Bovine rumen epithelium undergoes rapid structural adaptations during grain-induced subacute ruminal acidosis

Alterations in rumen epithelial structure and function during grain-induced subacute ruminal acidosis (SARA) are largely undescribed. In this study, four mature nonlactating dairy cattle were transitioned from a high-forage diet (HF; 0% grain) to a high-grain diet (HG; 65% grain). After feeding the HG diet for 3 wk, the cattle were transitioned back to the original HF diet, which was fed for an additional 3 wk. Continuous ruminal pH was measured on a weekly basis, and rumen papillae were biopsied during the baseline and at the first and final week of each diet. The mean, minimum, and maximum daily ruminal pH were depressed (P < 0.01) in the HG period compared with the HF period. During the HG period, SARA was diagnosed only during week 1, indicating ruminal adaptation to the HG diet. Microscopic examination of the papillae revealed a reduction (P < 0.01) in the stratum basale, spinosum, and granulosum layers, as well as total depth of the epithelium during the HG period. The highest (P < 0.05) papillae lesion scores were noted during week 1 when SARA occurred. Biopsied papillae exhibited a decline in cellular junctions, extensive sloughing of the stratum corneum, and the appearance of undifferentiated cells near the stratum corneum. Differential mRNA expression of candidate genes, including desmoglein 1 and IGF binding proteins 3, 5, and 6, was detected between diets using qRT-PCR. These results suggest that the structural integrity of the rumen epithelium is compromised during grain feeding and is associated with the differential expression of genes involved in epithelial growth and structure.     

Postmortem observations on rumen wall histology and gene expression and ruminal and caecal content of beef cattle fattened on barley-based rations

Sub-acute ruminal acidosis (SARA) can reduce the production efficiency and impair the welfare of cattle, potentially in all production systems. The aim of this study was to characterise measurable postmortem observations from divergently managed intensive beef finishing farms with high rates of concentrate feeding. At the time of slaughter, we obtained samples from 19 to 20 animals on each of 6 beef finishing units (119 animals in total) with diverse feeding practices, which had been subjectively classified as being high risk (three farms) or low risk (three farms) for SARA on the basis of the proportions of barley, silage and straw in the ration. We measured the concentrations of histamine, lipopolysaccharide (LPS), lactate and other short-chain fatty acids (SCFAs) in ruminal fluid, LPS and SCFA in caecal fluid. We also took samples of the ventral blind sac of the rumen for histopathology, immunohistopathology and gene expression. Subjective assessments were made of the presence of lesions on the ruminal wall, the colour of the lining of the ruminal wall and the shape of the ruminal papillae. Almost all variables differed significantly and substantially among farms. Very few pathological changes were detected in any of the rumens examined. The animals on the high-risk diets had lower concentrations of SCFA and higher concentrations of lactate and LPS in the ruminal fluid. Higher LPS concentrations were found in the caecum than the rumen but were not related to the risk status of the farm. The diameters of the stratum granulosum, stratum corneum and of the vasculature of the papillae, and the expression of the gene TLR4 in the ruminal epithelium were all increased on the high-risk farms. The expression of IFN-γ and IL-1β and the counts of cluster of differentiation 3 positive and major histocompatibility complex class two positive cells were lower on the high-risk farms. High among-farm variation and the unbalanced design inherent in this type of study in the field prevented confident assignment of variation in the dependent variables to individual dietary components; however, the CP percentage of the total mixed ration DM was the factor that was most consistently associated with the variables of interest. Despite the strong effect of farm on the measured variables, there was wide inter-animal variation.     

