Abstract The objective of this study was to evaluate the effects of different sealing strategies on aerobic stability and feed value of corn silage supplied to finishing lambs. The treatments were set up according to the silo sealing strategy: BP (black polyethylene film), BP + Bagasse (black polyethylene film + sugarcane bagasse) and BP + Silostop (Silostop® Orange oxygen barrier film + black polyethylene film). Six lambs per treatment were used, totaling 18 animals in an experimental period of 63 days. The silage from LP treatment presented the highest aerobic stability, however with lower dry matter digestibility coefficients. No significant differences were detected among treatments for intake and performance of lambs. But for final body weight, weight gain, daily average gain, feed efficiency and dry matter intake, the best results, in absolute value, were found for lambs fed with silage from LP + Bagasse treatment. The silage sealed exclusively with black polyethylene film showed greater aerobic stability. The different sealing strategies used in this experiment did not influence the performance of finishing Dorper x Santa Inês lambs.

Resumo Objetivou-se avaliar os efeitos de differentes estratégias de vedação sobre a estabilidade aeróbia e o valor alimentício da silagem de milho fornecida para cordeiros em terminação. Os tratamentos foram definidos de acordo com a estratégia de vedação do silo: LP (lona preta de polietileno), LP + Bagaço (lona preta de polietileno + bagaço de cana) e LP + Silostop (lona preta de polietileno + filme de barreira de oxigênio Silostop® Orange). Foram utilizados seis cordeiros por tratamento, totalizando 18 animais, em um período experimental de 63 dias. A silagem do tratamento LP apresentou maior estabilidade aeróbia, porém proporcionou menor coeficiente de digestibilidade da matéria seca. Não foi observada diferença significativa entre os tratamentos para o consumo e desempenho dos cordeiros. Todavia, para o peso corporal final, ganho de peso, ganho médio diário, eficiência alimentar e consumo de matéria seca, os melhores resultados, em valor absoluto, foram encontrados para os cordeiros alimentados com dieta à base da silagem coberta com LP + Bagaço. A silagem vedada exclusivamente com a lona preta de polietileno apresentou maior estabilidade aeróbia. As diferentes estratégias de vedação utilizadas nesse experimento não influenciaram o desempenho de cordeiros Dorper x Santa Inês em terminação.

ABSTRACT. The aim of this study was to relate the occurrence of visible losses in silage (effluent, spoiled top-layer and during feedout) with silage-making practices, physical and chemical characteristics of silage, and milk composition in Brazilian dairy herds. One-hundred and eight silos from 95 farms, in the State of Parana, were visited for data collection. Data were analyzed by Fisher's Exact and Pearson Correlation Test. Effluent loss was higher in silages with the lowest dry matter content. Using unwalled clamp (drive-over piles) silos, neglecting a protection over the plastic film, and unloading silage with a bucket increased the occurrence of top spoilage. Feedout losses were higher in farms where: the crop was harvested with self-propelled machines; the particle size was larger, and the silage density was lower. There was no relationship between visible losses and silage composition or milk composition, except for milk fat content that, unexpectedly, there was a positive correlation with spoiled silage in the top-layer. Silage losses are reduced by adopting good practices during silage production and feedout.

ABSTRACT The objective of this study was to review the effect of ensiling on the feeding value of flint corn grain and performance of feedlot cattle. In this meta-analysis, ensiled corn grain included both high-moisture corn and rehydrated corn grain. The criteria for a publication enter in the database were: diet was offered as a total mixed ration, diet contained at least 300 g/kg dry matter (DM) of ensiled or dry corn grain, and ensiled grain contained a minimum of 280 g/kg of moisture. The final dataset included 21 paired comparisons from eight publications, from 2002 to 2019. A sub dataset of digestibility trials contained six paired comparisons for starch digestibility and five paired comparisons for DM digestibility. The outcomes were compared using the Mixed procedure of SAS, including a random effect of comparison within study (paired comparison). Ensiling corn grain increased total-tract digestibility of DM (+4.59%) and starch (+3.33%), decreased DM intake by 14.1% (10.3 and 8.85 kg/d for dry and ensiled, respectively) and metabolizable energy intake by 4.39%, but did not affect average daily gain (1.61 and 1.58 kg/d for dry and ensiled corn, respectively). Therefore, ensiling corn grain increased feed efficiency by 18.3% (0.164 and 0.194, for dry and ensiled, respectively). The feeding value was on average 25.7% higher for ensiled corn grain compared with dry corn grain. Ensiling is an efficient strategy to improve the caloric value of flint corn grain for finishing cattle.

