Relationships of feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics of Nellore cattle differing in phenotypic residual feed intake

The objective of this study was to examine the relationship of DMI fluctuation, feedlot performance, feeding behavior, rumen morphometrics, and carcass characteristics in Nellore cattle classified by residual feed intake (RFI). One experiment was conducted in 2 consecutive years using individual pens (1.0 × 7.0 m) at the São Paulo State University feedlot, Dracena campus, Brazil. The experiment in year 1 started in June of 2012 with forty-eight 20-mo-old Nellore yearling bulls with an initial BW of 358.2 ± 19.4 kg. The experiment in year 2 started in January of 2013 with sixty 20-mo-old Nellore yearling bulls with an initial BW of 402.5 ± 33.0 kg. Experiments in years 1 and 2 lasted 94 and 84 d, respectively. All yearling bulls were categorized as high RFI (>0.5 SD above the mean, = 25), medium RFI (±0.5 SD from the mean, = 56), and low RFI (<0.5 SD below the mean, = 27). Visual appraisal to collect behavior data was made on d 40 (finishing period) of both years. Yearling bulls were harvested when average across treatment groups achieved a fat thickness of 4 mm at the 12th rib. Low-RFI yearling bulls had lower daily DMI, expressed either in kilograms ( < 0.01) or as percentage of BW ( < 0.01), and improved G:F ( < 0.01) when compared to high-RFI animals. No differences were observed ( > 0.10) for ADG, final BW, or HCW among RFI groups. Also, low-RFI yearling bulls had thinner final 12th rib ( < 0.01) and biceps femoris (P8) fat thickness ( < 0.01). Low-RFI yearling bulls were slower to consume ( = 0.03) and ruminate ( < 0.01) 1 kg of either DM or NDF. No significant ( > 0.10) RFI effect was observed for any ruminal morphometrics variables evaluated, with the exception of papillae area, in which low-RFI Nellore yearling bulls tended to have smaller ( = 0.07) papillae area than medium-RFI animals. In general, low-RFI Nellore yearling bulls consumed more particles larger than 19 and 8 mm and had a similar performance when compared to both medium- and high-RFI bulls; however, carcass fat composition was negatively impacted.

[Reduction of plant fibers in the digestive tract of the moose and the red deer]

A comparative study of the reduction of plant fibers moving in the digestive tract of nine red deer (Cervus elaphus) and six moose (Alces alces) was made. In the winter season, the character of fiber reduction in the moose and the red deer was similar. In the deer obtained in the early autumn, the relative concentration of small-sized fractions was significantly higher. A sharp decrease in the share oflarge-sized fibers was observed in the omasum as compared to the rumen and the reticulum. It was especially pronounced in the deer obtained in September. Deceleration of fibers of large-sized fractions in the rumen and the reticulum and the structure of the reticulo-omasal opening and its functions were considered.

[Endoscopy in cattle]

Endoscopy in the field of buiatrics has gained growing importance in recent years. Parts of the upper respiratory and gastrointestinal tract, the urethra and urinary bladder, the abdomen and the teat are all accessible by means of endoscopy. The direct visualisation of inner or outer organ surfaces allows for rapid diagnosis and even prognosis of different pathological conditions. Flexible endoscopes of different dimensions are used for endoscopic examination of the upper respiratory tract. Examining this region, endoscopy is in some cases superior to other imaging techniques because of the direct visualization of surfaces and their pathological conditions and the possibility of collecting biopsies under visual control. The same is documented for diseases of the oesophagus. On the other hand, rumenoscopy is of experimental character so far. Urethrocystoscopy is mainly performed for diagnostic purposes with either flexible or rigid optics. Theloscopy represents the "gold standard" for surgical intervention in cases of disturbance of milk flow, since mucosal tissue can be removed under visual control. Therefore, this indication is one of the most important applications for endoscopy performed by practitioners. Another important field for the application of therapeutic endoscopy is the treatment of left displaced abomasum by repositioning and fixation to the abdominal wall under endoscopic control.

Papillar Morphology of the Rumen of Forest Reindeer (Rangifer tarandus fennicus) and Semidomesticated Reindeer (R. t. tarandus)

The papillar morphology of the ventral and dorsal rumen of the wild forest reindeer (Rangifer tarandus fennicus Lönn.) and semidomesticated reindeer (R. t. tarandus L.) was studied in October and November 1996. The morphological measurements which were carried out were: the lengths of the papillae, the number of the papillae per square centimetre, the cross-sectional area and perimeter of sections cut from the middle of papillae. From these measurements mean papillar volume, areal papillar volume, mean papillar (epithelial) surface area, areal papillar surface and surface enlargement factor were calculated. No differences in these measurements between ventral and dorsal walls of the rumen were evident. The semidomesticated reindeer had longer papillar perimeters, larger mean and areal papillar surface areas, larger mean papillar volumes, and a larger surface enlargement factor in the ventral rumen than did forest reindeer. This may be a result of differences between feeding habits, the semidomesticated reindeer preferring a diet including more plants rich in carbohydrates e.g. lichens, which has resulted in a high production of volatile fatty acids and thus stimulation of papillar growth.

Effect of Milk Allowance on Concentrate Intake, Ruminal Environment, and Ruminal Development in Milk-Fed Holstein Calves

The aim of the present experiment was to test the hypothesis that a barley-based concentrate would induce an acidic ruminal environment in young calves and that increased milk allowance would alleviate this condition. Eight Holstein calves ruminally cannulated at d 7 +/- 1 of age were used to study the effect of variation in barley-based starter concentrate intake induced by 4 different milk allowances (3.10, 4.84, 6.60, and 8.34 kg of milk replacer/d; 123 g of dry matter/kg of milk) on the ruminal environment, blood variables, and fore-stomach development from wk 2 to 5 of age. Twelve ruminal fluid samples were collected during a weekly 24-h sampling in 4 consecutive weeks. Blood samples were collected by venipuncture between 1200 and 1300 h on ruminal sampling days. Rumen papillae development and visceral organ mass were recorded at slaughter. A linear treatment x week effect was observed for concentrate intake, with the calves fed the lowest milk allowance having the fastest increase in concentrate intake whereby these calves reached the same ME intake in wk 5 compared with calves with the highest milk allowance. Effects on ruminal variables were dominated by week of sampling, with minor differences among treatments. Ruminal pH was below 5.5 for 5 to 13 h/d and all calves with concentrate intake above 20 g of dry matter/d were observed to have a daily ruminal pH minimum at pH 5.5 or lower. The ruminal concentration of total volatile fatty acids (VFA) increased from 71 to 133 +/- 9 mmol/L in wk 2 to 5 and was characterized by a relatively high molar proportion of propionate, increasing from 34 to 40 mol/100 mol of VFA in wk 2 to 5. In addition, the presence of ethanol and propanol as well as numerous VFA esters points to a ruminal environment with a relatively high hydrogen pressure. Plasma glucose and insulin responded to the highest milk allowance in wk 2 to 4. Plasma VFA and ketone bodies increased with the lowest milk allowance in wk 4 to 5. At slaughter, empty wet weights of the rumen + reticulum and omasum as well as mass of digesta in these compartments were found to decrease linearly and perirenal fat was found to increase linearly with milk allowance, indicating that the milk allowance changed the body composition of the calves. Lengths of ruminal papillae in the atrium and ventral ruminal sac were not affected by treatment. We concluded that the ruminal environment of young calves fed a barley-based starter concentrate was characterized by a low ruminal pH and high VFA concentration regardless of the milk allowance.