Functional organization of the bovine rumen epithelium

The functional organization of the bovine rumen epithelium has been examined by electron and light microscopy combined with immunocytochemistry to define a transport model for this epithelium. Expression of connexin 43, an integral component of gap junctions, the tight-junction molecules claudin-1 and zonula occludens 1 (ZO-1), and the catalytic alpha-subunit of Na(+)-K(+)-ATPase was demonstrated by SDS-PAGE and Western blotting. From the lumen surface, four cell layers can be distinguished: the stratum corneum, the stratum granulosum, the stratum spinosum, and the stratum basale. Both claudin-1 and ZO-1 immunostaining showed plasma membrane staining, which was present at the stratum granulosum with decreasing intensity through the stratum spinosum to the stratum basale. The stratum corneum was negative for claudin-1 immunostaining. Transmission electron microscopy confirmed that occluding tight junctions were present at the stratum granulosum. Plasma membrane connexin 43 immunostaining was most intense at the stratum granulosum and decreased in intensity through stratum spinosum and stratum basale. There was intense immunostaining of the stratum basale for Na(+)-K(+)-ATPase, with weak staining of the stratum spinosum. Both the stratum granulosum and the stratum corneum were essentially negative. Stratum basale cells also displayed a high mitochondrial density relative to more apical cell layers. We conclude that epithelial barrier function may be attributed to the stratum granulosum and that cell-cell gap junctions allow diffusion to interconnect the barrier cell layer with the stratum basale where Na(+)-K(+)-ATPase is concentrated.     

Effects of faba bean,blue lupin and rapeseed meal supplementation on nitrogen digestion and utilization of dairy cows fed grass silage-based diets

There is increasing interest in using locally produced protein supplements in dairy cow feeding. The objective of this experiment was to compare rapeseed meal (RSM), faba beans (FBs) and blue lupin seeds (BL) at isonitrogenous amounts as supplements of grass silage and cereal based diets. A control diet (CON) without protein supplement was included in the experiment. Four lactating Nordic Red cows were used in a 4 × 4 Latin Square design with four 21 d periods. The milk production increased with protein supplementation but when expressed as energy corrected milk, the response disappeared due to substantially higher milk fat concentration with CON compared to protein supplemented diets. Milk protein output increased by 8.5, 4.4 and 2.7% when RSM, FB and BL were compared to CON. The main changes in rumen fermentation were the higher propionate and lower butyrate proportion of total rumen volatile fatty acids when the protein supplemented diets were compared to CON. Protein supplementation also clearly increased the ruminal ammonia N concentration. Protein supplementation improved diet organic matter and NDF digestibility but efficiency of microbial protein synthesis per kg organic matter truly digested was not affected. Flow of microbial N was greater when FB compared to BL was fed. All protein supplements decreased the efficiency of nitrogen use in milk production. The marginal efficiency (amount of additional feed protein captured in milk protein) was 0.110, 0.062 and 0.045 for RSM, FB and BL, respectively. The current study supports the evidence that RSM is a good protein supplement for dairy cows, and this effect was at least partly mediated by the lower rumen degradability of RSM protein compared to FB and BL. The relatively small production responses to protein supplementation with simultaneous decrease in nitrogen use efficiency in milk production suggest that economic and environmental consequences of protein feeding need to be carefully considered.     

Demonstration of substances of innate immunity in the integument of the Malayan pangolin (Manis javanica)

Using immunohistochemistry, the study demonstrates substances of the innate immunity in the skin of the Malayan pangolin (Manis javanica), referring mainly to the epidermis. The results obtained showed clear reaction differences between the dorsolateral body region with its strong cover of hard horny scales and the abdominal body part with a thick soft stratum corneum and a dense cover of fine hairs. Regarding pathogen recognition receptors, positive reactions for Toll-like receptors were generally weak for TLR2, in contrast to TLR4, that exhibited strong reactions in the epidermis of both body regions, with increasing staining intensities towards the stratum corneum; ß-glucan receptors showed positive reactions only for l-ficolin and mannose-binding lectin, but not for dectin-1, and only at the abdomen. A generally positive staining for both body regions was obtained for all cationic antimicrobial peptides tested, whereby cathelicidin exhibited strong reaction intensities in all epidermal layers, ß-defensin 2 staining was often limited to the stratum basale and the stratum spinosum, and positive reactions for ß-defensin 3 appeared distinctly only in the epidermis of the abdomen; for these peptides, positive reaction staining could also be found in the outer epithelial root sheath of hair follicles, their glandular annexes, and free cells of the dermis. Lysozyme was found in the vital epidermis of both body regions studied, with strong staining limited to the dorsum; strong reactions were also visible in the hair follicles.     

