective ruminal sulphoreduction of ABZSO and OFZ (substrate enantioselectivity). These findings contribute to interpret the chiral behaviour of benzimidazole-sulphoxide anthelmintics.

Sheep were 'compartmentalized' by surgically implanting cannulae in the rumen, abomasum and terminal ileum with a re-entrant cannula inserted between the cystic duct and the duodenum to monitor bile secretion. Doramectin, containing a trace of [3H]-doramectin, was administered both intravenously (i.v.) and intraruminally (i.r.) at a dosage of 150 microg/kg. The pharmacokinetic behaviour of [3H]-labelled products was determined in these pools, and also in peripheral plasma, urine and faeces. Parent doramectin was also determined in plasma, abomasal digesta fluid and bile. Following i.r. administration, [3H] compounds were almost entirely associated with particulate digesta. A 14.5 h half-life in the rumen prolonged the presence of [3H] in the abomasum. Doramectin appeared to be degraded in abomasal digesta because only 24% of abomasal [3H] was attributed to the parent drug. Absorption of doramectin resulted in a systemic availability of 35%, of which 1.6 and 23.6% of the dose was contained in urine and biliary secretions, respectively. Following i.v. administration, almost negligible quantities of [3H] were secreted into the rumen or abomasum and only 2.7% of the dose was excreted in urine, whereas 132% was secreted in bile. This indicated that approximately one-third of biliary metabolites were enterohepatically recycled with biliary metabolites, elevating the proportion of [3H] in fluid digesta in the small intestine. Passage of the i.r.-administered drug through the gastrointestinal tract (GIT) resulted in virtually complete faecal excretion of [3H] within 5 days, whereas the continued secretion of i.v.-administered [3H] in bile prolonged the presence of [3H] in the GIT, with faecal clearance not being complete for at least 10 days. This multi-compartmental study has provided more information on the behaviour of doramectin than can be obtained from examining drug disposition in the peripheral circulation alone. With this knowledge, it is anticipated that opportunities for improving drug performance will be identified.

To compare digestion in the forestomach of llamas and sheep, the animals were fed four different diets: hay alone (H), low in nitrogen; the same hay with soybean meal (HS), with barley (HB) and with both soybean meal and barley (HSB). The sheep intakes were restricted to obtain about the same intake level in the two species. On average, the digestibilities of DM, OM and NDF were significantly higher in llamas: respectively, +2.7, 3.6 and 5.3 for the four diets. Added barley impaired hay digestion in the sheep, but very little in the llamas. The llamas retained nitrogen better than the sheep owing to very low urine losses. For hay alone, the retention time of digesta in the forestomach was higher in the llamas than in the sheep. In contrast, there was no difference between species for the other diets. The pH and ammonia levels were higher in llamas. In contrast, the SCFA levels were lower. In all cases the in-situ rate of digestion was greater in llamas. The low intake of llamas generally observed in the literature does not account for their better digestion. The stability of the two first compartment pH levels and an excellent cellulolytic activity are determining factors in the better digestion efficiency of plant cell walls in the llamas. However, higher NH3 levels were observed in llamas, although the urinary N excretion was lower.

An experiment was carried out to examine the effect of increasing the proportion of Wimmera ryegrass hay in a lucerne hay-based diet on net transfer of nutrients to the intestine, and on the disappearance ofn-alkanes in the reticulo-rumen and the hindgut of sheep. Following a latin square design, four adult ewes were fed 1:0, 0·33:0·67, 0·67:0·33 and 0:1 proportions of legume and grass. Increasing the proportion of ryegrass in the diet linearly decreased the intake of DM (P= 0·017), organic matter (P= 0·021) and N (P= 0·001). However, neutral-detergent fibre intake was not affected (P= 0·148), nor was its digestibility coefficient (P>0·10). Diet had no effect on duodenal flows of nutrients (P>0·10), although the proportion of N intake (NI) recovered at the duodenum as non-NH3N (NAN) increased linearly withLolium rigidumin the diet (P= 0·002). Full recovery of NI as NAN was achieved at NH3concentrations in the rumen below 110 g/l. Microbial N contribution to NAN varied in a quadratic manner (PP>0·10). Duodenal recovery of consumedn-alkanes was not affected by diet and was complete for those present in higher concentrations in the forages. Isolated rumen bacteria contained significant amounts ofn-alkanes, contributing to the duodenal flow of these hydrocarbons in variable proportions depending on the diet consumed.

As part of a study on leukocytes in the ruminant forestomach the occurrence and distribution of T cells and major histocompatibility complex Class II positive (MHC-II +) cells in the forestomach mucosa of sheep were investigated. Samples were taken from the reticulum, atrium ruminis, ventral rumen, dorsal rumen and omasum of five healthy adult ewes and seven nearly fullborne foetuses. Frozen sections were stained with an indirect immunoperoxidase method using monoclonal antibodies against sheep MHC-II, CD4 and CD8 molecules and the sheep γδ T cell receptor. Both MHC-II + cells and T cells were distributed along the basal lamina of the epithelium, with either mainly intraepithelial (CD8 + and γδ + cells) or mainly subepithelial (MHC-II + and CD4 + cells) location. The MHC-II + cells showed dendritic morphology and were interpreted as Langerhans cells. In adult ewes CD4 + T cells comprised the major T cell subset at all sample sites. The number of T cells declined from the atrium ruminis through the ventral rumen to the dorsal rumen, while the number of Langerhans cells showed no marked variation between different sample sites. In foetuses, Langerhans cells showed a relatively high prevalence, while T cells were sparse and showed a more random distribution in the rumen wall. No marked variation between sample sites were observed in the fetal forestomachs. It is concluded that Langerhans cells and T cells are normally present in the forestomach mucosa of sheep, and it is suggested that the Langerhans cells represent a constituent component, while the prevalence and distribution of T cells may be influenced by antigen leakage through the epithelium.

Summary Submucosal and mucosal nerve plexuses in the ovine forestomach were examined by immunohistochemical staining for protein gene-product 9.5 (PGP 9.5) and for S-100 protein (S-100), using whole-mount specimens that had been prepared by treatment with KOH. Nerve fibers of various sizes and glial cells (i.e., Schwann cells and satellite cells) were stained with antibodies against PGP 9.5 and S-100 respectively. The network of the submucosal plexus in the rumen is irregular and some nerve bundles in the plexus cross over other bundles. Some of the nerve bundles penetrate the ruminal papillae. The submucosal plexus in the reticulum consists of a network in the reticular wall and the reticular folds. The submucosal plexus in the omasum is also divided into two segments; namely, the sublaminar and the intralaminar plexuses. Most of the submucosal ganglion cells are unipolar and smooth-surfaced, being located singly or in small groups. A few perikarya were detected in the ruminal papillae. The number of perikarya per unit surface area is greater in the caudal portion of the omasal lamina (19.32 ± 8.62 per cm 2 ). In the mucosal plexuses, a well-developed network of beaded fibers with PGP9.5-like immunoreactivity and a glial framework of S-100 like immunoreactivity was observed, in particular in the ruminal, reticular and omasal papillae. The intrapapillary nervous networks are interconnected by thin bundles of nerves in the interpapillary region. The present results suggest that some of the mucosal functions are intrinsically regulated by the submucosal and mucosal plexuses in the ovine forestomach.