Effect of Roughage Source and Roughage to Concentrate Ratio on Animal Performance and Rumen Development in Veal Calves

Sixty-four male Holstein-Friesian x Dutch Friesian veal calves (46 +/- 3.0 kg) were used to evaluate the effect of the inclusion of different levels and sources of dietary roughage on animal performance and rumen development. Treatments consisted of 1) C100 = concentrate only; 2) C70-S30 = concentrate (70%) with straw (30%), 3) C70-G30 = concentrate (70%) with dried grass (30%), 4) C70-G15-S15 = concentrate (70%) with dried grass (15%) and straw (15%), 5) C70-CS30 = concentrate (70%) with corn silage (30%), 6) C40-CS60 = concentrate (40%) with corn silage (60%), 7) C70-CS30-AL = concentrate (70%) with corn silage (30%) ad libitum, 8) C70-G15-S15-AL = concentrate (70%) with dried grass (15%) and straw (15%) ad libitum. All dietary treatments were provided in addition to a commercial milk replacer. Concentrate was provided as pellets and roughage was chopped. The dietary treatments 1 to 6 were supplied restrictedly to a maximum of 750 g of dry matter (DM) per day, whereas treatments 7 and 8 were offered ad libitum in combination with a reduced amount of milk replacer. Calves were euthanized after 10 wk. Straw supplementation (C70-S30 vs. C70-G30 and C70-CS30) reduced DM intake, and ad libitum supply of concentrate and roughage increased DM intake. Roughage addition did not affect growth performance. Rumen fermentation was characterized by low pH and high total volatile fatty acids and reducing sugar concentrations. Calves fed ad libitum showed lower ruminal lactate concentrations than calves fed restrictedly. Ammonia concentrations were highest in calves fed C-100 and lowest in calves fed ad libitum. The recovery of CoEDTA (added to milk replacer) varied between 20.5 and 34.9%, indicating that significant amounts of milk entered the rumen. Roughage addition decreased the incidence of plaque formation (rumen mucosa containing focal or multifocal patches with coalescing and adhering papillae covered by a sticky mass of feed, hair and cell debris) and the incidence of calves with poorly developed rumen mucosa. However, morphometric parameters of the rumen wall were hardly influenced by the type and level of roughage. Ruminal polysaccharide-degrading enzyme activities reflected the adaptation of the microorganisms to the dietary concentrate and roughage source. Results indicated that in veal calves, the addition of roughage to concentrate diets did not affect growth performance and positively influenced the macroscopic appearance of the rumen wall.

Comparison of two ruminoscopy techniques in calves

Two different techniques were tested in nine calves to describe endoscopically the visible structures of the rumen and the reticulum. Ruminoscopy using an orally introduced flexible endoscope proved to be unsatisfactory, but when the endoscope was introduced through a ruminal fistula in the left flank into the dorsal and ventral ruminal sacs, the blind sacs, ruminal pillars, the atrium of the rumen, the reticulum and the reticular groove could all be displayed effectively. Indentations of the ruminal wall caused by the left kidney, the spleen and the abomasum could be seen with the endoscope as could reticulo-ruminal contractions. The technique allowed visual evaluation of the mucosal surfaces and movement of the rumen, reticulum and reticular groove. The advantages and disadvantages of ruminoscopy in bovine medicine are discussed.

Effects of mild heat stress and grain challenge on acid-base balance and rumen tissue histology in lambs1

The effect of heat stress (HS) and grain challenge (GC) on acid-base balance and rumen tissue histology in lambs was investigated using 24 yearling wether lambs (58 +/- 4.5 kg of BW) in a 2 x 2 factorial experiment with repeated measures for day (10, 14, and 17) of sampling. The factors were temperature [thermoneutral zone (TN) vs. HS] and diet (control vs. GC). Lambs were blocked by BW and assigned to 1 of 4 treatments in temperature-controlled rooms: 1) TN (temperature = 18 to 20 degrees C; relative humidity = 30%; 2) TN + GC; 3) HS (temperature = 35 degrees C for 9 h/d, 20 degrees C for 15 h/d; relative humidity = 40%); and 4) HS + GC. Venous blood samples were collected at 1800 on the first day of GC (d 10), in the middle of GC (d 14), and at the end of the trial (d 17) by jugular venipuncture and analyzed for pH, gases, hematocrit, plasma ions, and total protein. After all measurements in live animals were taken on d 17, lambs were slaughtered, and tissue samples were obtained from the ventral sac of the rumen for histological assessment. Except for the concentration of plasma glucose (P = 0.04) and total protein (P < 0.01), there were no (P > 0.05) diet x temperature interactions. With HS, the concentration of Na+ and Cl- in the control group decreased at d 14 and then increased by d 17, and respiration rates in the control group decreased linearly (P < 0.05). Compared with the control group, respiration rates and the concentration of Cl- in the GC lambs increased linearly over time, whereas the concentration of Na+ decreased linearly (P < 0.05) across time. Under HS, the partial pressure of carbon dioxide, total carbon dioxide, the partial pressure of oxygen and oxygen saturation, and the concentration of Mg2+, glucose, and HCO3- showed quadratic (P < 0.05) responses with time. In both treatments, DMI, base excess of extracellular fluid, base excess of blood, and standard bicarbonate increased linearly (P < 0.05), and hematocrit, plasma protein, Ca2+, anion gap, and plasma strong ion difference decreased linearly (P < 0.05) across day. Compared with the control group, the GC group had decreased papillae count in the ruminal ventral sac (1.3 vs. 1.5; P < 0.05). These results suggest that under HS the acidifying effects of GC on acid-base balance in lambs were counteracted in the short-term through respiratory adaptation.

Technical Note: Technique for Dissection and Analysis of the Rumen in Young Calves

This paper discusses a technique used to evaluate rumen development in young calves, including removal, dissection, and analysis of tissue. The method allowed for examination of the different sacs of the rumen (dorsal, ventral, cranial, and caudal) using scanning electron microscopy to measure papillae denseness and histology slides to measure papillae length and width. Computer software was used to produce accurate measurements of papillae. The rumens of young calves were dissected, and samples were taken from the cranial, caudal, ventral, and dorsal sections. Calves were part of a nutrition research study, and dietary treatments did have an effect on development measurements such as length, width, and papillae denseness.

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 α-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 Corn Processing on Growth Characteristics, Rumen Development, and Rumen Parameters in Neonatal Dairy Calves

Neonatal Holstein calves were fed texturized calf starters containing 33% whole (WC), dry-rolled (DRC), roasted-rolled (RC), or steam-flaked (SFC) corn to investigate how corn processing method affects intake, growth, rumen and blood metabolites, and rumen development. In the first experiment, 92 Holstein calves (52 male and 40 female) were started at 2 +/- 1 d of age and studied for 42 d. Starter dry matter (DM) intake was measured and fecal scoring conducted daily. Growth and blood parameter measurements were conducted weekly. A subset of 12 male calves (3/treatment) was euthanized at 4 wk of age and rumen tissue sampled for rumen epithelial development measurements. Experiment 2 consisted of 12 male Holstein calves ruminally cannulated at 7 +/- 1 d of age. Rumen fluid and blood samples were collected during wk 2 to 6. In the first experiment, postweaning and overall starter and total DM intake were significantly higher in calves fed starter with DRC than RC or SFC. Postweaning and overall starter and total DM intake were significantly higher in calves fed starter with WC than SFC. Postweaning average daily gain was significantly greater in calves fed starter with DRC than SFC. Blood volatile fatty acid concentrations were significantly higher in calves fed starter with SFC than in calves fed all other treatments. Papillae length and rumen wall thickness at 4 wk were significantly greater in calves fed starter with SFC than DRC and WC, respectively. In experiment 2, calves fed starter with WC had higher rumen pH and lower rumen volatile fatty acid concentrations than calves fed all other starters. Rumen propionate production was increased in calves receiving starter with SFC; however, rumen butyrate production was higher in calves fed starter with RC. Results indicate that the type of processed corn incorporated into calf starter can influence intake, growth, and rumen parameters in neonatal calves. Calves consuming starter containing RC had similar body weight, feed efficiency, and rumen development but increased structural growth and ruminal butyrate production when compared with the other corn processing treatments.

