The objectives of this study were: 1) to compare the effects of live yeast (LY), yeast fermentation product (YFP), a mix of Lactobacillus acidophilus and Propionibacterium freudenreichii (MLP), and Lactobacillus plantarum included as additives in dairy cows’ diets on in vitro ruminal fermentation and gas production (GP); and 2) to evaluate the effects of L. plantarum as direct-fed microbials (DFM) in dairy cows’ diets on in vitro ruminal fermentation, GP, nutrient digestibility, and N metabolism. Three experiments were carried out: Exp. 1 had the objective to compare all additives regarding ruminal fermentation parameters: an Ankom GP system was used in a completely randomized design, consisting of four 48 h incubations, and eight replications per treatment. There were eight treatments: a basal diet without additive (CTRL) or with one of the following additives: LY, YFP, MLP, or L. plantarum at four levels (% of diet Dry Matter (DM)): 0.05% (L1), 0.10% (L2), 0.15% (L3), and 0.20% (L4). In Exp. 2, a batch culture was used to evaluate ruminal fermentation, and CO2 and CH4 production using the same treatments and a similar experimental design, except for having 16 replications per treatment. Based on Exp. 1 and 2 results, Exp. 3 aimed at evaluating the effects of the L. plantarum on ruminal true nutrient digestibility and N utilization in order to evaluate the use of L. plantarum as DFM. The treatments CTRL, MLP, L1, and L2 were used in a replicated 4 × 4 Latin square design using a dual-flow continuous culture system. Data were analyzed using linear and nonlinear regression; treatment means were compared through contrasts, and L treatments in Exp. 1 and 2 were tested for linear, quadratic, and cubic effects. In Exp. 1, all treatments containing additives tended to reduce OM digestibility as well as reduced total volatile fatty acids (VFA) concentration and total GP. The YFP had greater OM digestibility than LY, and MLP treatment had greater total VFA concentration compared to L. plantarum treatments. In Exp. 2, additives reduced CO2 production, and there were no major differences in CH4. In Exp. 3, all additives reduced NH3-N concentration. In conclusion, pH and lactate concentration were not affected in all three experiments regardless of additive tested, suggesting that these additives may not improve ruminal fermentation by pH modulation; and L. plantarum may improve ruminal N metabolism when used as DFM in high-producing dairy cows’ diets, mainly by reducing NH3-N concentration.

Camelina is an oil seed crop that belongs to the Brassica family (Cruciferae). Camelina meal is a by-product from the biofuel industry that contains on average 38% crude protein and between 10 to 20% of residual fat, which limits the inclusion levels of camelina meal in dairy cow diets as the main protein supplement. Thus, we conducted a solvent extraction on ground camelina seed on a laboratory scale. The objectives of this study were (1) to assess the effects of replacing canola meal (CM) with solvent-extracted camelina meal (SCAM) in lactating dairy cow diets; and (2) to determine the effects of SCAM on microbial fermentation and AA flow in a dual-flow continuous culture system. Diets were randomly assigned to 6 fermentors in a replicated 3 × 3 Latin square with three 10-d experimental periods consisting of 7 d for diet adaptation and 3 d for sample collection. Treatments were 0, 50, and 100% SCAM inclusion, replacing CM as the protein supplement. Diets contained 55:45 forage:concentrate, and fermentors were fed 72 g of dry matter/d equally divided in 2 feeding times. On d 8, 9, and 10 of each period, samples were collected for analyses of pH, volatile fatty acids (VFA), N metabolism, NH-N digestibility, and AA flow. Statistical analysis was performed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC), and linear and quadratic effects of SCAM inclusion were assessed. Total VFA concentration and pH were not affected by diets. Molar proportion of acetate decreased, whereas molar proportion of propionate increased with SCAM inclusion. Total branched-chain VFA concentration was the least in fermentors fed diet 0, and greatest in fermentors fed diet 50. Digestibility of NDF decreased in fermentors fed SCAM diets, and dry matter, organic matter, and crude protein true digestibility were similar across diets. Concentration of NH-N linearly decreased, and non-NH-N linearly increased with SCAM inclusion. Bacterial efficiency (calculated as g of bacterial N flow/kg of organic matter truly digested) tended to be greater in fermentors fed diet 100. Outflow of Arg linearly increased with SCAM inclusion, whereas overall AA flow was not affected by diet. In conclusion, replacing CM with SCAM increased propionate molar proportion and non-NH-N flow, and decreased NH-N flow and concentration, which may improve animal energy status and N utilization. Inclusion of SCAM did not change most AA flow, indicating that it can be a potential replacement for CM.