A simple, fast liquid–liquid extraction method was developed for studying hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) biodegradation using small sample volumes. The method was tested in vitro with anaerobic incubations of RDX with whole rumen fluid (WRF) and a commercial Sporanaerobacter acetigenes strain in methanogenic media for RDX. Additionally, validation experiments were conducted in deionized water in order to show applicability toward various aqueous matrices. Conditions for extraction were as follows: 300 μL of sample were mixed with an equal volume of a 0.34 M ammonium hydroxide solution to reach a basic pH, extracted with a hexane/ethyl acetate 1:1 (v/v) solution (1 mL) and shaken vigorously for 10 s. The resulting organic phase was transferred, then dried under a constant flow of N2 and reconstituted with acetonitrile (300 μL) for HPLC–UV and LC–MS/MS analysis. Percent recovery values were obtained (83–101%) in all matrices for RDX. In WRF (n = 3 animals), RDX degradation was observed with almost 100% elimination of RDX after 4 h. The five nitroso and ring cleavage metabolites were observed by mass spectrometry. Liquid cultures of S. acetigenes did not show significant RDX biodegradation activity. RDX extractions from deionized water samples indicated acceptable recoveries with low variability, suggesting suitability of the method for aqueous matrices. Overall, the new method demonstrated acceptable efficiency and reproducibility across three matrices, providing an advantageous alternative for studies where complex matrices and small volume samples are in use.

7 páginas, 2 figuras., A flock of approximately 1,000 sheep were exposed intermittently to food contaminated with T-2 toxin (T-2), a potent type-A trichothecene mycotoxin produced primarily by Fusarium sporotrichioides and Fusarium poae. In the acute stage of the intoxication, affected sheep developed anorexia, decreased water consumption, ruminal atony, soft faeces and apathy. One hundred and ninety of the exposed sheep died. The main gross lesions observed in animals dying during the acute disease were rumenitis and ulcerative abomasitis, depletion of lymphocytes in lymphoid organs, necrosis of the exocrine pancreas, myocarditis and intense oedema of the skin and brain. Sheep developing the chronic stage of disease showed weight loss and reproductive inefficiency and the main pathological features observed in animals dying during this stage were gastrointestinal inflammation, myocardial fibrosis and necrotic and suppurative lesions in the oral cavity. Opportunistic infections (e.g. mycotic mastitis or parasitic pneumonia) were also identified in these animals. Increased serum concentrations of lactate dehydrogenase and creatine kinase were observed, most likely related to heart lesions. T-2 toxins were detected in all samples of the diet of these animals that were analyzed. The changes in the sheep reported here are similar to those described previously in experimental studies. Lesions observed in the present animals suggest an additional cardiotoxic effect of T-2 in sheep.

Ruminal epithelium adapts to dietary change with well-coordinated alterations in metabolism, proliferation, and permeability. To further understand the molecular events controlling diet effects, the aim of this study was to evaluate protein expression patterns of ruminal epithelium in response to various feeding regimes. Sheep were fed with a concentrate-supplemented diet for up to 6 wk. The control group received hay only. Proteome analysis with differential in gel electrophoresis technology revealed that, after 2 days, 60 proteins were significantly modulated in ruminal epithelium in a comparison between hay-fed and concentrate-fed sheep ( P < 0.05). Forty proteins were upregulated and 20 proteins were downregulated in response to concentrate diet. After 6 wk of this diet, only 14 proteins were differentially expressed. Among these, 11 proteins were upregulated and 3 downregulated. To identify proteins that were modulated by dietary change, two-dimensional electrophoresis was coupled with liquid chromatography electrospray ionization mass spectrometry. The differential expression of selected proteins, such as esterase D, annexin 5, peroxiredoxin 6, carbonic anhydrase I, and actin-related protein 3, was verified by immunoblotting and/or mRNA analysis. The identified proteins were mainly associated with functions related to cellular stress, metabolism, and differentiation. These results suggest new candidate proteins that may contribute to a better understanding of the signaling pathways and mechanisms that mediate rumen epithelial adaptation to high-concentrate diet.

The reticular groove (RG) is a specialized region of ruminant forestomach which, in suckling animals, via a vagovagal reflex, transforms itself into a tube to ensure the direct transport of milk from the esophagus to the abomasum. The nervous mechanism controlling the RG movement is not fully understood; however, at this level, the enteric nervous system (ENS) shows the highest neuronal density when compared with other fore- stomach compartments. Because nitric oxide is considered the putative major mediator of non-adrenergic non-cholinergic smooth muscle relaxation, the aim of the present study was to investigate the ENS of the RG of suckling lambs, both in the floor and in the lip, with particular regard to nitric oxide synthase (NOS)-immunoreactivity (-IR), by means of double immunohistochemical staining. NOS antiserum was used in association with some neurochemical markers which have been utilized by many authors in ENS. A rich innervation of fibers extended along the entire length of the RG. Proceeding distally, the number of neurons stained with a pan-neuronal marker increased; they were more numerous in the lips and lip–floor junction than in the floor itself. However, the percentage of NOS-IR neurons was the same in the proximal and distal parts. Many NOS-IR neu- rons often co-expressed galanin and dopamine b-hydroxylase. Neurochemical markers, such as calbindin, calcitonin gene-related peptide, IB4 and neurofilament 200 kDa, usually used to identify primary sensory neurons were not expressed in RG neurons, and the co-localization of NOS with tyrosine hydroxylase and substance P was rarely found. When compared with other districts, the RG showed some peculiar aspects, such as the lack of both neurons in the submucosal plexus and the lack of typical sensory neurons.

The effects of duodenal distension on forestomach and abomasal motility were investigated in conscious sheep chronically fitted with intraparietal electrodes, a duodenal cannula, and an intracerebroventricular cannula. Duodenal distensions with a balloon inflated with 40 ml (DD40) of water reduced the frequency of forestomach and abomasal contractions by 45 and 32%, respectively, while distension with 80 ml (DD80) induced a total inhibition. Methysergide, a mixed 5HT1-5HT2 antagonist administered intravenously (200 micrograms/kg) or intracerebroventricularly (20 micrograms/kg) suppressed the DD40-induced inhibition and reduced that induced by DD80. Spiroxatrine, a selective 5HT1A antagonist, intravenously (100 micrograms/kg) or intracerebroventricularly (10 micrograms/kg), suppressed the DD40 and DD80-induced inhibition, which was also attenuated by the 5HT2 antagonist ritanserin given intravenously (200 micrograms/kg) or intracerebroventricularly (20 micrograms/kg). Granisetron, a 5HT3 antagonist, injected intravenously (150 micrograms/kg), abolished the effects of DD40 and DD80 while it had no antagonistic action on DD40 and DD80 when given intracerebroventricularly (15 micrograms/kg). It is concluded that in sheep, duodenal distension inhibits forestomach and abomasal motility through 5HT1A and 5HT2 receptors at the level of the central nervous system and 5HT3 receptors located peripherally.