Increasing magnesium intakes in relation to magnesium absorption in dry cows

Earlier studies with temporarily isolated rumen of heifers show saturation kinetics of Mg efflux across the rumen wall. Therefore, we hypothesized that high Mg intakes would not further increase the rate of Mg absorption in cows. To test our hypothesis, six ruminally fistulated non-pregnant dry cows were given diets with different Mg concentrations in a 6×6 Latin square design. Desired concentrations of Mg were attained by adding MgO to the basal diet and the Mg concentrations in the total rations were 3·8, 6·4, 9·1, 11·8, 14·1 and 17·3 g Mg/kg dry matter, which provided Mg intakes of 27·1, 44·6, 64·6, 83·5, 100·4 and 124·3 g/d, respectively. Increasing Mg intakes were associated with increased (P<0·001) faecal Mg excretion. However, apparent Mg absorption expressed as g/d was not significantly different for Mg intakes from 100·4 to 124·3 g/d while Mg absorption expressed as a proportion of intake was not significantly different for Mg intakes ranging from 64·6 to 124·3 g/d. Mg concentrations in rumen fluid after feeding increased (P<0·001) with increasing Mg intakes. Apparent absorption of Mg appeared to become saturated at a ruminal Mg concentration of 17·5 mM (Mg intake of 83·5 g/d). Group-mean post-feeding concentrations of Mg and Na in rumen fluid were significantly correlated (Pearson's r=−0·96; P=0·003, n=6). This study showed that under conditions of practical dairy cow feeding, Mg absorption was maximal at Mg intakes [ges ]84 g/d.

Development and Analysis of a Rumen Tissue Sampling Procedure

A procedure for rumen tissue sampling was developed to determine treatment effects on rumen development and papillae growth in young calves and to improve repeatability in rumen tissue sampling techniques. Rumens were collected from 42 male Holstein calves from 4 separate experiments. Rumen sampling areas (n = 9) included the caudal dorsal blind sac, cranial dorsal sac, cranial ventral sac, and the caudal and ventral portions of the caudal ventral blind sac. Right and left sides of the rumen were sampled. Five 1-cm2 sections were removed from each area and measured for papillae length (n = 20/area), papillae width (n = 20/area), rumen wall thickness (n = 5/area), and number of papillae per cm2 (n = 5/area). Correlations between areas, samples, and measurements were obtained, and comparisons between experiments, areas, samples, and measurements were performed for all variables. In addition, power analyses were conducted for all variables to determine the efficacy of the procedure in detecting treatment differences. Results indicate that samples should be taken from the caudal and cranial sacs of the dorsal and ventral rumen to sufficiently represent papillae growth and development throughout the entire rumen. The procedure is capable of detecting treatment differences for papillae length and papillae width, has a decreased but acceptable capability of detecting treatment differences for rumen wall thickness, but appears limited in ability to detect treatment differences for papillae per square centimeter. In conclusion, rumen tissue sampling to determine extent of rumen development in calves can be performed in a nonbiased and repeatable manner utilizing a limited number of calves.

Visceral Tissue Mass and Rumen Volume in Dairy Cows During the Transition from Late Gestation to Early Lactation

The objectives were to measure the effects of transition and supplemental barley or rumen-protected protein on visceral tissue mass in dairy cows and the effects of transition and barley on rumen volume and liquid turnover. Cows were individually fed a grass silage-based gestation ration to meet energy and protein requirements for body weight stasis beginning 6 wk before expected calving. A corn silage-based lactation ration was individually fed ad libitum after calving. In the visceral mass study, 36 cows were randomly assigned to one of 3 dietary treatments: basal ration or basal ration plus either 800 g dry matter (DM) of barley meal per day or 750 g DM of rumen-protected soybean protein per day. Cows were slaughtered at 21 and 7 d before expected calving date or at 10 and 22 d postpartum. Visceral mass and rumen papillae characteristics were measured. Diets had little effect on visceral mass. The mass of the reticulo-rumen, small intestine, large intestine, and liver was, or tended to be, greater at 22 d postpartum but not at 10 d postpartum before DM intake had increased. Rumen papillae mass increased at 10 d postpartum, perhaps in response to increased concentrates. Mesenteric fat decreased after calving, reflecting body fat mobilization. Ten rumen-cannulated cows were fed the basal gestation ration alone or supplemented with 880 g of barley meal DM. Rumen volumes and liquid dilution rates were measured at 17 and 8 d before calving and at 10, 20, and 31 d postpartum. Feeding barley had no effects. After calving, rumen DM volume and liquid dilution rate increased, but liquid volume did not increase. Changes in gastrointestinal and liver mass during transition were apparently a consequence of changes in DM intake and nutrient supply and not initiation of lactation per se.

An energy-rich diet causes rumen papillae proliferation associated with more IGF type 1 receptors and increased plasma IGF-1 concentrations in young goats

We tested the hypothesis that the dietary energy-dependent alterations of the rumen papillae size are accompanied by corresponding changes in systemic insulin-like growth factor (IGF)-1 concentration and in rumen papillary IGF type 1 receptors (IGF-1R). Young male goats (n=24) were randomly allocated to two groups (n=12) and fed a high level (HL) metabolizable energy [1200 kJ/(kg(0.75).d)] or a low level (LL) [500 kJ/(kg(0.75).d)] diet for 42 d. The concentration of ruminal total SCFA did not differ between the groups, but the molar proportion of butyric acid was enhanced by 70% in the HL group (P<0.05). Both the length and width of the papillae were greater (P<0.05) in the HL group, and the surface was 50-100% larger (P<0.05) in the tissue sampled from the artrium ruminis, the ventral ruminal sac and the ventral blind sac. Transport of Na+ across the rumen epithelium, which is amiloride sensitive, was higher (P<0.05) in the HL than in the LL group. Furthermore, the plasma IGF-1 concentration was about twofold higher in the HL group (P<0.05), and the maximal rumen epithelial IGF-1R binding was also higher in the HL (P<0.05) than in the LL group. IGF-1R mRNA and IGF-1 mRNA were detected in rumen papillae; however, they were unaffected by dietary treatments. DNA synthesis and cell proliferation of cultured rumen epithelial cells were higher (P<0.05) after IGF-1 treatment (25 or 50 microg/L) compared with those in the medium without IGF-1. Thus dietary energy-dependent alterations of rumen morphology and function are accompanied by corresponding changes in systemic IGF-1 and ruminal IGF-1R.

