Effect of increasing the proportion of dietary concentrate on gastrointestinal tract measurements and brush border enzyme activity in Holstein steers.

The aim of this study was to determine the time course for adaptation of the reticulo-rumen, omasum, abomasum, and small intestine in response to an abrupt increase in the proportion of grain in the diet. Adaptive responses include tissue and digesta mass, small intestinal length, and brush border enzyme activity in the duodenum, proximal jejunum, and ileum. Twenty-five Holstein steers (213 ± 23 kg; 5 to 7 mo of age) were blocked by body weight, and within block were randomly assigned to 1 of 5 treatments: the control diet (CTRL; 92% chopped grass hay and 8% mineral and vitamin supplement on a dry matter basis) or a moderate grain diet (MGD; 50% chopped grass hay, 42% rolled barley grain, and 8% mineral and vitamin supplement) that was fed for 3 (MGD3), 7 (MGD7), 14 (MGD14), or 21 d (MGD21). Dry matter intake was limited to 2.25% of body weight to ensure that changes in dry matter intake did not confound the results. On the last day of the dietary exposure, steers were slaughtered 2 h after feeding. Reticulo-rumen tissue mass and ruminal epithelium mass in the ventral sac of the rumen were not affected by the MGD. Wet reticulo-ruminal digesta mass decreased from CTRL to MGD7 and then increased, but reticulo-ruminal digesta dry matter mass did not differ between treatments. Omasal mass, omasal tissue mass, and omasum digesta mass decreased linearly with the number of days fed MGD, but abomasal tissue mass tended to increase linearly. Duodenal tissue mass tended to increase linearly, and ileal length increased linearly with the number of days fed MGD. Lactase activity in the proximal jejunum increased linearly and maltase activity in duodenum tended to increase linearly with days fed MGD. Aminopeptidase N activity in the proximal jejunum increased cubically with days fed MGD, and dipeptidylpeptidase IV activity in ileum tended to decrease from CTRL to MGD14 and then tended to increase. Adaptation to a diet with a greater proportion of concentrate involves changes in the mass and length of regions of the gastrointestinal tract and brush border enzyme activity. These changes take place gradually over at least 3 wk.

Morfologia dos pré-estômagos e de papilas ruminais de cordeiras Santa Inês em crescimento submetidas a dois planos nutricionais / Morphology of pre-stomach and ruminal papillae of growing Santa Inês female lambs under two nutritional schemes

Para se avaliar o efeito do plano nutricional e crescimento sobre a massa dos pré-estômagos, morfologia e quantificação de papilas ruminais, trinta e seis cordeiras da raça Santa Inês foram submetidas a dois planos nutricionais (ad libitum ou restrito) sendo abatidas em diferentes pesos vivo (20, 30 ou 40 kg de peso vivo), em um delineamento inteiramente casualizado balanceado em arranjo fatorial 2x3. Feito o abate, as vísceras foram pesadas livres de seu conteúdo em seguida mediu-se o volume de repleção do rúmen e retículo. Amostras do tecido ruminal oriundas dos sacos cranial e ventral foram coletadas para posteriormente serem realizadas com auxílio de lupa estereoscópica as medidas morfométricas das papilas ruminais, altura, largura da base, área, papilas por cm² e área absortiva por cm². Os resultados obtidos foram submetidos a análise de variância e as médias resultantes por tratamento foram comparadas por meio de teste de Student Newmann Keuls. Os diferentes planos nutricionais não influenciaram a massa das vísceras rúmen, retículo e omaso (P>0,05), no entanto, observou-se crescimento dessas vísceras em função do aumento do peso ao abate. O volume dessas vísceras foi afetado pelo peso ao abate, e observou-se menores volumes para animais com alimentação ad libitum (P<0,10). O número de papilas por cm² foi reduzido com o aumento do peso ao abate, sendo que altura e área foram aumentadas quando em pesos maiores. O plano nutricional afetou apenas a área e altura das papilas ruminais oriundas do saco cranial. A área absortiva não foi afetada pelos tratamentos. Plano nutricional e diferentes pesos vivos influenciam a morfologia dos pré-estômagos de cordeiras da raça Santa Inês.

