Tannin-Rich Plants as Natural Manipulators of Rumen Fermentation in the Livestock Industry.

Condensed tannins (CTs) are plant anti-herbivore compounds with antimicrobial activity that can be used in ruminant diets as ruminal microbiome manipulators. However, not all CTs from fodder legumes are bioactive due to their wide structural diversity. The aim of our study was to investigate the effect of 10 CT-containing plants (Flemingia macrophylla, Leucaena leucocephala, Stylosanthes guianensis, Gliricidia sepium, Cratylia argentea, Cajanus cajan, Desmodium ovalifolium, Macrotiloma axilare, D. paniculatum, and Lespedeza procumbens) on in vitro fermentation kinetics of Nelore beef cattle. Polyethylene glycol (PEG), a specific CT-binding agent, was added to neutralize condensed tannin. Tifton and alfalfa hay were used as controls lacking CT. The experimental layout included a randomized complete block with factorial design and four blocks. The data were subjected to analysis of variance followed by Duncan's test to determine differences (p < 0.05) among treatment means. The addition of PEG in browse incubations resulted in increased gas production, fermentation rate, short-chain fatty acid (SCFA) and N-NH3 release. Within our study, Lespedeza procumbens, Desmodium paniculatum, Leucaena leucocephala, Desmodium ovalifolium, and Flemingia macrophylla showed superior bioactivity compared to other species evaluated, suggesting a natural alternative for replacing ionophores to modify ruminal fermentation. Condensed tannins from L. pocumbens, D. paniculatum, L. leucocephala, D. ovalifolium, and F. macrophylla have the potential to modify rumen fermentation in beef cattle.

Acurácia, precisão e robustez de indicadores internos para predição da digestibilidade aparente total de matéria seca em equinos / Accuracy, precision and robustness of internal markers to predict total apparent digestibility of dry matter in horses

Objetivou-se com este trabalho avaliar a acurácia, a precisão e a robustez de diferentes indicadores internos na predição da digestibilidade aparente total da matéria seca (MS) para equinos. Foram utilizadas cinco éguas em manutenção, sem raça definida, com peso médio de 406±76,9kg e idade aproximada de 3,5 anos, alojadas em baias individuais. O experimento foi disposto em quadrado latino 5x5 (cinco dietas e cinco animais). Foram coletadas amostras dos alimentos fornecidos e das fezes para determinação bromatológica dos indicadores, e, para determinação das frações indigestíveis, foi realizada incubação in vitro. Os indicadores utilizados foram fibra em detergente neutro indigestível (FDNi), fibra em detergente ácido indigestível (FDAi), celulose indigestível (CELi) e lignina em detergente ácido indigestível (LDAi). Os indicadores estudados tiveram médias de taxa de recuperação (TR) muito próximas a 100%. Em razão de uma menor taxa de recuperação, os indicadores FDNi e LDAi apresentaram vieses negativos e diferentes de zero (P<0,05). Não houve diferença significativa entre os coeficientes angulares da regressão dos vieses dos indicadores e das variáveis consumo de MS, consumo de indicador e peso vivo (P>0,05). A FDAi parece ser o indicador mais indicado para se estabelecerem valores de referências para digestibilidade. Com base nos resultados, é possível sugerir que a CELi é o indicador mais indicado para se compararem fatores entre o mesmo estudo.(AU)

The aim of this study was to evaluate the accuracy, precision and robustness of different internal markers to predict total digestibility of dry matter for horses. Five no breed mares were used in maintenance, with an average weight of 406 ± 76.9kg and approximate age of 3.5 years, staying in individual stalls. The experiment was arranged in a 5x5 latin square design (five diets and five animals). Food samples were collected and the faeces provided for bromatological determining indicators and determining the indigestible fractions was carried out with in vitro incubation. The internal markers used were indigestible neutral detergent fiber (NDFi), indigestible acid detergent fiber (ADFi), indigestible cellulose (iCEL) and indigestible acid detergent lignin (LDAi). The indicators studied had mean recovery rate (TR) very close to 100%. Because they have a lower rate of recovery, NDFi and LDAi indicators have negative biases and differ from zero (P<0.05). There was no significant difference between the slopes of the regression of the biases of indicators and of variables dry matter intake, consumption indicator and body weight (P>0.05). The ADFi seems to be the most appropriate indicator to establish reference values for digestibility. The iCEL seems to be more appropriate to compare factors among the same study.(AU)

Effect of fiber digestibility and conservation method on feed intake and the ruminal ecosystem of growing steers.

