Participação do ruminoretículo e omaso na superfície absortiva total do proventrículo de bovinos

About 50% of volatile fatty acids (VFA) produced in the reticulorumen are absorbed in this compartment. The other 50% pass with the fluid phase to the omasum and are absorbed before the duodenum. The objective of this experiment was to measure the absorption surface of the reticulorumen and omasum aiming to compare it with the absorption magnitude. Eight adult bovines had their stomachs removed immediately after slaughtering. The stomach compartments were separated and weighed. Fragments were collected from several anatomical regions. Measurements of the total area of the internal surface were taken through image capture and analysis. The reticulorumen absorptive surface (7.7 m²) was larger (P<0.001) than the omasum absorptive surface (2.1 m²). The surface/digest ratio, however, was larger (P=0.07) in the omasum (0.22 m²/kg) than in the reticulorumen (0.12m²/kg), representing an omasum surface area for each digest unit 83.3% larger. The area of one of the rumen ventral sac fragments showed a positive correlation (0.84) with the total rumen surface area, indicating that it is possible to estimate the total rumen area by biopsy. The absorptive surface of the forestomach compartments seem to be compatible with absorption magnitude. However, further studies comparing VFA fractional absorption rate among forestomach compartments should be carried out.Cerca de 50% dos ácidos graxos voláteis (AGV) produzidos no ruminoretículo são absorvidos nesse compartimento e outros 50% passam com a fase fluida para o omaso e são absorvidos antes do duodeno. O objetivo deste trabalho foi mensurar a superfície de absorção do ruminoretículo e do omaso comparando-as com a magnitude de absorção. Oito bovinos adultos tiveram seu estômago removido imediatamente após o abate. Os compartimentos do estômago foram separados, pesados e tiveram fragmentos coletados em diversas regiões anatômicas. Procedeu-se a mensuração da área total da superfície interna por meio de captura e análise de imagens digitalizadas. A superfície absortiva do ruminoretículo (7,7 m²) foi maior (P<0,001) do que a do omaso (2,1 m²). A relação superfície/digesta, entretanto, foi maior (P=0,07) no omaso (0,22 m²/Kg) que no ruminoretículo (0,12m²/Kg), representando uma área superficial 83,3% maior no omaso por unidade de digesta. A área de um fragmento do saco ventral do rúmen apresentou correlação positiva (0,84) com a área total da superfície do rúmen, indicando ser possível a estimativa da área total do órgão por meio de biópsia. A superfície absortiva dos compartimentos parece ser compatível com a magnitude de absorção, entretanto, estudos que comparem a taxa fracional de absorção de AGV entre os compartimentos devem ser realizados

MORPHOLOGICAL RESPONSE OF THE RUMINAL AND OMASAL MUCOSAE TO THE VARIATION IN DIET ENERGY

ABSTRACT The absorption capacity of the rumen responds positively to direct and indirect stimulation by VFA; there is also evidence that the wall of the omasum also responds to these stimuli. To further investigate these reports, we compared the tissue morphologies of rumen and omasum biopsy samples. Four cows surgically fitted with ruminal cannulas were sequentially fed two diets. These diets included corn silage (S) and a combination of corn silage and commercial concentrate (CS). The animals were fed S for the first 18 days of the experiment, followed by CS for the next 18 days. They were then fasted for 72 h (F), and then had at least 18 days of re-feeding. Biopsy samples were taken from the blade of the omasum and the ventral sac of the rumen at different time points during each diet: samples were taken from S-diet animals at day 18; CS, at days 4 and 18; F, at the end of the 72 h; and re-fed animals, at days 4, 12, and 18. The mitotic index of the basal layers of the ruminal and omasal epithelia and the VFA concentration in the rumen were higher after 4 days of CS diet. There was a positive correlation between the mitotic indices of the rumen and omasum. The width of the ruminal papillae varied with different diets, and was highest on day 18 of the CS diet. Our results indicate that stimulation of cell division due to increased dietary energy simultaneously affected both compartments of the stomach