The influence of different fibrous supplements in the diet on ruminal histology and histometry in veal calves

The aim of this study was to determine whether the administration of four different solid feeds would influence selected morphological and morpho-functional aspects of the rumen mucosa in veal calves. The fibrous supplementation of the liquid diet of veal calves has been provided by recent EU formulation (EC Council Directive 91/629/1991; EC Council Directive 97/2/1997). Twenty-five Holstein calves were assigned to either exclusively liquid diet (milk replacer, control), or pelleted feed, corn silage, extruded feed, dried corn silage. The morpho-functional effects of the fibre-containing diets were examined evaluating histological and histometrical characteristics of ruminal mucosa after the slaughter of calves. There were slight to severe histological abnormalities in the rumens of all animals examined. The severe histological abnormalities were present in calves given pelleted feed, corn silage, and extruded feed. Dried corn silage caused less ruminal damage. We found that the length and epithelial thickness of ruminal papillae were higher in control veal calves than in dietary fibre-supplemented animals. The results of the present study, even if partially, support the EU prescription in the use of fibre diets in veal calves as integration of the traditional milk replacer diet.

Immunohistochemical evaluation of the muscularis mucosae in the ruminant forestomach

The muscularis mucosae and condensed fibrous layer of the ruminant forestomach were studied by immunohistochemistry using specific antibodies against alpha-smooth muscle actin (alphaSMA) and gamma-smooth muscle actin (gammaSMA). The specimens were collected from the rumen, reticulum and omasum of cattle, water buffalo, sheep, goat, Barbary sheep, Japanese serow, sika deer and mouse deer. The muscularis mucosae showed immunoreactivity for both alphaSMA and gammaSMA. On the other hand, the condensed fibrous layer appearing between the propria mucosa and tela submucosa was immunoreactive only for alphaSMA except for that in the goat and Barbary sheep reticulum which is intermingled with gammaSMA immunoreactivity. The distribution of muscularis mucosae and/or condensed fibrous layer varied among the compartments of forestomach and ruminant species. In the rumen, only the condensed fibrous layer was detected. On the other hand, the omasum contained only the muscularis mucosae. In the reticulum, both were detected. The amount of the condensed fibrous layer in the reticulum varied among different species in the following order of abundance: goat > Barbary sheep > sika deer> sheep > water buffalo > cattle and Japanese serow. Smooth muscle cells of external muscle layer were immunoreactive for alphaSMA and gammaSMA whereas those of blood vessels and pericytes were immunoreactive only for alphaSMA. The present findings on the actin immunoreactivity and distribution profile of muscularis mucosae and the condensed fibrous layer provide additional knowledge to further understand the histophysiological specialization of the different compartments of the ruminant forestomach.

Effect of short-term underfeeding on weight of splanchnic organs in ewes

We assessed the effect of short-term underfeeding on weight and protein mass of splanchnic tissues in adult ewes submitted to a factorial experimental design. In a pre-experimental period, 18 ewes divided into 2 groups of 9 were fed a second cut of natural grassland hay during 4 weeks at 112 or 38% of their energy maintenance requirements. Three ewes of each group were then fed the same hay during 4 weeks at either low (group L), moderate (group M) or high intake (group H), corresponding to 38, 75 or 112% of their energy maintenance requirements, respectively, then slaughtered. Fresh weight and protein mass of splanchnic organs were measured. No carry-over effect of the pre-experimental level of intake on weight and protein mass was observed for any splanchnic organs. Splanchnic tissues contributed at 10.7 and 8.6% to the decrease in live weight for groups M and L, respectively. The decrease in weight of splanchnic tissues (-15%) was mainly attributed to reticulorumen (-23%), liver (-21%), and at a lesser extent small intestine (-11%). No large change in the mass ratio between mucosa and muscular-serosa in both dorsal and ventral sacs occurred in the rumen wall. These results are discussed together with previous published results on long-term underfed ewes, and suggest that the decrease in energy expenditure in whole animal induced by underfeeding is mainly related to the decrease in splanchnic weight at short-term, and to the decrease in other tissues at long-term, splanchnic weight being stabilized.

Effects of intrinsic potassium in artificially dried grass and supplemental potassium bicarbonate on apparent magnesium absorption in dry cows

Literature data indicate that the form of K in the ration can affect its inhibitory influence on Mg absorption in ruminants. We tested whether identical amounts of K either intrinsically present in artificially dried grass or present in added KHCO3 have different effects on Mg absorption in dry cows. In a 3 x 3 Latin square design, six cows were fed rations consisting of low-K grass and concentrate with or without KHCO3 or a ration consisting of high-K grass with concentrate without added KHCO3. Each ration was given for a period of 4 wk. The ration low in intrinsic K contained 26 g of K/kg of dry matter, the ration low in intrinsic K plus KHCO3 contained 43 g of K/kg of dry matter, and the ration high in intrinsic K also contained 43 g of K/kg of dry matter. The three rations were balanced for crude protein, crude fat, crude fiber, Mg (2.2 g/kg of dry matter), Ca, P, and Na. Apparent Mg absorption was 10.8 +/- 1.54% of intake (mean +/- SE, n = 6) when the cows were fed the low-K ration, but dropped to 1.9 +/- 3.4 and 2.1 +/- 1.9% of intake, respectively, when the rations high in KHCO3 and high in intrinsic K were fed. The two high-K rations induced similar increases in ruminal K concentrations both before and after feed consumption. The feeding of KHCO3 did not influence ruminal pH. The intake of extra K may raise ruminal K concentrations, which increases the transmural potential difference so that Mg transport across the rumen epithelium becomes depressed. Thus, intrinsic and added K had identical effects on ruminal K concentrations and on Mg absorption. Feeding trials with ruminants in which K intakes are manipulated with the use of KHCO3 may reflect those cases when concentrations of K intrinsically present in feedstuffs may vary.

Effects of form of the diet on anatomical, microbial, and fermentative development of the rumen of neonatal calves

Eight neonatal, Holstein bull calves were paired by birth date and birth weight and randomly assigned to either a finely ground or unground control diet (chopped hay and rolled grain) to study the effects of the physical form of the diet on anatomical, microbial, and fermentative development of the rumen. The diets varied in particle size but were identical in composition (25% alfalfa hay and 75% grain mix). Calves were fed milk at 8% of birth weight daily until weaning. Feed intake was equalized for each pair of calves. Ruminal fluid samples were collected from ruminal cannulas to determine pH, fermentation products, and buffering capacity and to enumerate bacteria. Calves were slaughtered at 10 wk of age, and weights of the full and empty reticulorumen, abomasum, and omasum were recorded. Ruminal tissue samples were taken to assess papillary development by morphometric measurements. Calves had similar body weights at wk 10. Ruminal pH was affected by age and was lower for calves fed the ground diet. Total anaerobic bacterial counts were not affected by the physical form of the diet; however, calves fed the ground diet had lower numbers of cellulolytic bacteria and higher numbers of amylolytic bacteria than did calves fed the unground diet. Physical form of the diet did not affect the weights of the reticulorumen whether full or empty. However, calves fed the ground diet had heavier omasum weights, both full and empty. Physical form of the diet affected papillary size and shape but did not influence the muscle thickness of rumen. Results indicated that the physical form of the diet had a significant influence on the anatomical and microbial development of the forestomac and, therefore, might influence future performance.