-The objective of this study was to determine the optimal level of dried brewers' grains (DBG) to replace soybean meal in diets for lactating Holstein cows. Five cows, around 88±28 days in milk, were distributed in a 5 × 5 Latin square design and fed diets containing different levels of DBG (0, 25, 50, 75, and 100%). The forage:concentrate ratio of the diet was 50:50. Feed intake, dry matter, nutrient digestibility, microbial synthesis, milk production and composition, and the economic viability of the diets were evaluated. There was reduction in dry matter intake and, consequently, in crude protein and non-fiber carbohydrates with increased levels of DBG. This occurred due to physical limitation of rumen caused by increased neutral detergent fiber intake. Ether extract intake also increased with levels of DBG due to higher concentrations of this nutrient in the diet. Apparent dry matter, organic matter, ether extract, and neutral detergent fiber digestibility increased with replacement of soybean meal by DBG. Milk production showed a quadratic effect and the levels of fat, protein, and total solids reduced linearly. Each 1% of soybean meal replaced by DBG in concentrate led to a reduction of 0.04, 0.02, and 0.06 g kg -1 of milk fat, protein, and total solids, respectively. The milk production efficiency increased linearly and the microbial synthesis efficiency was not affected. The economic return increased along with the DBG levels. Thus, DBG levels replacing up to 75% of soybean meal can be used to feed lactating cows, since it provides improvements in digestibility, milk production efficiency, and economic return without affecting microbial efficiency.Key Words: by-product, digestibility, intake, milk composition, protein, purine Revista Brasileira de Zootecnia

The objective of this study was to evaluate the effect of inclusion of condensed tannins (CT) from black wattle (Acacia mearnsii) on feed intake, ruminal protozoa population, ruminal fermentation, and nutrient digestibility in Jersey steers. Five ruminally-cannulated steers were used in a 5 × 5 Latin square design, with five periods of 20 days each (14 days for diet adaptation and six days for sample collection per period). Treatments were composed of dietary inclusion levels of condensed tannins at 0, 5, 10, 15, and 20 g/kg of diet dry matter. Intakes of dry matter, organic matter, ether extract, crude protein, neutral detergent fiber, and total digestible nutrients were not affected by condensed tannins. The ruminal pH was reduced linearly with tannin levels. Ruminal ammonia nitrogen concentration was not affected by tannins. Tannins reduced the molar proportion of acetate and did not affect the ruminal protozoal population, which might be related to the low doses used. Digestibilities of dry matter, organic matter, and neutral detergent fiber were not altered; however, there was a linear reduction in crude protein digestibility. Based on these results, CT extracts from black wattle are not recommended for improving nutrient utilization in steers at the tested levels.

