The present study was conducted to evaluate the effect of lipids with different fatty acid profiles on the intake, performance, and enteric CH4 emission of Nellore steers. A total of 45 Nellore animals with an average initial BW of 419 ± 11 kg (at 15 ± 2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a DM basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without additional fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The lipid source significantly affected (P < 0.05) nutrient intake. The greatest intakes of DM, OM, and CP were observed in the animals that were fed the WF or PF diets, and the lowest intakes were observed in the animals that were fed the PO diet. Intake of NDF decreased (P < 0.05) with the addition of PO. Enteric methane emission (g/kg DMI) was reduced by an average of 30% when the animals were fed diets containing WS, LO, and PO (P < 0.05), and these diets caused a larger reduction in the energy loss in the form of methane compared to those without added fat and with added PF (3.3 vs. 4.7%). The different fatty acid profiles did not affect the backfat thickness or the loin eye area of the animals (P > 0.05). However, animals fed PO displayed lower daily weight gain (0.36 kg/d), feed efficiency (0.08 kg ADG/kg DM), HCW (245 kg), and hot yield percentage (52.6%) compared to animals that were fed the other diets. Therefore, PO compared to the other lipid sources used in this study reduces intake, performance, feed efficiency, and carcass yield. Therefore, PO is not suggested for feedlot-finished animals.

The present study was conducted to determine the effect of lipid sources with different fatty acid profiles on nutrient digestion and ruminal fermentation. Ten rumen and duodenal fistulated Nellore steers (268 body weight±27 kg) were distributed in a duplicated 5×5 Latin square. Dietary treatments were as follows: without fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF; Lactoplus), and whole soybeans (WS). The roughage feed was corn silage (600 g/kg on a dry matter [DM] basis) plus concentrate (400 g/kg on a DM basis). The higher intake of DM and organic matter (OM) (p<0.001) was found in animals on the diet with PF and WF (around 4.38 and 4.20 kg/d, respectively). Treatments with PO and LO decreased by around 10% the total digestibility of DM and OM (p<0.05). The addition of LO decreased by around 22.3% the neutral detergent fiber digestibility (p = 0.047) compared with other diets. The higher microbial protein synthesis was found in animals on the diet with LO and WS (33 g N/kg OM apparently digested in the rumen; p = 0.040). The highest C18:0 and linolenic acid intakes occurred in animals fed LO (p<0.001), and the highest intake of oleic (p = 0.002) and C16 acids (p = 0.022) occurred with the diets with LO and PF. Diet with PF decreased biohydrogenation extent (p = 0.05) of C18:1 n9,c, C18:2 n6,c, and total unsaturated fatty acids (UFA; around 20%, 7%, and 13%, respectively). The diet with PF and WF increased the concentration of NH3-N (p<0.001); however, the diet did not change volatile fatty acids (p>0.05), such as the molar percentage of acetate, propionate, butyrate and the acetate:propionate ratio. Treatments PO, LO and with WS decreased by around 50% the concentration of protozoa (p<0.001). Diets with some type of protection (PF and WS) decreased the effects of lipid on ruminal fermentation and presented similar outflow of benefit UFA as LO.

-The objective of this study was to evaluate the effects of supplementation with different sources of energy and nitrogenous compounds on the in vitro growth and production of bacteriocin of lactic acid bacteria. Incubations were performed by using ruminal fluid from a rumen-fistulated Holstein-Zebu steer. The animal was kept on a Brachiaria decumbens pasture receiving 200 g/day of supplemental crude protein. Substrates and inoculum were placed in glass flasks considering eight treatments: cellulose, cellulose and casein, cellulose and soy peptone, cellulose and urea, starch, starch and casein, starch and soy peptone and starch and urea. Successive incubations were conducted to select microorganisms according to the energy sources and nitrogenous compounds. Starch favoured growth of lactic acid bacteria when compared to cellulose. Supplementation with true protein (soy peptone and casein) stimulated the growth of these bacteria when compared to the control (without supplementation with nitrogenous compounds). The addition of urea did not stimulate the growth of lactic acid bacteria. No antimicrobial activity was detected from colonies of isolated lactic acid bacteria. Sources of true protein increase the competition between non-structural and structural carbohydrates fermenting bacteria.

