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Byline: R. A. Nurfitriani, A. Jayanegara, N. R. Kumalasari , S. Ratnakomala, Rohmatussolihat, N. F. Sari, R. Fidriyanto, K. A. Sarwono, W. D. Astuti , A. Fitri, Y Widyastuti and [...]

Flexibility in gut morphology has fitness consequences in herbivores. To accommodate dietary variation in energy concentration, rumen-reticulum absorptive capacity and organ mass might also covary. We hypothesized that low energy diets result in greater food intake but lower volatile fatty acid concentrations. The consequence would be heavy rumen-reticulum organs and low absorptive capacity. We measured rumen-reticulum organ mass and absorptive capacity in captive white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) from central Texas, USA. Deer consumed a pelleted ration, ad libitum, of 1.77 kcal/g (low) or 2.67 kcal/g (standard) digestible energy from the time animals were weaned. In December, 4.5- and 5.5-year-old deer were euthanized, the rumen-reticulum was extracted, thoroughly rinsed, wrung out, and weighed. Four 1 cm x 3 cm samples were extracted from four regions of the rumen and mucosal surface area was measured. Our surrogate of food intake and mastication intensity was first molar height. Molar height was lower in animals consuming the low energy diet. Analyses indicated sex-specific responses. Males eating the low energy diet had heavier rumen-reticulum organs, but females did not. Females consuming the low energy diet had a lower surface enlargement factor, but males did not. The processes driving variation in rumen-reticulum morphology from dietary variation require further examination. Key words: diet, gastrointestinal tract, instantaneous response, morphology, Odocoileus virginianus, white-tailed deer. Resume: La souplesse de la morphologie du tube digestif a des consequences sur l'aptitude chez les herbivores. Pour composer avec des variations de la teneur energetique du regime alimentaire, la capacite d'absorption du rumen-reticulum et la masse de cet organe pourraient aussi covarier. Nous postulons que des regimes alimentaires peu energetiques se traduisent en un apport alimentaire plus important, mais des concentrations d'acides gras volatils plus faibles avec, comme consequences, des organes rumens-reticulums lourds et une faible capacite d'absorption. Nous avons mesure la masse de l'organe rumen-reticulum et sa capacite d'absorption chez des cerfs de Virginie (Odocoileus virginianus (Zimmermann, 1780)) du centre du Texas en captivite. Les cerfs mangeaient a volonte, des leur sevrage, de la nourriture en boulettes caracterisee par des teneurs en energie digestible de 1,77 kcal/g (faible) ou 2,67 kcal/g (normale). En decembre, des cerfs de 4,5 et 5,5 ans ont ete euthanasies et leurs rumensre ticulums ont ete extraits, rinces en profondeur, essores et peses. Quatre echantillons de 1 cm sur 3 cm ont ete extraits de quatre regions du rumen et la superficie des muqueuses a ete mesuree. Nous avons utilise la hauteur des premieres molaires comme valeur de substitution de l'apport alimentaire et de l'intensite de la mastication. La hauteur des premieres molaires etait plus faible chez les animaux consommant la nourriture pauvre en energie. Des analyses ont fait ressortir des reponses differentes selon le sexe. Parmi les animaux consommant la nourriture peu energetique, les males, mais non les femelles, avaient des rumens-re ticulums plus lourds, alors que les femelles presentaient un facteur d'expansion de la surface plus faible, mais non les males. Les processus a l'origine des variations de la morphologie du rumen-reticulum decoulant de variations du regime alimentaire necessitent plus d'attention. [Traduit par la Redaction] Mots-cles: regime alimentaire, tube digestif, reaction instantanee, morphologie, Odocoileus virginianus, cerf de Virginie., Introduction Herbivores display flexibility in digestive anatomy that has been tied to animals exploiting a diversity of foods, which in turn increases the variety of environments that can be inhabited. [...]