A new method of measuring diet abrasion and its effect on the development of the forestomach

Twelve newborn Holstein bull calves were used to evaluate the effects of dietary abrasiveness, determined by a new method, on ruminal development. Calves were blocked by age and body weight and were assigned to one of three different diets. Each diet had the same ingredients but different particle sizes, which resulted in different abrasive values. No differences were detected in molar percentages of volatile fatty acids in ruminal fluid or in plasma concentrations of urea, glucose, or beta-hydroxybutyrate. The pH of ruminal fluid was lower for calves fed the fine and intermediate diets than for those fed the coarse diet. Digesta-free weights of the stomach and stomach compartments were similar among calves fed the three diets, except that omasum weights were heavier for calves fed the fine diet. Length of the ruminal papillae increased as the abrasive value of the diet decreased. Measurements of ruminal tissue layers from the ventral floor of the cranial sac were not different among diets, but the keratin portion represented more of the epithelial layer for calves fed the diet with the lowest abrasive value, thus decreasing the percentage of metabolically active tissue for those calves.

The effect of formalin on rumen surface area in red deer

Previously published studies have related the surface area of rumen wall to diet. The validity of studies that utilize preserved material depends upon the predictability of any change in rumen dimension brought about by preservation. Changes in the surface are of different sections of the rumen wall of red deer (Cervus elaphus) were monitored after immersion in 10% formal saline solution at room temperature for 2, 7 and 14 days. There was a high degree of variability (0-39.5%) in wall-area reduction. Ignoring such changes when calculating the factor of increase in surface area (FISA), a composite of papillary surface area and density, can result in errors of up to 39.5%. This study questions the validity of using FISA calculations when formalin-preserved specimens are used in studies of rumen response to diet. Rumen papillary dimensions were not significantly changed by preservation in formalin.

Effects of dietary energy intake and protein concentration on performance and visceral organ mass in lambs

Eighty-eight early-weaned Hampshire x Targhee crossbred lambs (initial BW 23 +/- 3.9 kg) were used in a 2 x 2 factorial design experiment to determine the effects of DM and CP intake on lamb performance and weight and accretion rates of visceral organs during two periods of growth, divided at 36 kg live weight. There were 10 lambs per replicate and two replicate pens per treatment. Dry matter intake was 100 or 85% of ad libitum, and protein intake was 100 (normal) or 125% (high) of the calculated NRC (1985) requirement. Over both periods, lambs allowed ad libitum access to feed had greater (P < .05) ADG, rumen/reticulum, large intestine, and liver weights and faster accretion rates than lambs fed at 85% of ad libitum; however, there were no differences (P = .87) in feed efficiency. For the total trial, lambs fed high protein had greater (P < .01) DMI, ADG, liver and kidney weight and accretion rates, and increased (P < .01) feed efficiency during period 1 compared with lambs fed normal protein concentrations. Diets containing high concentrations of dietary protein resulted in greater DMI and ADG throughout the feeding period compared with diets formulated at NRC (1985) recommended concentrations, indicating that NRC (1985) protein recommendations may limit lamb performance. Restricted feeding resulted in reduced visceral organ mass compared with offering feed for ad libitum consumption. Restricted feeding increased efficiency of feed utilization for gain, in part, through reductions in visceral organ mass.

Physical constraints on voluntary intake of forages by ruminants

Voluntary dry matter intake (VDMI) of forages by ruminants may be limited by distention resulting from restricted flow of digesta through the gastrointestinal tract. An animal's capacity for fill depends on the weight and volume of digesta that causes distention and the flow rate of digesta from the organ in which distention occurs. The reticulorumen is generally regarded as the site in the gastrointestinal tract for which distention limits VDMI with high-fill diets, although evidence suggests that distention of the abomasum may also limit VDMI. Linear decreases in VDMI have been noted with increasing amounts of inert fill inserted into the reticulorumen, but results have not been consistent across several experiments. Reduction in VDMI depends on the extent to which intake is limited by fill before insertion of inert fill; hence animals with high energy requirements consuming relatively low-energy, high-fill diets are affected to the greatest extent. Because NDF generally ferments and passes from the reticulorumen more slowly than other dietary constituents, it has a greater filling effect over time than non-fibrous feed components and has been found to be the best single chemical predictor of VDMI. However, many other factors affect fill, including particle size, chewing frequency and effectiveness, particle fragility, indigestible NDF fraction, rate of fermentation of the potentially digestible NDF, and characteristics of reticular contractions. These factors are only partially accounted for in models that have been developed to predict VDMI. Increased accuracy of prediction of VDMI is expected as models continue to evolve.

Identification of two cDNA clones encoding small proline-rich proteins expressed in sheep ruminal epithelium

Small proline-rich (SPRR) proteins are markers frequently associated with squamous cell differentiation. They have been proposed to be a novel group of precursor polypeptides for the cornified envelope in epidermal keratinocytes. A plus/minus screening procedure was used to identify cDNA clones expressed in mature but not in neonatal sheep ruminal epithelium. Two clones encoding SPRR proteins were identified and are reported here. Clone 27 encodes an ovine SPRR protein corresponding to the human type-II SPRR protein. Clone 26 encodes an ovine SPRR protein similar to human type-II SPRR protein, but which also contains an N-terminal His-Pro repeat similar to the paired repeats found in the Drosophila paired proteins. The unique combination of a paired domain and an SPRR protein has not been reported prior to this study. The tissue distribution indicates that specific expression of the genes corresponding to these two clones occurs in the epithelium of the ruminant forestomach, and to a lesser extent in skin epithelium. In situ hybridization demonstrated that the SPRR mRNA for both clones were localized in the stratum granulosum, in support of their putative physiological function, i.e. formation of the cornified envelope. Based on Northern blot analysis, mRNA complementary to the two clones appears in the ruminal epithelium by 1 week of age, corresponding to the formation of the stratum granulosum during ruminal epithelial development. The different patterns of changes in amount of mRNA corresponding to these clones during rumen epithelial development indicate that they play different roles in rumen epithelial development.

The stomach of the sambar deer (Cervus unicolor unicolor)

In New Zealand, the sambar deer is reported to feed on a variety of grasses and browse material. In the specimens studied, the average volume of the sambar rumen was about 151. Thick, non-papillated pillars divided the rumen into a saccus dorsalis and a saccus ventralis. The lining of the rumen was covered with papillae; those in the roof area were short and poorly developed. The omasum was a well-developed organ with 47-71 (mean 57) laminae. These were covered with short and poorly developed papillae. It is concluded that these sambar deer stomachs were typical of a grass-roughage feeder. This contrasts with the previous classification of the sambar deer as an intermediate feeder.

Effect of diet energy concentration and of age of Holstein-Friesian bull calves on growth rate, urea space and fat deposition, and ruminal volume

Holstein-Friesian bull calves were fed diets of three metabolizable energy concentrations: 11.7, 10.9, and 10.0 MJ/kg of DM, and the same content of CP, 145 g/kg. Two trials were carried out. Initial weights were 195 and 180 kg and final weights were 490 and 600 kg for Trials 1 and 2, respectively. The live weight gains (kg/d) were .93, 1.06, and 1.16 in Trial 1 and .98, 1.11, and 1.16 in Trial 2 on the low-, medium-, and high-energy diet, respectively. In Trial 2, measurements were made of ruminal fluid volume and urea space, which expresses the protein mass in the body. Ruminal fluid volume of young calves was high, exceeding 250 mL/kg live weight. Proportional to live weight, it tends to decrease from the age of 213 d to slaughter. It was higher on the lower-energy diet (P < .01). Rate of fat deposition between 250 and 600 kg body weight did not increase even on the diet with 11.7 MJ/kg, although these calves were fatter (P < .05) at slaughter than those on the low-energy diets. The ratios of depot fats (g of fat/kg of hot carcass) in both trials were close for each energy level, in spite of a 100-kg difference in live weight at slaughter. It was 24.0, 29.8, and 40.7 for calves fed low-, medium-, and high-energy diets, respectively, in Trial 1 and 27.7, 37.1, and 40.4, respectively, in Trial 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Is lamina muscularis mucosae present in the ruminal mucosa of cattle? Immunohistochemical and ultrastructural approaches

The cells in the condensed fibrous layer in the lamina propria of the ruminal mucosa of the calves and cows were studied at the light microscopic level. Abundant actin-immunoreactive cells were detected both in the calves and cows, while desmin-immunoreactive cells were moderate in frequency in the cows and low or absent in the calves. Vimentin-immunoreactive cells were abundant in the cows but moderate to low in frequency in the calves. These cells were distributed to form a condensed layer being more abundant in the ruminal papillae than the interpapillar mucosae in the cows and equal in the papillae and interpapillar mucosae in the calves. At the ultrastructural level, smooth muscle cells and fibroblasts were abundant in the deep core of the ruminal papilla of the cows. The present results suggest that the condensed fibrous layer revealed in the ruminal mucosae contains smooth muscle cell population which could be regarded as the specialized lamina muscularis mucosae.