OMASAL MORPHOLOGY OF DAIRY COWS FED WITH HIGH OR LOW GRAIN CONTENT DIET PRIOR PARTURITION

ABSTRACT Little is known about the morphological response of the omasum in dairy cows that consume a high-energy diet pre-partum. The aim of this study was to investigate whether a transitional diet with high grain content is able to induce changes in omasum morphology. Six weeks before the expected calving, four Holstein cows were fed a standardization diet, and four weeks before delivery, the cows were fed a diet with high grain content (HGC) or low (LGC) grain content. After calving, all of the cows were fed a high energy lactation diet. The cows that were fed the HGC diet pre-partum had higher dry matter and nutrient intake than the cows that were fed the LGC diet. The mitotic index of the omasum epithelium was higher than the mitotic index in the rumen, but apparently the response to the diet stimuli was slower. In the cows that were fed the HGC diet, the omasum papillae were taller one week before parturition and two weeks post-partum. Cows that were fed the HGC diet had a thinner epithelium due to thinner non-keratinized layers of the omasum epithelium. We conclude that the omasum mucosa of dairy cows responds to the stimuli of a pre-partum HGC diet, which was indicated by the greater height of the omasum papillae and by the reduced thickness of the omasum epithelium. It seems that the mitotic index responds a little more slowly, but the response to the diet stimuli is stronger in the omasum epithelium than in the rumen

Potential of wet blue leather waste for ruminant feeding

The objective of this study was to find an alternative to minimize environmental contamination by leather waste using it as ruminant feed. The wet blue leather wastes (WB) without chrome extraction were compared with the leather wastes in which the chrome was extracted (CE). Both materials had 99.7% of dry matter (DM), but the crude protein level was higher (90.4%) in CE than in WB (74.3%). In situ effective ruminal degradability of DM was 59.7% and it was 63.1% for CP in CE. The WB did not suffer degradation in the rumen. In vitro abomasal digestibility of CE was 100%. The percentage of degradation per hour was higher for CE (8.2%) than for WB (0.08%). The mineral content was higher in wet blue leather wastes (10.4%) than in CE (0.4%) reflecting the chrome level and demonstrating that the removal process of this mineral is efficient. The use in animal feed is presented as a viable alternative for the disposal of waste and scrap generated by the leather tanning industry and treated by the extraction method, thus minimizing environmental contamination and providing a source of protein for animal feed

Determination of volatile fatty acids clearance in intact ruminal digesta

Abstract Cannulated cows were allocated to a cross-over design to evaluate the technique for determination of volatile fatty acid (VFA) clearance by infusion of marker solution into intact ruminal digesta, and verify the technique sensibility to the variation in the diet. Animals received diet of forage or forage plus concentrate and infusion of valeric acid and Cr-EDTA solution into intact or evacuated ruminal digesta. The total fractional rate of VFA clearance (FRVFAC) was estimated by the exponential decay of valerate over time. The passage FRVFAC to the omasum was assumed as the decay in ruminal Cr concentration and the absorption FRVFAC was estimated by the difference. The total FRVFAC and absorption did not differ between techniques. The passage FRVFAC, however, was lower when the marker solution was added into the evacuated digesta, probably reflecting the destabilization of the rumen environment during the evacuation and the largest volume of fluid observed in animals with evacuated digesta. In conclusion, the infusion of marker solution into intact digesta with homogenization performed by ruminal motility could be usable for the VFA ruminal clearance determination since it seems to cause lesser disturbance in the ruminal environment.Resumo Bovinos canulados foram alocados em um delineamento cruzado para avaliar a técnica de determinação do clearance de ácidos graxos voláteis (VFA) por infusão de solução marcadora na digesta ruminal intacta, e verificado a sensibilidade da técnica à variação na dieta. Os animais receberam dieta de forragem ou forragem juntamente com concentrado e infusão de ácido valérico e solução de Cr-EDTA na digesta ruminal intacta ou evacuada. A taxa fracional total de depuração de AGV (FRVFAC) foi estimada pelo decaimento exponencial do valerato ao longo do tempo. A passagem FRVFAC para o omaso foi assumida como o decaimento na concentração ruminal de Cr e a absorção FRVFAC foi estimada pela diferença. A FRVFAC total e a absorção não diferiram entre as técnicas. A passagem FRVFAC, entretanto, foi menor quando a solução marcadora foi adicionada na digesta evacuada, provavelmente refletindo a desestabilização do ambiente ruminal durante a evacuação e o maior volume de líquido observado em animais com digesta evacuada. Em conclusão, a infusão da solução marcadora na digesta intacta com homogeneização realizada pela motilidade ruminal poderia ser utilizada para a determinação da depuração ruminal de VFA, uma vez que parece causar menor distúrbio no ambiente ruminal.Resumen Los bovinos canulados fueron asignados en un delineamiento cruzado para evaluar la técnica de determinación del clearance de ácidos grasos volátiles (VFA) por infusión de solución marcadora en la digesta ruminal intacta, y verificado la sensibilidad de la técnica a la variación en la dieta. Los animales recibieron dieta de forraje o forraje junto con concentrado e infusión de ácido valérico y solución de Cr-EDTA en la digesta ruminal intacta o evacuada. La tasa fraccional total de depuración de AGV (FRVFAC) fue estimada por el decaimiento exponencial del valerato a lo largo del tiempo. El pasaje FRVFAC para el omaso fue asumido como el decaimiento en la concentración ruminal de Cr y la absorción FRVFAC fue estimada por la diferencia. La FRVFAC total y la absorción no difirieron entre las técnicas. El paso FRVFAC, sin embargo, fue menor cuando la solución marcadora fue agregada en la digestión evacuada, probablemente reflejando la desestabilización del ambiente ruminal durante la evacuación y el mayor volumen de líquido observado en animales con digestión evacuada. En conclusión, la infusión de la solución marcadora en la digesta intacta con homogeneización realizada por la motilidad ruminal podría ser utilizada para la determinación de la depuración ruminal de la VFA, ya que parece causar menor disturbio en el ambiente ruminal