ABSTRACT. The experiment was carried out to evaluate total and partial digestibility of nutrients, the efficiency of microbial protein synthesis, in situ degradability and ruminal parameters in cattle fed diets with rehydrated corn grain silages, okara or soybean grain. Three Holstein steers were distributed in a 3 x 3 Latin square design. The treatments evaluated were: SO (corn grain silage + 30% okara), SSG (corn grain silage + 20% soybean grain) and CG (dry corn grains). The ruminal digestibility of non-fiber carbohydrates (NFC) increased in SO (88.34%) and SSG treatments (87.87%), compared to the CG treatment (63.48%). The minimum ruminal pH value was 6.01, observed 4.13 hours after feeding a diet with SO. The highest ammonia-N contents were 15.25 and 15.07 mg dL-1 observed in SSG and SO, respectively, 2.45 and 2.61 hours after feeding. Treatments SO and SSG showed higher fraction A content (readily degradable fraction) and C (constant rate of degradability of fraction B). The effective degradability (ED) of dry matter (DM) was higher for the diets SO and DE of CP was higher for treatments SO and SSG. SSG and SO result in better utilization of nutrients by animals.

ABSTRACT We ensiled different levels of okara and ground corn to evaluate the effects on the fermentative pattern, aerobic stability, and chemical composition of resulting silages. The experimental design was completely randomized with four replicates per treatment. The okara levels were (dry matter basis): control (without okara) and 200, 300, 400, and 500 g kg−1 okara, with four replicates per treatment. Control silage did not contain okara, but water was added to adjust the moisture content (400 g kg−1 as fed). Mixtures were ensiled in lab-scale silos and stored for 150 days. Compared with the control silage, okara inclusion linearly increased crude protein (from 89.1 to 251 g kg−1 DM), ether extract (from 39.6 to 136 g kg−1 DM), neutral detergent fiber (from 79.9 to 174 g kg−1 DM), acid detergent fiber (from 22.4 to 119 g kg−1 DM), and ash (from 12.2 to 32.4 g kg−1 DM), whereas decreased dry matter content and in vitro dry matter digestibility (from 830 to 730 g kg−1 DM). The use of okara linearly increased lactic acid concentration but also intensified secondary fermentation. On the other hand, aerobic stability of silages increased due to okara inclusion because of the higher amount of short-chain fatty acids, such as butyric and acetic acids, which accumulated during fermentation. Okara inclusion in corn grain silage must be conditioned to the dry matter content at ensiling, but must not exceed 200 g kg−1 on dry matter basis.

ABSTRACT Our objective was to determine the effects of maturity and storage length on the fermentation pattern, ruminal disappearance of nutrients, and recovery of digestible nutrients in flint corn (Zea mays L.) silage harvested with a pull-type machine without a kernel processor. Corn plants were harvested at 300 g kg−1 DM (low dry matter, LDM) or 400 g kg−1 DM (high dry matter, HDM) and stored for 0, 7, 14, 30, 60, 90, 120, and 180 d in laboratory silos. Corn harvested at HDM had a higher proportion of long particles (>19 mm), more intact kernels, and lower kernel processing score. There was an interaction between maturity and storage length for several fermentation end-products, DM recovery, ruminal disappearance of nutrients, and recovery of digestible DM. Overall, the concentrations of fermentation end-products were higher in LDM than in HDM silage. The DM recovery decreased over time, mainly for LDM silage. Ruminal disappearance of nutrients (starch, CP, and DM) increased with storage length, with greater values for LDM silage at shorter storage, but closer values among LDM and HDM at longer storage periods. The recovery of digestible DM (DM recovery × ruminal disappearance) slightly increased in LDM silage up to 26 d of fermentation, but it markedly increased in HDM silage, mainly up to 60 d of storage. Storing for longer periods is a strategy to partially offset the negative impact of maturity on the digestibility of flint corn silage harvested with pull-type machines without kernel processor.

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.

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.