Expression and localization of monocarboxylate transporters and sodium/proton exchangers in bovine rumen epithelium

Monocarboxylate-H+ cotransporters, such as monocarboxylate transporter (MCT) SLC16A, have been suggested to mediate transruminal fluxes of short-chain fatty acids, ketone bodies, and lactate. Using an RT-PCR approach, we demonstrate expression of MCT1 (SLC16A1) and MCT2 (SLC16A7) mRNA in isolated bovine rumen epithelium. cDNA sequence from these PCR products combined with overlapping expressed sequence tag data allowed compilation of the complete open reading frames for MCT1 and MCT2. Immunohistochemical localization of MCT1 shows plasma membrane staining in cells of the stratum basale, with intense staining of the basal aspects of the cells. Immunostaining decreased in the cell layers toward the rumen lumen, with weak staining in the stratum spinsoum. Immunostaining in the stratum granulosum and stratum corneum was essentially negative. Since monocarboxylate transport will load the cytosol with acid, expression and location of Na+/H+ exchanger (NHE) family members within the rumen epithelium were determined. RT-PCR demonstrates expression of multiple NHE family members, including NHE1, NHE2, NHE3, and NHE8. In contrast to MCT1, immunostaining showed that NHE1 was predominantly localized to the stratum granulosum, with a progressive decrease toward the stratum basale. NHE2 immunostaining was observed mainly at an intracellular location in the stratum basale, stratum spinosum, and stratum granulosum. Given the anatomic localization of MCT1, NHE1, and NHE2, the mechanism of transruminal short-chain fatty acid, ketone body, and lactate transfer is discussed in relation to a functional model of the rumen epithelium comprising an apical permeability barrier at the stratum granulosum, with a cell syncitium linking the stratum granulosum to the blood-facing stratum basale.     

Effects of the acid–base treatment of corn on rumen fermentation and microbiota,inflammatory response and growth performance in beef cattle fed high-concentrate diet

Beef cattle are often fed high-concentrate diet (HCD) to achieve high growth rate. However, HCD feeding is strongly associated with metabolic disorders. Mild acid treatment of grains in HCD with 1% hydrochloric acid (HA) followed by neutralization with sodium bicarbonate (SB) might modify rumen fermentation patterns and microbiota, thereby decreasing the negative effects of HCD. This study was thus aimed to investigate the effects of treatment of corn with 1% HA and subsequent neutralization with SB on rumen fermentation and microbiota, inflammatory response and growth performance in beef cattle fed HCD. Eighteen beef cattle were randomly allocated to three groups and each group was fed different diets: low-concentrate diet (LCD) (concentrate : forage = 40 : 60), HCD (concentrate : forage = 60 : 40) or HCD based on treated corn (HCDT) with the same concentrate to forage ratio as the HCD. The corn in the HCDT was steeped in 1% HA (wt/wt) for 48 h and neutralized with SB after HA treatment. The animal trial lasted for 42 days with an adaptation period of 7 days. At the end of the trial, rumen fluid samples were collected for measuring ruminal pH values, short-chain fatty acids, endotoxin (or lipopolysaccharide, LPS) and bacterial microbiota. Plasma samples were collected at the end of the trial to determine the concentrations of plasma LPS, proinflammatory cytokines and acute phase proteins (APPs). The results showed that compared with the LCD, feeding the HCD had better growth performance due to a shift in the ruminal fermentation pattern from acetate towards propionate, butyrate and valerate. However, the HCD decreased ruminal pH and increased ruminal LPS release and the concentrations of plasma proinflammatory cytokines and APPs. Furthermore, feeding the HCD reduced bacterial richness and diversity in the rumen. Treatment of corn increased resistant starch (RS) content. Compared with the HCD, feeding the HCDT reduced ruminal LPS and improved ruminal bacterial microbiota, resulting in decreased inflammation and improved growth performance. In conclusion, although the HCD had better growth performance than the LCD, feeding the HCD promoted the pH reduction and the LPS release in the rumen, disturbed the ruminal bacterial stability and increased inflammatory response. Treatment of corn with HA in combination with subsequent SB neutralization increased the RS content and helped counter the negative effects of feeding HCD to beef steers.     