Absorption and metabolism of volatile fatty acids by rumen and omasum Absorção e metabolismo de ácidos graxos voláteis pelo rúmen e omaso

Volatile fatty acids (VFA) absorption and metabolic capacity of rumen and omasum were compared, in vitro. Fragments of rumen wall and omasum laminae were taken from eight adult crossbred bovines. An isolated fragment of the mucosa was fitted in a tissue diffusion chamber. Valeric acid and CrEDTA were added to ruminal fluid and placed on the mucosal side and buffer solution was placed on the serosal side. Fractional absorption rates were measured by exponential VFA:Cr ratio decay over time. Metabolism rate was determined as the difference between VFA absorbed and VFA which appeared on the serosal side over time. Mitotic index was higher in omasum (0.52%) than in rumen epithelium (0.28%). VFA fractional absorption rate was higher in omasum (4.6%/h.cm²) than in rumen (0.4%/h.cm²). Acetate, propionate, butyrate, and valerate showed similar fractional absorption rates in both fragments. Percentage of metabolized acetate and propionate was lower than butyrate and valerate in both stomach compartments. In the rumen, individual VFA metabolism rates were similar (mean of 7.7 , but in the omasum, valerate (90.0 was more metabolized than butyrate (59.6 propionate (69.8 and acetate (51.7 . Correlation between VFA metabolism and mitotic index was positive in the rumen and in the omasum. In conclusion, VFA metabolism and absorption potential per surface of the omasum is higher than that of the rumen. Variations on rumen and omasum absorption capacities occur in the same way, and there are indications that factors capable of stimulating rumen wall proliferation are similarly capable of stimulating omasum walls.<br>A capacidade de absorção e metabolismo de ácidos graxos voláteis (AGV) pelo rúmen e omaso foi comparada, in vitro. Fragmentos da parede do rúmen e das lâminas do omaso foram coletados de oito bovinos mestiços adultos. Um fragmento isolado da mucosa foi colocado em uma câmara de difusão tecidual. Ácido valérico e CrEDTA foram adicionados ao fluido ruminal e colocados no compartimento da câmara voltados para a mucosa e uma solução tampão foi colocada no compartimento voltado para a serosa. As taxas fracionais de absorção foram medidas pela queda exponencial da relação VFA:Cr ao longo do tempo. A taxa de metabolismo foi determinada pela diferença entre a quantidade de AGV absorvida e a detectada no compartimento serosal da câmara. O índice mitótico foi mais alto no epitélio do omaso (0.52%) do que no do rúmen (0.28%), bem como a taxa fracional de absorção, 4.6%/h.cm² e 0.4%/h.cm², respectivamente. Acetato, propionato, butirato e valerato tiveram taxas fracionais de absorções similares em ambos os compartimentos. As porcentagens do acetato e do propionato metabolizados foram mais baixas do que a do butirato e valerato em ambos os compartimentos. No rúmen, a taxa metabólica individual dos AGV foi similar (média de 7.7 mas, no omaso, o valerato (90.0 foi mais metabolizado do que o butirato (59.6 propionato (69.8 e acetato (51.7 . A correlação entre o metabolismo de AGV e o índice mitótico foi positiva no rúmen e no omaso. Concluiu-se que o potencial de metabolismo e de absorção de AGV por unidade de área do omaso é mais alto do que o do rúmen. A variação da capacidade de absorção do rúmen e do omaso ocorre na mesma direção e existem indícios de que os fatores capazes de estimular a proliferação da parede do rúmen são também capazes de estimular a parede do omaso