For the evaluation of nutritional schemes and change on the pre-stomach morphology and quantification of rumen papillae, 36 Santa Inês female lambs were submitted to two nutritional schemes (ad libitum or restrict) and slaughtered with different live weights (20, 30 or 40 kg) in a completely randomized factorial design 2x3. After slaughter, the viscera were weighed empty and their volume was measured. Samples of ruminal wall from the cranial and ventral sacs were collected and with a stereomicroscope photographed and analyzed regarding height, basal width, area, papillae per cm² and absorptive area per cm². The results were submitted to analyses of variance and the means were compared by Student Newman Keuls test. The different nutritional schemes did not influence the weight of rumen, reticulum or omasum (P>0.05), although, growth of the viscera was observed by increase in live weight. The viscera volume was affected by live weight, and smaller volume was observed in the animals fed ad libitum diet (P<0.10). The number of papillae per cm² was reduced by the increase in live weight. Height and area of papillae were larger in heavier animals. The nutritional scheme only affected height and area of papillae of the cranial sac. The absorptive area was not affected by the treatments. Different nutritional schemes and live weights affect the pre-stomach morphology of Santa Ines female lambs.

Identification of differentially expressed proteins in ruminal epithelium in response to a concentrate-supplemented diet.

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

Dose response to cinnamaldehyde supplementation in growing beef heifers: ruminal and intestinal digestion.

The objective of this study was to determine if cinnamaldehyde (CIN) could be used to improve feed intake, digestion, and immune status in growing beef heifers fed high-concentrate diets. The experiment was designed as a 4 x 4 Latin square using 4 ruminally and duodenally cannulated beef heifers with 4 treatments: control (no CIN added), 400 mg/d of CIN (low), 800 mg/d of CIN (medium), and 1,600 mg/d of CIN (high), and four 21-d periods. Feed intake, rumen pH and fermentation characteristics, site and extent of digestion, microbial N synthesis, blood metabolites, and acute phase protein response were measured. The diets consisted of 15% barley silage, 80% dry-rolled barley grain, and 5% supplement (DM basis). Intakes (kg/d) of DM, OM, NDF, starch, and N were quadratically (P = 0.04) changed with increasing CIN supplementation. The amount of OM fermented in the rumen quadratically (P = 0.02) decreased with increasing CIN. Digestibilities (% of intake) of OM, NDF, and N in the rumen were not affected by supplementing with low and medium CIN, but they were reduced by 8% (P = 0.10), 31% (P = 0.05), and 17% (P = 0.05), respectively, with high CIN. Similarly, digestibilities of OM and NDF in the total tract also tended to be reduced by 7% (P = 0.10) and 20% (P = 0.10), respectively, with high CIN because supplementation of CIN had minimal effects on intestinal digestibility. Flows (g/d) of microbial N and other nutrients to the duodenum were not affected by CIN supplementation, even though the amount of ruminal fermented OM varied with level of CIN supplementation. Rumen pH, total VFA concentration, and molar proportions of individual VFA were not affected by CIN. Although concentrations of NEFA (P = 0.06) and triglyceride (P = 0.01) were quadratically changed with increasing CIN supplementation, blood concentrations of glucose and urea N, white blood cell counts, serum amyloid A, and lipopolysaccharide in plasma were not affected by CIN. Plasma haptoglobin numerically (P = 0.11) decreased with the medium dose of CIN fed compared with control. The results indicate that supplementation of a high-concentrate diet with a low dose of CIN resulted in small increases in nutrient availability in the rumen due to increased feed intake and greater ruminal digestion of OM. However, feed intake and ruminal digestion of feeds were adversely affected when a high dose of CIN was used.

[The effect of flavomycin on digestion in fattening bulls]. / Einfluss von Flavomycin auf die Verdauung bei Mastbullen.

Three friesian bulls (Genotype 31) were fitted with re-entrant cannulas at the duodenum to investigate the influence of a flavomycin supplement of the digestion in the forestomachs and the other parts of the digestive tract. The supplement of flavomycin increased the total digestibility of the organic matter. The digestibility of starch and sugar was between 97% and 98%. The balance of the nutrients in the digestive tract shows, that by flavomycin supplementation the degradation of organic matter and crude protein in the fore stomach was decreased and the amount of the organic matter and crude protein in the gut was increased. The balance of the amino acids in the gut showed that after flavomycin ca. 30 g more amino acids were found in the gut. The synthesis of bacterial protein in the forestomachs was, after flavomycin application, slightly reduced as was the degradation rate of the feed protein.

Opioid inhibitory control of the ruminant stomach motility: functional importance of the hypothalamus.

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

The failure of the oesophageal groove reflex, when fluids are given with an oesophageal feeder to newborn and young calves.