The present study was conducted to determine the effects of lipid sources with different fatty acids profile on meat fatty acids profile and beef quality traits of Nellore. A total of 45 Nellore animals with an average initial body weight of 419±11 kg (at 15±2 mo) were distributed in a completely randomized design consisting of 5 treatments and 9 replicates. The roughage feed was maize silage (600 g/kg on a dry matter [DM] basis) plus concentrate (400 g/kg on a DM basis). The dietary treatments were as follows: without fat (WF), palm oil (PO), linseed oil (LO), protected fat (PF), and soybean grains (SG). No effects of lipid sources were observed (p>0.05) on beef color, pH, water-holding capacity, and sarcomere length. Beef from cattle fed PO had greater shear-force values (p<0.05) compared to beef from cattle fed WF. Deposition of main unsaturated fatty acids (oleic, linoleic, and linolenic) was greater in treatments WF, SG, and LO, respectively, while the values of conjugated linoleic acid (CLA) were greater when animals were fed LO. The inclusion of LO in the diet enhances the concentration of CLA in longissimus muscle and subcutaneous fat besides improving the atherogenicity index and elongase activity. As such, LO can be used with the aim to improve the quality of beef from confined Nellore cattle. Conversely, the use of PO is not recommended since it may increase the concentration of undesirable unsaturated fatty acids in muscle and subcutaneous fat, shear-force and the atherogenicity index.

RESUMO -Objetivou-se avaliar os efeitos de diferentes formas químicas de compostos nitrogenados (proteicos e não-proteicos) e de carboidratos (amiláceos e fibra solúvel) sobre o consumo, a digestibilidade e a síntese ruminal de proteína microbiana em bovinos sob suplementação durante o período das águas. Foram utilizados cinco novilhos mestiços Holandês × Zebu, com peso vivo (PV) médio inicial de 211 ± 35 kg, fistulados no rúmen e abomaso. Os tratamentos foram: controle (somente pasto); e suplementos formulados à base de milho + farelo de soja; milho + ureia; polpa cítrica + farelo de soja; e polpa cítrica + ureia. Os suplementos foram balanceados para apresentar 30% de proteína bruta (PB), com base na matéria seca (MS), e fornecidos na quantidade de 3 g/kg PV. O experimento foi conduzido segundo delineamento em quadrado latino 5 × 5, em esquema fatorial 2 × 2 + 1, composto de duas fontes de compostos nitrogenados, duas fontes de carboidratos e tratamento controle. O consumo de pasto reduziu com o fornecimento de suplementos, com coeficiente médio de substituição de 2,11 g de MS de pasto/g de MS de suplemento. A suplementação não alterou os coeficientes de digestibilidade total e ruminação da MS nem o teor dietético de nutrientes digestíveis totais (NDT). Os animais sob suplementação apresentaram maiores coeficientes de digestibilidade total e ruminal da proteína bruta. A eficiência de síntese de proteína microbiana (EFSM), média de 123,1 g PB microbiana/kg de NDT, não foi alterada pela suplementação. Contudo, os animais sob suplementação com milho apresentaram maior EFSM em comparação aos animais sob suplementação com polpa cítrica (137,6 e 106,1 g PB microbiana/kg de NDT, respectivamente). A suplementação proteico-energética para bovinos mantidos em pastos tropicais durante o período das águas não causa benefícios nutricionais, o que reflete o alto coeficiente de substituição da forragem pelo suplemento.Palavras-chave: amido, fibra solúvel, suplementação proteico-energética, ureia Intake and digestibility in cattle under grazing during rainy season and supplemented with different sources of nitrogenous compounds and carbohydratesABSTRACT -The objective of this work was to evaluate the effects of different chemical forms of nitrogenous compounds (protein and non-protein) and carbohydrates (starch and soluble fiber) on intake, digestibility, and ruminal synthesis of microbial protein in cattle supplemented during rainy season. It was used five crossbred Holstein × Zebu steers, with average initial body weight of 211 ± 35 kg and fistulated in the rumen and abomasum. The treatments were: control (only pasture), and supplements based on corn + soybean meal; corn + urea, citrus pulp + soybean meal, and citrus pulp + urea. The supplements were balanced to present 30% of crude protein (CP), on dry matter (DM) basis, and provided at 3 g/kg BW. The experiment was carried out according to a 5 × 5 Latin square design in a 2 × 2 + 1 factorial arrangement, composed of two sources of nitrogenous compounds, two sources of car...