Fiber digestibility is an important factor regulating DMI in ruminants. Additionally, the ensiling process can also affect digestibility and chemical composition of the forage. The objective of this study was to investigate effects of sugarcane NDF digestibility (NDFD) and conservation method on intake, rumen kinetics, and the ruminal ecosystem of steers. Eight ruminally cannulated Nellore steers (275±22 kg BW) were used in a replicated 4×4 Latin square design with a 2×2 factorial arrangement of treatments. Two sugarcane genotypes divergent for stalk NDFD were used: IAC86-2480 with high NDFD and SP91-1049 with low NDFD. Experimental diets were formulated with 40% sugarcane, either freshly cut or as silage, and 60% concentrate on a DM basis. Each experimental period lasted for 14 d, with the last 4 d used for determination of intake, ruminal evacuation, and ruminal fluid collection. The effect of fiber digestibility on DM and NDF intake was dependent on the forage conservation method (P=0.01). High NDFD increased (P<0.01) DMI only when sugarcane was offered as silage, having no effect (P=0.41) on DMI when offered as freshly cut. Conservation method had no effect on total ruminal mass, with only a tendency (P<0.10) for greater NDF and indigestible NDF ruminal mass in steers fed the low-NDFD genotype. The NDF turnover and passage rates were greater (P<0.05) for the genotype with high NDFD but only when offered as silage. Liquid turnover rate in the rumen was greater (P=0.02) for diets containing silage, with no effect of genotype (P=0.87). There was no effect of NDFD genotype on ruminal pH (P=0.77); however, diets containing sugarcane as silage increased (P<0.01) ruminal pH. Total concentration of short chain fatty acids (P=0.05) and proportions of propionate (P=0.01) were greater for diets containing fresh sugarcane. Diets with fresh sugarcane increased the ruminal population of Streptococcus bovis (P<0.01) and Ruminococcus albus (P=0.03). The relative population of R. albus was also greater (P=0.04) for diets containing the sugarcane genotype with high NDFD. Feeding diets containing the sugarcane genotype with high NDFD increased Fibrobacter succinogenes population but only when sugarcane was fed as freshly cut (P=0.02). Using sugarcane genotypes with high NDFD can increase intake and benefit fiber-degrading bacteria in the rumen.

Effect of sorghum tannins in sheep fed with high-concentrate diets / Efeito do tanino do sorgo em dietas de ovinos com alto concentrado

The aim of this study was to evaluate the nutritional value of three sorghum cultivars with different concentrations of condensed tannins in sheep diets. Six adult sheep (LW=56kg) with rumen and duodenal fistulas were assigned to experimental groups using two 3x3 Latin Square designs. The diets were formulated using three sorghum cultivars: LTC (low-tannin cultivar), MTC (medium-tannin cultivar) and HTC (high-tannin cultivar). Microbial nitrogen (MN) concentration in the duodenum was measured using a 15N trace technique. LTC, MTC and HTC diets presented values of 788, 722 and 747 (SE=20.6) g kg-1 for dry matter digestibility and 633, 535 and 530 (SE=35.8) g/kg for crude protein digestibility. The LTC diet was significantly different from the other diets (P<0.05). The nitrogen balance was 145.5, 94.8 and 83.8g kg-1 (SE=13.0) for LTC, MTC and HTC, respectively, with LTC showing greater nitrogen retention (P<0.05). Values obtained for MN in the digesta were 301, 364 and 469 (SE=30.6) g kg-1 for LTC, MTC and HTC, respectively, and there was no statistical difference (P>0.05) between the diets. The presence of condensed tannins in the sorghum interfered with the sheep's nitrogen retention; however, the microbial protein supply to the duodenum of the animals was not inhibited.