Net absorption rates for SCFA, sodium, chloride, magnesium, and water were measured in the temporarily isolated and washed reticulorumen of sheep. The animals were either fed hay ad lib. plus concentrates once daily or were deprived of food for two days. Food deprivation led to decreased net absorption of all the substances tested. Comparing the solutes, the relative decreases varied between 43% (butyrate) and 56% (acetate). The decrease in solute absorption was accompanied by diminished water absorption. It is concluded that the reduction in absorption may be beneficial for the animal in that energy consumption is diminished and the reservoir function of the forestomach will be maintained longer. However, the reduced absorptive capacity may lead to a deficiency of magnesium, which is thought to be absorbed mainly by the forestomachs.

The forestomach plays an important role in the digestion physiology of ruminants. The aim of this study is to clarify the morpho-functional role of the mucosa in each of the three compartments of the forestomach in three domestic ruminants species, viz cattle, buffalo and sheep, by means of structural, histochemical and immunocytochemical methods, including transmission electron microscopy, light microscopy and scanning electron microscopy. These methods were chosen to demonstrate the indirect evidence for the presence of nitric oxide (NO) employing NADPHd and nitric oxide synthase I (NOS I). The various cell layers of the forestomach epithelium are described and illustrated in detail. An intense NADPHd staining was observed in the granulosa, spinosa and basal layers of the epithelium, in particular in the cytoplasm over the nucleus. NOS I immunoreactivity was found in all specimens of the forestomach mucosa. The results of this study might reflect a possible role of NO in delaying the onset of cellular apoptosis in the forestomach mucosa of the domestic ruminants, by playing a role in the production of cell energy.

In conscious sheep, Leu-enkephalin (10 and 20 micrograms.kg-1) administered into the third cerebral ventricle caused a psychosedative action and a significant inhibition of the frequency of rumen contractions. The amplitude of the first rumen contractions, following immediately after the end of the Leu-enkephalin's infusion (at a dose of 20 micrograms) and the average amplitude of primary rumen contractions were also significantly inhibited. The hypothalamic isolation prevented both the inhibitory effect of Leu-enkephalin on the rumen motility and the drug induced psychosedative action. In contrast, Leu-enkephalin (20 micrograms.kg-1), significantly enhanced phasic contractions of the rumen after hypothalamic isolation. However the hypothalamic isolation did not prevent Leu-enkephalin induced inhibition of the mean amplitude of rumen contractions, but this inhibition was not significant (NS). The character of the histopathological changes induced by the isolation of the hypothalamus showed descending degenerative changes of the neuronal pathways connecting the hypothalamus to the pons and lower to the medulla. These results do suggest that the isolation of the hypothalamus causes the degeneration of the descending inhibitory opioid pathways connecting the hypothalamus to the gastric centers of the medulla and point act out the functional importance of descending tonic opioid inhibitory control of ruminant forestomach motility.

Flubendazole (FLBZ) is a broad-spectrum benzimidazole anthelmintic compound used in pigs, poultry and humans. Its potential for parasite control in ruminant species is under investigation. The objective of the work described here was to identify the main enzymatic pathways involved in the hepatic and extra-hepatic biotransformation of FLBZ in sheep. Microsomal and cytosolic fractions obtained from sheep liver and duodenal mucosa metabolised FLBZ into a reduced FLBZ metabolite (red-FLBZ). The keto-reduction of FLBZ led to the prevalent (∼98%) stereospecific formation of one enantiomeric form of red-FLBZ. The amounts of red-FLBZ formed in liver subcellular fractions were 3-4-fold higher (P < 0.05) compared to those observed in duodenal subcellular fractions. This observation correlates with the higher (P < 0.05) carbonyl reductase (CBR) activities measured in the liver compared to the duodenal mucosa. No metabolic conversion was observed following FLBZ or red-FLBZ incubation with sheep ruminal fluid. Sheep liver microsomes failed to convert red-FLBZ into FLBZ. However, this metabolic reaction occurred in liver microsomes prepared from phenobarbital-induced rats, which may indicate a cytochrome P450-mediated oxidation of red-FLBZ. A NADPH-dependent CBR is proposed as the main enzymatic system involved in the keto-reduction of FLBZ in sheep. CBR substrates such as menadione and mebendazole (a non-fluoride analogue of FLBZ), inhibited this liver microsomal enzymatic reaction, which may confirm the involvement of a CBR enzyme in FLBZ metabolism in sheep. This research is a further contribution to the understanding of the metabolic fate of a promissory alternative compound for antiparasitic control in ruminant species. Fil: Maté, María Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; Argentina Fil: Virkel, Guillermo Leon. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lifschitz, Adrian Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; Argentina Fil: Ballent, Mariana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Lanusse, Carlos Edmundo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias. Departamento de Fisiopatología. Laboratorio de Farmacología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina

Four wethers fitted with ruminal, duodenal and ileal cannulas were used to study effects of maturity of alfalfa hay on intake, digestion and rate of passage of nutrients in various sites of the digestive tract. Pre-, early-, and mid-bloom hays were harvested from the same field; full-bloom hay was acquired from elsewhere due to weather conditions. Dry matter intake decreased (P c .05) as intakes of NDF and ADF increased. This was attributed to decreased digestibility and increased retention time of undigested residues. Digestion of OM in the stomach (% of intake) was 44.2, 47.4, 38.8 and 35.1 for pre-, early-, mid- and full-bloom hay, respectively. Digestion of ADF in the stomach was lower for mid-bloom than for pre and early-bloom hay (P c .05). Degradation of alfalfa protein in the rumen was 94, 88, 81 and 78% for pre-, early-, mid- and full-bloom hay, respectively. Concentration of ruminal NH3 N, flow of N at the duodenum, fecal N and urinary N decreased as maturity advanced (P c .05), but they appeared to be related primarily to the N content of the hay and to N intake. Digestion of N in the small intestine (g/d) decreased as maturity advanced (P c .05). Duodenal flow of total amino acids was greater (P c .05) when animals consumed pre-bloom hay than when they consumed more mature hays. Relative feed value calculated from the detergent fiber analysis correlated with actual value determined biologically (r = +.81). Intake and site of nutrient digestion of alfalfa hay were influenced by the stage of maturity at