Forage and splanchnic tissue mass in growing lambs: effects of dietary forage levels and source on splanchnic tissue mass in growing lambs

Forty-two crossbred lambs (33.4 kg initial body weight; twenty-four wethers and eighteen ewes) were used in a 42 d experiment with a 2 x 3 factorial treatment arrangement to determine effects of forage level and source on splanchnic tissue mass. Diets were 250 and 750 g/kg of chopped lucerne (Medicago sativa) (A), ryegrass (Lolium multiflorum)-wheat (Triticum aestivum) (RW) or bermudagrass (Cynodon dactylon) (B) hay, with the remainder being maize-based concentrate. Five lambs per treatment were slaughtered at the end of the experiment and measurements made of internal organs and contents of the gastrointestinal tract (GIT). Digestible organic matter intake (DOMI) on the 7 d preceding slaughter was 0.89, 0.83, 0.90, 0.83, 0.77 and 0.61 (SE 0.05) kg/d, and live-weight gain was 0.20, 0.17, 0.18, 0.10, 0.10 and 0.07 (SE 0.02) kg/d for diets A-25, RW-25, B-25, A-75, RW-75 and B-75 respectively. Total GIT mass (fresh) was higher (P < 0.05) for 750 than 250 g forage/kg and for B than RW (4.80, 4.57, 5.55, 5.84, 5.99 and 6.91 kg for diets A-25, RW-25, B-25, A-75, RW-75 and B-75 respectively). Non-fat organic matter was 259, 295, 292, 303, 277 and 264 g for the total GIT; 93, 102, 103, 106, 95 and 97 g for the reticulo-rumen (forage level x type (diet A v. diets RW and B) interaction; P < 0.05); and 204, 196, 202, 177, 156 and 127 g for the liver (SE 10) with diets A-25, RW-25, B-25, A-75, RW-75 and B-75 respectively. In summary, differences in properties of forage A and the grasses at 250 g/kg diet may have influenced GIT mass independent of energy intake and digesta mass. Conversely, with 750 g dietary forage/kg, higher digesta mass for diet B than diet RW appeared responsible for high reticulo-rumen mass relative to DOMI. Greater digesta mass for 750 than 250 g forage/kg may have elevated intestinal tissue mass/DOMI with diets A and B but not with diet RW, for which NDF digestibility was highest.

[Transmural electrical stimulation in the reticular groove of adult cattle]

An in vitro study of the smooth muscle of the fore third of the reticular groove bottom was carried out in adult bovines, to determine the most favorable parameters for electrical transmural stimulation (ETS). The mechanical activity of the preparations was registered isometrically and the electric stimuli were applied by means of ring-shaped platinum electrodes. Results show that the response of this tissue to ETS is of a phasic and synchronic nature in accordance with the stimulus. The parameter values necessary to produce a homogeneous, quantifiable and reproducible response were the following: Supermaximum voltage 70-100 V, frequency 30 Hz, pulsing time 4 ms, stimulus time 5 s and intervals between each stimulus 4 min. The intervals among stimuli where 3 min long to establish the frequency curves of 2, 6, 10, 20 and 30 Hz.

Normal laparoscopic anatomy of the bovine abdomen

Three laparoscopic procedures were performed on each of 6 adult Jersey cows in the first trimester of gestation to describe normal laparoscopic anatomy of the bovine abdomen. Also, a technique for laparoscopy of the cranioventral portion of the abdomen was described. Right paralumbar fossa, left paralumbar fossa, and cranioventral midline laparoscopy were performed 72 hours apart of each cow. Physical examination findings, CBC, serum biochemical analysis, and peritoneal fluid analysis before and 72 hours after the first surgery were used to assess the effects of the procedures on the cows. Exploratory celiotomy was performed 2 weeks after the last laparoscopy. The cows were then reexamined 6 weeks after the last procedure. The t-test for paired data was used for statistical analysis; the level of significance was P < 0.05. Laparoscopy was performed without complication in all cows. Adverse effects of laparoscopy, individually or serially, were not observed. Significant differences were not found between CBC, serum biochemical, and peritoneal fluid variables taken before and 72 hours after surgery.

Actin filaments in the ruminal epithelium of cattle

Phalloidin and immunogold labeling were used to localize actin filaments in the ruminal pilar epithelium of adult cattle on the light and electron microscopic level. Incubation with rhodaminyl-phalloidin permitted an overview of general actin distribution pattern. Distinct subcellular localization of actin was revealed with the biotin-streptavidin bridge technique in a postembedding procedure. Superior fixation of membranes and filaments was achieved with tannic acid-glutaraldehyde. Surface-etching prior to immunoincubation ensured restoration of actin immunoreactivity. Patterns of distribution in non-keratinized and keratinized epithelial cells as well as in pericytes and endothelial cells point to cell-specific cytoskeletal and motile functions of actin filaments.

Responses in the voluntary intake of hay or silage by lactating cows to intraruminal infusions of sodium acetate or sodium propionate, the tonicity of rumen fluid or rumen distension

Rumen-fistulated lactating cows were individually fed on hay or silage and intakes were monitored during 3 h treatment periods and for 2 h after. Each experiment used five, six or seven animals and the treatments were applied in a Latin Square design. Sodium acetate infusions of 1.8-11.0 mol in 4.5 litres water caused a dose-related depression in hay intake, the extent being 82 g dry matter (DM)/mol infused (P < 0.01). Sodium acetate infusions of 6.0-15.0 mol in 4.5 litres water caused a dose-related depression in silage intake of 118 g DM/mol infused. Rumen fluid pH for both diets was unaffected by treatment. Acetate and Na concentrations were increased and significantly negatively correlated with intake of both diets. Infusions of 2-8 mol sodium propionate caused a dose-related depression of hay intake which was significant when cow and day effects were accounted for. Sodium propionate infusions of 4-8 mol significantly depressed silage intake by 140 g DM/mol infused (P < 0.001). Rumen fluid pH was unaffected by treatment while propionate and Na concentrations were elevated and significantly negatively correlated with intake for both diets. Inflation of a rubber balloon in the rumen with 12.5-20 litres warm water resulted in a dose-dependent depression in hay intake of 66 g DM/l distension (P < 0.05). There was significant overeating during the 2 h following the 20 litre treatment. With silage, 15-25 litres of balloon distension for 3 h resulted in a dose-dependent depression in intake of 28 g DM/l distension (P < 0.001). There was no significant overeating during the 2 h following distension. When given in physiological amounts, at the lower end of the range used in these experiments, acetate, propionate and distension of the rumen did not significantly affect hay intakes. However, in each case the linear relationship between intake depression and level of treatment suggested that these factors could contribute to the control of feed intake.