O objetivo do presente estudo foi avaliar o valor nutricional de três cultivares de sorgo com diferentes concentrações de tanino condensado em dietas de ovinos. Seis carneiros machos, adultos, castrados, canulados no rúmen e duodeno foram divididos em três grupos experimentais, em um delineamento em quadrado latino 3x3. Os tratamentos foram representados por três dietas experimentais contendo diferentes cultivares de grão de sorgo: LTC (cultivar com baixa concentração de tanino), MTC (cultivar com concentração média de tanino) e HTC (cultivar com concentração alta de tanino). As concentrações de nitrogênio de origem microbiana no duodeno (MN) foram mensuradas pela técnica de marcador isótopo estável 15N. As dietas LTC, MTC e HTC apresentaram valores de 788, 722 e 747g.kg-1 (EP=20,6) para a digestibilidade aparente da matéria seca e 633, 535 e 530g.kg-1 (EP=35,8) para a digestibilidade aparente da proteína bruta. A dieta LTC apresentou diferença significativa quando comparada às demais dietas para as avaliações de digestibilidade (P<0,05). Os valores encontrados para o balanço de nitrogênio foram de 145,5; 94,8 e 83,8g.kg-1 (EP=13,0) para LTC, MCT e LTC, respectivamente, sendo a dieta LTC a que apresentou maior retenção de nitrogênio (P<0,05). Os valores obtidos para MN na digesta foram de 301, 364 e 469 para LTC, MTC e HTC, respectivamente, e não apresentaram diferenças estatísticas (P>0,05). As diferentes concentrações de taninos condensados nos cultivares de sorgo resultaram em melhorias na digestibilidade e retenção de nitrogênio das dietas, entretanto o fluxo de proteína microbiana não foi inibido.

Impacto ambiental provocado pelo P em dietas suplementadas com enzima fitase e proteína ideal para suínos em crescimento: estudo do fluxo do P no metabolismo animal / Environmental impact provoked by P in diets supplemented with phytase enzyme and ideal protein for growing pigs: study of the P flow in the animal metabolism

Avaliou-se a possibilidade de redução da concentração do fósforo inorgânico em dietas formuladas para suínos de acordo com o conceito de proteína ideal, utilizando-se um modelo experimental para o estudo do fluxo do P no metabolismo animal. Utilizaram-se 20 suínos machos castrados em delineamento em blocos ao acaso, com cinco tratamentos e quatro repetições. Os tratamentos corresponderam à adição de 0, 250, 500, 750 e 1000UF/kg de dieta. No primeiro dia da fase experimental, os animais receberam, por via endovenosa, uma solução radioativa com 7,4MBq de 32P. No final do período experimental, os animais foram sacrificados e coletaram-se amostras de tecidos do músculo Longissimus dorsi, coração, fígado, rins e ossos. Pode-se reduzir em 50 por cento a suplementação de P em dietas para suínos em crescimento adicionando-se 750UF/kg de dieta, em rações à base de milho e farelo de soja, balanceadas de acordo com o conceito de proteína ideal, diminuindo-se significativamente a excreção de P nas fezes.

The study was developed to evaluate a possible of reduction of the inorganic P concentration in diets formulated for pigs in agreement with the concept of ideal protein, using Lopes et al. model. Twenty male pigs were used in a randomized blocks design, with five treatments and four replicates. The animals were housed in metabolic cages for 17 days, being 10 days for adaptation and seven days for collection of feces and urine. Samples of blood were collected for five days. On the first day of the experimental phase, each animal was intravenously injected with 7.4 MBq 32P. At the end of the experiment, the animals were slaughtered and samples of muscle (loin), heart, liver, kidney, and bones were collected. The supplementation in growing pigs can be reduced in 50 percent by adding 750UF/kg of diet in rations based in corn and soybean meal, balanced in agreement with concept of ideal protein, decreasing the P fecal excretion.