ABSTRACT The objective was to evaluate the effects of corn silage supplemented with 1-propanol or inoculated with L. buchneri on the ruminal fermentation profile, digestibility, and production traits of lactating Holstein cows. Whole-corn plants were harvested at 350 g/kg dry matter (DM) and packed in nine bag silos (13 t/silo). At ensiling, two treatments were applied: control (no additive; six silos) and L. buchneri inoculation with 1 × 105 cfu/g (three silos). Feeding started after 247 days of storage; one L. buchneri and two control silos were opened in each experimental period. Twenty-one multiparous Holstein cows (~33 kg/day of milk) were allocated to seven balanced 3 × 3 Latin squares with 21-day periods (14 days of adaptation). The experimental diets contained (DM basis): 80 g/kg cottonseed, 95 g/kg citrus pulp, 180 g/kg soybean meal, 90 g/kg corn grain (ground), 25 g/kg minerals and vitamins premix, and 530 g/kg of corn silage. Source of corn silage was the only difference between experimental treatments: control, L. buchneri, or control silage supplemented with 1-propanol (10 g/kg of diet DM). The 1-propanol was dissolved in water (1:1) and sprinkled onto the ration during mixing, immediately before each feeding. Dry matter intake, nutrient digestibility, milk yield, and composition were not affected by treatments. Cows fed 1-propanol had greater concentrations of 1-propanol in the rumen fluid, higher concentration of glucose, and lower concentration of non-esterified fatty acids in blood plasma. Corn silage inoculated with L. buchneri at 1 × 105 cfu/g does not affect silage fermentation, ruminal fermentation profile, or milk production. Supplementation of 1-propanol at 10 g/kg affects the ruminal fermentation profile without affecting feed intake and milk production of mid-lactating dairy cows.

RESUMO Pouco é conhecido a respeito da resposta morfológica do omaso de vacas leiteiras que consomem dieta alta em energia no pré-parto. Este estudo visou investigar se a dieta de transição com alto teor de grãos induz mudanças na morfologia do omaso. Seis semanas antes do parto esperado, quatro vacas Holandesas foram alimentadas com uma dieta de padronização e a partir de quatro semanas antes foram alimentadas com dieta com alto (ATG) ou baixo (BTG) teor de grãos. Após o parto, todas as vacas foram alimentadas com dieta lactacional de alta energia. As vacas que foram alimentadas com ATG antes do parto tiveram maior ingestão de matéria seca e de nutrientes do que as vacas que foram alimentadas com BTG. O índice mitótico (IM) do epitélio do omaso foi mais alto do que o do rúmen, mas aparentemente a resposta ao estímulo da dieta foi mais lenta. As papilas do omaso nas vacas que foram alimentadas com ATG foram mais altas uma semana antes e duas semanas após o parto. As vacas que foram alimentadas com ATG tiveram o epitélio do omaso menos espesso devido à menor espessura das camadas não queratinizadas. Concluímos que a mucosa do omaso de vacas leiteiras responde ao estímulo da dieta com ATG fornecida antes do parto, indicado pela maior altura das papilas e menor espessura do epitélio. Parece que o IM responde mais lentamente, porém mais fortemente ao estímulo da dieta no omaso do que no rúmen.

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.

RESUMO A capacidade de absorção do rúmen responde, positivamente, a estímulos diretos e indiretos dos AGV e existem evidências de que a parede do omaso também responde a esses estímulos. Sendo assim, comparamos a morfologia do rúmen e omaso obtidos por biopsia. Quatro vacas, implantadas com uma cânula ruminal, foram alimentadas, sequencialmente, com duas dietas. Uma dieta consistia de silagem de milho (S), sendo a outra composta de silagem de milho e concentrado comercial (CS). Os animais foram alimentados com S por 18 dias de experimento, seguido por CS para os próximos 18 dias. Eles foram, em seguida, mantidos em jejum durante 72 h (F) e, em seguida, foram realimentados por 18 dias. Biópsias da lâmina do omaso e do saco ventral do rúmen foram obtidas em diferentes momentos para cada dieta: S, no dia 18; CS, nos dias 4 e 18; F, no final das 72 h e realimentação, nos dias 4, 12 e 18. O índice mitótico (IM) da camada basal do epitélio ruminal e omaso e a concentração de AGV no rúmen foram superiores após 4 dias de CS. Houve uma correlação positiva entre os índices de mitose do rúmen e omaso. A largura das papilas ruminais variou com diferentes dietas, e foi maior no dia 18 do regime alimentar CS. Os nossos resultados indicam que a estimulação da divisão das células, em razão do aumento da energia da dieta tiveram efeitos simultâneos em ambos os compartimentos do estômago.

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.