The aim of this study was to identify ruminal bacteria that form stearic acid (18 : 0) from linoleic acid (cis-9,cis-12-18 : 2). One 18 : 0-producing isolate, P-18, isolated from the sheep rumen was similar in morphology and metabolic properties to 'Fusocillus' spp. isolated many years ago. Phylogenetic analysis based on nearly full-length 16S rRNA gene sequence (1300 bp) analysis indicated that the stearate producer was most closely related to Clostridium proteoclasticum B316(T). Clostridium proteoclasticum B316(T) was also found to form 18 : 0, as were other bacteria isolated elsewhere, which occurred in the same family subclass of the low G+C% Gram-positive bacteria, related to Butyrivibrio fibrisolvens. These bacteria are not clostridia, and the ability to form 18 : 0 was present in all strains in contrast to proteolytic activity, which was variable. Production of 18 : 0 occurred in growing, but not in stationary-phase, bacteria, which made detection of biohydrogenating activity difficult, because of the inhibitory effects of linoleic acid on growth.

Triclabendazole (TCBZ) is an halogenated benzimidazole (BZD) compound worldwide used to control immature and adult stages of the liver fluke Fasciola hepatica. The purpose of this investigation was to characterize in vitro the patterns of hepatic and ruminal biotransformation of TCBZ and its metabolites in sheep. TCBZ parent drug was metabolized into its sulphoxide (TCBZSO), sulphone (TCBZSO2) and hydroxy derivatives by sheep liver microsomes. The same microsomal fraction was also able to oxidize TCBZSO into TCBZSO2 and hydroxy‐TCBZSO (HO‐TCBZSO). TCBZ sulphoxidation was significantly (P

The reticulum and the reticular groove are functional distinct compartments within the ovine forestomach. While the reticulum takes part in various motor functions, such as mixing, retaining, and rejecting the forestomach ingesta, the reticular groove serves mainly as a bypass between the esophagus and the abomasum. To accomplish these different tasks, the compartments develop specific motility patterns that are controlled by intrinsic neural circuits. In this study the intrinsic innervation by myenteric neurons was analyzed by quadruple immunohistochemistry against cholineacetyl transferase (ChAT), nitric oxide synthase (NOS), substance P (SP), and vasoactive intestinal peptide (VIP). Four neurochemically different subpopulations of myenteric neurons were found in the reticulum and the floor of the reticular groove: ChAT/-, ChAT/SP, NOS/-, and NOS/VIP. The neuronal proportions were calculated relative to all myenteric neurons. Neurons of the reticulum were mostly immunoreactive for ChAT (89% +/- 3%), whereas neurons adjacent to the reticular groove predominantly expressed a nitrergic phenotype (62% +/- 4%). ChAT-positive neurons were also immunoreactive for SP (ChAT/SP: 64% +/- 3% reticulum; 25% +/- 1% reticular groove) or were purely cholinergic (ChAT/-: 25% +/- 4% reticulum; 13% +/- 3% reticular groove). NOS-positive neurons colocalized VIP (NOS/VIP: 10% +/- 3% reticulum; 46% +/- 1% reticular groove) or none of the other neurotransmitters (NOS/-: 1% +/- 1% reticulum; 17% +/- 3% reticular groove). Analysis of the soma sizes revealed that in both compartments the nitrergic neurons were significantly larger than the cholinergic neurons. It is suggested that the specific neurochemical code in combination with a specific morphology leads to a precise regulation of the specialized tasks of the reticulum and reticular groove by subpopulations of myenteric neurons.

The ability of five ruminal fungi in syntrophic co-culture with the methanogen Methanobrevibacter smithii to degrade perennial ryegrass ( Lolium perenne) stem fragments and leaf blades was studied to determine the susceptibilities of non-autoclaved fresh tissues to fungal degradation. Autoclaving did not significantly increase fungal degradation of stem fragments but strongly increased degradation of leaf blades by a species of Caecomyces. In methanogenic co-cultures, non-autoclaved stem fragments were degraded more extensively by Neocallimastix frontalis and Piromyces isolates than by Caecomyces isolates. The N. frontalis and Piromyces isolates showed the greatest rates of stem degradation. When interactions between Fibrobacter succinogenes and methanogenic co-cultures of fungi growing on ryegrass stem were investigated, N. frontalis inhibited F. succinogenes. This has not been observed previously. In contrast, a Caecomyces species interacted positively with F. succinogenes to increase stem degradation, suggesting that F. succinogenes and Caecomyces spp. may have complementary fibrolytic activities. All five fungi tested failed to grow on fresh non-autoclaved leaf blades. In a repeat experiment with leaves from a separate harvest, leaf blades were degraded by N. frontalis but not by a Caecomyces species. We suggest that ryegrass leaf blades may contain natural anti-fungal compounds. Our results confirm the superiority of fungi in the degradation of intact stem and indicate that in vitro studies with non-autoclaved forage tissues may yield new information on forage factors affecting rumen microbes.

The evaluation of species diversity can be performed using species richness (number of species), diversity (number and relative proportions of species) or evenness (equitability of the proportion of each species). A large number of indices related to diversity or evenness is available but their mathematical properties remain unexplained, and hence their use is somewhat unreliable. We intended to present an array of well defined methods, based on discriminant analysis, to evaluate diversity in helminth communities of ruminants. The database used concerned seven cattle farms and seven sheep farms located in temperate areas, from which at least three necropsies were undertaken in autumn. The hosts were chosen because they had experienced nearly a complete grazing period and no anthelmintic treatment was performed for a minimum of 2 months before the necropsies were undertaken, so that the helminth communities could be considered as representative of each farm at one specific moment. We used discriminant analyses to evaluate diversity, based either on proportions of species, or on proportions of species arranged in decreasing order, or on a set of six indices of diversity selected from the most commonly used. We showed that actual proportions were the most efficient in cattle but not in lambs, and that discriminant analyses based on six indices of diversity or based on actual proportions of species ranked in decreasing order yielded very similar results in both host communities. We rejected the use of one single index for evaluating diversity in all cases and proposed the following procedure: actual proportions of species provide information on interactions between species and, when there is limited or no interaction, a combination of diversity indices or single indices could be used for estimating diversity. When interactions between species have to be taken into account, the best information will be obtained either from species proportions arranged in decreasing order or a combination of biodiversity indices.