Cinética do fósforo em tecidos de ovinos em crescimento alimentados com diferentes fontes de cálcio / Kinetics of phosphorus in tissues of lambs fed different sources of calcium

Foram utilizados 12 cordeiros machos, inteiros, com peso médio de 31,6kg. Os cordeiros foram alimentados com dietas à base de milho e farelo de soja, suplementadas com diferentes fontes de cálcio: calcário calcítico (CC), feno de alfafa (FA), polpa cítrica (PC) e farinha de conchas de ostras (FCO). Os animais receberam injeção de 7,4 MBq do radiofósforo (32P) e após sete dias foram abatidos para posteriores análises. Utilizou-se o delineamento em blocos ao acaso, com quatro tratamentos e três repetições. A taxa de retenção de 32P, as atividades específicas relativas e padronizadas, e a quantidade de P inorgânico nos tecidos foram iguais para todos os tratamentos (P>0,05). A comparação entre os tecidos mostrou que a concentração de P inorgânico e a taxa de retenção de 32P (P<0,01) foram mais altas nos ossos em relação aos tecidos moles (P<0,01). A retenção de 32P apresentou a seguinte ordem decrescente: rins, fígado, coração, músculos e ossos (P<0,01). A reabsorção óssea de P foi maior que a deposição de P, levando ao balanço negativo do elemento para a maioria dos animais. Concluiu-se que as diferentes fontes de cálcio não interferiram na cinética do P e que a quantidade de P ingerida não atendeu às exigências de P dos animais.

Sixteen growing rams, averaging 31.6kg were studied. They were fed diets based on corn and soya meal, supplemented with different sources of calcium: limestone (CC), alfalfa hay (FA), citrus pulp (PC) and oyster shell meal (OSM). The animals received an injection of 7.4 MBq of radioactive P (32P) and after 7 days they were slaughtered for further analyses. Experimental measurements were analyzed as a completely randomized design with four treatments and three repetitions. The rate of 32P retention, the relative specific activity, the standardized specific activity and the inorganic P in tissue were similar for all treatments (P>0.05). The comparison between tissues showed that the concentration of inorganic P and rate of 32P retention was greater in bone (P<0.01) than in soft tissue. The 32P retention presented the following decreasing order: kidney, liver, heart, muscle and bone (P<0.01). P resorption in bone was higher than P accreted in bone, leading to a negative balance of P in bone for the majority of animals. The means for P accreted in bone were 1.56, 3.29, 2.74 and 2.06g/animal and the means for P resorption in bone were 2.82, 4.51, 4.09 and 3.05g/animal for limestone (CC), alfalfa hay (FA), citrus pulp (PC) and oyster shell meal (OSM), respectively. P resorption values were higher than P accretion in bone leading to a negative balance of P for the majority of animals. It was concluded that the different sources of calcium did not interfere in the kinetics of phosphorus and the amount of P absorbed did not attend P demands of the animals.

A revised model for studying phosphorus and calcium kinetics in growing sheep.

The objective of the study was to revise a model of P kinetics proposed by Vitti et al. (2000) and extend its use to study Ca flows in growing sheep. Twelve Santa Ines male sheep, 8 mo of age, with average BW of 31.6 kg were injected with 32P and 45Ca to trace the movement of P and Ca in the body. The original model had 4 pools representing the gut, plasma, soft tissues, and bone. In the revised model, instantaneous values rather than averages for pool derivatives were incorporated, and the model was extended to represent absorption and excretion of phytate P explicitly. The amendments improved the model, resulting in higher flows between plasma and bone than between plasma and tissue and, therefore, a more accurate representation of P metabolism. Phosphorus and Ca metabolism were then assessed conjointly using the revised model. The results showed that P and Ca metabolism are closely related as evidenced by the ratio of these minerals in the bidirectional flows between plasma and bone and between plasma and tissue. Phytate P digestibility was 47%, and P retention was negative (-1.4 g/d), suggesting that a feed characteristic impaired P utilization and led to P deficiency. The revised model provides an improved prediction of P and Ca metabolism that can be used to assess mineral requirements and to estimate losses to the environment.