ResumoObjetivou-se com este trabalho determinar os parâmetros fisiológicos de vacas da raça Holandês em lactação durante a estação de inverno e de primavera e correlacionar tais parâmetros com os índices bioclimáticos. Foram utilizadas nove vacas da raça Holandês em um delineamento inteiramente ao acaso, em arranjo de parcelas subdivididas com medidas repetidas no tempo. Os dados foram coletados durante o inverno e a primavera, nos quais foram medidas a frequência respiratória (FR), a frequência cardíaca (FC), a temperatura superficial (TS) e a temperatura retal (TR) dos animais, além da temperatura do ar, a umidade relativa e a temperatura de globo negro. Foram calculados o Índice de Temperatura e Umidade (ITU), Índice de Temperatura de Globo Negro e Umidade (ITGU) e Carga Térmica Radiante (CTR). O ITU, ITGU e CTR apresentaram aumentos no período da tarde, sugerindo um ambiente passível de estresse. Não foram observadas diferenças estatísticas (P>0,05) entre as estações do inverno e da primavera para nenhuma das variáveis fisiológicas. Somente a FC mostrou-se acima dos limites fisiológicos para bovinos. A FC, FR e TS apresentaram correlação positiva e significativa (P<0,01) com o ITU e o ITGU e a CTR. Contudo, não foi detectado estresse térmico nos animais na estação de inverno e da primavera, embora os parâmetros fisiológicos tenham apresentado correlação com os índices bioclimáticos. Palavras Chave: ITU, ITGU, CTR, vacas leiteiras, produção de leite AbstractThe objective of this study was to determine the physiological parameters of Holstein cows in milking during the winter and spring season and correlate these parameters with the bioclimatic indexes. We used nine Holstein cows in a completely randomized delimitation in a subdivided plot arrangement with repeated measures in time. Data were collected during the winter and spring, which were measured respiratory rate (RR), heart rate (HR), superficial temperature (ST) and rectal temperature (RT) from animals, besides the air temperature, the relative humidity and black globe temperature. It was calculated the temperature and humidity index (THI), the Black Globe Temperature and Humidity Index (BGTH) and Radiant Heat Load (RHL). The THI, BGTH and RHL showed increases in the afternoon suggesting an environment susceptible to stress. There were no statistical differences (P>0.05) between the seasons of winter and spring for any of the physiological variables. Only HR was above physiological limits for cattle. HR, RR and ST showed significant positive correlation (P<0.01) with the THI and BGTH and RHL. However, heat stress was not detected in animals in the winter and spring seasons, although the physiological parameters have shown a correlation with the bioclimatic indexes.

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The objective of this study was to determine the effect of replacing soybean meal with dried brewers' grains (DBG) in intake and digestibility of the nutrients and the ruminal parameters of cattle. Four ruminal cannulated Jersey oxen with initial body weight of 662.7 ± 85.5 kg were distributed in a 4x4 Latin square design. The treatments were levels of 0%, 33%, 66% and 100% DBG replacing soybean meal in the diet. Dry matter (DM) and crude protein (CP) intake were not influenced by the treatments. There were linear increases in ether extract (EE), neutral detergent fibre (NDF) and acid detergent fibre (ADF) intakes because of higher levels of these nutrients in diets with DBG. Non-fibre carbohydrate (NFC) and total digestible nutrient (TDN) intake showed a decreasing linear effect. Dry matter and NFC digestibility decreased linearly with rising DBG levels, while EE, CP, NDF and ADF digestibilities were not affected. Ruminal pH was not influenced by DBG levels in the diet. There was a quadratic effect in ammonia nitrogen (NH 3 -N) concentration in the rumen, with the maximum occurring at a level of 36.7% DGB. The replacement of soybean meal with DBG in cattle diets did not alter DM intake and ruminal pH, but reduced TDN intake. ______________________________________________________________________________________

The objective of this study was to evaluate the effects of five levels of condensed tannins (CT) from black wattle (Acacia mearnsii) in the diets of lactating dairy cows on intake, nutrient digestibility, ruminal microbial protein synthesis, milk production, composition, oxidative profile, and blood metabolites. Five Holstein cows (88 ± 26.8 days in milk) were allocated in a 5 x 5 Latin square design for a period of 20 days (14 days of diet adaptation and six for sampling). Treatments were the inclusion levels of CT at 0, 5, 10, 15 and 20 g/kg of dry matter (DM) in the diet. There was no effect of CT on DM intake. The digestibility of DM and neutral detergent fiber changed quadratically, with the maximum values at 12.2 and 11.4 g/kg of DM, respectively. There was no effect on ruminal microbial protein synthesis and milk production; however, milk casein concentration was reduced linearly. There was no effect on the milk oxidative profile. Inclusion of CT at levels up to 20 g/kg of DM did not affect intake or microbial protein synthesis; however, added CT depressed the production of energy corrected milk and milk casein concentration.