A. D. S. Vieira

Fatores determinantes do desempenho reprodutivo de vacas Nelore na região dos Cerrados do Brasil Central

The objective of this trial was to evaluate the effects of calving order (CO) and body condition score (BCS), scale 1(thin) to 5 (fat), on reproductive performance of 468 Nellore cows (391 multiparous and 77 primiparous) grazing Brachiaria decumbens Stapf at Brazilian Central West (Cerrados region) during four breeding seasons (from 11/1 to 1/31 of the following year). Calving order quadratically affected pregnancy rate (PR) in this trial; PR of CO1 cows was 69% while that of cows from CO5 to CO8 was 90% followed by a gradual decline until 80% PR in C012 cows. Body condition score at weaning also affected PR. For instance, CO1 cows with BCS of 2.0 and 3.5 had 52.7 and 82.5% of PR, respectively. Cows from CO4 to CO8 and BCS of 3.5 showed 96% of PR. CO1 cows that calved late in the season had 37.7% of PR but independent of CO, cows that calved earlier in the calving season had PR greater than 80%. CO1 cows calved 350.12 days after the start of the mating season while multiparous cows calved earlier (328.32 days). CO1 had the longest calving interval (CI) averaging 392.10 days whereas that from CO5 to CO9 cows averaged 365 days. Calving interval was affected by year, CO, number of days spent to calve in the calving season, and body weight change in the mating season. In addition, cows body weight (BWW) and BC at weaning (BCW) were both affected by CO and year. Body weight of calves at weaning increased from CO1 to CO4/CO5 averaging 159 kg for calves from CO1 cows and 169 kg when all CO levels were included. High production and reproductive performance are obtained from CO3 to CO8 and BCS above 3.0 and 3.5 for multiparous and primiparous Nellore cows, respectively.

Desenvolvimento e desempenho reprodutivo de novilhas Nelore criadas a pasto nos cerrados do Centro-Oeste brasileiro

A model fitted to grazing females Nellore during the rearing periods of the Cerrado Region of Central Brazil was simulated and validated in this study. Body weight gain (BWG) was determined during three years as follows: 1) first dry season after weaning on Brachiaria brizantha (Hochst) Stapf., 2) rainfall season and 3) second dry season both on Panicum maximum Jacq. cv. Tanzânia and averaged 0.020, 0.550, and 0.172 kg, respectively. In the second rainfall season during the rearing period heifers grazed Brachiaria decumbens Stapf. At 24.33 months of age the heifers body weight (BW) averaged 299 kg while in the beginning of the mating season their age and BW averaged, respectively, 25.51 ± 0.99 months (CV = 3.50%) and 309.33 ± 19.19 kg (CV = 6.20%). On average, animals calved 326.71 ± 19.98 days (CV = 6.11) after the beginning of the mating season and 36.26 months of age. The mean pregnancy rate was 88.4%. The pregnant heifers were 25.58 ± 9.97 days older and 9.8 ± 7.04 kg heavier than those non-pregnant. The mean BW and body condition in the middle of the mating season were 360 ± 31.00 and 2.94 ± 0.60, before calving 436 ± 30.86 kg and 4.57 ± 0.40, and at weaning 369 ± 33.89 kg and 3.11 ± 0.64, respectively. The mean weaning rate was of 75.6%. Calves mean BW and age at weaning were of 158 ± 20.1 kg and 202 ± 16.6 days, respectively. Nellore heifers grazing Brachiaria decumbens Stapf. and bred at 24/26 months of age showed high production.

Isolation and identification of bacteriocinogenic strain of Lactobacillus plantarum with potential beneficial properties from donkey milk

The goal of this study was to isolate and characterize a lactic acid bacteria (LAB) from donkey milk with potential beneficial properties.

Determinação da fixação biológica de nitrogênio no amendoim forrageiro (Arachis spp.) por intermédio da abundância natural de 15N

The biological nitrogen fixation (BNF) of five Arachis pintoi (BRA31534, BRA31828, BRA31796, BRA15121 E BRA30333) and two A. repens (BRA31801 e BRA31861) accessions, grown in a Dark Red Latosol prone to seasonal flooding was evaluated using the 15N natural abundance method (d15N). Stolons of each accession were planted in November 1999, in plots of 2.0 m by 2.0 m, with four replications allotted to randomized blocks. Plant mass above five cm was harvested in January 2000. There were significant differences among the tested accessions for dry matter (DM) production and total N content, with BRA31534 and BRA31828 producing 4.2 t/ha of DM, and 102 and 110 kg N/ha respectively. BRA3033 and BRA31861 produced only 2.6 t DM/ha and 59 and 65 kg/ha of total N, respectively. The proportion of N derived from N2 fixation, estimated by comparison of the d15N of Arachis accessions with non N-fixing plants growing in the same area, ranged from 36% (BRA15121) to 90% (BRA31128), equivalent to 26 and 99 kg N/ha, respectively. There was a positive and significant correlation (r = 0.92, p<0.05) between plant total N content and N derived from BNF, but a negative and significant correlation (r = -0.93, p<0.001) was found between plant total N and N derived from soil. It was concluded that plant production by the most promising accessions was the result of an efficient symbiosis with soil Bradyrhizobium native strains, with BNF supplying plant N nutritional requirements.