BackgroundForestomach fermentation in Australian marsupials such as wallabies and kangaroos, though analogous to rumen fermentation, results in lower methane emissions. Insights into hydrogenotrophy in these systems could help in devising strategies to reduce ruminal methanogenesis. Reductive acetogenesis may be a significant hydrogen sink in these systems and previous molecular analyses have revealed a novel diversity of putative acetogens in the tammar wallaby forestomach.ResultsMethanogen-inhibited enrichment cultures prepared from tammar wallaby forestomach contents consumed hydrogen and produced primarily acetate. Functional gene (formyltetrahydrofolate synthetase and acetyl-CoA synthase) analyses revealed a restricted diversity of Clostridiales species as the putative acetogens in the cultures. A new acetogen (growth on H2/CO2 with acetate as primary end product) designated isolate TWA4, was obtained from the cultures. Isolate TWA4 classified within the Lachnospiraceae and demonstrated >97% rrs identity to previously isolated kangaroo acetogens. Isolate TWA4 was a potent hydrogenotroph and demonstrated excellent mixotrophic growth (concomitant consumption of hydrogen during heterotrophic growth) with glycerol. Mixotrophic growth of isolate TWA4 on glycerol resulted in increased cell densities and acetate production compared to autotrophic growth. Co-cultures with an autotrophic methanogen Methanobrevibacter smithii revealed that isolate TWA4 performed reductive acetogenesis under high hydrogen concentration (>5 mM), but not at low concentrations. Under heterotrophic growth conditions, isolate TWA4 did not significantly stimulate methanogenesis in a co-culture with M. smithii contrary to the expectation for organisms growing fermentatively.ConclusionsThe unique properties of tammar wallaby acetogens might be contributing factors to reduced methanogen numbers and methane emissions from tammar wallaby forestomach fermentation, compared to ruminal fermentation. The macropod forestomach may be a useful source of acetogens for future strategies to reduce methane emissions from ruminants, particularly if these strategies also include some level of methane suppression and/or acetogen stimulation, for example by harnessing mixotrophic growth capabilitiesElectronic supplementary materialThe online version of this article (doi:10.1186/s12866-014-0314-3) contains supplementary material, which is available to authorized users.

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We evaluated the differences between the supplementation of urea in rumen and/or abomasum on forage digestion, nitrogen (N) metabolism, and urea kinetics in cattle fed a low-quality tropical forage. Five Nellore heifers were fitted with rumen and abomasum fistulas and assigned to a Latin square design. The treatments were: control, continuous infusion of urea in the abomasum (AC), continuous infusion of urea in the rumen, a pulse dose of urea in the rumen every 12 hours (PR), and a combination of PR and AC. The control exhibited the lowest (P<0.10) fecal and urinary N losses, which were, overall, increased by supplementation. The highest urinary N losses (P<0.10) was observed when urea was either totally or partially supplied as a ruminal pulse dose. The rumen N balance was negative for the control and when urea was totally supplied in the abomasum. The greatest microbial N production (P<0.10) was obtained when urea was partially or totally supplied in the abomasum. Urea supplementation increased (P<0.10) the amount of urea recycled to the gastrointestinal tract and the amount of urea-N returned to the ornithine cycle. The greatest (P<0.10) amounts of urea-N used for anabolism was observed when urea was totally and continuously infused in the abomasum. The continuous abomasal infusion also resulted in the highest (P<0.10) assimilation of microbial N from recycling. The continuous releasing of urea throughout day either in the rumen or abomasum is able to improve N accretion in the animal body, despite of mechanism responsible for that being different.