[EN] purpose of this study was to establish the metabolic behaviour of both preruminant kid goats and lambs, when they are kept at different environmental temperatures (12,24 and 30°C). The animals were fed ad libitum with a milk replacer for the first two months of life. Blood samples were taken from all the animals on days 30, 40, 50 and 60 post partum, to determine serum levels of glucose, insulin, free fatty acids, triiodothyronine (T3) and thyroxine (T4), both when fasting and 4 hours after starting feeding. The high sensitivity of both kinds of animal to the lowest of the environmental temperatures used, particularly for the first periods of life here considered, was established from the glucose/insulin and T3/T4 molar ratios and from the concentrations of free fatty acids. The results obtained by species were also evidence of metabolic behaviour typical of leanner animals in kids., [ES] El objeto del presente estudio consiste en aclarar el particular comportamiento metabólico en el cabrito y en el cordero prerrumiante cuando se les mantiene a diferentes temperaturas ambientales (12, 24 y 30 °C). Los animales se alimentan ad libitum, en base a un mismo lactorreemplazante, durante sus primeros dos meses de vida. Los días 30, 40, 50 y 60 de edad se obtienen muestras de sangre de todos los animales, determinándose los niveles séricos de glucosa, insulina, ácidos grasos libres, triyodotironina (T3) y tiroxina (T4), tanto en ayuno como 4 h después de iniciada la toma de alimento. De los valores obtenidos para las relaciones molares de glucosa/insulina y T3/T4 así como las concentraciones de ácidos grasos libres, según clase de animal, temperatura ambiental, momento de toma de muestra y edad, se deducen la alta sensibilidad que ambas clases de animales muestran frente a la más baja de las temperaturas ensayadas, sobre todo durante sus primeros estadíos de vida. Igualmente y en función de las respuestas obtenidas según clase de animal, se deduce para cabritos un comportamiento metabólico típico de las especies de desarrollo más magro., This study was supported financially by the Interministerial Commission of Science and Technology. Spain (Project GAN90-0781).

We assessed the effects of a long and severe period of underfeeding, followed by a rapid refeeding with a high-concentrate diet, on weight, protein mass, and cellularity of the splanchnic organs in adult ewes. Twenty-four ewes, allocated to four groups of six, were fed a forage diet (50% regrowth of natural grassland hay and 50% wheat straw) either at maintenance (groups M and MO) or at 40% maintenance (groups U and UO) for 78 d. Groups M and U were then slaughtered, and groups MO and UO were subsequently overfed a high-concentrate diet (52% hay, 20% barley, 16% rapeseed meal, 4% fish meal, and 8% Megalac) at 236% maintenance for 26 d before being slaughtered. During the experiment, feed was adjusted to maintain feed supply at a constant percentage of animal requirements. After slaughter, fresh weight, dry weight, and protein mass of the reticulorumen, omasum, abomasum, small intestine, large intestine, and liver were measured. Cellularity was assessed from nucleic acids and protein contents for both ruminal mucosa and muscular-serosa layers, jejunum, and liver. The concentrations of ubiquitin and cathepsin D mRNA were measured in ruminal mucosa and muscular-serosa layers and in jejunum. Underfeeding decreased protein mass of splanchnic organs, especially in liver (-29%) and reticulorumen (-39%). Refeeding previously underfed animals increased protein mass of liver (+102%) and small intestine (+59%). No carry-over effect of the previous level of intake (UO vs. MO) was observed on the protein mass of splanchnic tissues after 26 d of refeeding. Variations in liver mass were mainly due to hypertrophy, as determined by the protein:DNA ratio, whereas variations in small intestinal mass were mainly due to hyperplasia, as determined by the amount of DNA. By contrast, changes in rumen mass associated with increasing ME intake seemed to be related to hypertrophy in the muscular-serosal component and hyperplasia in the epithelial component. The concentrations of ubiquitin and cathepsin D mRNA in the rumen and jejunum were not modified by feeding level, demonstrating that the expression of these genes for proteolytic enzymes was unchanged under these conditions.

A total of 74 embryos and fetuses were used in a comparative analysis of the epithelium of the non-glandular stomach compartments of merino sheep during development. The mechanical protection showed by the tegumentary epithelium in the superficial layers of the rumen, reticulum and omasum is supported by a buffer system of neutral mucopolysaccharides secreted by the deeper strata. Neutral mucopolysaccharides first appeared in epithelial cells at 46 days of fetal life. Acid mucopolysaccharides, mucins, and mucoid compounds were not detected. Growth curves and formulas were constructed for the epithelial layers.

Previous studies indicated large, thin-walled, milk-filled rumens in lethal grey and white Karakul lambs. There was also a significant decrease in the number and size of the myenteric plexuses and the number of ganglion cells in these lambs. The purpose of this study was to determine whether the myenteric ganglia of the affected lambs are functional, by testing for the presence of vaso-active intestinal peptide, somatostatin, neurotensin, neuropeptide Y, met-enkephalin, calcitonin gene-related peptide and substance P in the myenteric ganglia and nerve fibres in the forestomach and abomasum of grey, white and black Karakul lambs. Four 1-cm2 samples were taken from analogous areas of the wall of the rumen, reticulum, omasum and abomasum of five grey, five white and five black newborn Karakul lambs. They were pinned to wax squares, fixed for 18 h in Zamboni's fixative, dehydrated and rehydrated through graded alcohols and stored in phosphate-buffered saline. The outer longitudinal muscle layer of each sample of the rumen, reticulum, omasum and abomasum was separated from the rest of the tissue layers, stained for each of the seven neuropeptides by employment of the immunofluorescence technique, and studied with a Leitz Orthoplan fluorescent microscope. All the material studied tested positive for all the neuropeptides. It is concluded that all the peptides tested for were present in all the lambs and that the myenteric ganglia are therefore functional in the lethal lambs.

One hundred forty four ovine embryos and feti were used in an investigation to determine mathematical models describing the histomorphometric growth of tissues and compartments of the ruminant stomach. The results indicate that during prenatal life the diameter of the gastric chambers increase more slowly than the length. The tissue layers of the gastric walls, particularly the muscular tunic of all compartments demonstrated a uniform tendency toward more rapid development than the compartment walls proper.

Homozygous grey Karakul lambs are born with a lethal genetic factor responsible for death at weaning age. When put on a high roughage diet under field conditions they develop distended, thin-walled rumens and sand impacted abomasa. Homozygous white Karakul lambs have a similar factor but survive for a longer period. Black Karakul lambs are not affected. The present study was undertaken to compare by image analysis the number and size of the myenteric ganglia, and the number of myenteric neurones in the walls of the fore-stomach and abomasum of 24-h-old grey, white and black Karakul lambs. One square centimetre samples were taken from analogous areas of the rumen, reticulum, omasum and abomasum of 38 embalmed Karakul lambs. Haematoxylin and eosin stained histological sections of each sample were studied with a Vids 2 Image Analyzer. One way analysis of variance indicated a significant difference between the groups regarding the number and size of the myenteric ganglia and in the number of myenteric neurones in the reticulum, rumen and abomasum. The number and size of the ganglia and the number of neurones was greatest in the black lambs and decreased progressively in the white and grey lambs. The omasum was not affected. It is suggested that the paucity of myenteric ganglia and neurones in the regions examined is instrumental in causing the lethal condition described above.