Scaling relationships between body mass and gut capacity are valuable to predicting digestive efficiency. Interspecific scaling relationships between body mass and gut capacity have consistently estimated a slope of 1.0; however, intraspecific scaling relationships between body mass and gut capacity have been highly variable. We examined the influence of demands of growth and production on scaling relationships of body mass and rumen-reticulum characteristics in white-tailed deer (Odocoileus virginianus (Zimmermann, 1780)) because little is known about how juvenile and subadult ruminants accommodate increased digesta masses. We sampled 108 animals over a 2-year period and assessed the influence of body mass, time of kill, crude protein (%), and acid detergent fiber (%) in the rumen, lactation, sex, and back fat on rumen-reticulum organ mass, rumen-reticulum capacity, wet mass of the digesta, and the dry mass of the digesta. Juvenile and subadult white-tailed deer had rumen-reticulum organ masses, capacity, and digesta masses that were similar to adults because body mass and rumen-reticulum scaling relationships all had scalars similar to 1.0. Thus, under the confines of our study, ontogeny plays only a minor role in the physiological characteristics of the rumen-reticulum and the scaling relationships of body mass and rumen-reticulum capacity. Key words: body mass, digesta mass, Odocoileus virginianus, ontogenetic, rumen-reticulum, scaling. Les relations d'echelle entre la masse corporelle et la capacite du tube digestif sont utiles pour predire l'efficacite de la digestion. Si les relations interspecifiques d'echelle entre la masse corporelle et la capacite du tube digestif donnent uniformement une pente estimee de 1,0, les relations intraspecifiques d'echelle entre la masse corporelle et la capacite du tube digestif sont tres variables. Nous examinons l'influence des demandes de la croissance et de la production sur les relations d'echelle entre la masse corporelle et des caracteristiques du reticulo-rumen chez le cerf de Virginie (Odocoileus virginianus (Zimmermann, 1780)), puisque les connaissances sur l'adaptation des ruminants juveniles et subadultes a l'augmentation des masses de digesta sont tres limitees. Nous avons echantillonne 108 animaux sur une periode de 2 ans et evalue l'influence de la masse corporelle, du moment de la mort, du contenu en proteines brutes (%) et en fibres au detergent acide (%) dans le rumen, de la lactation, du sexe et du gras dorsal sur la masse du reticulo- rumen, la capacite de ce dernier, la masse fraiche du digesta et la masse seche du digesta. Les cerfs juveniles et subadultes presentaient des masses et capacites du reticulo-rumen et des masses du digesta semblables a celles d'adultes etant donne que les relations d'echelle entre la masse corporelle et les caracteristiques du reticulo-rumen etaient toutes caracterisees par des scalaires de l'ordre de 1,0. Ainsi, dans les limites de l'etude, l'ontogenie ne joue qu'un role mineur dans la determination des caracteristiques physiologiques du reticulo-rumen et des relations d'echelle entre la masse corporelle et la capacite du reticulo-rumen. Mots-cles : masse corporelle, masse du digesta, Odocoileus virginianus, ontogenetique, reticulo-rumen, echelle. [Traduit par la Redaction], Introduction Scaling relationships between body mass and gut capacity have been used to help explain digestive efficiency among and within species. Studies by Jarman (1974) and Bell (1971) indicated that [...]

Ten ruminally cannulated heifers (BW = 416 kg; SD = 24) were used to test the effect of the form and frequency of supplemental energy on forage DMI and digestibility. Five treatments were arranged in a replicated, 5 x 4 Latin rectangle (n = 8), and included no supplement (control), dry-rolled corn (DRC) fed daily, DRC fed on alternate days (DRC-A), dried distillers grains plus solubles (DDGS) fed daily, and DDGS fed on alternate days (DDGS-A). Supplements fed daily were fed at 0.40% of BW, whereas alternate day-fed supplements were fed at 0.80% of BW every other day. Chopped grass hay (8.2% CP) was fed to allow ad libitum DMI, and the intake pattern was measured. Control heifers had greater (P < 0.01) hay DMI than supplemented heifers (1.88 vs. 1.66% of BW daily, respectively), although total DMI was lower (P < 0.01) for control. Hay DMI did not differ (P = 0.45) between DRC and DDGS, and tended to be lower (P = 0.08) by heifers on DDGS-A and DRC-A than by heifers supplemented daily. Hay intake was lower (P < 0.01) on supplementation days for DDGS-A and DRC-A than on nonsupplemented days. Heifers in alternate-day treatments had fewer (P < 0.01) and larger (P < 0.01) meals and spent less (P < 0.01) time eating than those supplemented daily. Average rumen pH was greater (P = 0.05) for control than supplemented heifers (6.30 vs. 6.19). Control heifers had greater (P = 0.04) rates and extents of NDF disappearance than supplemented heifers. Rate of hay NDF disappearance was lower (P = 0.02) for DRC than for DDGS. Supplementation decreased hay DMI and changed digestion kinetics. Supplementation frequency affected amount and pattern of DMI. Rate of hay NDF disappearance was greater for DDGS than DRC. Key words: beef, digestibility, forage, intake, supplementation