Combination of legume-based herbage and total mixed ration (TMR) maintains intake and nutrient utilization of TMR and improves nitrogen utilization of herbage in heifers

Diets combining herbage and total mixed rations (TMR) are increasingly used in temperate regions for feeding ruminants, but little information is available regarding the effects on nutrient intake and digestion of this feeding management in beef cattle. The aim of this study was to determine the effects of combining TMR (10% CP and 13% ADF), and legume-based herbage (14% CP and 27% ADF) on intake, nutrient digestion, ruminal fermentation, microbial N flow and glucose and nitrogen metabolism in heifers. The experiment was a 3×3 Latin square design replicated three times; each period lasted 18 days (10 adaptation days and 8 measurement days). Nine cross-bred (Aberdeen Angus×Hereford) heifers (214±18 kg) fitted with permanent rumen catheters and housed in individual metabolic cages were assigned to one of three treatments: 24 h access to TMR (T), 24 h access to herbage (H) or combined diets with 18 h access to TMR and 6 h access to herbage (T+H). Data were evaluated using a mixed model. Animals fed T+H (TMR 71% and herbage 29%) diets tended to have a higher dry matter intake as a proportion of their BW than animals fed T. The T+H diet did not change ruminal fermentation (pH, N–NH₃ and volatile fatty acids) or the N metabolism relative to the T diet, but increased the glucagon concentration and altered glucose metabolism. Conversely, animals fed T+H had increased purine derivatives excretion, increased N use efficiency for microbial protein synthesis and decreased plasma urea and urinary N excretion relative to animals fed H diet. The use of combined diets led to consumption of nutrients similar to a TMR diet, without reducing nutrient use and could improve N utilization compared with the herbage-only diet.     

Morphology and microanatomy of harbor porpoise (Phocoena phocoena) dorsal fin tubercles

The unique pattern of small tubercles on the leading edge of the dorsal fins of harbor porpoises (Phocoena phocoena) has been widely noted in the literature, though their structure or function has never been conclusively identified. We examined external morphology and microanatomy of the tubercles for further understanding of the nature of the tubercles. Measurements were taken of height and peak‐to‐peak distance of the tubercles using scaled photographs. Mean tubercle height was standardized as a percentage of the dorsal fin height and ranged from 0.63 to 0.87%. Mean peak‐to‐peak distance ranged from 4.2 ± 2.0 to 5.6 ± 2.0 mm. The microstructure analysis of the dorsal fin leading edge, trailing edge and tubercles revealed an epidermal thickness of 0.7–2.7 mm with the thickest epidermis at the tubercular apex. The epidermis contained three distinct strata (=layers), including the stratum corneum, spinosum, and basale. The stratum corneum was significantly thickened in tubercles, over four times thicker than in the leading or trailing edge of the fin. The stratum spinosum, composed of lipokeratinocytes and lamellar oil bodies, was significantly thinner in the trailing edge than in the other two sites. There was no significant difference in the stratum basale among the three sites. Volume fraction of lipokeratinocytes was significantly higher at the sides of the leading edge and the apex of the tubercles, while volume fraction of lamellar oil bodies was significantly lower at the apex of the tubercles. Though the function of the tubercles is unknown, their position, hardened structure and increased epidermal stratum corneum suggest that they may have hydrodynamic importance. J. Morphol., 2011. © 2010 Wiley‐Liss, Inc.     

Localization of Na,K-ATPase in lingual epithelia

Na,K-ATPase was localized in canine fungiform and circumvallfltepapillae by immunocytochemical and histochemical methods. Monoclonalantibodies raised against the -subunit of Na,K-ATPase showedspecific staining in the stratum basale and in the lower layersof the stratum spinosum. Small stained wavy lines, interpretedas trigerrunal fibers, were found in the epithelium near tastebuds. In contrast, conventional histochemical methods showedno staining in the epithelium. In both immunocytochemical and histochemical methods taste budswere densely stained. The histochemical stain in taste budswas essentially eliminated by levamisole and L-cysteine butremained in the presence of 10 mM ouabain or in the absenceof potassium. These data suggest that the majority of the histochemicalstain arises from phosphatases other than Na,K-ATPase.     