The fate of colostrum and other fluids given with an oesophageal feeder was studied in newborn calves and in young calves up to 3 weeks by means of radiological techniques. Any fluid given with an oesophageal feeder was found in the forestomachs, since it apparently did not induce an oesophageal groove reflex. Also when suckling was induced during feeding with the oesophageal feeder, the oesophageal groove reflex did not occur. The outflow of colostrum and other fluids from the forestomachs to the abomasum and small intestine occurred for the most part within 3 hours. Only the emptying of the ventral ruminal sac was sometimes delayed for 24 or 48 hours. The results obtained in calves up to 3 weeks old did not differ from those obtained in newborn calves. It was concluded that although colostrum given by oesophageal feeder entered the forestomachs, the rapid flow to the abomasum and small intestine created the conditions for a sufficient absorption of immunoglobulins. Application of colostrum with an oesophageal feeder in newborn calves promises to be a timesaving and effective method for creating an optimum passive immunity of the calves.

Effects of zinc, copper, and manganese supplementation of high-concentrate ration on gastrointestinal absorption of copper and manganese in Holstein calves.

Sixteen Holstein bull calves were fed a high-concentrate ratio supplemented with zinc, copper, and manganese, alone or in combination, for 10 wk. After 6 days of preliminary feeding of chromic oxide, fecal grab-samples were collected for 6 days. Calves were slaughtered, and samples of the contents of the reticulo-rumen, omasum, abomasum, small intestine, cecum, and large intestine were analyzed for chromic oxide, copper, and manganese. Absorption along the gastrointestinal tract, measured by comparison of one segment with the previous segment, indicated net secretion of copper in the abomasum but net absorption from the rest of the tract. The exception was that net secretion into the reticulo-rumen was associated with low dietary copper. Net secretion of manganese was mainly in the small intestine and cecum in all treatments. A higher proportion of copper apparently was absorbed when this mineral was supplemented in the ration. However, absorption of manganese was decreased slightly when manganese was supplemented in the ration. Reabsorption of manganese in the large intestine was probably greater than that of copper.

Fertilizer calcium as a factor affecting the voluntary intake, digestibility and retention time of pangola grass (Digitaria decumbens) by sheep.

1. Pangola grass (Digitaria decumbens) grown with and without calcium fertilizer was cut at three stages of regrowth to measure voluntary intake of dry matter (DM) and digestibility of various components of the dried-grass diet by sheep kept in metabolism crates. To determine the extent of a simple Ca deficiency half the sheep on each diet was supplemented with 1-4 g Ca/d. Retention times of the various dietary components in the reticulo-rumen were also determined. 2. Feeding a Ca supplement had no effect on voluntary intake or digestibility. 3. Ca fertilizer increased the Ca content of the grass from 2-2 to 3-8 g/kg DM and DM digestibility from 0-455 to 0-476 (P less than 0-01) due to an increase in the digestibility of the hemicellulose. 4. Voluntary intake was increased from 38-8 to 43-2 g/kg body-weight0.75 per d by Ca fertilizer due to an 18% reduction in the period of time the DM was retained in the reticulorumen. 5. Regressions relating voluntary intake to DM digestibility for the Ca-fertilized and control grass were significantly different (P less than 0-01). When compared at the same DM digestibility the voluntary intake of the Ca-fertilized grass was 2-6 g/kg body-weight0.75 per d higher than that of the control. 6. It was concluded that Ca fertilizer increased both DM digestibility and voluntary intake as a result of changes in the structural composition of the grass and not by a simple increase in the Ca content of the diet.

Liquid feed passage route into stomach compartments, influence of abomasal infusions on plasma glucose, and supplementation of dry rations with liquid feeds from lick-wheel feeders.

Passage route into stomach compartments of liquid feeds containing a marker was studied by feeding a liquid supplement and molasses from a lick-wheel feeder and by infusing the liquid supplement into the reticulorumen 30 min prior to sampling contents of the reticulorumen and abomasum and 4 h prior to sampling blood for plasma glucose. Recovery from reticulorumen and concentration of marker in abomasal ingesta gave no evidence of rumen bypass, this supported by a gross correlation of .92 between rumen ammonia nitrogen and nonprotein nitrogen intake from liquid feeds. Plasma glucose values were not different. Preinfusion and postinfusion plasma glucose values were similar for abomasal infusion of about 454 g of molasses, 20% crude protein liquid supplement, and for the basal diet. Values were lower for abomasal infusion of the 35% crude protein liquid supplement (Pro-Lix) than for the 20% crude protein liquid supplement. When complete rations containing 11.5, 13.0, and 14.5% crude protein were supplemented with either molasses or a 20% crude protein liquid supplement fed from lick-wheel feeders, intake averaged .53 and .34 kg per animal daily for the respective liquid feeds. There was no effect on milk yield, solids-corrected milk, milk fat content, protein content, solids-not-fat percent, or body weight change. There was an interaction of protein level and liquid feeds in which plasma glucose was increased by liquid feeds in higher but not in lower protein diets.