The objective of this experiment was to investigate the possibility of estimating the outflow of nutrients and microbial protein from the rumen based on sampling reticular contents as an alternative to duodenal sampling. Microbial protein flow estimates were also compared with a third method based on sampling of ruminal contents. Reticular and duodenal digesta and ruminal contents were recovered from 4 cows used in a 4 x 4 Latin square design experiment, in which the ruminal effects of 4 exogenous enzyme preparations were studied. Large and small particulate and fluid markers were used to estimate digesta flow in a triple-marker model; [sup.15]N was used as a microbial marker. Reticular and duodenal digesta were segregated into small and large particles (SP and LP, respectively) and a fluid phase, and ruminal digesta was segregated into particulate and fluid phases. Compared with digesta recovered at the duodenum, reticular digesta had lower OM and greater NDF contents. The proportion of microbial N was notably greater in the fluid phase of reticular digesta. Ruminal outflow of DM and OM was greater (by 17 and 28%) and that of NDF was lower (by 14%) when estimated from duodenal compared with reticular samples. There was no difference in the estimated flow of starch and nonammonia and microbial N between the reticular and duodenal techniques. Microbial N flow estimated based on ruminal sampling was similar to those based on duodenal and reticular sampling. The ruminal method, however, grossly overestimated flow of DM, OM, and NDF. This study supports the concept that microbial protein outflow from the rumen can be measured based on sampling of ruminal or reticular digesta. The reticular sampling technique can also provide reliable estimates for ruminal digestibility of OM, N, and fiber fractions. These findings need to be confirmed in experiments with basal diets varying in structure and forage-to-concentrate ratios. Key words: dairy cow, duodenal digesta, microbial protein synthesis, reticular digesta

The objective of this study was to understand the effects of fumarate addition on methane (C[H.sub.4]) and VFA production in the rumen through a meta-analysis of its effects on ruminal batch cultures. Because the reduction of fumarate to succinate can draw electrons away from ruminal methanogenesis, fumarate has been studied as a potential feed additive to decrease C[H.sub.4] production in ruminants. The average decrease in C[H.sub.4] in batch cultures was of 0.037 [micro]mol/ [micro]mol of added fumarate, which is considerably lower than 0.25 [micro]mol/[micro]mol, the decrease predicted from the stoichiometry of the reactions involved. One reason that fumarate was not effective at decreasing C[H.sub.4] in batch cultures was that only an average of 48% of added fumarate appeared to be converted to propionate. Secondly, the incorporation of reducing equivalents in the conversion of fumarate to propionate was almost entirely offset by their release from an average of 20% of added fumarate that appeared to be converted to ace tate. Thermodynamic calculations indicated that the conversion of added fumarate to both propionate and acetate was feasible. Fumarate appears to be more effective in decreasing C[H.sub.4] production and increasing propionate in continuous culture than in batch culture. This suggests that microbial adaptation to fumarate metabolism can be important. Variation in populations of fumarate-reducers, methanogens, and protozoa could all be involved. Fumarate supplementation for an extended period may result in the amplification of otherwise small populations of fumarate-reducers. Addition of some of these organisms may be helpful to improve fumarate conversion to propionate. Strategies based on enhancing the rumen's capacity to convert fumarate to propionate by maintaining a low fumarate concentration have been effective. Thermodynamic considerations should be taken into account when designing strategies for C[H.sub.4] abatement through the addition of external electron acceptors. Key words: fermentation, fumarate, meta-analysis, methane, rumen