1. The metabolism of albendazole (ABZ), albendazole sulphoxide (ABZSO) and albendazole sulphone (ABZSO2) by ruminal, abomasal and ileal fluids of sheep and cattle was investigated under anaerobic conditions in vitro. 2. None of the compounds was metabolically changed by incubation with abomasal fluids of sheep and cattle. 3. ABZ and ABZSO were extensively metabolized by sheep and cattle ruminal and ileal fluids. ABZSO2 was unaffected by incubation with these gastrointestinal fluids. 4. The rate of ABZ oxidation into ABZSO was greater for cattle ruminal and ileal fluids than for sheep fluids. 5. ABZSO was reduced back to ABZ by ruminal and ileal fluids of both species. This reducing activity was significantly higher for both ruminal and ileal fluids of sheep compared with those of cattle.

Three trials were conducted to assess effects of metabolizable protein and NE deficiencies on changes in body composition, organ mass and metabolism, and animal growth performance during restriction and realimentation. Growth of lambs was restricted to achieve no change in BW for periods of 5 to 6 wk by limiting intake of metabolizable protein or NE. In Trial 1, changes in body composition and visceral organ mass and metabolism during restriction were compared to unrestricted controls using 36 lambs. Trial 2 was designed to investigate changes in growth, body composition, and visceral organs during restriction and realimentation periods using 44 lambs. Trial 3 was limited to evaluation of differences in performance and carcass characteristics of previously restricted and unrestricted ram lambs (15 total). Results of Trial 1 indicated that liver weights were decreased with nutrient restrictions. Body protein mass was conserved in energy-restricted (ER) lambs and lost in protein-restricted (PR) lambs. Fat was mobilized at similar rates for PR and ER lambs. In Trial 2, liver and intestinal weights, as well as in vitro oxygen consumption by liver slices, were decreased with nutrient restrictions. The reductions persisted after 2 wk of realimentation, yet no compensatory growth was observed. Feed intakes were increased gradually during the first 2 wk of realimentation. Composition of gain during the realimentation period was similar to that of unrestricted lambs. In Trial 3, neither gain nor feed efficiency during realimentation was enhanced as a result of previous nutrient deficiencies. Absence of compensatory growth in Trial 3 is possibly attributable to differences in gastrointestinal fill. Lambs subjected to short-term PR and ER seem to have similar recuperative capacity.

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Ten abomasally cannulated crossbred wether lambs (avg wt, 33 kg) were used in a replicated 5 x 5 latin square design to determine the site and extent of apparent absorption of Mg when fed different sources of Mg. Lambs were fed twice daily 220 g of chopped mixed grass hay and 180 g of a corn-based supplement (control; .13% mg, DM basis), or the control diet supplemented with Mg (.26% Mg, DM basis) from MgO, magnesium citrate (MgC), smectite-vermiculite (Mg-Mica) or MgOH. Lambs were maintained in metabolism stalls during each of the five experimental periods. Each period consisted of a 7-d dietary adjustment followed by a 3-d collection of abomasal samples, feces and urine. Abomasal contents were sampled four times daily during the 3-d collection period. The diet contained .5% chromium oxide as a digestion marker. Apparent absorption of Mg was .17, .55, .85, .78 and .82 g/d for lambs fed the control, MgO, MgC, Mg-Mica and MgOH diets, respectively. Apparent absorption of Mg (g/d) was similar (P greater than .05) in the lambs fed the supplemented diets and greater (P less than .05) than in those fed the control diet. Preintestinal absorption of Mg was .21, .57, 1.08, .14 and .92 g/d when the control, MgO, MgC, Mg-Mica and MgOH diets were fed. Lambs fed the control and Mg-Mica diets absorbed similar (P greater than .05) quantities of Mg in the preintestinal region and less (P less than .05) than lambs fed the MgO, MgC and MgOH diets.(ABSTRACT TRUNCATED AT 250 WORDS)

1. In Expt 1, fractional synthesis rates (FSR) of tissue protein were measured along the gastrointestinal tract (GIT) of six 1-week-old, milk-fed lambs by using a large amount of L-[3,4(n)-3H]valine.2. In Expt 2, eighteen lambs were used to determine the fractional growth rate (FGR) of gastrointestinal tissue protein.3. FSRMinimum(Min) and FSRMaximum(Max) were calculated assuming plasma or tissue homogenate free valine specific radioactivity was representative of the valine precursor pool for protein synthesis. There were no significant differences between FSR(Min) and FSR(Max) in any gastrointestinal tissue of lambs used in Expt 1 (P > 0.05). FSR gradually and significantly (P > 0.05) increased from the oesophagus (FSR(Max)26.5%/d). reticulo-rumen (30.1%/d), omasum (41.0%/d) and abomasum (56.1%/d) to small intestine (87.5%/d), and then declined significantly (P < 0.05) towards the caecum (45.2%/d) and the colon (38.4%/d). No significant differences were observed between FSR in the duodenum, jejunum or ileum (P > 0.05).4. FGR ranged from 2,6%/d in the oesophagus to 8,7%/d in the omasum. The ratio, FGR:FSR, which reflected the efficiency of protein deposition, was at a maximum in the stomachs and caecum and at a minimum in the small intestine.5. The relative contribution of the oesophagus, stomachs, small intestine and large intestine to GIT protein synthesis was 1, 13, 76 and 10% respectively. The GIT accounted for approximately 11.5% of whole-body protein synthesis.

1. Intra-arterial infusions of vasoactive intestinal polypeptide (VIP) were made in anaesthetized lambs in which activity of the reticulo-omasal orifice (ROO) was recorded manometrically and in conscious lambs in which activity of the reticulum, ROO and abomasum were recorded by electromyographic (EMG) techniques. 2. Spontaneous rhythmic opening and closing movements of the ROO occurred in anaesthetized lambs at 3-5 min-1. Infusions of VIP into the left gastric artery at rates of 0.5-3.0 nmol min-1 produced changes in activity of the ROO. Within 120 s of commencement of the infusions there was an increase in frequency and magnitude of the movements of the ROO for up to 120 s. This was followed with infusion of VIP at the lower levels (0.5-1.0 nmol min-1), by a marked reduction and sometimes complete loss of the rhythmic movements. There was always complete cessation of activity of the ROO with infusion of VIP at 1.5-3.0 nmol min-1. 3. In conscious lambs the frequency of the diphasic reticular EMG bursts which recur at intervals of ca. 1 min was not affected by infusions of VIP at 3.0 nmol min-1 for 10 min. 4. Between each diphasic reticular EMG burst in the conscious lamb there was normally phasic activity of the ROO consisting of EMG bursts of long (ca. 4 s) and short (ca. 1 s) duration. Within 90 s of commencement of infusion of VIP at 3.0 nmol min-1 short-burst EMG activity disappeared with the remaining long bursts being of greater duration (5.4 +/- 1.2 s) than before infusion. After a series of four to fifteen such more prolonged long bursts there was quiescence of the EMG of the ROO. After infusion of VIP EMG activity recommenced first as a series of eight to fourteen long bursts which was followed by the reappearance also of short-burst activity. Infusions of VIP at 8-10 nmol min-1 produced a more prompt cessation of EMG activity of the ROO. Of other peptides which were infused only PHI (a peptide with N-terminal histidine and C-terminal isoleucine amide) produced cessation of the EMG activity of the ROO. However, on a molar basis VIP was 2-3 times more potent than PHI in causing cessation of activity of the ROO. 5. Infusion of VIP at 3.0 nmol min-1 produced a cessation or diminution of EMG activity of the body, antrum and pylorus of the abomasum.(ABSTRACT TRUNCATED AT 400 WORDS)