Immunohistochemical localization of irisin in skin,eye, and thyroid and pineal glands of the crested porcupine (Hystrix cristata)

Irisin was first identified in muscle cells. We detected irisin immunoreactivity in various organs of the crested porcupine (Hystrix cristata). In the epidermis, irisin immunoreactivity was localized mainly in stratum basale, stratum spinosum and stratum granulosum layers; immunoreactivity was not observed in the stratum corneum. In the dermis, irisin was found in the external and internal root sheath, cortex and medulla of hair follicles, and in sebaceous glands. Irisin immunoreactivity was found in the neural retina and skeletal muscle fibers associated with the eye. The pineal and thyroid glands also exhibited irisin immunoreactivity.     

Mycotoxin-contaminated diets and an adsorbent affect the performance of Nellore bulls finished in feedlots

Mycotoxins are present in almost all feedstuffs used in animal nutrition but are often ignored in beef cattle systems, even though they can affect animal performance. The objective of this study was to evaluate the effects of mycotoxins and a mycotoxin adsorbent (ADS) on performance of Nellore cattle finished in a feedlot. One hundred Nellore cattle (430 ± 13 kg) were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. The factors consisted of two diets with either natural contamination (NC) or exogenous contamination (EC) and the presence (1 g/kg of DM; ADS) or absence of a mycotoxin adsorbent. The NC and EC diets had the following contaminations, respectively: 0.00 and 10.0 µg/kg aflatoxins, 5114 and 5754 µg/kg fumonisins, 0.00 and 42.1 µg/kg trichothecenes B, 0.00 and 22.1 µg/kg trichothecenes A and 42.9 and 42.9 µg/kg fusaric acid. At the beginning of the experiment, all animals were weighed, and four randomly selected animals were slaughtered to evaluate the initial carcass weight. After 97 days of treatment, all animals were weighed and slaughtered. There was no interaction among factors for the DM intake (DMI; P = 0.92); however, there was a tendency for the EC diets to decrease the DMI by 650 g/day compared to animals fed NC diets (P = 0.09). There was a trend for interaction among factors (P = 0.08) for the average daily gain (ADG), where the greatest ADG was observed for cattle fed the NC diet (1.77 kg), and the lowest was observed for those fed the EC diet (1.51 kg). The NC + ADS and EC + ADS treatments presented intermediate values for ADG. The animals fed the NC diet had a greater final BW (596 kg) than animals fed the EC treatment (582 kg; P = 0.04). There was a tendency for interaction among factors for carcass gain (P = 0.08). Similarly to ADG, the highest carcass gain was observed for animals fed the NC diet (1.20 kg), and the lowest was observed for those fed the EC diet (1.05 kg). The NC + ADS and EC + ADS treatments presented intermediate values. The natural contamination groups had greater carcass gain than that of the EC groups, and the use of the ADS recovered part of the weight gain in animals fed the EC diet. In conclusion, mycotoxins at the levels evaluated affected the performance of beef cattle, and adsorbents may mitigate their impact.     

Protein metabolism,body composition and oxygen consumption in young bulls divergent in residual feed intake offered two contrasting forage-based diets