Safety, beneficial and technological properties of Enterococcus faecium isolated from Brazilian cheeses

This study aimed to characterize the safety and technological properties of Enterococcus faecium strains isolated from Brazilian Coalho cheeses. High levels of co-aggregation were observed between Enterococcus faecium strains EM485 and EM925 and both Escherichia coli and Clostridium perfringens . Both strains presented low levels of hydrophobicity. E. faecium EM485 and EM925 were both able to grow in the presence of 0.5% of the sodium salts of taurocholic acid (TC), taurodeoxycholic acid (TDC), glycocholic acid (GC), and glycodeoxycholic acid (GDC), although they showed the ability to deconjugate only GDC and TDC. Both strains showed good survival when exposed to conditions simulating the gastro intestinal tract (GIT). When tested for the presence of virulence genes, only tyrosine decarboxylase and vancomycin B generated positive PCR results.

Supplementation with fruit and okara soybean by-products and amaranth flour increases the folate production by starter and probiotic cultures

The ability of two starter cultures (Streptococcus (S.) thermophilus ST-M6 and St. thermophilus TA-40) and eleven probiotic cultures (St. thermophilus TH-4, Lactobacillus (Lb.) acidophilus LA-5, Lb. fermentum PCC, Lb. reuteri RC-14, Lb. paracasei subsp. paracasei, Lb. casei 431, Lb. paracasei subsp. paracasei F19, Lb. rhamnosus GR-1, and Lb. rhamnosus LGG, Bifidobacterium (B.) animalis subsp. lactis BB-12, B. longum subsp. longum BB-46, and B. longum subsp. infantis BB-02) to produce folate in a modified MRS broth (mMRS) supplemented with different fruit (passion fruit, acerola, orange, and mango) and okara soybean by-products and amaranth flour was investigated. Initially, the folate content of each vegetable substrate was determined: passion fruit by-product showed the lowest folate content (8±2ng/mL) and okara the highest (457±22ng/mL). When the orange by-product and amaranth flour were added to mMRS, all strains were able to increase folate production after 24h of fermentation. B. longum subsp infantis BB-02 produced the highest concentrations (1223±116ng/mL) in amaranth flour. Okara was the substrate that had the lowest impact on the folate production by all strains evaluated. Lb. acidophilus LA-5 (297±36ng/mL) and B. animalis subsp. lactis BB-12 (237±23ng/mL) were also able to produce folate after growth in mMRS containing acerola and orange by-products, respectively. The results of this study demonstrate that folate production is not only strain-dependent but also influenced by the addition of different substrates in the growth media.

The impact of fruit and soybean by-products and amaranth on the growth of probiotic and starter microorganisms

The ability of different fruit by-products, okara, and amaranth flour, to support the growth of probiotic and non-probiotic strains was evaluated. The tests were conducted with three commercial starter cultures (Streptococcus thermophilus), ten probiotic strains (seven Lactobacillus spp. and three Bifidobacterium spp. strains), and two harmful bacteria representative of the intestinal microbiota (Escherichia coli and Clostridium perfringens). In vitro fermentability assays were performed using a modified MRS broth supplemented with different fruits (acerola, orange, passion fruit, and mango), and soy (okara) by-products or amaranth flour. Orange and passion-fruit by-products were the substrates that most promoted the growth of bacterial populations, including pathogenic strains. On the other hand, the acerola by-product was the substrate that showed the highest selectivity for beneficial bacteria, since the E. coli and Cl. perfringens populations were lower in the presence of this fruit by-product. Although the passion fruit by-product, okara, and amaranth stimulated the probiotic strains, the growth of the pathogenic strains studied was higher compared to other substrates. Different growth profiles were verified for each substrate when the different strains were compared. Although pure culture models do not reflect bacterial interaction in the host, this study reinforces the fact that the ability to metabolize different substrates is strain-dependent, and acerola, mango, and orange by-products are the substrates with the greatest potential to be used as prebiotic ingredients.