The objective of this study was to evaluate the effect of covering methods on the nutritive value of corn silage and performance of dairy cows. Whole-plant corn was harvested at 340 g/kg of dry matter (DM) and ensiled for 135 d in horizontal silos covered with one of the following methods: oxygen barrier film (45-µm thick) + white-on-black polyethylene film (200-µm thick) over the oxygen barrier film (OB+WB); white-on-black polyethylene film (200-µm thick) (WB); black polyethylene film (200-µm thick) (B); or recycled black polyethylene film (200-µm thick) covered with a layer of 10 cm of sugarcane bagasse (RB+SB). Nutrient composition, fermentation profile, and yeast and mold counts in edible silages were similar across treatments. Silage temperature during the storage period was 24.6, 28.7, 28.4 and 33.1 °C for RB+SB, OB+WB, WB and B, respectively, and the proportion of spoiled silage ranged from 28.7 (for the RB+SB treatment) to 74.2 g/kg DM (for the B treatment). Dry matter intake was similar across treatments and averaged 21.9 kg/d. Milk production was higher for cows fed corn silage covered with RB+SB (34.4 kg/d) compared with those fed corn silage covered with B (30.4 kg/d), resulting in higher feed efficiency for RB+SB treatment. Silages covered with OB+WB and WB had intermediate values. In vivo digestibility of organic matter was higher for cows fed corn silage covered with RB+SB compared with those fed corn silage covered with WB and B, but were similar to those fed corn silage covered with OB+WB. The utilization of oxygen barrier films and the protection of polyethylene film with sugarcane bagasse are effective strategies to increase the recovery of digestible nutrients and, consequently, to enhance production efficiency of lactating dairy cows.

Lactobacillus buchneri 40788 and the fibrolytic enzymes β-glucanase and xylanase were applied to chopped sugarcane to study their effects on the nutritive value of silage. Sugarcane was mechanically harvested after 14 mo of growth and treated without (control) or with L. buchneri at a theoretical application rate of 5 × 10(4) cfu/g, 1 × 10(5) cfu/g, or 1 × 10(5) cfu/g plus enzymes. Forage was packed into farm-scale bag silos (40 t/silo) and stored for 92 d. Fifty-six bulls (32 Nellore and 24 Charolais × Nellore) were housed in 20 collective pens and fed diets comprising (dry matter [DM] basis) 458 g/kg sugarcane silage and 542 g/kg concentrates for an 84-d period. Treated silages had higher concentrations of acetic acid and lower concentrations of ethanol. Total mixed rations (TMR) containing inoculated silages exhibited significantly lower neutral detergent fiber (NDF) concentration and, consequently, higher in vitro DM digestibility (IVDMD). Thus, animals fed TMR containing treated silages spent less time chewing per day and per kilogram of DM intake (DMI), even at higher DMI levels. Nonetheless, the intake of NDF was similar across treatments (0.77 to 0.79 kg/100 kg BW) but markedly lower than the value reported for traditional forages. Average daily gain was significantly greater for animals fed TMR based on inoculated silages due to the higher DMI (14% on average) and the higher energy content of the diets, as indicated by the higher feed efficiency (12% on average). The dose of inoculants used and the addition of fibrolytic enzymes had no significant effects on silage parameters or animal performance. Therefore, inoculation of L. buchneri during sugarcane ensilage can alter the fermentation pattern by increasing acetic acid yield, reducing silage nutrient losses, and improving feed efficiency by bulls.

O presente ensaio experimental avaliou inoculação de aditivo composto por Lactobacillus plantarum, L. brevis e Enterococcus faecium em relação à silagem sem aditivo (Controle). As silagens foram confeccionadas em silos experimentais e armazenadas por 30, 60, 90 ou 120 dias antes da abertura dos silos. Foi avaliada a composição bromatológica da forragem antes e após a ensilagem, e as perdas fermentativas durante o processo. O aditivo avaliado reduziu (p <0,01) a produção de efluente (11,4 kg t-1) em relação à silagem Controle (14,0 kg t-1). A inoculação com aditivo elevou os teores de Fibra em Detergente Neutro (FDN) e Fibra em Detergente Ácido (FDA), de 45,6 e 24,5% para 47,0 e 25,1% para as silagens controle e com aditivo, respectivamente. Os tempos de armazenamento influenciaram (p < 0,01) a produção de efluente, a perda de matéria seca (PMS), os teores de FDN e FDA, e o pH das silagens. As silagens apresentaram bons parâmetros de qualidade e as perdas fermentativas observadas foram bastante reduzidas, dadas as adequadas características da cultura do milho para a ensilagem.

This trial evaluated the addition of Lactobacillus plantarum, L. brevis and Enterococcus faecium combo additive against a control treatment. The silages were made in laboratory silos that were stored for 30, 60, 90 or 120 days before opening. We evaluated the chemical composition of the forage before and after ensiling and the fermentative losses of silages. The additive decreased (p < 0.01) effluent production (11.4 kg ton-1) compared to control silage (14.0 kg ton-1), but it increased (p < 0.01) the Neutral Detergent Fiber (NDF) and Acid Detergent Fiber (ADF) from 45.6% and 24.5% to 47.0 and 25.1% for control and additive silages, respectively. The storage periods affected (p < 0.01) effluent production, Dry Matter Losses (DML), NDF, ADF and pH variables. Fermentative losses were very low because of the adequate characteristics of maize for ensilage.

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.

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.

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.