Protein metabolism and body composition have been identified as major determinants of residual feed intake (RFI) in beef cattle fed high-starch fattening diets. This study aimed to evaluate if these two identified RFI determinants in beef cattle are the same across two contrasting silage-based diets. During two consecutive years, an 84-day feed efficiency test (Test A) immediately followed by a second 112-day feed efficiency test (Test B) was carried out using a total of 100 animals offered either one of two diets (either corn silage- or grass silage-based) over 196 days. At the end of Test A, the 32 animals most divergent for RFI (16 extreme RFI animals per diet, eight low RFI and eight high RFI) were identified and evaluated during Test B for their i) N use efficiency (NUE; N retention/N intake) calculated either from a 10-d nitrogen balance trial or from estimations based on body composition changes occurring during the whole experiment (Test A and Test B; 196 days), ii) carcass and whole-body protein turnover rates analysed through the 3-methyl-histidine urinary excretion and the N isotopic turnover rates of urine, respectively, and iii) body composition measured at the slaughterhouse at the end of Test B. Oxygen consumption was measured during Test B for the 100 animals by two GreenFeed systems. Irrespective of the diet, efficient RFI animals tended (P = 0.08) to improve their NUE when N retention was estimated for 196 days or when considering their lower urinary urea-N to total N ratio (P = 0.03). In contrast, NUE calculated during the 10-d N balance showed no differences (P = 0.65) across RFI groups suggesting that this method may not be suitable to capture small NUE differences. Efficient RFI individuals presented higher dressing percentage and muscle deposition in the carcass (P = 0.003) but lighter rumen (P = 0.001), and a trend for lower oxygen consumption (P = 0.08) than inefficient RFI animals irrespective of the diet. Lower protein degradation rates of skeletal muscle and lower protein synthesis rates of plasma proteins were found in efficient RFI cattle but only with the corn silage-based diet (RFI × Diet; P = 0.02). The higher insulinaemia associated with the corn silage-based diet (P = 0.001) seemed to be a key metabolic feature explaining the positive association between protein turnover and RFI only in this diet. Feed N was more efficiently used for growth by efficient RFI animals regardless of the diet but lower protein turnover rates in efficient RFI animals were only observed with corn silage-based diets.     

Effect of Haylage and Monensin Supplementation on Ruminal Bacterial Communities of Feedlot Cattle

The objective of this study was to investigate the ruminal bacterial communities as affected by monensin, haylage, and their interaction of feedlot cattle fed 60 % dried distillers grains with solubles in a replicated 4 × 4 Latin square design. Pyrosequencing analysis of the V1–V3 region (about 500 bp) of 16S rRNA gene from the four dietary treatments (3 treatment plus one control diets) collectively revealed 51 genera of bacteria within 11 phyla. Firmicutes and Bacteroidetes were the first and the second most predominant phyla, respectively, irrespective of the dietary treatments. Monensin supplementation decreased the proportion of Gram-positive Firmicutes while increasing that of Gram-negative Bacteroidetes. However, the monensin supplementation did not reduce the proportion of all genera of Gram-positive bacteria placed within Firmicutes and lowered that of some genera of Gram-negative bacteria placed within Bacteroidetes. Haylage supplementation appeared to attenuate inhibition of monensin on some genera of bacteria. Factors other than monensin and haylage could affect ruminal bacterial communities.     

Effects of monolaurin on ruminal methanogens and selected bacterial species from cattle, as determined with the rumen simulation technique

Before being able to implement effective ruminal methane mitigation strategies via feed supplementation, the assessment of side effects on ruminal fermentation and rumen microbial populations is indispensable. In this respect we investigated the effects of monolaurin, a methane-mitigating lipid, on methanogens and important carbohydrate-degrading bacteria present in ruminal fluid of dairy cattle in continuous culture employing the rumen simulation technique. In six experimental runs, each lasting for 10 days, four diets with different carbohydrate composition, based on hay, maize, wheat and a maize-wheat mixture, either remained non-supplemented or were supplemented with monolaurin and incubated in a ruminal-fluid buffer mixture. Incubation liquid samples from days 6 to 10 of incubation were analyzed with relative quantitative polymerase chain reaction (qPCR) of 16S rRNA genes to assess monolaurin-induced shifts in specific rumen microbial populations in relation to the corresponding non-supplemented diets. Monolaurin completely inhibited Fibrobacter succinogenes in all diets while the response of the other cellulolytic bacteria varied in dependence of the diet. Megasphaera elsdenii remained unaffected by monolaurin in the two diets containing maize, but was slightly stimulated by monolaurin with the wheat and largely with the hay diet. The supply of monolaurin suppressed Methanomicrobiales below the detection limit with all diets, whereas relative 16S rRNA gene copy numbers of Methanobacteriales increased by 7-fold with monolaurin in case of the hay diet. Total Archaea were decreased by up to over 90%, but this was significant only for the wheat containing diets. Thus, monolaurin exerted variable effects mediated by unknown mechanisms on important ruminal microbes involved in carbohydrate degradation, along with its suppression of methane formation. The applicability of monolaurin for methane mitigation in ruminants thus depends on the extent to which adverse effects on carbohydrate-degrading bacteria actually impair the supply of digested carbohydrates to the animal.     