Publisher Summary This chapter discusses the digestion, absorption, and transport of lipids in ruminant animals. In the simple-stomached animal, the processes of digestion and absorption of dietary fats begin essentially when they reach the small intestine. In the ruminant animal, the situation is very different and the events that occur within the complex polygastric arrangement of the alimentary tract, principally pregastric microbial fermentation of cellulose and other plant polymers not normally hydrolyzed by digestive enzymes, have a profound effect on the chemical and physical nature of the lipids subsequently presented to the small intestine for digestion. Two major processes occur within the rumen, which have an important bearing on the composition and distribution of the lipid components of the digesta and their subsequent metabolism within the intestine. These processes, which are intrinsically bound together, are lipolysis of the dietary lipids and hydrogenation of their unsaturated fatty-acid constituents. These make an immense contribution directly to the lipid metabolism of the host animal after absorption from the rumen and indirectly through their involvement in bacterial and protozoal lipid synthesis.

1. Six closely shorn sheep were given brome grass (Bromus inermis) pellets at the rate of 59 or 98 g dry matter (dm)/h and maintained at ambient temperatures of 2–5° and 22–25° for 35 d. Measurements of digestion, rate of passage of digesta, and nitrogen transformations were made during the last 13 d of temperature exposure.2. Cold exposure at the lower level of intake reduced the apparent digestibility of dm and organic matter (om) approximately 0.055 units. Apparent digestibility of dm and om was further decreased approximately 0.03 units with the higher level of food intake in the cold. Apparent N digestibility was significantly depressed from 0.62 to 0.59–0.60 for sheep exposed to cold at both levels of intake.3. Exposure of sheep to cold resulted in a decrease in the turnover time of the particulate marker, 103Ru, from 19 h to 10.12 h in the rumen, a decrease in rumen volume, and a significant increase in dm and om which escaped digestion in the stomach. Volatile fatty acid and methane production in the rumen were highly correlated with the amount of om digested in the stomach. Methane production in the rumen comprised 0.81 of total production in warm sheep, and 0.68–0.74 of total production in cold-exposed sheep.4. More om and non-ammonia-N were apparently digested in the intestines of sheep exposed to cold than in warm sheep at the same food intake, but the apparent digestibilities in the intestines of dm, om and non-ammonia-N leaving the abomasum did not change significantly between treatments. The retention time of 103Ru in the intestines was 17.18 h in sheep given 59 g dm food/h at both exposure temperatures, but was reduced to 12 h for cold-exposed sheep given 98 g dm/h. Methane production in the postruminal tract was increased at the higher food intake, but there was no difference between warm and cold-exposed sheep at the same food intake.5. The rate of irreversible loss of plasma urea and rumen ammonia was measured by infusion of [15N]urea and [15N]ammonium chloride. Exposure to cold reduced the irreversible loss of plasma urea from 0.85 to 0.75–0.77 g N/g N intake, and the irreversible loss of rumen ammonia from 0.66 to 0.57–0.61 g N/g N intake. The transfer of plasma urea-N to the rumen ammonia pool was significantly greater (9.5 g N/d) in the cold-exposed sheep than the value (7.3 g N/d) in warm sheep.6. The efficiency of microbial synthesis in the rumen was increased in cold-exposed sheep, and was related to the amount of N recycled through the rumen ammonia pool from intraruminal sources. The effect of dilution rate and fermentation patterns on efficiency of microbial synthesis is discussed.

1. Fistulated sheep given a concentrate diet were used to study the behaviour of solute ([51Cr]EDTA) and particle ([103Ru]phenanthroline) markers in the stomach under conditions of continuous feeding.2. An injection of a mixed dose of [51Cr]EDTA and [103Ru]phenanthroline was given into the rumen and the time course of marker concentrations in the rumen and the abomasum was recorded. The curves were analysed on the assumption that the stomach of the sheep could be represented as two mixing compartments (reticulo-rumen and abomasum) and a time delay (omasum). This model provided a very good description of the data.3. [103Ru]phenanthroline associated with small particles was retained in the rumen much longer than [51Cr]EDTA. Although exchange of [103Ru]phenanthroline occurred between large and small particle fractions, the results suggested that small particles may have been retained somewhat longer in the rumen than solutes. However, it was clear from the results that the mean retention times for particulate matter in the rumen could not be simply obtained using adsorbable markers.4. Cyclical fluctuations in the concentration of [51Cr]EDTA in the rumen indicated that there were daily variations in net water flux in the rumen.5. The presence of protozoa was associated with much shorter retention times of both solutes and particles in the rumen. Protozoa were also associated with reduced rumen volumes.

The effect of intravenous (IV) vs intracerebroventricular (ICV) administrations of pentagastrin on gastro-intestinal motility and rumination were investigated by electromyography in sheep; these effects were compared to those obtained after a previous IV or ICV injection of proglumide. When ICV administered at a dose of 20 ng X kg-1, pentagastrin did not significantly affect the frequency of reticular and abomasal spiking activity but elicited a 13 to 37 min period of rumination after a delay of 23 +/- 7 min. In contrast, when IV infused at a rate of 20 ng X kg-1 X h-1 during 20 min, pentagastrin inhibited significantly the frequency of reticular and abomasal contractions for 30 to 40 min but did not induce rumination. Proglumide ICV administered (0.8 mg X kg-1) abolished the rumination induced by central injection of pentagastrin whereas a 10 times higher dose administered systemically (8 mg X kg-1 IV) did not block these effects. Both of ICV and IV administrations of proglumide at respectively 0.8 and 8 mg X kg-1 were unable to antagonize the inhibitory effects of pentagastrin on reticulum and abomasum motility. It was concluded that (i) pentagastrin acts centrally to induce rumination and that (ii) proglumide selectively blocks these effects but not the pentagastrin induced gastro-intestinal hypomotility.