Six ruminally and duodenally cannulated Angus-Jersey crossbred steers (450 kg of BW) were used in a 6 x 6 Latin square to evaluate the effect of kernel vitreousness and moisture on intake and digestibility of high-moisture corn. Arranged in a 2 x 3 factorial, diets included a floury (FLO) or a vitreous (VIT) endosperm corn hybrid harvested at 28.1% (DRY), 31.2% (MID), or 35.7% (WET) kernel moisture content. Diet DM consisted of 88.25% high-moisture corn, 6% chopped alfalfa hay, 2% corn gluten meal, 0.75% urea, and 3% supplement. Supplement was included to ensure that the diets contained a minimum (DM basis) of 0.6% Ca, 0.6% K, 0.2% S, 33 mg/kg of monensin, and 11 mg/kg of tylosin. Geometric mean diameter of lyophilized high-moisture corn tended to be less (P = 0.06) for VIT than for FLO, and the calculated particle surface area was 15.8% greater (P = 0.03). An interaction of vitreousness with the quadratic effect of moisture was noted (P < 0.001), such that fraction a and effective degradation for starch tended to be greater for the vitreous hybrid at the least and greatest moisture content but lower for the vitreous hybrid at the intermediate moisture content. Intake and ruminal disappearance of DM, OM, and starch were not influenced by vitreousness or moisture, with ruminal starch disappearance averaging 90.9%. Intestinal starch digestion measured as a percentage of starch entering the intestines averaged 91% and was greater (P < 0.05) for VIT than FLO corn. Averaged across moisture levels, total tract starch digestibility was greater (P < 0.003) for VIT than FLO. Compared with FLO kernels, VIT kernels appeared to be more brittle and therefore shattered more readily when rolled, particularly at the driest kernel moisture level. Furthermore, increased surface area of smaller particles may have been responsible for the greater starch utilization from VIT corn. In contrast with the results from other in situ and in vivo trials with dry-rolled corn grain, in which the starch from vitreous hybrids was less rapidly or completely digested, hybrids with more vitreous starch, when fed as high-moisture corn, had greater total tract starch digestibility, primarily due to greater postruminal starch digestion. Key words: in situ, intestine, rumen, starch, steer

The rumen has several important physiological functions: absorption, transport, metabolic activity, and protection. To clarify the molecular basis underlying the physiological function of the rumen, reticulum, omasum, and abomasum, we used mRNA differential display to isolate and identify differentially expressed genes in these tissues. We isolated 18 transcripts that coexpressed in the rumen, reticulum, and omasum. Five genes, ribosomal protein 19 (RPS19), basic helix-loop-helix domain containing class B2 (BHLHB2), NADH dehydrogenase flavoprotein 2 (NDUFV2), exosome component 9 (EXOSC9), and ribosomal protein 23 (RPS23), were highly expressed in the rumen of adult Holstein and Japanese Black cattle. Significant differences of expression were observed in the abomasum compared with the rumen, reticulum, and omasum. To investigate the expression pattern of these genes during the neonatal growth stage, the relative levels of gene expression were analyzed in the rumen and abomasum of 3-wk-, 13-wk-, and 18- to 20-mo-old Holstein cattle. The expression level of RPS19 did not change with age in the rumen and abomasum. The levels of BHLHB2, NDUFV2, and EXOSC9 mRNA in the abomasum decreased (P < 0.05) after weaning and declined (P < 0.05) further in adults; in contrast, expression in the rumen was not altered. Interestingly, the levels of RPS23 mRNA in the rumen increased (P < 0.05) after weaning and further increased in the adult; however, the level of expression of this gene decreased (P < 0.05) in the abomasum with weaning and age. This indicates that the 4 tissues, especially the rumen and abomasum, have different developmental pathways after birth and subsequent onset of rumination. Key words: abomasum, cattle, differential display reverse transcriptase polymerase chain reaction, rumen