Rubber seed oil and flaxseed oil supplementation alter digestion,ruminal fermentation and rumen fatty acid profile of dairy cows

Rubber seed oil (RO) that is rich in polyunsaturated fatty acids (FA) can improve milk production and milk FA profiles of dairy cows; however, the responses of digestion and ruminal fermentation to RO supplementation in vivo are still unknown. This experiment was conducted to investigate the effect of RO and flaxseed oil (FO) supplementation on nutrients digestibility, rumen fermentation parameters and rumen FA profile of dairy cows. Forty-eight mid-lactation Holstein dairy cows were randomly assigned to one of four treatments for 8 weeks, including basal diet (CON) or the basal dietary supplemented with 4% RO, 4% FO or 2% RO plus 2% FO on a DM basis. Compared with CON, dietary oil supplementation improved the total tract apparent digestibility of DM, neutral detergent fibre and ether extracts ( P < 0.05). Oil treatment groups had no effects on ruminal digesta pH value, ammonia N and microbial crude protein ( P > 0.05), whereas oil groups significantly changed the volatile fatty acid (VFA) profile by increasing the proportion of propionate whilst decreasing total VFA concentration, the proportion of acetate and the ratio of acetate to propionate ( P < 0.05). However, there were no differences in VFA proportions between the three oil groups (P > 0.05). In addition, dietary oil supplementation increased the total unsaturated FA proportion in the rumen by enhancing the proportion of trans-11 C18:1 vaccenic acid (VA), cis-9, trans-11 conjugated linoleic acid (CLA) and α-linolenic acid (ALA) ( P < 0.05). These results indicate that dietary supplementation with RO and FO could improve nutrients digestibility, ruminal fermentation and ruminal FA profile by enhancing the VA, cis-9, trans-11 CLA and ALA composition of lactating dairy cows. These findings provide a theoretical basis for the application of RO in livestock production.     

Effects of feed withdrawal duration on animal behaviour,rumen microbiota and blood chemistry in feedlot cattle: implications for rumen acidosis

Feed withdrawal (FW) is a frequent issue in open outdoor feedlot systems, where unexpected circumstances can limit the animals’ access to food. The relationship among fasting period, animal behaviour during feed reintroduction (FR) and acidosis occurrence has not been completely elucidated. Twenty steers fitted with rumen catheters were fed a high-concentrate diet (concentrate : forage ratio 85 : 15) and were challenged by a protocol of FW followed by FR. The animals were randomly assigned to one of the four treatments: FW for 12 h (T12), 24 h (T24), 36 h (T36) or no FW (control group) followed by FR. The steers’ behaviour, ruminal chemistry, structure of the ruminal microbial community, blood enzymes and metabolites and ruminal acidosis status were assessed. Animal behaviour was affected by the FW–FR challenge ( P < 0.05). Steers from the T12, T24 and T36 treatments showed a higher ingestion rate and a lower frequency of rumination. Although all animals were suspected to have sub-acute ruminal acidosis (SARA) prior to treatment, a severe case of transient SARA arose after FR in the T12, T24 and T36 groups. The ruminal pH remained below the threshold adopted for SARA diagnosis ( pH value = 5.6) for more than three consecutive hours (24, 7 and 19 h in the T12, T24 and T36 treatments, respectively). The FW–FR challenge did not induce clinical acute ruminal acidosis even though steers from the T36 treatment presented ruminal pH values that were consistent with this metabolic disorder (pH threshold for acute acidosis = 5.2). Total mixed ration reintroduction after the withdrawal period reactivated ruminal fermentation as reflected by changes in the fermentation end-products. Ruminal lactic acid accumulation in steers from the T24 and T36 treatments probably led to the reduction of pH in these groups. Both the FW and the FR phases may have altered the structure of the ruminal microbiota community. Whereas fibrolytic bacterial groups decreased relative abundance in the restricted animals, both lactic acid producer and utiliser bacterial groups increased ( P < 0.05). The results demonstrated a synchronisation between Streptococcus (lactate producer) and Megasphaera (lactate utiliser), as the relative abundance of both groups increased, suggesting that bacterial resilience may be central for preventing the onset of metabolic disturbances such as ruminal acidosis. A long-FW period (36 h) produced rumen pH reductions well below and lactic acid concentration increased well above the accepted thresholds for acute acidosis without any perceptible clinical signs.     