The voluntary intake of hay and silage by lactating cows in response to ruminal infusion of acetate or propionate, or both, with or without distension of the rumen by a balloon

In order to test the hypothesis that negative feedback signals from abdominal receptors are integrated in an additive manner in the control of voluntary food intake, cows with rumen fistulas were given intraruminal infusions of sodium acetate or sodium propionate, or both, with or without distension of the rumen by balloon. Intakes were monitored during the 3 h experimental period and for 2 h after and samples of rumen fluid were taken for estimation of short-chain fatty acid concentrations and osmolality. Six cows in mid-lactation were fed on hay and concentrates and given, into the rumen, 5.5 mol sodium acetate, 5.2 mol sodium propionate and 7.5 l of distension. Compared with the control (water infusion), neither acetate, propionate nor distension significantly depressed hay intake when given separately. When given in combination, however, the following significantly depressed intake during the 3 h treatment period: propionate + distension, acetate + distension, acetate + propionate + distension. Seven cows in early lactation were fed on silage and concentrates and given, into the rumen, 9.0 mol sodium acetate, 4.0 mol sodium propionate and 10.0 litres of distension. Again, none of the three given alone depressed silage intake to a significant extent during the 3 h treatment period, whereas the following combinations had a significant effect: propionate + distension, acetate + distension, acetate + propionate + distension. Basal rumen osmolalities were similar for the two types of feed but infusion of the sodium salts caused a very much greater increase with silage than with hay.(ABSTRACT TRUNCATED AT 250 WORDS)

Periparturient changes in intake, ruminal capacity, and digestive characteristics in beef cows consuming alfalfa hay

Four multiparous, ruminally fistulated Angus x Hereford cows (average BW = 568 kg) were bred to the same bull and used to monitor periparturient changes in DMI, ruminal capacity, and digestion and fermentation characteristics. Cows were individually fed alfalfa hay (16.0% CP, 51.3% NDF) at 130% of the average DMI of the previous 5-d period. Ruminal capacity and DM fill were measured once every 2 wk by removing the ruminal contents from each cow and filling the empty rumen with water. Dry matter intake was measured daily. Ruminal VFA, pH, NH3, and total tract DM digestibility (DMD) were measured during three 7-d periods (average of 58 d before calving, 16 d before calving, and 25 d after calving). Ruminal capacity and DM fill varied in a quadratic manner (P < .01); both were least 6 d before calving. Forage DMI (quadratic effect; P = .02) increased moderately during the prepartum period but increased dramatically after parturition. Although postpartum (d 22) ruminal capacity was only 5% greater than at 61 d before calving, postpartum DMI was 69% greater than DMI measured 61 d before calving. Indigestible ADF (IADF) passage rate changed quadratically with period (P = .01); the greatest IADF passage rate was observed 6 d before calving. Ruminal VFA (mM) also tended to change quadratically (P = .08); the highest concentrations occurred 25 d after calving. The acetate:propionate ratio declined linearly with period (P = .01). Ruminal fluid dilution rate, pH, NH3, and DMD did not change significantly over time.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between rumen bacterial concentrations and total numbers

Based on data from 33 sheep, bacterial concentrations per gram of rumen contents were correlated highly with total bacterial numbers (r = .99). Diets ranged from all forage to 90% concentrate. Similar data were obtained from cattle fed a corn silage diet (r = .95); however, the slope of the regression lines differed between species. Weight of rumen contents was correlated poorly with total bacterial numbers.

Effects of subcutaneous melatonin implants during long daylength on voluntary feed intake, rumen capacity and heart rate of red deer (Cervus elaphus) fed on a forage diet

Subcutaneous melatonin implants were administered to castrated hand-reared male red deer (Cervus elaphus) during a 63 d period in spring, after which effects on voluntary feed intake (VFI), rumen pool size, rumen capacity (i.e. volume) and heart rate were measured on four occasions, evenly spread over a 12-month period, with the deer individually fed indoors on a diet of lucerne (Medicago sativa) chaff. Blood samples for hormone determinations were taken at intervals throughout the study. Day-time plasma melatonin concentration was approximately 5 pg/ml in control animals, whereas during melatonin administration it increased to 60-150 pg/ml and declined to 30 pg/ml by 142 d after the last implantation. Melatonin administration markedly depressed plasma prolactin concentration during the period of implantation, but thereafter plasma prolactin concentration rose in the treated animals during autumn and winter, whilst it declined in control animals over this period. VFI, rumen pool size and heart rate in control animals attained highest values in summer and lowest values in winter, showing a pronounced seasonal cycle. Melatonin administration depressed all these values in late spring and summer and increased all the values in autumn and winter, relative to control animals, and appeared to move the cycles by approximately 6 months. Melatonin-treated animals showed maximum values for all these measurements during winter. The castrated male deer showed little seasonal change in live weight, which was not affected by melatonin administration. The findings support the view that melatonin probably mediates the effect of daylength on digestive function in red deer. Rumen capacity remained relatively constant throughout the year, but rumen pool size as a proportion of rumen capacity increased with increasing VFI.

[Preparatory feeding of the dry stage cow in regard to nutritional condition and the status of the rumen mucosa and rumen flora at calving]

Excessive fat deposition prior to calving and a negative energy balance post partum predispose the high producing cow for an intensive postpartal lipolysis and for the health problems resulting thereof. It was postulated that a well proliferated ruminal mucosa at the beginning of lactation could improve the energy supply by stabilizing the pH of the rumen content with energy rich feed and by providing a high absorption capacity for volatile fatty acids. Results of earlier experiments dealing with this problem are reviewed. Furthermore there is described a pilot experiment with 9 dry cows, which was directed to stimulate rumen mucosa growth ante partum by a low energy ration (roughage) during the first half of the dry period and a high energy ration during the last 3 to 4 weeks prior to calving, without inducing a fat cow. The ruminal mucosa reacted to that feeding regimen as expected and desired. The body weight of 3 cows in moderate and 4 cows in medium body condition increased by 7.2% or 3% during 8 to 11 or 7 to 9 weeks respectively. One of two fat cows lost 4.9% of her body weight within 8 to 9 weeks while the condition of the second animal remained unchanged. No problems were observed at calving. A further progress is expected by feeding the dry cows in two groups with different rations according to their body condition at the end of lactation. Results of experiments as well as practical experiences show that no more than 8 to 10 days are necessary to adapt the ruminal flora to a mixed ration (roughage + concentrates).(ABSTRACT TRUNCATED AT 250 WORDS)

The stomach of the Kafue lechwe (Kobus leche kafuensis)

The Kafue lechwe is endemic to the Kafue Flats area of Zambia. It is semi-aquatic in habit, feeding upon grasses above and below the waterline. The volume of the lechwe rumen is 17 L in the male and 14 L in the female. It has strong and definite pillars. The interior of the rumen is papillated except in the roof area and on the pillars. The omasum has more than 70 laminae which are papillated on the reticular end. The anatomy of the lechwe stomach is similar to the stomachs of other water dependent grazers such as Bohor Reedbuck, Waterbuck, Uganda Kob and Puku.