Constraints to milk production in grazing dairy cows in Brazil and management strategies for improving their productivity.

Productivity in most Brazilian dairy herds is low and depends exclusively on pasture. To study the productive potential of pastures and to devise strategies to further improve pasture and animal productivity in this production system, studies were carried out to obtain basic on-farm information. The constraints which affect productivity and reproductive performance of dairy cows, the effects of restrictions in suckling time of calves, and strategic supplementation during the dry season upon animal production were the evaluated parameters. From March 1992 through February 1997, studies were carried out on four private farms in the northern region of the State of São Paulo. Between March 1992 and February 1994 (Study 1--survey phase), 142 cows (parity = 1-6) grazed pasture which consisted of signal grass (Brachiaria decumbens and Brachiaria brizanta). Once-a-month data were collected on body weight, body condition, and milk production. Reproduction parameters were assessed by milk progesterone profiles. From March 1996 to February 1997 (Study 2--intervention phase), 45 lactating dairy cows from two farms were hand-milked once a day and the calf suckling was restricted to two hours after milking. Data were collected on milk production and cow body weight. In Study 1, cows were grouped by calving date for the analysis of the reproductive and production data. Concentrations of blood metabolites, hemoglobin, and hematocrit were compared among randomly selected cows (n = 69) from all farms. Estimated pasture available per hectare (ha) at any time, crude protein (CP), and dry matter digestibility (DMD) of pasture available for grazing differed (p < 0.05) between seasons [pasture available = 1.2, 1.4, 1.8 and 2.2 t/ha (SE = 0.70); CP = 42, 60, 48 and 57 g/kg (DM) (SE = 10.1); DMD = 399, 468, 401 and 457 g/kg (DM) (SE = 21), respectively, for dry season 1992 (D92), wet season 1992 (W92), dry season 1993 (D93), and wet season 1993 (W93)]. The proportion of animals showing ovarian activity at 90 days postpartum (DPP) was higher for cows which calved in the wet season than cows which calved in the dry season. In Study 2, milk production tended to the higher (7.3 and 6.5 kg/day, respectively, for the intervention and survey studies; p = 0.08). The data suggest that milk production is being limited by pasture availability, the quality of pasture, and the lack of supplementation. We suggest that, although supplementing cows in the dry period may have an economic advantage, better pasture management needs to be introduced. Stocking rate must be adapted to pasture productivity and pasture quality throughout the year.

Métodos de extraçäo para determinaçäo de progesterona em fezes de coelho (Oryctolagus cuniculus) através de radioimunoensaio / Evaluation of extraction methods for progesterone determination in rabbit (Oryctolagus cuniculus) feces by radioimmunoassay

O propósito deste estudo foi determinar uma metodologia mais prática para a extraçäo de progesterona (P4) das fezes e observar se os perfis plasmáticos de progesterona (P4) durante a gestaçäo de coelhas era refletida na concentraçäo total de P4 nas fezes. Esta espécie animal foi utilizada como modelo para as diferentes metodologias. O plasma e as fezes foram coletadas de 11 coelhas, durante período de 42 dias. Três métodos diferentes de extraçäo de P4 foram testados. A P4 total foi medida com auxílio de radioimunoensaio de fase sólida (RIE) utilizando 125 sobrescrito I-P4 como traçador. Os resultados sugerem que foi possível extrair P4 total das fezes de coelhas com metanol e éter de petróleo. Os teores de P4 plasmática e fecal foram comparados entre animais gestantes e ovariectomizados. Foi possível a diferenciaçäo (p<0,01) dos teores totais de P4 excretados nas fezes entre a 2º até 28º dia após cobertura