Expression of KIT receptor tyrosine kinase protein in normal human skin: preliminary observations

KIT proto-oncogene is a receptor tyrosine kinase critical for signal transduction in several cell types. An understanding of KIT distribution in normal skin may reveal new insights into its implication in cutaneous biology and its associated disease states. This study examines expression patterns of KIT protein in normal human skin. KIT protein expression was examined in 50 specimens of normal human skin using specific antibodies (CD117) and immunoperoxidase staining methods. KIT protein expression was seen in keratinocytes (stratum basale), melanocytes, mast cells, and in both sebaceous and sweat glands. In contrast, KIT protein expression was absent in stratum spinosum, stratum granulosum, stratum corneum, blood vessels and arrector pili muscle. Thus, the expression of KIT protein in normal human skin suggests its possible role in regulation of cutaneous development and function.     

Isolation and Identification of Ruminal Methanogens from Grazing Cattle

To obtain information on the diversity of ruminal methanogens in grazing animals, three ruminal methanogens from grazing cattle were characterized and identified. Two of the isolates were rod-shaped, with one staining Gram-positive and being non-motile (BRM9), and the other (BRM16) staining Gram-negative and being motile. These isolates grew only on H₂/CO₂ and formate, and optimally at 38°C and pH 6.5–7.0. The third isolate (CM1) was non-motile, pseudosarcina-shaped, and grew on H₂/CO₂, acetate, and methyl-containing compounds, with optimal growth at 40°C and pH 6.5. DNA was prepared from the three isolates, and their 16S rRNA genes were sequenced. Phenotypic data and comparisons of nearly complete 16S rDNA sequences showed that BRM9, BRM16, and CM1 are strains of Methanobacterium formicicum, Methanomicrobium mobile, and Methanosarcina barkeri respectively. To the best of our knowledge, this is the first information on ruminal methanogens in cattle maintained under grazing management. Received: 26 October 1999 / Accepted: 22 November 1999     

Meat odour and flavour and indoles concentration in ruminal fluid and adipose tissue of lambs fed green herbage or concentrates with or without tannins

A 2 × 2 factorial experiment was carried out to evaluate the effect of herbage or concentrate feeding system and tannin addition to diet on skatole and indole in ruminal fluid and adipose tissue and meat sensory properties. Twenty-eight male lambs aged 45 days were randomly assigned to one of two feeding systems (vetch green herbage or concentrates, n = 14) and within feeding system to one supplement (quebracho tannins added to the diet or none). Animals were kept in singular pens and slaughtered at the age of 105 days. Indole (P < 0.05) and skatole (P < 0.01) concentrations in ruminal fluid were higher in lambs fed herbage compared to those given concentrates. Skatole in ruminal fluid tended to be present at lower concentrations in animals that received the tannin supplementation (P = 0.07). Indole was also higher in the caudal fat of animals fed green vetch compared to those fed concentrate (P = 0.04). Skatole concentration was lower in the fat of lambs fed concentrates compared to those given herbage (P = 0.05) and was lower in the fat of animals supplemented with tannins compared to the animals not supplemented (P = 0.01). Sheep meat odour was lower in meat from animals supplemented with tannins compared to those not supplemented (P < 0.01). It is concluded that tannins are more effective in reducing skatole formation in ruminants when they are associated with concentrate diets than green herbages.