Efficacy of plastic pot scrubbers as a replacement for roughage in high-concentrate cattle diets

Effects of plastic pot scrubbers on feedlot performance and ruminal metabolism of steers fed all-concentrate diets were determined. In Trial 1, 31 crossbred steers (means initial BW, 290 kg) were penned and fed individually. Treatments were 1) 85% concentrate-15% corn silage diet, 2) 100% concentrate diet, and 3) 100% concentrate diet + ruminal insertion of eight plastic pot scrubbers per steer. During the first 112 d of the trial, steer ADG did not differ (P greater than .10) due to treatment. From d 113 to 152, steers provided with pot scrubbers had 16% greater ADG than those fed the 100% concentrate diet without pot scrubbers (P = .18). In Trial 2, 78 crossbred steers (means initial BW, 315 kg) were penned individually and fed the diets used in Trial 1. Steers fed the 100% concentrate diet received zero, four or eight pot scrubbers. From d 113 to 167, steers provided with four or eight pot scrubbers or fed the 85% concentrate diet had greater (P less than .10) gains than steers fed the 100% concentrate diet without pot scrubbers. In Trial 3, 120 steers (means initial BW, 286 kg) were grouped in 12 pens and limit-fed an all-concentrate diet for 84 d. Sixty steers were provided with six pot scrubbers each. Performance was not affected (P greater than .10) by the use of pot scrubbers during the 84-d growing phase. During the subsequent 84-d finishing phase, half the steers receiving each treatment were switched to either an 85% concentrate-15% corn silage or an 100% concentrate diet offered for ad libitum consumption.(ABSTRACT TRUNCATED AT 250 WORDS)

A unifying mathematical analysis of methods to estimate rumen volume using digesta markers and intraruminal sampling

A theoretical exposition of methods for estimating the quantity of digesta in the rumen using digesta-flow markers and intraruminal sampling is given, with emphasis on the kinetic assumptions underlying each method. Single- and dual-marker approaches to estimating volume in steady and non-steady-state are presented.

Physiological and pathological effects of feeding high levels of magnesium to steers

The effects of feeding high levels of Mg were evaluated in a 130-d study with 24 steers. Six steers were allotted to each of four diets supplemented with MgO to attain .3, 1.4, 2.5 or 4.7% Mg, DM basis. Chromic oxide was used as digesta marker; fecal grab samples were collected once daily during nine consecutive 10-d periods. Steers fed 2.5 and 4.7% Mg refused some feed during the study, so their respective dietary Mg intakes were 2.4 and 3.7% (DM basis). Severe diarrhea and a lethargic appearance were observed in steers fed the two higher Mg levels. Fecal DM and apparent DM digestibility decreased linearly (P less than .01) with increased dietary Mg. Apparent Mg absorption (g/d) increased linearly (P les than .01) and apparent Ca and P absorption (g/d) decreased linearly (P less than .01) with addition of Mg to the diet. Increasing dietary Mg linearly elevated blood serum and erythrocyte Mg (P less than .01; P less than .05, respectively) and serum inorganic P (P less than .05) and linearly decreased serum Ca (P less than .01). Magnesium concentration in liver, kidney, skeletal muscle and rib-bone and P in skeletal muscle all increased linearly (P less than .05) with dietary Mg. Increasing dietary Mg in the steers caused a progressive degeneration of the stratified squamous epithelium of rumen papillae. A progressively more serious Mg toxicosis condition developed over time in steers fed diets containing 2.4 and 4.7% Mg.

Intraruminal administration of milk in the calf as a model for ruminal drinking: morphological and enzymatical changes in the jejunal mucosa

In order to develop a calf model for studying the syndrome of ruminal drinking (RD) in veal calves, three dual-fistulated calves were used to test the effect of intraruminal administration of milk replacer on the jejunal mucosa. Biopsies of the proximal jejunal mucosa were taken through a jejunal fistula and the mucosal morphology and the activities of two brush border enzymes, lactase and alkaline phosphatase, were determined. Means of villus length and brush border enzyme activities decreased during the period of intraruminal administration of milk. The hyperplastic villus atrophy in this model was similar to that found in chronic RD patients in previous studies. This could not be associated with isolation of pathogenic micro-organisms from the faeces and is probably the consequence of the intraruminal milk feeding procedure itself. Clinical recovery from the signs of RD occurred rapidly after intraruminal administration of milk ceased and was followed by restoration of villus length and brush border enzyme activities 3-4 weeks later.

Distribution of methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves in the forestomach of cattle

The distribution of methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves in the forestomach of calves and cows was studied, using immunohistochemical methods. Methionine-enkephalin-Arg6-Gly7-Leu8-immunoreactive nerves were found in all regions of the bovine forestomach. Cell bodies were found mainly in myenteric ganglia, and nerve fibers were found principally in muscular layers. Nerve fibers and ganglia were concentrated in the lips of the reticular groove, but were least numerous in ruminal and omasal walls. The reduced number of immunoreactive nerves in cows, compared with the number of those in calves, was striking, especially in the lips of the reticular groove and the omasal leaves. Results may indicate that the importance of methionine-enkephalin-Arg6-Gly7-Leu8-containing nerves in the physiologic regulation of the forestomach of the calf is different from that of the cow.

Anatomical studies into the ruminal mucosa of pygmy goats in relation to their age

The ruminal mucosa of 15 pygmy goats of different age (Z1 approximately 4-5 months, Z2 approximately 1 year, Z3 approximately 1.5-5 years) were studied gross-anatomically concerning their colour, clumping of papillae, fodder precipitations on the papillae, areas poor in papillae or devoid of them and the development of papillae. The density of papillae/cm2 in the 3 groups investigated was 79.4; 67.3; 58.0; the mean length of the papillae (mm) 1.75; 1.86; 2.96; the mean breadth of the papillae (mm) 1.3; 1.2; 2.0; the area of the ruminal mucosa (cm2) 799; 943; 1 195; the area of the ruminal pillars (cm2) 38; 41; 69; the number of the papillae/rumen 59,940; 58,022; 64,782; the total absorptive area (cm2) 3,802; 3,854; 11,268; the surface magnifying factor 4.0; 3.4; 8.4.

Histological studies into the ruminal mucosa of pygmy goats in relation to their age

Ruminal mucosae of 15 pygmy goats of different age (Z1 approximately 4-5 months, Z2 approximately 1 year, Z3 approximately 1.5-5 years) and sex were investigated histologically. The thickness of the Stratum corneum of the 3 experimental groups was in the Atrium ruminis 23.0, 23.0 and 29.1 microns, in the Recessus ruminis ventralis 22.8, 28.0 and 30.0 microns, that of the Stratum germinativum and Stratum granulosum in the Atrium ruminis 74.8, 78.4 and 82.3 microns and in the Recessus ruminis ventralis 87.4, 84.7 and 87.7 microns, that of the Corpus papillare in the Atrium ruminis 75.3, 75.2 and 74.4 and in the Recessus ruminis ventralis 85.0, 78.9 and 71.6 microns. The cell nuclear volumes of the basal and parabasal cells of papillae originating from the Atrium ruminis (a) and the Recessus ruminis ventralis (b) in the individual experimental groups were in case of a 103.2; 100.2 and 117.3 microns3 resp. in case of b 93.4; 96.4 and 119.7 microns3.

Transruminal and transreticular palpation of abdominal viscera of the permanently fistulated dairy cow

A detailed description is given of the abdominal viscera which are palpated through the walls of the rumen and reticulum of the live dairy cow surgically prepared with a permanent fistula. Transruminal and transreticular palpation can be complementary to transrectal and transcolonic examination in gaining detailed knowledge of the topography of abdominal viscera in the live dairy cow.