The influence of concentrate intake on the subsequent intake of hay was investigated in sheep fitted with a rumen cannula and electrodes on the reticulum wall to measure volatile fatty acids concentration and reticular motility, respectively. In sheep fasted during night time, a previous meal of concentrates given 30, 60 or 120 min before feeding hay, did not modify significantly (p less than 0.05) the first hour and the first 3 hour intake of hay despite a large increase in ruminal total volatile fatty acid concentration. However, the daily intake of hay was significantly (p less than 0.05) reduced. Similarly, the reticular motility in response to feeding hay was not affected by the previous meals of concentrate. It is concluded that in fasted sheep on a hay ration the short-term satiation of a hay meal is not affected by foregoing intake of concentrates and that the hay intake is not controlled by ruminal volatile fatty acid levels.

experimental studies of the pharmacological control of the reticulo-rumen reveal two major central inhibitory pathways: (i) an adrenergic system which inhibits the magnitude of reticulo-ruminal movements and involves alpha 2-receptors and (ii) an inhibitory opioid system, which modulates the rate of the contractions. In addition, the coarseness of the stomach contents and the masticatory movements represent the major excitatory inputs to the gastric centres, hence the hypomotility and stasis observed in disease processes which lead to anorexia. Finally, the amplitude of reticular contractions will tend to vary inversely with the rate of contractions following the administration of stimulatory drugs acting centrally. As a practical statement, a direct action on the gastric centres is possible for drugs such as alpha blockers and/or morphine antagonists. Reflex excitatory effects may be induced by stimulation of muscarinic receptors of the reticulorumen wall as long as it remains below the threshold of a neuromuscular blockade. The highly complex mechanisms whereby reticuloruminal movements are regulated provide for (i) drug interactions, like those of histamine antagonists and opioid agonists, (ii) reflex inhibition of both amplitude and frequency of contractions arising from an enhanced abomaso-duodenal motility, like that induced by serotonin, and (iii) reflex stimulation of the rate of contractions elicited by the i.v. injection of catecholamines, an effect limited to the sheep. The multifactorial nature of reticuloruminal function suggests that treatment is unlikely to effect a cure but should materially re-establish a more normal motility. Further studies, required in diseased animals to provide for a curative use of drugs and a more thorough understanding of drug effects in normal ruminants, represent only a first step toward rational therapy. In addition, the extrapolation of drug effects from sheep to calves or cattle could be hazardous, especially for drugs whose mechanisms of action are currently unknown.

1. Six sheep, three animals per diet, were prepared with rumen fistulas and fed on frozen grass or grass–maize pellets to give magnesium intakes of 1·79 and 2·23 g/d respectively. The mean apparent availabilities of Mg in sheep fed on frozen grass and grass–maize pellets were 0·31 and 0·36 respectively.2. The rumen contents were fractionated by straining the digesta through linen cloth and then differentially centrifuged to give 20 000gand 100 000gsupernatant fractions.3. In all sheep, regardless of diet, at 4 and 16 h after a meal, 50 and 60% respectively of the total Mg in the rumen contents was found in strained rumen fluid while 30 and 38% respectively of the total Mg was found in the 100 000gsupernatant fraction.4. The net absorption of Mg from the temporarily isolated and washed reticulo-rumen was studied using either 100 000 g supernatant fractions of rumen contents from sheep fed on one or other of the two diets, or inorganic buffers containing the same concentration of Mg and other macroelements.5. The Mg was readily absorbed from the 100 000gsupernatant fraction placed in the rumen with the rate of absorption being 7·3 μmol/1 per min (505 mg/d) from the supernatant fraction obtained from sheep fed on frozen grass and 11.3 μmo/1 per min (781 mg/d) from the supernatant fraction from sheep fed on grass–maize pellets. In the same sheep, the previously described rates of Mg absorption from the 100 000gsupernatant fraction were similar to those obtained from the comparable inorganic buffers.6. The effects of varying concentrations of potassium and sodium on the net absorption rate of Mg (as24Mg) and on the one-way efflux of Mg (as28Mg) from supernatant fractions or rumen fluid and inorganic buffers were investigated using the temporarily-isolated and washed rumen in three sheep. Although the net absorption rate of24Mg from supernatant fractions or buffers containing similar K concentrations varied significantly between sheep, a similar percentage decrease in the absorption rates of both24Mg and28Mg was found for each sheep as the K concentration was increased.7. One pair of sheep was fed on the frozen grass and the other pair was fed on the grass–maize pellets. Their daily intakes of K were then increased to 50 g/d for 14 d by intrarumen infusion of potassium chloride. In three of the four sheep the plasma Mg concentration fell within 12 h of the start of the KCl administration. In all sheep urinary excretion of Mg decreased and its faecal output increased. The increased intake of K had no effect on the distribution of Mg in the rumen contents.8. Gel-filtration chromatography of the 100 000gsupernatant fractions, regardless of the diet, showed that over 90% of the Mg in the 100 000gsupernatant fractions was associated with a low-molecular-weight fraction of about 200 Da which corresponded to the elution volume of magnesium chloride in 0·1 M-sodium chloride.9. It is concluded that any binding of Mg ions to small organic molecules in the 100 000gsupernatant fraction of rumen contents played no significant role in the restriction of Mg absorption from the reticula-rumen. The depressent effect of increased K concentration in rumen contents on the net absorption of Mg is via a reduction in the absorptive flux rather than by increased secretion of Mg into the rumen fluid.

Four experiments were conducted to study factors affecting digestibility of forages in cattle, sheep, goats and white-tailed deer. In a series of digestion trials (Exp. 1), the dry matter digestibility of a moderately high fiber diet was greater in cattle than in deer. Digestibilities of the diet in sheep and goats were intermediate and not different from either extreme. In a second series of trials (Exp. 2), relative organic matter digestibilities were for goats more than sheep more than deer. However, in Exp. 2, intake in goats was very low and digestibility appeared to be positively related to retention time and inversely related to turnover rate. Results of three trials (Exp. 3) suggested that rate of digestion was related more to diet than to the animal species consuming the diet. In grazing animals (Exp. 4), goats digested a smaller percentage of consumed material than either cows or sheep during three of four seasons even though diets were of similar in vitro digestibility. This difference was related to a faster turnover and shorter retention time in goats. These data support the concept that there are species differences in gastrointestinal dynamics which may be which may be important determinants of adaptability to grazing conditions.

Barker I. K. and Titchen D. A. 1982. Gastric dysfunction in sheep infected with Trichostrongylus colubriformis, a nematode inhabiting the small intestine. International Journal for Parasitology12: 345–356. Six of 12 lambs infected with Trichostrongylus colubriformis had reduced abomasal acidification (pH 4.0–8.1) in comparison with uninfected pair-fed and replete controls (pH